JP2001251326A - Data transmission system, data transmission method and data transmitter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a data transmission system having 1st and 2nd source devices 102, 103 transmitting video data (isochronous data) 205, 206 outputted from 1st and 2nd data output sections 1011, 1012 and a SYNC device 101 receiving video data sent from each source and outputting the data to a video synthesizer 1020 that transmits each of video data, supplied from each data output section to the source devices, from each source device to one SYNC device synchronously in the unit of frames. SOLUTION: The SYNC device 101 in the video synthesizer 1020 transmits synchronous information (reference signal information) 2071 to each of the source devices 102, 103 and each source device generates timing reference signals 208b1, 208b2 for each of the data output sections 1011, 1012 on the basis of the synchronous information.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data transmission system, a data transmission method, and a data transmission device, and more particularly, to an isochronous transmission requiring a transmission with a reduced transmission delay via a transmission path such as a data bus. The present invention relates to a transmission process for transmitting data and asynchronous data that is not synchronized with other data.

[0002]

2. Description of the Related Art Conventionally, there is a system for transmitting isochronous data having high real-time properties such as audio data and video data. Such a data transmission system includes, for example, a security system having a plurality of surveillance cameras and one display device, combining video data from each camera, and displaying the synthesized data on one display device, or left and right side mirrors of an automobile. Alternatively, the present invention can be used in an in-vehicle rear confirmation system or the like, which has a camera for photographing the left and right rear sides of a car, and combines video data from the cameras and displays it on a monitor in the car.

FIG. 30 is a diagram showing an example of a conventional data transmission system. Data transmission system 30 shown in FIG.
00 is a first data output unit 3101 outside the present system.
Video data 3012 from the first isochronous data Dt
1 and transmits the isochronous data Dt1 at a predetermined timing.
And a second source device (transmitter) that receives video data 3013 from the second data output unit 3102 outside the system as second isochronous data Dt2 and transmits the isochronous data Dt2 at a predetermined timing. (Device) 3003. Here, the data output units 3101 and 31
Reference numeral 02 denotes an imaging device such as a CCD (charge coupled device) camera. The first source device 3002 holds the isochronous data Dt1 for a certain period of time, that is, a transmission buffer 302 that holds the data from the input time to the transmission timing.
Two. The second source device 3003 holds the transmission buffer 3 for holding the isochronous data Dt2 for a certain period of time, that is, from the input time to the transmission timing.
023.

[0004] The data transmission system 3000
Is a sink device 3001 which is connected to each of the source devices 3002 and 3003 via a transmission path 3000a such as a data bus, receives isochronous data transmitted from each of the source devices 3002 and 3003, and outputs the data at a predetermined timing.
And stores the isochronous data 3011 output from the sink device 3001 and stores the stored isochronous data in the video synthesizing device 3200 outside the system.
And a video data buffer 3030 for outputting at an output timing corresponding to 0. Here, the sink device 3001 receives the received isochronous data Dt1, Dt
2 is held for a certain period of time, that is, from the time of reception to the output timing.

In addition, the data transmission system 3000
Are the sink device 3001 and the source devices 3002, 30
In addition to the isochronous data, asynchronous data such as command data for controlling each device can be transmitted to and received from the communication device 03 via the transmission line 3000a. As shown in FIG. 30, a transmission path 3000a such as a data bus is used.
Source devices 3002, 300 interconnected by
3 and a data transmission system 3000 composed of a sink device 3001, a multimedia LAN (Loc
al AreaNetwork) or multimedia bus.

Next, the operation will be described. Hereinafter, as a specific operation of the data transmission system 3000, the first and second video data 3012 and 30 output from the data output units (cameras) 3101 and 3102 outside the system are described.
13 is transmitted by the data transmission system 3000 to the video synthesizing apparatus 3200 outside the system, and the video synthesizing apparatus 3200 performs the operation of synthesizing and displaying both the video data 3012 and 3013.

That is, the video data 301 output from each of the data output units 3101 and 3102 outside the system
2, 3013 are input to corresponding source devices 3002, 3003 in the system 3000, respectively. In the source device 3002, the input video data 3012
Is stored in the transmission buffer 3022, and thereafter, the video data 3012 is converted to the isochronous data Dt at a predetermined timing.
1 is output to the transmission path 3000a. In the source device 3003, the input video data 3013 is held in the transmission buffer 3023, and thereafter, the video data 3013 is transmitted to the isochronous data Dt2 at a predetermined timing.
Is output to the transmission path 3000a.

Then, in the sink device 3001, the isochronous data Dt1 and Dt2 transmitted from the source devices 3002 and 3003 to the transmission line 3000a at a predetermined timing are received, and the received isochronous data Dt1 and Dt2 are received. It is held in the buffer 3021. After that, the sink device 3001 performs a process of outputting the isochronous data Dt1 and Dt2 held in the reception buffer 3021 as a sync output 3011 to the video data buffer 3030 at a fixed timing. At this time, the isochronous data Dt1,
Dt2 is output in the order in which it is received by the sink device.

In the video data buffer 3030, each of the isochronous data Dt1 and Dt input as a sync output
One of the two data is subjected to a process of delaying the data so that the output timings for the individual frames coincide with each other, and are combined from the buffer 3030 as data forming the same frame. The exponential isochronous data Dt1 and Dt2 are output to the external video synthesizing device 3200 at the same timing. This video synthesizing device 3
In 200, a composite video of the video captured by each camera is displayed based on the composite video data obtained by the composite processing of the isochronous data Dt1 and Dt2.

[0010]

In the conventional data transmission system 3000 described above, the first and second source devices 3
002 and 3003 transmit video data (isochronous data) to the sink device 3001 at their own timings, so that the sink device 3001 receives isochronous data Dt1 and Dt2 from each source device at an arbitrary timing. It is stored in the transmission buffer 3021. For this reason, the output timing corresponding to each frame of the isochronous data Dt1 output as the buffer output 3011 from the transmission buffer 3021 corresponds to each frame of the isochronous data Dt2 output as the buffer output 3011 from the transmission buffer 3021. Does not match the output timing corresponding to.

Therefore, the conventional data transmission system 300
0, a video data buffer 3030 for storing a buffer output 3011 is provided at the subsequent stage of the transmission buffer 3021. In the buffer 3030, the output timing corresponding to each frame of the isochronous data Dt1 and the isochronous data Dt1
The deviation from the output timing corresponding to each frame at t2 is absorbed. However, in the video data buffer 3030, the isochronous data is delayed in order to absorb a difference in output timing of each isochronous data from the sink device 3001. As a result, the delay of the data between the time when the sink device 3001 receives a plurality of video data as isochronous data and the time when each of the video data is output from the video data buffer 3030 in synchronization with each frame is obtained. Will occur.

In the following, with respect to the problem caused by the data delay, a plurality of cameras for visual assistance in place of a rearview mirror in an automobile and the data transmission system 3000 will be described.
Equipped with, for example, a case in which video data from a plurality of cameras for visual assistance in place of a rearview mirror and the like is transmitted by the system so that these composite images are displayed on an on-vehicle monitor. explain. In this case, the image of the scenery behind the vehicle displayed on the monitor mounted on the vehicle is compared with the image of the real time captured by the camera and the image of the past that is delayed by a timing corresponding to the data delay in the sink device 3001. turn into. In a car, it is not permissible to display a past video that is slightly behind real time on a monitor that replaces the rearview mirror.
Therefore, there is a problem that the conventional data transmission system 3000 is not practical for use in a system in which data delay is not allowed, such as the above-described rear-view confirmation system mounted on a vehicle. Further, the conventional data transmission system 3000 has a problem that a video data buffer 3030 for synchronizing video data corresponding to each data output unit output from the sink device 3001 on a frame basis is required.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and synchronizes individual isochronous data supplied from a plurality of independent information sources to a transmitting terminal on a frame basis to a receiving terminal. Which can be transmitted to
A data transmission system capable of synchronizing the respective isochronous data on a frame basis without using a data buffer and outputting the data from a receiving terminal to a required data processing device;
It is an object to provide a data transmission method and a data transmission device.

[0014]

A data transmission system according to the present invention (claim 1) is isochronous data processed at a timing synchronized with a reference signal having a fixed period, and is processed at an arbitrary timing. A transmission line for transmitting asynchronous data, a plurality of source devices for transmitting the isochronous data to the transmission line, and one or more sink devices for receiving the plurality of isochronous data transmitted to the transmission line; A data transmission system comprising: a specific device, which is one of the sink device and the plurality of source devices, for reproducing a predetermined reference signal serving as a reference for processing timing of the isochronous data. Assume that the reference signal information is transmitted to the transmission path, a plurality of source devices other than the specific device, receive the reference signal information transmitted to the transmission path to obtain the predetermined reference signal, The reference signal is obtained by the outputs of the isochronous data synchronized.

According to a second aspect of the present invention, in the data transmission system according to the first aspect, the data transmission on the transmission path is repeatedly performed for each transmission frame which is a unit of transmission data. A frame header for storing information indicating the beginning of each transmission frame,
An isochronous data slot for storing the isochronous data is provided, and the specifying device transmits the reference signal information by including the reference signal information in the frame header.

According to a third aspect of the present invention, in the data transmission system of the second aspect, the specific device periodically transmits a special frame header including the reference signal information.

According to a fourth aspect of the present invention, in the data transmission system according to the first aspect, the data transmission on the transmission path is performed for each transmission frame which is a unit of transmission data. A frame header for storing information indicating the start of each transmission frame, an isochronous data slot for storing the isochronous data, and an asynchronous data slot for storing the asynchronous data. In addition to the process of receiving the isochronous data, the process of transmitting and receiving the asynchronous data is performed, and the source device transmits and receives the asynchronous data in addition to the process of transmitting the isochronous data. Processing, the specific device stores the reference signal information in the isochronous data slot or the asynchronous data slot. In which was assumed to be trust.

According to a fifth aspect of the present invention, in the data transmission system according to the first aspect, the specific device includes a source device that is a transmission source of the isochronous data, and a transmission destination of the isochronous data. A transmission / reception specifying packet storing information specifying the sink device is transmitted to the transmission line, and a specific transmission / reception specifying packet transmitted from the specific device includes the reference signal information. .

According to a sixth aspect of the present invention, in the data transmission system of the fifth aspect, the specific device periodically transmits a specific transmission / reception designation packet including the reference signal information. is there.

According to a seventh aspect of the present invention, in the data transmission system according to the first aspect, the sink device and the source device perform a process of transmitting and receiving a data packet storing the isochronous data or the asynchronous data. And the specific device is a source device that is a source of the isochronous data, a sink device that is a destination of the isochronous data, and a sink device or a source device that is a source and a destination of the asynchronous data. Is transmitted to the transmission path, and the reference signal information is transmitted in the form of isochronous data or asynchronous data.

According to the present invention (claim 8), in the data transmission system according to claim 1, the sink device and the source device perform a process of transmitting and receiving a data packet storing the isochronous data or the asynchronous data. The data transmission on the transmission path is repeatedly performed by a unit transmission process for transmitting data within a predetermined time, and a sink device and a source for transmitting a data packet in each transmission cycle which is a period of the unit transmission process. The device performs arbitration for acquiring a transmission right to transmit a data packet, and the device of the transmission source that has acquired the transmission right of the data packet by the arbitration and the device of the transmission destination corresponding to the transmission source device. The specific device indicates the start timing of the transmission cycle, which is the period of the unit transmission process. It sends a cycle start packet every predetermined time, and in which was assumed to be transmitted to the transmission line including the reference signal information in the isochronous data or asynchronous data.

According to a ninth aspect of the present invention, in the data transmission system according to the first aspect, a plurality of individual transmission systems each including one or more of the source devices and one or more of the sink devices are formed, and each of the individual transmission systems is provided. One of the plurality of devices constituting the system sends the reference signal information to another device in the individual transmission system to which the particular device belongs, and the identification information of each of the individual transmission systems A device other than the device receives the reference signal information transmitted from the specific device and reproduces a reference signal unique to each individual transmission system.

According to a tenth aspect of the present invention, in the data transmission system according to the first aspect, the sink device includes a phase detector for detecting a phase shift amount of the plurality of received isochronous data, Phase difference information indicating the amount of phase shift detected by the detector is transmitted, and at least one of the plurality of source devices is transmitted to the reference signal based on the phase difference information transmitted from the sink device. The timing at which the reference signal is reproduced from the information is corrected so that the phase shift amount in the sink device is reduced.

[0024] A data transmission system according to the present invention (Claim 11) includes a source device for transmitting isochronous data processed at a timing synchronized with a reference signal having a fixed period, and a source device for transmitting isochronous data transmitted from the source device. A data transmission system comprising: a sink device for receiving temporal data; and first and second transmission lines, which connect the source device and the sink device in a one-to-one correspondence, and have different data transmission directions. In the system, the sink device sends reference signal information for reproducing a predetermined reference signal serving as a reference for processing timing of the isochronous data to a source device via the first transmission path. The source device receives the reference signal information from the sink device and reproduces the predetermined reference signal from the received reference signal information. Regeneration process, and in synchronism with the predetermined reference signal the reproduction, the second the isochronous data
The transmission speed of isochronous data in the second transmission line is set to be greater than the transmission speed of reference signal information in the first transmission line. It was fast.

According to a twelfth aspect of the present invention, in the data transmission system according to the eleventh aspect, the sink device and the source device perform transmission / reception processing of asynchronous data processed at an arbitrary timing. Data transmission on the road is performed for each transmission frame which is a unit of transmission data, and data transmission from the sink device to the source device is performed at an arbitrary timing with a frame header indicating a head of each transmission frame. The data transmission from the source device to the sink device is performed in units of a first transmission frame having an asynchronous data slot for storing asynchronous data to be processed. A second transmission frame having an isochronous data slot for storing Shall be carried out as a unit, the sink device, the reference signal information is intended to be transmitted included in the frame header of the first transmission frame.

According to a thirteenth aspect of the present invention, in the data transmission system according to the twelfth aspect, the sink device includes:
The frame header including the reference signal information is transmitted at a constant period.

According to a fourteenth aspect of the present invention, in the data transmission system of the eleventh aspect, the sink device and the source device perform transmission and reception processing of asynchronous data processed at an arbitrary timing. Data transmission on the road is performed for each transmission frame which is a unit of transmission data, and data transmission from the sink device to the source device is performed at an arbitrary timing with a frame header indicating a head of each transmission frame. The data transmission from the source device to the sink device is performed in units of a first transmission frame having an asynchronous data slot for storing asynchronous data to be processed. A second transmission frame having an isochronous data slot for storing Shall be carried out as a unit, the sink device, the reference signal information is to transmit included in the asynchronous data.

According to the present invention (claim 15), in the data transmission system according to claim 11, the sink device comprises:
It is assumed that information specifying a device serving as a transmission source of the isochronous data and a device serving as a transmission destination of the isochronous data is stored in a transmission / reception designation packet and transmitted to a first transmission path,
The specific transmission / reception designation packet transmitted from the sink device includes the reference signal information.

[0029] According to the present invention (claim 16), in the data transmission system according to claim 15, the sink device comprises:
A specific transmission / reception designation packet including the reference signal information,
It is to be sent periodically.

According to the present invention (claim 17), in the data transmission system according to claim 11, the sink device includes:
Performs transmission / reception processing of asynchronous data processed at an arbitrary timing, and specifies a device to be a source of the isochronous data or asynchronous data and a device to be a destination of the isochronous data or asynchronous data. The information is stored in a transmission / reception designation packet and transmitted to the first transmission path, and the reference signal information is stored in a required asynchronous data packet among asynchronous data packets including asynchronous data and transmitted to the first transmission path. The source device performs the transmission / reception process of asynchronous data processed at an arbitrary timing, and sends out the isochronous data packet storing the isochronous data to the second transmission path. It is what it was.

According to the present invention (claim 18), in the data transmission system according to claim 1 or 11, the transmission line is constituted by using an optical fiber.

According to a nineteenth aspect of the present invention, in the data transmission system according to the first aspect, the sink device and the source device transmit and receive data as an optical signal, and the transmission path is connected to a plurality of input terminals. An optical star coupler having a plurality of output terminals and outputting an optical signal supplied to any one of the input terminals from all output terminals, and the output terminals of the sink device and the source device and the input terminals of the optical star coupler. It comprises an output side optical fiber to be connected, and an input side optical fiber connecting the input terminals of the sink device and the source device and the output terminal of the optical star coupler.

According to a twenty-second aspect of the present invention, in the data transmission system according to the eleventh aspect, the sink device transmits output data as an electric signal, receives the input data as an optical signal, and transmits the source device to the source device. The output data is transmitted as an optical signal, and the input data is received as an electric signal. A first transmission path for transmitting data from the sink device to the source device is constituted by a conductor that propagates an electric signal. And a second transmission path for transmitting data from the source device to the sink device is configured by an optical fiber that propagates an optical signal.

According to a twenty-first aspect of the present invention, in the data transmission system according to the first or eleventh aspect, the source device is a video data having an imaging unit for performing an imaging process or a video playback unit for performing a playback process of video data. It is connected to an output unit and transmits the video data output from the video data output unit to the transmission line as isochronous data, and the sink device is used as a video processing device that synthesizes or records a plurality of video data. A plurality of video data connected and transmitted as isochronous data from the plurality of source devices are received and supplied to the video processing device.

According to a twenty-second aspect of the present invention, in the data transmission system according to the twenty-first aspect, the source device includes:
A video compression section for compressing the video data supplied from the video data output section and outputting compressed video data is provided, and the compressed video data is transmitted as the isochronous data.

According to a twenty-third aspect of the present invention, in the data transmission system according to the first or eleventh aspect, the sink device, the source device, and a transmission line connecting these devices are mounted on a vehicle, and The device is connected to an in-vehicle video data output unit having an imaging unit that performs an imaging process or a video playback unit that performs a playback process of video data, and transmits video data output from the video data output unit as isochronous data. A plurality of video data transmitted as isochronous data from the plurality of source devices, wherein the sink device is connected to an on-board video processing device that synthesizes or records a plurality of video data. And the video data is supplied to the video processing device. It constitutes a network for transmission.

According to the data transmission method of the present invention (claim 24), the isochronous data processed at a timing synchronized with a reference signal having a fixed period, and the asynchronous data processed at an arbitrary timing, A data transmission method for transmitting data from a plurality of source devices, which are transmission sources of temporal data, to one or more sink devices, which are destinations of the temporal data, via a transmission path. A data transmission step of transmitting reference signal information for reproducing a predetermined reference signal serving as a reference of processing timing from the specific device among the sink device and the plurality of source devices to the transmission path; A signal reproducing step of receiving the reference signal information transmitted to the transmission line and reproducing the reference signal in the source device.

According to a data transmission method according to the present invention (claim 25), isochronous data processed at a timing synchronized with a reference signal having a fixed period is transmitted from a source device which is a transmission source of isochronous data. A method for transmitting data to a sink device, which is a transmission destination of the isochronous data, connected to the source device so as to have a one-to-one correspondence relationship, and serves as a reference for processing timing of the isochronous data. An information transmitting step of transmitting reference signal information for reproducing a predetermined reference signal from the sink device to the source device via the first transmission line; and, in the source device, the reference signal information from the sink device. And a signal reproducing step of reproducing the predetermined reference signal and synchronizing the isochronous data with the reproduced predetermined reference signal via the second transmission path. And a data transmission step of transmitting, in which the transmission speed of isochronous data in the second transmission path, and as faster than the transmission speed of the reference signal information in the first transmission path.

A data transmission apparatus according to the present invention (claim 26) is connected to a transmission line and is processed at an isochronous data processed at a timing synchronized with a reference signal having a fixed period and at an arbitrary timing. A data transmission device for transmitting or receiving asynchronous data via the transmission path, the controller controlling transmission and reception of the isochronous data and the asynchronous data, and the isochronous data received as the asynchronous data And a reference signal generator for reproducing the reference signal based on reference signal information for reproducing a predetermined reference signal serving as a reference for the processing timing.

According to a twenty-seventh aspect of the present invention, in the data transmission apparatus according to the twenty-sixth aspect, an image pickup unit for performing an image pickup process and outputting video data is provided. The output is synchronized with the reference signal reproduced by the generator, and the controller transmits the video data output from the imaging unit to the transmission path as the isochronous data.

According to a twenty-eighth aspect of the present invention, in the data transmission device according to the twenty-seventh aspect, there is provided a video compression section for compressing video data from the image pickup section and outputting compressed video data, and The compressed video data is transmitted as the isochronous data.

[0042]

Embodiments of the present invention will be described below. (First Embodiment) FIG. 1 is a diagram showing a data transmission system according to a first embodiment of the present invention. The data transmission system 10 according to the first embodiment receives highly real-time data such as audio data or video data from a first data output unit 1011 such as a camera outside the system, and converts the data to isochronous data. The first to be transmitted as Dt1
, And real-time data such as audio data or video data from a second data output unit 1012 such as a camera outside the system.
And a second source device 103 for transmitting the data as isochronous data Dt2.

The data transmission system 10 receives the isochronous data Dt1 and Dt2 transmitted from each of the source devices 102 and 103, and outputs the data to a video synthesizing device 1020 outside the system. A first transmission line 100a for transmitting data between the sink device 101 and the first source device 102;
A second transmission line 100b for transmitting data between the source devices 102 and 103, and a third transmission line 1 for transmitting data between the second source device 103 and the sink device 101.
00c.

In the data transmission system 10, the sink device 101, the first and second source devices 1
02, 103, and the first to third transmission paths 100a to 100a to
100c forms one ring-shaped data transmission path. Also, the data transmission system 1100
Is a device in which each of the devices 101 to 103 operates on the same system clock, that is, these devices 101 to 103
3, the operation clock of one device (for example, the sink device 101) is added to the other devices (the source devices 102, 10).
The operation clock of 3) is synchronized.

FIG. 2A is a diagram showing a specific configuration of the sink device. The sink device 101 is connected to the transmission line 100c.
For receiving transmission data Td from the transmission line 10
The controller 201a performs a process of transmitting the transmission data Td to the transmission data 0a and a process of controlling the video synthesizing device 1020 outside the system, and generates a reference signal 208a based on the reference signal information Is included in the received transmission data Td. And a reference signal generator 202a.

The above-mentioned reference signal is a signal having a fixed period serving as a reference for processing timing of isochronous data (hereinafter also referred to as a timing reference signal). Information on the period and phase of the reference signal to be reproduced (hereinafter referred to as synchronization information)
It is. The isochronous data is not limited to video data and audio, but may be any data that is processed at a timing synchronized with a reference signal having a fixed period. Further, the asynchronous data is not limited to the control command and the like, and may be any data as long as it is processed at an arbitrary timing.

Here, the reference signal 208a is a frame synchronization signal for determining the timing at which the video synthesizing device 1020 synthesizes isochronous data for each frame. The reception process of the controller 201a is a process of receiving the transmission data Td from the transmission path 100c and outputting the isochronous data 204a1 and 204a2 included in the data to the video synthesizing device 1020 outside the system. The transmission process of the controller 201a is performed by synchronizing information (reference signal information) 207a from the video synthesizing device 1020.
Is transmitted to the transmission line 100a as a part of the transmission data Td. The synchronization information 207a is a synchronization signal indicating the timing at which the video synthesizing device 1020 synthesizes a plurality of isochronous data for each frame. Further, the control processing of the controller 201a
Asynchronous data 203a such as a command for controlling 020
Is a process of transmitting and receiving to and from the video synthesizing apparatus 1020.

In the data transmission system 10 of the first embodiment, since the sink device 101 outputs the synchronization information of the data transmission system 10, the controller 201a outputs the synchronization information included in the received transmission data Td. It is not necessary to perform the synchronization information output process of outputting the information Is to the reference signal generator 202a and the operation of generating the reference signal 208a based on the synchronization information Is in the reference signal generator 202a. However, when a source device other than the sink device 101 of the data transmission system 10 generates the synchronization information of the data transmission system 10, the synchronization information output processing in the controller 201a and the generation of the reference signal 208a in the reference signal generator 202a. The operation will be performed.

FIG. 2B is a diagram showing a specific configuration of the first source device. This source device 102 is connected to the transmission line 1
A controller 201b1 that performs a process of receiving the transmission data Td from the transmission data 00a, a process of transmitting the transmission data Td to the transmission path 100b, and a process of controlling the first data output unit (camera) 1011 outside the system; Reference signal generator 202b1 that generates reference signal 208b1 based on synchronization information Is included in transmission data Td
And

Here, the reference signal 208b1 is the first signal 208b1.
Is a synchronization signal that determines the timing at which the data output unit 1011 outputs video data of each frame. The reception process of the controller 201b1 is a process of receiving transmission data from the transmission line 100a and outputting the synchronization information Is included in the transmission data to the reference signal generator 202b1.
The transmission process of the controller 201b1 is performed in the first
The video data 205 from the data output unit 1011 of FIG.
0b. Controller 201b
The first control process is a process of transmitting / receiving asynchronous data 203b1 such as a command for controlling the first data output unit 1011 to / from the data output unit 1011.

In the data transmission system 10 according to the first embodiment, the sink device 101
However, when the source device 102 outputs the synchronization information of the data transmission system 10, the controller 201b1 performs the transmission process in addition to the isochronous data transmission process. , The synchronization information 207b1 indicating the operation timing from the first data output unit 1011 as part of the transmission data Td.
0b is also transmitted. The synchronization information 207b1 indicating the operation timing is, specifically, a frame synchronization signal indicating the timing at which the first data output unit 1011 outputs the video data of each frame to the source device 102.

FIG. 2C is a diagram showing a specific configuration of the second source device. This source device 103 is connected to the transmission line 1
The controller 201b2 performs a process of receiving the transmission data Td from the transmission data 00b, a process of transmitting the transmission data Td to the transmission path 100c, and a process of controlling the second data output unit (camera) 1012 outside the system. Reference signal generator 202b2 that generates reference signal 208b2 based on synchronization information Is included in transmission data Td
And

Here, the reference signal 208b2 is
Is a synchronization signal that determines the timing at which video data of each frame is output by the data output unit 1012. The reception process of the controller 201b2 is a process of receiving transmission data from the transmission line 100b and outputting the synchronization information Is included in the transmission data to the reference signal generator 202b2.
The transmission process of the controller 201b2 is performed in the second
The video data 206 from the data output unit 1012 of the transmission line 10 as a part (isochronous data) of the transmission data Td.
This is a transmission process for transmitting data to 0c. Controller 201b
The control process 2 is a process of transmitting and receiving asynchronous data 203b2 such as a command for controlling the second data output unit 1012 to and from the data output unit 1012.

In the data transmission system 10 according to the first embodiment, the sync device 101 generates the synchronization information of the data transmission system 10 as described above.
When the source device 103 outputs the synchronization information of the data transmission system 10, the controller 201b2
In the transmission process, in addition to the transmission process of the isochronous data, a process of transmitting the synchronization information 207b2 indicating the operation timing in the second data output unit 1012 to the transmission path 100c as a part of the transmission data Td is also included. Done. The synchronization information 207b2 indicating the operation timing is, specifically, a frame synchronization signal indicating the timing at which the second data output unit 1012 outputs the video data of each frame to the source device 103.

FIG. 3 shows transmission lines 100a to 100c.
It is a figure which shows the data structure (transmission frame format) of the transmission data transmitted above. The transmission data Td includes a plurality of data blocks transmitted at a fixed period, that is, transmission frames (# 1), (# 2), (# 3),.
k) It is composed of Td1, Td2, Td3,..., Tdk. For example, the transmission frame (# 2) Td2 is
Frame header 3 indicating the head of the transmission frame (# 2)
01, an isochronous data slot 302 for each source device to transmit isochronous data, and an asynchronous data slot 303 for transmitting asynchronous data such as control data and status data.

Here, the isochronous data slot 302 is
First individual data slot 302a1, second individual data slot 302a2, third individual data slot 30
.., M-th individual data slot 302
am. Each of the individual data slots 302a1 to 302am is allocated in advance to isochronous data transmitted from each source device. For example, in the first embodiment, the first individual data slot 302a
1 is assigned to isochronous data transmitted from the first source device 102 to the sink device 101, and the second individual data slot 302a2 is assigned to isochronous data transmitted from the source device 103 to the sink device 101. Have been assigned.

In the first embodiment, the asynchronous data slot is not divided into individual data slots like the isochronous data slot 302, but the asynchronous data slot is Each individual data slot is divided into a sink device 101, source devices 102, 103
It is also possible to assign to each data output from. Further, if necessary, each of the devices 101 to 103 is
It is also possible to use asynchronous data slots for data transmission.

FIG. 4 is a diagram showing transmission data propagating on a transmission path in the data transmission system 10 according to the first embodiment.
(a)) and reference signals (FIGS. (b) and (c)) reproduced by the first and second source devices. Transmission data Td
In the n-th transmission frame (#n) and the (n + 1) -th transmission frame (# n + 1), frame headers 401 and 402 indicating the head of each frame are arranged, and following these frame headers, Isochronous data slot 3
02 and an asynchronous data slot 303 are arranged. Here, the frame header 401 in the n-th transmission frame (#n) is a special frame header including unique synchronization information of isochronous data corresponding to this frame. The frame header 402 in the (n + 1) -th transmission frame (# n + 1) is a normal frame header that does not include the synchronization information. Note that a normal frame header 402 or a special frame header 401 is always arranged at the head of each transmission frame.

The unique synchronization information of the isochronous data included in the special frame header is reproduced as a reference signal 208b1 (FIG. 4B) by the reference signal generator 202b1 of the source device 102. The synchronization information is supplied to the reference signal generator 202b2 of the source device 103 by using the reference signal 2
08b2 (FIG. 4 (c)).

Next, the operation will be described. FIG. 5 is a diagram for explaining the operation of the data transmission system 10. FIG. 5A shows the reference signal generator 2 of the source device 102.
FIG. 5B shows the video data 205 input from the first data output unit 1011 to the controller 201b1 of the source device 102. FIG. FIG. 5C shows the source device 10.
3 shows the reference signal 208b2 output from the reference signal generator 202b2 of FIG. 3, and FIG.
012 to the controller 201b2 of the source device 103
2 shows video data 206 input to the. 5E shows transmission data Td on the transmission path 100. FIGS. 5F and 5G show video data 204a1 output from the controller 201a of the sink device 101 to the video synthesizing device 1020. , 204a2 (that is, the first and second
Video data 205, 2 output from the data output unit of
06). The synchronization signals shown in FIGS. 5A and 5C are the same as the synchronization signals shown in FIGS. 4B and 4C, respectively.

First, synchronization information 207a is input to the sink device 101 from the video synthesizing device 1020 outside the system. This synchronization information is supplied to the video synthesizing device 1020 by two video data, ie, the first and second data output units 10.
It represents a timing signal serving as a reference for a process of synthesizing video data from 11 and 1012. For example,
As the synchronization information, a frame synchronization signal indicating the beginning of a video frame is used.

The synchronization information (reference signal information) is not limited to the frame synchronization signal, but may be any information that can reproduce the frame synchronization signal. For example, the synchronization information may include frequency information indicating a frequency of the frame synchronization signal and phase information indicating a phase of the frame synchronization signal. Here, the frequency information is information indicating that the frame synchronization signal is obtained by dividing the system operating clock by X (X is a positive integer), or information indicating the cycle of the reference signal. The phase information is information indicating the timing of a rising edge or a falling edge of the frame synchronization signal, time information indicating a phase with respect to the rising edge or the falling edge, and the like.
The operation clock of the above system may be any one of the sink device 101 and the source devices 102 and 103 in the data transmission system 10, the video synthesizing device 1020 outside the system, and the first and second data output units (cameras). An operation clock is used.

When the synchronization information 207a from the video synthesizing device 1020 external to the system is input to the sink device 101, the controller 201a multiplexes the synchronization information on a special frame header 401 of a predetermined transmission frame and multiplexes the synchronization information on the transmission line 100a. A transmission process for sending to is performed. In addition,
The simplest method of multiplexing the synchronization information into the special frame header 401 is a method of synchronizing the special frame header 401 with a frame synchronization signal to generate the synchronization information. That is, the special frame header 401 is provided for every predetermined number of transmission frames.
It occurs at the rising or falling timing of the frame synchronization signal. As a result, the receiving side of the transmission data knows that the timing at which the special frame header of the transmission frame is received is the timing at which the processing of the frame is started. In this case, the special frame header 401 and the normal frame header 402 need to be distinguished by each device, and the special frame header 401 includes an identification bit for distinguishing the special frame header 401 from the normal frame header 402. Thus, the special frame header 4
01 by multiplexing the special frame header 401
Need not particularly include frequency information and phase information for reproducing the frame synchronization signal.

In the source device 102, the sink device 101
When the transmitted transmission data Td is received via the transmission path 100a, the controller 201b1 outputs the synchronization information included in the special frame header 401 in the received predetermined transmission frame to the reference signal generator 202b1. Is performed. Then, the reference signal generator 202b1
Then, based on the synchronization information Is from the controller 201b1, a reference signal 208b for processing video data
1 (FIG. 4 (b)) is reproduced.

When the timing at which the special frame header 401 is output is the rising or falling timing of the frame synchronization signal itself, the source device transmits the special frame header 401 from the sink device 101 to the special frame header 401.
Is received at least once, the phase of the frame synchronization signal with respect to the head of the transmission frame can be determined from the timing at which the head of the transmission frame is received and the timing at which the special frame header 401 is received. Therefore, for transmission frames subsequent to the transmission frame including the special frame header 401, a frame synchronization signal can be generated based on the timing at which the beginning of each transmission frame is received.

The timing reference signal 208 generated by the reference signal generator 202b1 of the source device 102
b1 (FIG. 5A) is output to the first data output unit 1011 outside the system. Then, in the first data output unit (camera) 1011, the imaging process is performed by the source device 10.
The video data 205 is output in synchronization with the timing reference signal 208b1 from the second device 2 and obtained by the imaging process to the source device 102.

Then, the controller 201b1 of the source device 102 holds the video data 205 (FIG. 5B) from the data output unit 1011. After that, the controller 201b1 inserts the video data 205 into the isochronous data slot 302a1 of the received transmission frame as isochronous data as shown in FIG. Transmission processing for transmission is performed.

In the source device 103, the source device 102
When the transmitted transmission frame is received via the transmission path 100b, the controller 201b2 performs a process of outputting the synchronization information included in the special frame header 401 in the received predetermined transmission frame to the reference signal generator 202b2. Done. Then, the reference signal generator 202b2 uses the timing reference signal 2 for processing the video data based on the synchronization information from the controller 201b2.
The frame synchronization signal 08b2 (FIG. 4C) is reproduced.

The timing reference signal 208 generated by the reference signal generator 202b2 of the source device 103
b2 (FIG. 5C) is output to the second data output unit 1012 outside the system. Then, in the second data output unit (camera) 1012, the imaging process is performed by the source device 10.
The video data 206 is output in synchronization with the timing reference signal 208b2 from the third device 3 and obtained by the imaging process to the source device 103.

Then, the controller 201b2 of the source device 103 holds the video data 206 (FIG. 5 (d)) from the data output unit 1012. Thereafter, the controller 201b2 inserts the video data 206 as isochronous data into the isochronous data slot 302a2 of the received transmission frame as shown in FIG. Transmission processing for transmission is performed.

The transmission data (FIG. 5E) transferred from the source device 103 is transmitted to the sink device 101 by the transmission line 100c.
Is received via the isochronous data slot 30 of the received predetermined transmission frame.
2a1 and 302a2, and copies the copied isochronous data to the source device 102.
And the video data 204a1 and 204a2 from 103
The process of outputting to the video synthesizing device 1020 as (FIGS. 5F and 5G) is performed. These two types of video data 204a
1, 204a2 is in a state where frame synchronization is established,
Video data 205, 20 input from the first and second data output units to the first and second source devices 102, 103
6, the frame synchronization of the two types of video data is established when the video data is output from the sink device 101 to the video synthesizing device. Thereafter, the controller 201a of the sink device 101 performs a process of transferring the transmission frame (# n + 1) including the normal frame header, the isochronous data slot, and the asynchronous data slot to the first source device 102.

As described above, in the data transmission system 10 according to the first embodiment, the synchronization information supplied from the video synthesizing device 1020 is multiplexed into the transmission data by the sink device 101 as a special frame header of the transmission frame, and the data is transmitted to the source device. To the source devices 102 and 10
3, the same special frame header 401 output from the sink device 101 is received, and the timing reference signal is reproduced from the same synchronization information included in the received special frame header 401. As shown in, the reference signal generators 202b1 and 202b2 of the source devices 102 and 103 output timing reference signals 205 and 206 having the same period and phase to the first and second data output units, respectively. Become. However, a data delay due to reception and transfer in each device and a data delay in a transmission path are ignored.

Further, in the data transmission system 10 of the first embodiment, the frame synchronization signal is transmitted from the first and second source devices 102 and 103 as the timing reference signal to the first and second data output units outside the system. 1011 and 1
012, the first and second data output units 10
Two pieces of video data input to the source devices 102 and 103 from 11 and 1012 are in a state where frame synchronization is established. In other words, the two video data are stored in the source device 1 with frame synchronization established.
02 and 103 are input to the controllers 201b and the source devices 102 and 10 in a state where frame synchronization is established.
3 to the sink device 101.

As a result, in the sink device receiving a plurality of isochronous data, a plurality of isochronous data with frame synchronization established are received as video data from the first and second data output units. This eliminates the need for a video data buffer between the sink device 101 and the video synthesizing device that absorbs the difference in processing timing of the corresponding frames of the two video data. Can avoid a data delay from receiving a plurality of video data as isochronous data to outputting the video data to the video synthesizing apparatus.

In the first embodiment, the case has been described where the synchronization information for reproducing the timing reference signal is transmitted using the special frame header 401 of the transmission frame. The transmission may be performed using the data slot 303 or the isochronous data slot 302.

The case where the synchronization information is transmitted using the isochronous data slot 302 will be specifically described below. FIG. 6 is a diagram for explaining the usage status of the isochronous data slot 302 in a predetermined transmission frame (#n). FIG. 6A shows a transmission frame that propagates from the sink device 101 to the source device 102 on the transmission line 100a. FIG. 6B shows that the source device 10
2 shows a transmission frame propagating from No. 2 to the source device 103. FIG. 6C shows that the source device 103
1 shows a transmission frame propagating from the device to the sink device 101.

The predetermined transmission frame (#n) has a frame header 301 indicating the head thereof, an isochronous data slot 302 for transmitting isochronous data, and transmission of asynchronous data such as control data and status data. And an asynchronous data slot 303 for Also,
Isochronous data slot 3 of a given transmission frame (♯n)
02, as shown in FIG. 3, the first individual data slot 302a1, the second individual data slot 302a2,.
.. Are divided into the m-th individual data slot 302am. Here, the first dedicated data slot 302a1 is allocated to isochronous data transmitted from the first source device 102 to the sink device 101, and the second dedicated data slot 302a2 is allocated to the source device 103 Are assigned to isochronous data transmitted from the to the sink device 101.

Further, the sink device 101 sends the source device 1
In the first individual data slot 302a1 (FIG. 6A) of the transmission frame (#n) transmitted to the transmission device 02, isochronous data 601 that has been transmitted from the source device 102 to the sink device 101 is stored. ing. Transmission frame transmitted from the sink device 101 to the source device 102 ($ n)
Data 602 including synchronization information transmitted from the sink device 101 to the source devices 102 and 103 is stored in the second individual data slot 302a2 of FIG. 6A.

The first individual data slot 302a1 of the transmission frame (#n) (FIG. 6B) transmitted from the source device 102 to the source device 103 has
Data 603 transmitted to the sink device 101 from the
Is stored. From the source device 103 to the sink device 1
The isochronous data 604 transmitted from the source device 103 to the sink device 101 is stored in the second individual data slot 302a2 of the transmission frame (#n) (FIG. 6C) transmitted to 01. .

Next, the operation of the data transmission system 10 when synchronizing information is transmitted using the isochronous data slot 302 of the transmission frame will be briefly described. In the sink device 101, the isochronous data slot 3 of the transmission frame
02, the data 602 including the synchronization information is inserted into the second individual data slot 302a2, and the transmission frame is transmitted to the source device 102.

In the source device 102, the sink device 101
When the transmission frame (FIG. 6A) is received from the second individual data slot 302a2,
2 reproduces the timing reference signal based on the synchronization information included in the first data output unit 10.
11 is performed. In addition, the source device 10
2, the video data 603 supplied from the first data output unit 1011 is converted to the isochronous data 60 stored in the first individual data slot 302a1 of the transmission frame.
A process of replacing the data with “1” and transferring the data to the source device 103 is performed.

In the source device 103, the source device 102
When the transmission frame (FIG. 6 (b)) is received, the stored data 60 in the second individual data slot 302a2 is received.
2 reproduces the timing reference signal based on the synchronization information included in the second data output unit 10.
12 is performed. In addition, the source device 10
In 3, the video data 604 supplied from the second data output unit 1012 is replaced with the data 602 stored in the second individual data slot 302a2 of the transmission frame and transferred to the sink device 101.
In the sink device 101, when a transmission frame (FIG. 6C) from the source device 103 is received, the first and second individual data slots 302a1, 302a in the transmission frame are received.
Isochronous data 6 with frame synchronization established from 02a2
03, 604 is obtained.

As described above, the isochronous data slot 302 for transmitting isochronous data is used as a transmission slot for isochronous data from the source device to the sink device, and the synchronization information is transmitted from the sink device to the source device. Also in a data transmission system used as a slot, it is possible to obtain a plurality of isochronous data for which frame synchronization has been established by a sink device. In FIG. 6, the case where the synchronization information is transmitted using the isochronous data slot has been described. However, the synchronization information may be transmitted using the asynchronous data slot 303. It is possible to obtain a plurality of isochronous data for which frame synchronization has been established.

In the first embodiment, as the data transmission system, the sink device 101
In the data transmission system 10, one of the two source devices transmits the synchronization information to the sink device and the other source device. In this case, the same effect as in the first embodiment can be obtained. In the first embodiment, the data transmission system sequentially transfers synchronization information generated in the sink device 101 in a fixed direction between the sink device 101 and the source device forming a ring-shaped transmission path. However, the data transmission system may transmit synchronization information directly from the sink device to each source device. In this case, the same effect as in the first embodiment can be obtained.

Further, in the first embodiment, the case where the sink device and the source device constituting the data transmission system perform data transmission based on one piece of synchronization information has been described, but the data transmission system constitutes this. A plurality of data transmission devices (that is, a plurality of sink devices and a plurality of source devices) are divided into a plurality of groups, and the data transmission devices belonging to each group perform data transmission based on different synchronization information for each group. There may be.

Further, in the first embodiment, the case where the timing reference signal used in the data transmission system is a frame synchronization signal indicating the head of each video frame (that is, indicating the timing of starting signal processing for each video frame) As described above, the timing reference signal is a signal (block synchronization signal) indicating the timing of signal processing for each block when signal processing for each video frame is performed for each block dividing the video frame.
It may be.

The timing reference signal may be a signal (channel synchronization signal) indicating the timing of signal processing for each of the left and right channels of the audio signal. In this case, since the signal processing for each of the left and right channels of the audio signal is performed for each processing unit (audio frame) of the audio signal, the signal processing for each of the left and right channels is performed by the channel synchronization signal. Can be synchronized for each audio frame.

In the first embodiment, a case has been described in which a camera is connected to each source device as a data output unit outside the system, and a video synthesizing device is connected to the sink device as a device outside the system. However, the data output unit outside the system connected to the source device
A device outside the system that is a video sending device such as R and is connected to the sink device may be a display device such as a monitor or a navigation system, or a video recording device. For example, by using a camera as a data output unit outside the system connected to the source device and a display device outside the system connected to the sink device, it is possible to realize a navigation system based on actual video on a vehicle. In addition, by using a camera as the data output unit outside the system connected to the source device and a video recording device as the device outside the system connected to the sink device, a surveillance camera system and an on-vehicle drive recorder (when an accident or theft occurs) Device for recording a video of time).

Further, in Embodiment 1, specific members constituting a transmission line in the data transmission system are not specifically shown, but an optical fiber may be used for this transmission line. Also, in the first embodiment, video data transmitted on the transmission path as isochronous data in the data transmission system is MPEG data even if it is uncompressed data.
The data may be data compressed by a compression method or the like corresponding to (Moving Picture Experts Group).

(Embodiment 2) FIG. 7 is a diagram showing a data transmission system according to Embodiment 2 of the present invention. The data transmission system 20 according to the second embodiment receives highly real-time data such as audio data or video data from a first data output unit 1011 such as a camera outside the system, and converts the data to isochronous data. A first source device 702 transmitting the data as Dt1 and a highly real-time data such as audio data or video data from a second data output unit 1012 such as a camera outside the system receive the data as isochronous data. And a second source device 703 for transmitting as Dt2.

The data transmission system 20 receives the isochronous data Dt1 and Dt2 transmitted from each of the source devices 702 and 703, and outputs the data to a video synthesizing device 1020 outside the system. A first transmission path 700a for transmitting data between the sink device 701 and the first source device 702;
A second transmission path 700b for transmitting data between the source devices 102 and 103, and a second source device 10
3 and a third transmission line 700c for transmitting data between the sink device 101 and the sink device 101.

In the data transmission system 20, the sink device 701, the first and second source devices 7
02, 703, and the first to third transmission paths 700a to 700a to
One ring-shaped data transmission path is formed by 700c. Also, this data transmission system 20
A device in which each of the devices 701 to 703 operates with the same system clock, that is, the operation clock of one of the devices 701 to 703 (for example, the sink device 701) is changed to the other device (the source device 702, 703) Are synchronized with each other. In the second embodiment, each of the devices 701 to 703 has an identification ID as an identification ID for identifying the device.
D (ID: # 1), ID (ID: # 2), ID
(ID: # 3) is set.

FIG. 8A is a diagram showing a specific configuration of the sink device. This sink device 701 has a transmission path 700c
For receiving transmission data Td from the transmission line 70
0a, a controller 801a that performs processing for controlling the video synthesizing apparatus 1020 outside the system, and a reference signal (hereinafter referred to as a timing reference signal) based on synchronization information Is included in the received transmission data Td. Selection of selecting and outputting one of the reference signal generator 802a that generates 808a and one of the transmission data Td from the transmission path 700c and the output data Od0 from the controller 801a based on the control signal Cs0 from the controller. A switch 809a.

Here, the timing reference signal 808a
Is a synchronization signal for determining the timing at which the video synthesizing device 1020 synthesizes isochronous data for each frame. The reception process of the controller 801a is a process of receiving the transmission data Td from the transmission path 700c and outputting the isochronous data 804a1 and 804a2 included in the data to the video synthesizing device 1020 outside the system.
The transmission process of the controller 801a is performed by synchronizing the synchronization information 807a from the video synthesizing device 1020 with the transmission data T.
an output process of outputting to the transmission path 700a as a part of d.
The transmission data from the transmission path 700c is directly transmitted to the transmission path 70c.
0a.
09a is controlled so that the output process and the transfer process can be switched by the control signal Cs0. Further, the synchronization information 807a is stored in the video synthesizing device 102.
0 is a frame synchronization signal indicating the timing of synthesizing a plurality of isochronous data for each frame. Further, the control process of the controller 801a
This is a process of transmitting and receiving asynchronous data 803a such as a command for controlling the image synthesizing device 20 to and from the video synthesizing device 1020.

The selection switch 809a is connected to the transmission line 70
0c, a second input terminal T1b (B side) to which the output data Od0 from the controller 801a is input, and an output terminal T2 connected to the transmission path 700a. And the controller 801
The output terminal T2 is controlled by the control signal Cs0 from
It is connected to one of the first and second input terminals T1a and T1b.

In the data transmission system 20 according to the second embodiment, since the sink device 701 outputs the synchronization information of the data transmission system 20, the synchronization included in the transmission data Td received by the controller 801a. A synchronization information output process for outputting information Is to the reference signal generator 802a, and a timing reference signal 80 based on the synchronization information Is in the reference signal generator 802a.
It is not necessary to perform the operation for generating 8a. However, when a source device other than the sink device 701 of the data transmission system 20 generates the synchronization information of the data transmission system 20, the synchronization information output process in the controller 801a and the generation of the timing reference signal 808a in the reference signal generator 802a are performed. The generating operation is performed.

FIG. 8B is a diagram showing a specific configuration of the first source device 702. As shown in FIG. The source device 702 includes a process of receiving the transmission data Td from the transmission line 700a, a process of transmitting the transmission data Td to the transmission line 700b, and a first data output unit (camera) 101 outside the system.
801b1 that performs processing for controlling the transmission data Td, a reference signal generator 802b1 that generates a timing reference signal 808b1 based on the synchronization information Is included in the received transmission data Td, the transmission data Td from the transmission path 700a, and the controller. Output data Ob from 801b1
And a selection switch 809b1 for selecting and outputting one of them based on a control signal Cs1 from the controller.

Here, the timing reference signal 808b
Reference numeral 1 denotes a synchronization signal that determines the timing at which the first data output unit 1011 outputs video data of each frame. The reception process of the controller 801b1 is a process of receiving transmission data from the transmission path 700a and outputting the synchronization information Is included in the transmission data to the reference signal generator 802b1. The transmission process of the controller 801b1 includes an output process of outputting the video data 805 from the first data output unit 1011 as a part (isochronous data) of the transmission data Td to the transmission line 700b.
a transfer process of transferring the transmission data from the transmission line 700a to the transmission line 700b as it is,
The control signal Cs1 controls the switching between the output processing and the transfer processing. Further, the control processing of the controller 801b1 is performed by using asynchronous data 8 such as a command for controlling the first data output unit 1011.
03b1 is a process of transmitting and receiving data to and from the data output unit 1011.

The selection switch 809b1 is connected to the transmission line 7
A first input terminal T1a (A side) connected to
A second input terminal T1b (B side) to which output data Od1 from the controller 801b1 is input;
b, and an output terminal T2 connected to the controller 8
01b1 by the control signal Cs1 from the output terminal T
2 is connected to one of the first and second input terminals T1a and T1b.

In the data transmission system 20 of the second embodiment, the sink device 701 is
However, when the first source device 702 outputs the synchronization information of the data transmission system 20, the controller 801b1 performs output processing and transfer processing as transmission processing. In the first,
The synchronization information 807b1 indicating the operation timing is transmitted from the data output unit 1011 as part of the transmission data Td.
00b is also performed. The synchronization information 807b1 indicating the operation timing specifically indicates the timing at which the first data output unit 1011 outputs the video data of each frame to the source device 702.

FIG. 8C is a diagram showing a specific configuration of the second source device 703. The source device 703 includes a process of receiving the transmission data Td from the transmission line 700b, a process of transmitting the transmission data Td to the transmission line 700c, and a second data output unit (camera) 101 outside the system.
801b2 that performs processing for controlling the transmission data Td, a reference signal generator 802b2 that generates a timing reference signal 808b2 based on the synchronization information Is included in the received transmission data Td, the transmission data Td from the transmission path 700b and the controller Output data Ob from 801b2
And a selection switch 809b2 for selecting and outputting one of the two based on the control signal Cs2 from the controller.

Here, the timing reference signal 808b
Reference numeral 2 denotes a synchronization signal that determines the timing at which the second data output unit 1012 outputs video data of each frame. The reception process of the controller 801b2 is a process of receiving transmission data from the transmission path 700b and outputting the synchronization information Is included in the transmission data to the reference signal generator 802b2. The transmission process of the controller 801b2 includes an output process of outputting the video data 806 from the second data output unit 1012 as a part (isochronous data) of the transmission data Td to the transmission line 700c,
b) to transfer the transmission data from b to the transmission path 700c as it is.
The control signal Cs2 controls the switching between the output processing and the transfer processing. Further, the control process of the controller 801b2 is performed by controlling asynchronous data 8 such as a command for controlling the second data output unit 1012.
03b2 is a process of transmitting and receiving the data 03b2 to and from the data output unit 1012.

The selection switch 809b2 is connected to the transmission line 7
00b, a first input terminal T1a (A side),
A second input terminal T1b (B side) to which output data Od2 from the controller 801b2 is input;
c, and an output terminal T2 connected to the controller 8
01b2, the output terminal T
2 is connected to one of the first and second input terminals T1a and T1b.

In the data transmission system 20 according to the second embodiment, the sink device 701 is
However, when the second source device 703 outputs the synchronization information of the data transmission system 20, the controller 801b2 performs output processing and transfer processing as transmission processing. In the second
The synchronization information 807b2 indicating the operation timing is transmitted from the data output unit 1012 as part of the transmission data Td.
The process of transmitting the data to 00c is also performed. Specifically, the synchronization information 807b2 indicating the operation timing indicates the timing at which the second data output unit 1012 outputs the video data of each frame to the source device 703.

FIG. 9 is a diagram showing a data structure (transmission frame format) of transmission data transmitted on the transmission paths 700a to 700c. In a transmission frame 903 which is a repeating unit of data transmission, a transmission / reception designation packet and
Subsequent data packets form a set, and a predetermined set of transmission / reception designation packets and data packets are transmitted.
Here, the transmission / reception designation packet is a packet in which information specifying a device (transmission source device) that transmits the immediately following data packet and a device (transmission destination device) that receives the data packet is stored. Further, the data packet is a packet that stores data transmitted and received between the devices specified by the storage information of the immediately preceding transmission / reception designation packet, which is output from each device. The transmission / reception designation packet 901
a1 to 901ak are the first to kth transmission / reception designation packets in the transmission frame 903, and data packets 902a1 to 902ak are the first to kth data packets in the transmission frame 903.

Each of the transmission / reception designation packet and the data packet is transmitted from one of the devices 701 to 703, and during a period corresponding to one frame (frame period), the transmission / reception designation packet and the data packet are transmitted. And a data packet are transmitted at regular time intervals Tc. Note that the transmission / reception designation packet is transmitted on the transmission line at regular time intervals as a packet storing NULL information that does not specify the transmission source device and the transmission destination device even during a time period during which the isochronous data is not output in the frame period. Is done. In other words, the transmission / reception designation packet is always transmitted on the transmission line at regular time intervals without interruption during each frame period.
Then, during a period of each transmission frame, a predetermined number of transmission / reception designation packets and data packets are transmitted as one set, and
Further, a transmission frame as a unit of such data transmission is repeatedly transmitted.

Next, the operation will be described. In the following description, the data transmission system 2 according to the second embodiment will be described.
In the case of 0, it is assumed that the sink device 701 sends a transmission / reception designation packet at regular intervals. The transmission / reception designation packet 901a1 designates the first source device 702 (ID: # 2) as the transmission device of the data packet 902a1, and designates the sink device 701 (ID: # 1) as the reception device of the data packet 902a1. Shall be. The transmission / reception designation packet 901a2 is used as a transmission device of the data packet 902a2 by the second source device 703.
(ID: # 3) and the sink device 701 (ID: # 1) as the receiving device of the data packet 902a2. The transmission / reception designation packet 901a3
Is a packet storing NULL data that does not specify the source device and the sink device.

The data transmission operation of the data transmission system 20 according to the second embodiment is performed by transmitting video data from the first and second data output units (cameras) to the corresponding two source devices 702 and 703 from the corresponding two source devices. The operation is such that two video data transmitted to one sink device 701 and received by the sink device are output to a video synthesizing device 1020 outside the system.

The basic operation of data transmission system 20 according to the second embodiment will be described below. In the data transmission system 20, the selection switches 809a, 809b1, and 809b2 of the devices 701 to 703 are normally in a data transfer state in which the output terminal T2 is connected to the first input terminal Ta1 (A side). I have. In this data transfer state, first, in the sink device 701, the selection switch 8
09a is controlled by a control signal Cs0 from the controller 801a so that the transmission line 700a is connected to the output side (B side) of the controller 801a. Then, a transmission / reception designation packet 901a1 is transmitted from the controller 801a to the transmission line 700a via the selection switch 809a. At this time, since the output terminals T2 of the selection switches 809b1 and 809b2 of the source devices 702 and 703 are connected to the first input terminal (A side) Ta1, the source devices 702 and 703 transmit the transmission / reception designation packet 901a1. Transfer processing and controller 801
In b1 and 801b2, a process of receiving the transmission / reception designation packet 901a1 is performed.

Specifically, in the first source device 702, the transmission / reception designation packet 901 from the sink device 701 is transmitted.
a1 is connected to the controller 801b1 via the transmission line 700a.
At the same time, the transmission / reception designation packet 901a1 is transferred to the third source device 703 via the transmission path 700b. In the second source device 703, the transmission / reception designation packet 901a1 from the source device 702 is input to the controller 801b2 via the transmission line 700b, and at the same time, the transmission / reception designation packet 901a1 is
0c to the sink device 701.

As described above, the transmission / reception designation packet 901a1 output from the sink device 701 is
a, the source device 702, the transmission line 700b, the second source device 703, and the transmission device 700c return to the sink device 701 again. At this time, in the selection switch 809a of the sink device 701, the output terminal T2 is connected to the second input terminal T1b (B side). Controller 801a of device 701
Discarded at. Selection switch 80 of sink device 701
In 9a, after the transmission / reception designation packet 901a1 is discarded, the output terminal T2 is connected to the first input terminal T1a (A side).

As described above, when the transmission / reception designation packet 901a1 is input to each device, that is, the sink device 701, the source device 702, and 703, the controller of each device analyzes the input transmission / reception designation packet 901a1. Then, an operation according to the analysis result is performed.

Hereinafter, mainly the operation of the above controller will be specifically described. Here, the sink device 701
The transmission / receipt designation packet 901a1 transmitted from the server includes information that designates the first source device 702 as a data supply source and designates the sink device 701 as a data supply destination. The transmission / reception designation packet 901a2 transmitted from the sink device 701 includes information for designating the source device 703 as a data supply source and the sink device 701 as a data supply destination. The transmission / reception designation packet 901a3 transmitted from the sink device 701 includes NULL information that does not designate a source device and a sink device.

(Operation of Transmission Cycle of First Transmission / Reception Specifying Packet 901a1) First, the sink device 701 sends the first
The operation from transmission of the transmission / reception designation packet 901a1 until the packet returns to the sink device 701 will be described.

In the sink device 701, the controller 80
1a, the selection switch 809 is selected by the control signal Cs0.
The connection state at a is switched. That is, in the selection switch 809a, the normal connection state in which the first input terminal T1a (A side) is connected to the output terminal T2 and the data output state in which the second input terminal T1b (B side) is connected to the output terminal T2. Can be switched to a state. The transmission / reception designation packet 901a1 generated by the controller 801a is output to the transmission path 700a via the selection switch 809a.

When the transmission / reception designation packet 901a1 is received by the first source device 702, the first source device 70
In 2, the controller 801b1 analyzes the transmission / reception designation packet 901a1, and sends the transmission / reception designation packet 901a1 to the transmission path 700b via the selection switch 809b1.

After that, the connection state of the selection switch 809b1 is switched by the control signal Cs1 from the controller 801b1 according to the analysis result of the transmission / reception designation packet 901a1. Here, the transmission / reception designation packet 90
Since 1a1 includes information for specifying the first source device 702 as a data source, the selection switch 809b
1 so that the output data Od1 of the controller 801b1 is output to the transmission line 700b.
a (A side) and the normal connection state in which the output terminal T2 is connected to the second input terminal T1b (B side) and the data output state in which the output terminal T2 is connected by the control signal Cs1 from the controller 801b1. Can be switched. Then, a data packet 902a1 storing video data from the first data output unit 1011 outside the system is output from the controller 801b1 to the transmission path 700b via the selection switch 809b1.

When the transmission / reception designation packet 901a1 sent from the first source device 702 is input to the second source device 703, the second source device 703
The transmission / reception designation packet 90 is sent by the controller 801b2.
1a1 is analyzed, and the transmission / reception designation packet 901a1 is transmitted to the transmission path 700c via the selection switch 809b2. Here, the transmission / reception designation packet 901a1 is used as the data supply source by the second source device 7.
03, the selection switch 809b2 maintains the normal connection state in which the first input terminal T1a (A side) is connected to the output terminal T2 by the control signal Cs2 from the controller 801b2. . The data packet 902a1 following the transmission / reception designation packet 901a1 is transferred to the transmission line 700c via the selection switch 809b2.

When the transmission / reception designation packet 901a1 is input to the sink device 701 via the transmission path 700c,
In the sink device 701, the controller 801a analyzes the transmission / reception designation packet 901a1. At this time, in the selection switch 809a, the second input terminal T1b
Since (B side) is in the data output state connected to the output terminal T2, the transmission / reception designation packet 901a1 from the transmission path 700c is not output to the transmission path 700a and is discarded. After that, the sink device 701
Is switched from the data output state to the normal connection state by the control signal Cs0 from the controller 801a.

When the data packet 902a1 following the transmission / reception designation packet 901a1 is input to the sink device 701, the controller 801a sends the transmission / reception designation packet 9
Processing according to the analysis result of 01a1 is performed. That is,
Since the transmission / reception designation packet 901a1 includes information for designating the sink device 701 as the data supply destination, the controller 801a requires the transmission / reception designation packet 901a.
Isochronous data (video data from the first data output unit 1011) stored in the data packet 902a1 subsequent to 1 is extracted and held. At this time, the selection switch 809a is in the normal connection state in which the first input terminal T1a (A side) is connected to the output terminal T2.
The data packet 902a1 from the transmission path 700c is output to the transmission path 700a via the selection switch 809a.

(Operation of Transmission Cycle of Second Transmission / Reception Specifying Packet 901a2) Next, an operation from transmission of the second transmission / reception specifying packet 901a2 from the sink device 701 to reception of the packet by the sink device 701 will be described. I do.

After the transmission of the first data packet 902a1, the controller 801a of the sink device 701
The transmission / reception designation packet 901a2 is generated, and the connection state of the selection switch 809a is changed to the second input terminal T1b by the control signal Cs0 from the controller 801a.
(B side) is switched to the data output state connected to the output terminal T2. Then, the transmission / reception designation packet 901
a2 is the transmission path 700a via the selection switch 809a.
Is output to

The first data transmitted from the sink device 701
Data packet 902a1 of the first source device 702
, The data packet 902a1 is discarded. That is, at this time, the selection switch 80
In 9b1, since the second input terminal T1b (B side) is in the data output state connected to the output terminal T2, the data packet 902a1 from the transmission path 700a is not output to the transmission path 700b. Thereafter, in the selection switch 809b1, the connection state is switched to the normal connection state by the control signal Cs1.

After the first data packet 902a1, the second transmission / reception designation packet 901a2 sent from the sink device 701 is input to the first source device 702. The controller 801b2 analyzes the transmission / reception designation packet 901a2. The transmission / reception designation packet 901
Since a2 does not include information for specifying the first source device 702 as a data supply source, the selection switch 809b
1, the control signal Cs1 from the controller 801b1
Thereby, the normal connection state in which the first input terminal T1a is connected to the output terminal T2 is maintained. The transmission / reception designation packet 901a2 is transmitted to the transmission path 700b via the selection switch 809b1.

When the second transmission / reception designation packet 901a2 is received by the second source device 703, the second transmission / reception designation packet 901a2 is analyzed by the controller 801b2 and the transmission / reception designation packet 901a2 is analyzed. 901a2 is transmitted to the transmission path 700c via the selection switch 809b2.

After that, the selection switch 809b2 is controlled to be switched by the control signal Cs2 from the controller 801b2 according to the analysis result of the transmission / reception designation packet 901a2. Here, since the transmission / reception designation packet 901a2 includes information designating the second source device 703 as a data supply source, the connection state of the selection switch 809b2 is controlled by the control signal Cs2 from the controller 801b2.
Thereby, the output data Od2 of the controller 801b2 is switched to a data output state in which the output data Od2 is output to the transmission path 700c. Then, the second data output unit 1 outside the system
The second data packet 902a2 storing the video data from 012 is output from the controller 801b2 to the transmission path 700c via the selection switch 809b2.

The above-mentioned second transmission / reception designation packet 901a2
Is input to the sink device 701 via the transmission path 700c, in the sink device 701, the controller 801a analyzes the transmission / reception designation packet 901a2.
At this time, in the selection switch 809a, since the second input terminal T1b (B side) is connected to the output terminal T2,
Second transmission / reception designation packet 901 from transmission path 700c
a2 is not output to the transmission line 700a and is discarded. Thereafter, the selection switch 809a of the sink device 701 switches from the data output state to the normal connection state according to the control signal Cs0 from the controller 801a.

The second data packet 902a2 following the second transmission / reception designation packet 901a2 is the sink device 701.
, The controller 801a performs a process according to the analysis result of the transmission / reception designation packet 901a2. That is, since the transmission / reception designation packet 901a2 includes information for designating the sink device 701 as a data supply destination, the controller 801a causes the second data packet 901 following the second transmission / reception designation packet 901a2 to be transmitted.
Isochronous data (video data from the second data output unit 1012) stored in 2a2 is extracted and held. At this time, since the selection switch 809a is in the normal connection state in which the first input terminal T1a (A side) is connected to the output terminal T2, the second data packet 902a2 from the transmission path 700c is not connected to the selection switch 809a. Via the transmission line 700a.

(Operation of Transmission Cycle of Third Transmission / Reception Specifying Packet 901a3) Next, an operation from transmission of the third transmission / reception specifying packet 901a3 from the sink device 701 to reception of the packet by the sink device 701 will be described. I do.

After the transmission of the second data packet 902a2, the controller 801a of the sink device 701
Then, the third transmission / reception designation packet 901a3 is generated, and the connection state of the selection switch 809a is switched to the data output state by the control signal Cs0 from the controller 801a. Then, the third transmission / reception designation packet 901a3 is transmitted to the transmission path 7 via the selection switch 809a.
00a.

The second data transmitted from the sink device 701
Data packet 902a2 of the first source device 702
, The data packet 902a2 is transferred to the second source device 703. That is, at this time, in the selection switch 809b1, the first input terminal T1a (A
Side) is in the normal connection state connected to the output terminal T2, so that the data packet 902 from the transmission path 700a
a2 is output to the transmission path 700b.

When the third transmission / reception designation packet 901a3 sent from the sink device 701 is input to the first source device 702 following the second data packet 902a2, the first source device 702 The transmission / reception designation packet 901a3 is analyzed by the controller 801b2. As a result of this analysis, since the transmission / reception designation packet 901a3 does not include information for designating the first source device 702 as a data supply source, in the selection switch 809b1, the first input terminal T1a is connected to the output terminal T1a.
2 is maintained in the normal connection state. For this reason,
The transmission / reception designation packet 901a3 is transmitted to the transmission path 700b via the selection switch 809b1.

When the second data packet 902a2 sent from the first source device 702 is input to the second source device 703, the data packet 902a2 is discarded. That is, at this time, in the selection switch 809b2, since the second input terminal T1b (B side) is in the data output state connected to the output terminal T2, the data packet 902a2 from the transmission path 700b is transmitted to the transmission path 700c. There is no output. Thereafter, in the selection switch 809b2, the connection state is switched to the normal connection state by the control signal Cs2.

Following the second data packet 902a2, when the third transmission / reception designation packet 901a3 sent from the sink device 701 is input to the second source device 703, the second source device 703 The transmission / reception designation packet 901a3 is analyzed by the controller 801b2. As a result of this analysis, the third transmission / reception designation packet 901a3 does not include information for designating the second source device 703 as a data supply source. The normal connection state in which the input terminal T1a is connected to the output terminal T2 is maintained. Further, the third transmission / reception designation packet 901a3 is transmitted to the transmission line 700c via the selection switch 809b2.

The third transmission / reception designation packet 901a3
Is input to the sink device 701 via the transmission line 700c, in the sink device 701, the controller 801a analyzes the transmission / reception designation packet 901a3.
At this time, the selection switch 809a is connected to the second input terminal T
Since 1b (B side) is in the data output state connected to the output terminal T2, the third transmission / reception designation packet 901a3 from the transmission path 700c is not output to the transmission path 700a and is discarded. Becomes Thereafter, the selection switch 809a of the sink device 701 switches from the data output state to the normal connection state according to the control signal Cs0 from the controller 801a.

After that, in the sink device 701, similarly to the third transmission / reception designation packet 901a3, transmission / reception of the transmission / reception designation packets 901a4 to 901an storing NULL information is performed until one frame period elapses. . These transmission / reception designation packets 901a4
901an do not include information for specifying the data supply source and the data supply destination, so that none of the source devices generates data packets corresponding to the transmission / reception specification packets 901a4 to 901an, and the transmission / reception specification packets 901a4 to 901an Is performed only.

In the data transmission system 20 according to the second embodiment, the transmission processing of the transmission / reception designation packet and the data packet is repeatedly performed for each transmission frame. Thus, data transmission is performed between the devices specified by the transmission / reception specifying packet. In this case, the first data output unit 10
11 and the video data 806 from the second data output unit 1012 are transmitted from each of the source devices 702 and 703 to the sink device 701 in frame units.

Since the transmission interval of the transmission / reception designation packet is a fixed time, the size of the data packet is finite. Therefore, the size of data to be transmitted from one source device to the corresponding sink device in one transmission frame period, for example, the data size of one frame of video data transmitted from the first source device to the sink device However, if the data size is larger than the data size that can be stored in the data packet 902, it becomes difficult for the data transmission system 20 to transmit isochronous data having high real-time properties such as video data.

Therefore, when transmitting isochronous data having a large data size, a method of generating a plurality of transmission / reception designation packets designating the same source device and the same sink device within one transmission frame period. Can be considered. In this method, isochronous data having a large data size can be distributed and transmitted in a plurality of data packets within one transmission frame period, whereby a higher rate isochronous data can be transmitted within one frame period. Data transmission can be performed.

In the data transmission system 20 of the second embodiment, when performing the data transmission operation using the transmission / reception designation packet and the data packet described above, the unique synchronization corresponding to the isochronous data transmitted by the data packet is performed. The information (reference signal information) is stored and transmitted in a transmission / reception designation packet together with information (transmission data designation information) designating a source device as a data supply source and a sink device as a data supply destination.

Hereinafter, the first transmission / reception designation packet includes:
A data transmission operation for storing and transmitting the synchronization information together with the transmission data designation information will be described. FIG. 10 shows transmission data (FIG. 10A) propagating on a transmission path in the data transmission system 20 according to the second embodiment, and reference signals reproduced by the first and second source devices (FIG. 10B). , Figure (c)). During a predetermined transmission frame period of the transmission data Td, the transmission / reception designation packet 1001
a1 to 1001a3 are transmitted. A corresponding data packet 1002a1 is transmitted following the transmission / reception designation packet 1001a1, and a corresponding data packet 1002a follows the transmission / reception designation packet 1001a2.
a2 has been transmitted.

Here, the transmission / reception designation packet 1001a1
Indicates transmission source designation information indicating the first source device 702 as a source of data stored in the data packet 1002a1 corresponding to the packet 1001a1, and indicating the sink device 701 as the destination of the transmission.
This is a special transmission / reception designation packet including synchronization information (reference signal information) unique to isochronous data. The transmission / reception designation packet 1001a2 indicates transmission data designation information indicating the second source device 703 as a supply source of data stored in the data packet 1002a2 corresponding to the packet 1001a2, and indicating the sink device 701 as the supply destination. Is included. The transmission / reception designation packet 10
01a3 includes NULL information, and there is no corresponding data packet.

The unique synchronization information of the isochronous data included in the special transmission / reception designation packet is stored in the source device 70.
2 at the reference signal generator 802b1.
The synchronization information is reproduced as a reference signal 808b2 (FIG. 10C) by the reference signal generator 802b2 of the source device 703.

FIG. 11 is a diagram for explaining the operation of each device in the data transmission system 20. FIG.
(a) is a reference signal generator 802b1 of the source device 702.
FIG. 11B shows the reference signal 808b1 output from the
From the first data output unit 1011 to the source device 702
Data 8 input to the controller 801b1
05 is shown. FIG. 11C shows the reference signal 80 output from the reference signal generator 802 b 2 of the source device 703.
8b2, and FIG. 11 (d) shows the second data output unit 10
12 shows video data 806 input to the controller 801b2 of the source device 703. further,
FIG. 11E shows the transmission data Td on the transmission line in the data transmission system 20. FIGS. 11F and 11G show the transmission data Td from the controller 801a of the sink device 701 to the video synthesizing device 10.
20 video data 804a1 and 804a2 output to
(That is, video data 805 and 806 output from the first and second data output units). Note that FIG.
(a) and the synchronization signal shown in FIG.
This is the same as the synchronization signal shown in (b) and FIG. 10 (c).

First, synchronization information 807a is input to the sink device 701 from the video synthesizing device 1020 outside the system. This synchronization information is supplied to the video synthesizing device 1020 by two video data, ie, the first and second data output units 10.
It represents a timing signal serving as a reference for a process of synthesizing video data from 11 and 1012. For example,
As the synchronization information, a frame synchronization signal indicating the beginning of a video frame is used.

The synchronization information is not limited to the frame synchronization signal, but may be any information that can reproduce the frame synchronization signal. For example, the synchronization information may include frequency information indicating a frequency of the frame synchronization signal and phase information indicating a phase of the frame synchronization signal. here,
The frequency information is information indicating that the frame synchronization signal is obtained by dividing the operating clock of the system by X (X is a positive integer), or information indicating the cycle of the frame synchronization signal. The phase information is information indicating the timing of a rising edge or a falling edge of the frame synchronization signal, time information indicating a phase with respect to the rising edge or the falling edge, and the like. The operation clock of the above system includes the sink device 701 and the source device 802 in the data transmission system 20.
803 or a video synthesizing device 1020 outside the system
And first and second data output units (cameras) 1011 and 10
Twelve operation clocks are used.

When the synchronization information 807a from the video synthesizing device 1020 outside the system is input to the sink device 701, the controller 801a multiplexes the synchronization information into a special transmission / reception designation packet 100a1 of a predetermined transmission frame and transmits the multiplexed information to the transmission path. A transmission process for sending to 700a is performed. It should be noted that the synchronization information is transmitted to the special transmission / reception designation packet 10
The simplest method of multiplexing the transmission / reception designation packet 01a1 is a method of multiplexing the transmission / reception designation packet 1001a1 in synchronization with the frame synchronization signal. That is, one for every predetermined number of transmission frames
The two special transmission / reception designation packets are multiplexed at the rising or falling timing of the frame synchronization signal. As a result, on the transmission data receiving side, the timing at which the special transmission / reception designation packet of the transmission frame is received is the timing at which the processing of the frame is started. In this case, the special transmission / reception designation packet 1001a1 and the normal transmission / reception designation packet 1001a2 need to be distinguished by each device.
An identification bit for distinguishing this from the normal transmission / reception designation packet 1001a2 is included. By multiplexing the special transmission / reception designation packet 1001a1 in the transmission frame in this way, it is not necessary to particularly include frequency information and phase information for reproducing the frame synchronization signal in the special transmission / reception designation packet 1001a1.

In the first source device 702, the special transmission / reception designation packet 1001 transmitted from the sink device 701
When a1 is received via the transmission path 700a, the controller 801b1 transmits synchronization information included in the received special transmission / reception designation packet 1001a1 to the reference signal generator 80.
Processing for outputting to 2b1 is performed. Then, in the reference signal generator 802b1, based on the synchronization information from the controller 801a of the sink device 701, a timing reference signal 808b1 (see FIG.
The frame synchronization signal (b)) is reproduced.

The special transmission / reception designation packet 1001a
1 is the rising or falling timing of the frame synchronization signal itself, the source device 702 receives the special transmission / reception designation packet 1001a1 from the sink device 701 at least once, and receives the head of the transmission frame. The phase of the frame synchronization signal with respect to the beginning of the transmission frame can be determined from the timing thus obtained and the timing at which the special transmission / reception designation packet 1001a1 is received. Therefore, for transmission frames subsequent to the transmission frame including the special transmission / reception designation packet 1001a1, a frame synchronization signal can be generated based on the timing at which the beginning of each transmission frame is received.

Then, the timing reference signal 808 generated by the reference signal generator 802b1 of the source device 702
b1 (FIG. 11A) is output to the first data output unit 1011 outside the system. Then, in the first data output unit (camera) 1011, the imaging process is performed by the source device 7.
The video data 805 is output in synchronization with the timing reference signal 808b1 from the second device 02 and obtained by the imaging process to the source device 702 (FIG. 11B).

Then, the controller 801b1 of the source device 702 holds the video data 805 from the data output unit 1011. After that, the controller 8
In 01b1, the video data 805 is stored as isochronous data in the data packet 1102a1 (data packet 1002a1 in FIG. 10A), and the data packet 1102a1 is stored in the received special transmission / reception designation packet 11
01a1 (in FIG. 10A, the special transmission / reception designation packet 10
Transmission processing for transmission to the transmission path 700b is performed so as to follow 01a1) (FIG. 11 (e)).

In the second source device 703, the special transmission / reception designation packet 1001 transmitted from the sink device 701
When a1 is received via the transmission path 700b, the controller 801b2 uses the reference signal generator 80 to synchronize the synchronization information included in the received special transmission / reception designation packet 1001a1.
Processing for outputting to 2b2 is performed. Then, in the reference signal generator 802b2, based on the synchronization information from the controller 801a of the sink device 701, the timing reference signal 808b2 (see FIG.
(c)) is reproduced.

The timing reference signal 808 generated by the reference signal generator 802b2 of the source device 703
b2 (FIG. 11C) is output to the second data output unit 1012 outside the system. Then, in the second data output unit (camera) 1012, the imaging process is performed by the source device 7.
The video data 806 is output in synchronization with the timing reference signal 808b2 from FIG.

The controller 801b2 of the source device 703 holds the video data 806 from the data output unit 1012. However, since the special transmission / reception designation packet 1001a1 does not include information for designating the second source device 703 as a data supply source, when the special transmission / reception designation packet 1001a1 is received by the source device 703, the controller 80
Processing for storing and outputting the video data 806 held in 1b2 in a data packet is not performed. And
After receiving the special transmission / reception designation packet 1001a1, when receiving the transmission / reception designation packet 1002a2 including the information for designating the second source device 703 as the data source, the video data 806 held in the controller 801b2 is converted into the data packet 1102a2. (FIG. 10
In (a), the data packet 1002a2) is stored in the data packet 1002a2, and the data packet 1102a2 is
1a2 (in FIG. 10A, the transmission / reception designation packet 1001a
Output processing is performed subsequent to 2) (FIG. 11 (e)).

Then, in the sink device 701, the data packet 1 follows the special transmission / reception designation packet 1001a1.
002a1 is received and the transmission / reception designation packet 1001a
When the data packet 1002a2 is received subsequent to the data packet 1002, the controller 801a copies the isochronous data included in the received data packets 1002a1 and 1002a2 and copies the isochronous data 804a1 (FIG. 1).
1 (f)) and 804a2 (FIG. 11 (g))
A process of outputting the video data 805 and 806 from the video synthesizer 2703 to the video synthesizing apparatus 1020 is performed.

Since these two types of video data are input from the first and second data output units to the first and second source devices 702 and 703 with frame synchronization established, From the sink device 701 to the video synthesizing device 10
20, the frame synchronization of the two types of video data is established. After the data packet 1002a2 is transmitted from each source device, the NU of the transmission / reception designation packet 1001a3 or the like is transmitted.
The transmission / reception designation packet storing the LL information is transmitted from the plurality of sink devices 701. Since the transmission / reception designation packet does not include the data transmission information, each source device transmits the data packet following the transmission / reception designation packet. Is not performed.

As described above, in the data transmission system 20 according to the second embodiment, the sync device 701 stores the synchronization information supplied from the video synthesizing device 1020 in the special transmission / reception designation packet 1001a1 and transmits it to the source device. Since the source device 702 and 703 receive the same special transmission / reception designation packet 1001a1 output from the sink device 701 and reproduce the timing reference signal from the synchronization information included in the received special transmission / reception designation packet 1001a1, As shown in FIGS. 11A and 11C, each of the reference signal generators 802b of the source devices 702 and 703
1 and 802b2, the timing reference signals 808b1 and 808b2 having the same period and the same phase are the first and second timing reference signals.
Is output to the data output unit. However, a data delay due to reception and transfer in each device and a data delay in a transmission path are ignored.

In the data transmission system 20 according to the second embodiment, the frame synchronization signal is transmitted from the first and second source devices 702 and 703 as the timing reference signal to the first and second data output units outside the system. 1011 and 1
012, the first and second data output units 10
Two pieces of video data input to the source devices 702 and 703 from 11 and 1012 are in a state where frame synchronization is established. In other words, the two video data are input to the controllers 801b1 and 801b2 of the source devices 702 and 703 at the same timing, and output from the source devices 702 and 703 to the sink device 701 at the same timing.

As a result, in the sink device receiving a plurality of isochronous data, a plurality of isochronous data with frame synchronization established are received as video data from the first and second data output units. This eliminates the need for a video data buffer between the sink device 701 and the video synthesizing device to absorb the difference in the processing timing of the corresponding frames of the two video data. Can avoid a data delay between receiving a plurality of video data as isochronous data and outputting the video data to the video synthesizing apparatus.

In the second embodiment, as the data transmission system, the synchronization information is transmitted in the special transmission / reception designation packet 10.
Although the data transmission system 01a1 is stored and transmitted, the data transmission system may store and transmit synchronous information in a data packet together with asynchronous data and isochronous data. Further, in the second embodiment, as the transmission / reception designation packet, a device for transmitting a data packet immediately after the data packet and a device for receiving the data packet are designated. Channels may be allocated, and the transmission / reception designation packet may designate a transmission channel of a device that transmits a data packet and a reception channel of a device that receives a data packet.

In the second embodiment, as a data transmission system, the sink device 701 is
2 and 703, the data transmission system 20 is configured such that one of the two source devices transmits synchronization information to a sink device and another source device. In this case, the same effect as in the second embodiment can be obtained. In the second embodiment, as a data transmission system, synchronization information generated in the sink device 701 is sequentially transmitted in a certain direction between the sink device 701 and the source devices 702 and 703 forming a ring-shaped transmission path. Although the transfer is described, the data transmission system may directly transmit the synchronization information from the sink device to each of the source devices. In this case, the same effect as in the second embodiment is obtained. can get.

Further, in the second embodiment, the case where the sink device and the source device constituting the data transmission system perform data transmission based on one piece of synchronization information has been described. A plurality of data transmission devices (i.e., a plurality of sink devices and a plurality of source devices) are divided into a plurality of groups, and the data transmission devices belonging to each group perform data transmission based on different synchronization information for each group. It may be. In the second embodiment, a data transmission system in which a transmission / reception designation packet is transmitted at regular time intervals has been described. However, in the data transmission system, a transmission / reception designation packet is transmitted at an arbitrary time interval. It may be.

Further, in the second embodiment, the case where the timing reference signal used in the data transmission system is a frame synchronization signal indicating the beginning of each video frame (that is, indicating the timing at which signal processing for each video frame is started) As described above, the timing reference signal is a signal (block synchronization signal) indicating the timing of signal processing for each block when signal processing for each video frame is performed for each block dividing the video frame.
It may be.

The timing reference signal may be a signal (channel synchronization signal) indicating the timing of signal processing for each of the left and right channels of the audio signal. Since the signal processing for each of the left and right channels of the audio signal is performed for each processing unit (audio frame) of the audio signal, the signal processing for each of the left and right channels is performed by the channel synchronization signal.
Synchronization can be performed for each audio frame.

In the second embodiment, a case has been described in which a camera is connected to each source device as a data output unit outside the system, and a video synthesizing device is connected to the sink device as a device outside the system. However, the data output unit outside the system connected to the source device is a VTR
And a device outside the system connected to the sink device may be a display device such as a monitor or a navigation system, or a video recording device.

For example, by using a data output unit outside the system connected to the source device as a camera and a device outside the system connected to the sink device as a display device, it is possible to realize a navigation system using in-vehicle real video. . In addition, by using a camera as the data output unit outside the system connected to the source device and a video recording device as the device outside the system connected to the sink device, a surveillance camera system and an on-vehicle drive recorder (when an accident or theft occurs) Device for recording a video of time).

Further, in Embodiment 2, specific members constituting a transmission line in the data transmission system are not specifically shown, but an optical fiber may be used for this transmission line. Also, in the second embodiment, video data that propagates on the transmission path as isochronous data in the data transmission system is MPEG (Mo
(ving Picture Experts Group).

In the second embodiment, as a data transmission system, a plurality of devices for data transmission, that is, a sink device 701, first and second source devices 702, 70
Reference numeral 3 denotes a connection connected by a ring-shaped data transmission path, but the form of the transmission path connecting each device in the data transmission system is not limited to that of the second embodiment.

FIG. 12 is a diagram showing an example of a data transmission system in which the connection form of each device is different from that of the second embodiment. This data transmission system 20a is configured as shown in FIG.
As shown in the figure, a sink device 1201, first and second source devices 1202, 1203 are connected by a data bus 1200 as a transmission path. In this case, since the packets output from the respective devices disappear after being received by the predetermined device, each of the devices 1201 to 1203 does not need to discard the transmitted packet, and the second embodiment does not need to discard the transmitted packet.
Of the respective devices 701 to 703 are deleted.

FIG. 13 is a diagram showing another example of a data transmission system in which the connection form of each device is different from that of the second embodiment. This data transmission system 20b has the configuration shown in FIG.
As shown in FIG. 3, a data input side transmission line and a data output side transmission line of the sink device 1301, the first and second source devices 1302 and 1303 are separated by using a multi-input multi-output signal distributor 1310. Are connected to each other by a bus.

In the data transmission system 20b, the sink device 1301, the first and second source devices 1302, 1
Transmission data output from the transmission path 303
The signal is transmitted to the signal distributor 1310 via 301b, 1302b, and 1303b. The transmission data input to the signal distributor 1310 is transmitted simultaneously to the transmission lines 1301a and 1301.
The data is output to the sink device 1301, the first and second source devices 1302 and 1303 via the devices 2a and 1303a.

Here, the sink device 1301, the first and second source devices 1302 and 1303 are the sink device 701 and the first and second source devices 7 of the second embodiment.
02, 703. In addition, the transmission paths 1301a to 1303a and 1301b to 1303
As b, for example, an optical fiber is used, and for the signal distributor 1310, for example, a multi-input multi-output optical star coupler is used.

In such a data transmission system 20b, unlike the data transmission system 20 of the second embodiment, even if a part of the transmission path (for example, the transmission path 1301a) is disconnected, the first and second data transmissions from the sink device 1301 are performed. Data transmission to the second source devices 1302 and 1303 is possible.

FIG. 14 is a diagram showing another example of a data transmission system in which the connection form of each device is different from that of the second embodiment. This data transmission system 20c
As shown in FIG. 14, a multi-input multi-output signal distributor 131
0 is used to separate the data input side transmission line and the data output side transmission line of the data transmission device group of the first, second and third groups, and each group is connected by a bus.

Here, the data transmission device group of the first group includes, for example, the sink device 1401 and the first source device 1
404 and a second source device 1406. In this data transmission device group, the distributor 1310 transmits the
The transmission data input to the sink device 1401 via the transmission line 1401a is transmitted to the first source device 141 via the transmission line 1401b.
04 is output. Transmission data from the first source device 1404 is transmitted to the second source device 1406 via the transmission path 1401c. The transmission data output from the second source device 1406 is transmitted to the distributor 1310 via the transmission line 1401d.

The data transmission device group of the second group includes, for example, a third source device 1402 and a fourth source device 1405. In this data transmission device group, transmission data input from the distributor 1310 to the third source device 1402 via the transmission line 1402a is transmitted to the transmission source 1
The signal is output to the fourth source device 1405 via the terminal 402b. The transmission data output from the fourth source device 1405 is transmitted to the distributor 1310 via the transmission line 1402c.

The third group of data transmission devices includes, for example, a fifth source device 1403. In this data transmission device group, the transmission line 1
The transmission data input to the fifth source device 1403 via 403a is transmitted to the distributor 1310 via the transmission path 1403b.

Here, the sink device 1401 has the same configuration as the sink device 701 of the second embodiment, and each of the source devices 1402 to 1405 has the same configuration as the source device 702 or 703 of the second embodiment. Has become. Further, each of the transmission lines 1401a to 1401d, 1
For example, optical fibers are used as 402a to 1402c and 1403a and 1403b.
For example, a multi-input multi-output optical star coupler 10 is used for 10.

The data transmission system 20c
One sink device 1401 and five source devices 1402
The data transmission system shown in FIG. 14 has source devices 1402-1406.
May be replaced with a sink device, and the number of sink devices and the number of source devices are not limited to fixed numbers. At least one sink device and two source devices may be used. What is necessary is just to include.

(Third Embodiment) FIG. 15 is a diagram showing a data transmission system according to a third embodiment. The data transmission system 30 according to the third embodiment receives highly real-time data such as audio data or video data from a first data output unit 1011 such as a camera outside the system, and converts the data to isochronous data. A first source device 1502 for transmitting as Dt1 and a highly real-time data such as audio data or video data from a second data output unit 1012 such as a camera outside the system, and the data is converted to isochronous data. And a second source device 1503 for transmitting as Dt2.

The data transmission system 30 receives the isochronous data Dt1 and Dt2 transmitted from each of the source devices 1502 and 1503, and outputs the data to the video synthesizing device 1020 outside the system. A data transmission device 1504 for receiving data from the data processing unit 1030 and transmitting the data.
Here, the data processing unit 1030 is a device that outputs video data such as a camera or a video playback device (VTR), or a device that receives video data such as a video synthesis device or a video display device. Further, the data transmission device 150
Reference numeral 4 denotes a source device for transmitting video data input from outside the system, or a sink device for receiving video data from a transmission path in the system and outputting the video data to the outside of the system.

The data transmission system 30 includes a first transmission line 1500a for transmitting data between the sink device 1501 and the first source device 1502, a first transmission device 15002, and a second source device 1502. A second transmission path 1500b for transmitting data between the data transmission apparatuses 1503; and a third transmission path 1500c for transmitting data between the first source apparatus 1502 and the data transmission apparatus 1504. I have.

In the data transmission system 30, the sink device 1501, the first and second source devices 1502 and 1503, the data transmission device 1504, and the first to third transmission lines 1500a to 1500c
One tree-shaped data transmission path is formed. In the third embodiment, each of the devices 1501 to 1504 has an identification ID (ID: # 1), an identification ID (ID: # 2), and an identification ID (ID: # 3), an identification ID (ID: # 4) is set.

FIG. 16A is a diagram showing a specific configuration of the sink device. This sink device 1501 is
Receiving transmission data Td from the transmission path 15
And a controller 1601a for performing a process of transmitting the transmission data Td to the transmission data Td, a process of controlling the video synthesizing device outside the system, and an arbitration process for data transmission, and synchronization information Is included in the received transmission data Td. And a reference signal generator 1602a for generating a reference signal 1608a based on the

Here, the reference signal 1608a is a frame synchronization signal for determining the timing at which the video synthesizing device 1020 synthesizes isochronous data for each frame. The reception process of the controller 1601a is a process of receiving the transmission data Td from the transmission path 1500a and outputting the isochronous data 1604a1 and 1604a2 included in the data to the video synthesizing device 1020 outside the system. The transmission process of the controller 1601a is to transmit the synchronization information 1607a from the video synthesizing device 1020 to the transmission path 1500a as a part of the transmission data Td. The synchronization information 1607a is a frame synchronization signal indicating the timing at which the video synthesizing device 1020 combines a plurality of isochronous data for each frame. Further, the control process of the controller 1601a is a process of transmitting and receiving asynchronous data 1603a such as a command for controlling the video composition device 1020 to and from the video composition device 1020. The arbitration process of the controller 1601a is as follows.
The right to transmit data is given to any of the data transmission devices connected via the transmission paths 1500a to 1500c, that is, any one of the sink device 1501, the first and second source devices 1502 and 1503, and the data transmission device 1504. This is a process of determining whether to give.

In the data transmission system 30 according to the third embodiment, since the sink device 1501 outputs the synchronization information of the data transmission system 30, the synchronization included in the transmission data Td received by the controller 1601a. Synchronization information output processing for outputting information Is to the reference signal generator 1602a, and reference signal generator 160
At 2a, a reference signal 1608 is generated based on the synchronization information Is.
The operation for generating a is not performed. However, when a source device other than the sink device 1501 of the data transmission system 30 generates the synchronization information of the data transmission system 30, the synchronization information output processing in the controller 1601a and the reference signal 1 in the reference signal generator 1602a are performed.
The generating operation of 608a is performed.

FIG. 16B is a diagram showing a specific configuration of the first source device. The source device 1502 controls a process of receiving the transmission data Td from the transmission lines 1500a to 1500c, a process of transmitting the transmission data Td to the transmission lines 1500a to 1500c, and a first data output unit (camera) 1011 outside the system. 1601b1 that performs arbitration processing for data transmission and arbitration processing for data transmission;
Signal 1608b based on the synchronization information Is included in
1 which generates a reference signal generator 1602b1.

Here, the reference signal 1608b1 is a frame synchronization signal that determines the timing at which the first data output unit 1011 outputs video data of each frame. In the reception process of the controller 1601b1, the transmission data from the transmission path 1500a is received, and the synchronization information Is included in the transmission data is transmitted to the reference signal generator 161.
02b1 is included. In the transmission processing of the controller 1601b1, the video data 1605 from the first data output unit 1011 is used as a part (isochronous data) of the transmission data Td on the transmission path 1500b.
And the process of transmitting the transmission data from the first source device 1501 to the second source device 1503 via the transmission path 1500b. The control process of the controller 1601b1 is performed by the asynchronous data 160 such as a command for controlling the first data output unit 1011.
3b1 is a process of transmitting and receiving 3b1 to and from the data output unit 1011.

In the data transmission system 30 of the third embodiment, the sink device 1501 generates synchronization information of the data transmission system 30. The source device 1502 outputs the synchronization information of the data transmission system 30. In this case, in the controller 1601b1, in addition to the isochronous data transmission process, the first data output unit 1011 uses the synchronization information 1607b1 indicating the operation timing as at least a part of the transmission data Td as the transmission process. Processing for transmitting to the transmission paths 1500a and 1500b is also performed. Synchronization information 160 indicating the above operation timing
Specifically, 7b1 indicates the timing at which the first data output unit 1011 outputs video data of each frame to the source device 1502.

FIG. 16C is a diagram showing a specific configuration of the second source device. The source device 1503 receives the transmission data Td from the transmission path 1500b, transmits the transmission data Td to the transmission path 1500b,
Second data output unit (camera) 1012 outside the system
1601b2 that performs a process of controlling communication and an arbitration process for data transmission
And synchronization information Is included in the received transmission data Td.
And a reference signal generator 1602b2 for generating a reference signal 1608b2 based on the

Here, the reference signal 1608b2 is a frame synchronization signal that determines the timing at which the second data output unit 1012 outputs video data of each frame. The reception process of the controller 1601b2 is a process of receiving transmission data from the transmission path 1500b and outputting the synchronization information Is included in the transmission data to the reference signal generator 1602b2. The transmission process of the controller 1601b2 is a transmission process of transmitting the video data 1606 from the second data output unit 1012 to the transmission path 1500b as a part (isochronous data) of the transmission data Td. The control process of the controller 1601b2
This is a process of transmitting and receiving asynchronous data 1603b2 such as a command for controlling the data output unit 1012 to and from the data output unit 1012.

FIG. 17 shows transmission paths 1500a to 1500c.
It is a figure which shows the data structure (transmission frame format) of the transmission data transmitted above. In a transmission frame 1710 which is a repetition unit of data transmission, a cycle start packet 170 indicating the head of the transmission frame
Following 1, the various packets 1703 to 1705 are transmitted.

Here, the cycle start packet 1
701 is transmitted by one of the devices 1501 to 1504 at regular intervals. In the data transmission system 30, the cycle start packet 1701 is transmitted from the sink device 1501 at regular intervals. Packet 170
3, 1704 are the first and second source devices 15 respectively.
This packet is a packet (isochronous data packet) stored in isochronous data, which is transmitted from No. 02, 1503. The packet 1705 is a packet (asynchronous data packet) transmitted from the sink device 1501 and storing asynchronous data.

Immediately before transmitting each data packet,
There is an arbitration period Ap required for arbitration processing for data transmission. During this period, arbitration processing for deciding which apparatus is to be given a data transmission right is performed by a plurality of apparatuses holding data to be transmitted. Is being done. Therefore, no data packet is transmitted from any device during the arbitration period Ap. After the arbitration period Ap has elapsed, it becomes possible to transmit a data packet from the device that has acquired the data transmission right by the arbitration process. In the data transmission system 30 of the third embodiment, the cycle start packet 1701
Subsequently, a process of transmitting various packets 1703 to 1705 is repeatedly performed for each transmission frame 1710.

Next, the operation will be described. In the following, as a data transmission operation of the data transmission system 30 according to the third embodiment, video data from the first and second data output units (cameras) 1011 and 1012 are converted into two corresponding source devices 1502 and 1502. The video synthesizing apparatus 102 transmits the two video data received from the sink apparatus 1501 to the one sink apparatus 1501 and combines and displays the two pieces of video data.
The operation of outputting to 0 will be described.

FIG. 18 shows a data structure (FIG. 17A) of data propagating through a transmission line in the data transmission system 30 according to the third embodiment, and a reference signal transmitted by the first and second source devices in the system. (Figures (b) and (c)) are generated. That is, when a predetermined asynchronous data packet 1705a output from the sink device 1501 is received by the first source device 1502 via the transmission line 1500a, the first source device 1502 causes the timing reference signal 1608b1 (see FIG. b)) is generated. Also, the predetermined asynchronous data packet 1705a is
500a, first source device 1502, and transmission line 15
When received by the second source device 1503 via 00b, the first source device 1502 generates a timing reference signal 1608b2 (FIG. 18 (c)).

Next, the operation will be described. First, synchronization information 1607a is input to the sink device 1501 from the video synthesizing device 1020 outside the system. This synchronization information
This represents a timing signal which is a reference for a process of synthesizing two video data, that is, video data from the first and second data output units 1011 and 1012 in the video synthesizing device 1020. For example, a frame synchronization signal indicating the beginning of a video frame is used as the synchronization information.

The synchronization information is not limited to the frame synchronization signal, but may be any information that can reproduce the frame synchronization signal. For example, the synchronization information may include frequency information indicating a frequency of the frame synchronization signal and phase information indicating a phase of the frame synchronization signal. here,
The frequency information is information indicating that the frame synchronization signal is obtained by dividing the operating clock of the system by X (X is a positive integer), or information indicating the cycle of the frame synchronization signal. The phase information is information indicating the timing of a rising edge or a falling edge of the frame synchronization signal, time information indicating a phase with respect to the rising edge or the falling edge, and the like.

When the synchronization information 1607a is input to the sink device 1501 from the video synthesizing device 1020 outside the system, the controller 1601a sends the synchronization information
07a is stored as asynchronous data in an asynchronous data packet, and arbitration processing is performed.
When the data transmission right is acquired by the arbitration process, the asynchronous data packet 1 storing the asynchronous data
A process of transmitting 705a to the source devices 1502 and 1503 is performed. The asynchronous data packet 1705a includes, in addition to the synchronization information 1607a, control data for controlling data transmission between the devices and status data indicating the status of each device. Therefore, the control data and the status data are transmitted and received as asynchronous data together with the synchronous information.

In this case, in the controller 1601a,
The control data and status data in the asynchronous data are distinguished from the synchronization information stored in the same asynchronous data packet. Accessed by

In the first source device 1502, the asynchronous data packet 170 transmitted from the sink device 1501
5a is received via the transmission path 1500a, the controller 1601b1 sends the received packet 1705a
Is output to the reference signal generator 1602b1. Then, the reference signal generator 160
In 2b1, a frame synchronization signal which is a timing reference signal 1608b1 (FIG. 18B) for processing video data is reproduced based on synchronization information from the controller 1601b1.

The timing reference signal 1 generated by the reference signal generator 1602b1 of the source device 1502
608b1 (FIG. 19A) is output to the first data output unit 1011 outside the system. Then, in the first data output unit (camera) 1011, the imaging process is performed in synchronization with the timing reference signal 1608 b 1 from the source device 1502, and video data 1605 obtained by the imaging process is output to the source device 1502. (Fig. 19
(b)).

Then, the controller 1601b1 of the source device 1502 holds the video data 1605 from the data output unit 1011. Thereafter, the controller 1601b1 stores the video data 1605 as isochronous data in the isochronous data packet 1703a, and when the data transmission right is acquired by the arbitration process, the transmission path 1500a as shown in FIG. A process of transmitting the isochronous data packet 1703a storing the video data 1605 thereon is performed. In the controller 1601b1, the asynchronous data packet 1
705a is transmitted to the second source device 1503 via the transmission path 1500b.

At the second source device 1503, the asynchronous data packet 170 transmitted from the sink device 1501
5a is received via the transmission path 1500b, the controller 1601b2 sends the received packet 1705a
Is output to the reference signal generator 1602b2. Then, the reference signal generator 160
In 2b2, based on the synchronization information Is from the controller 1601b2, a frame synchronization signal which is a timing reference signal 1608b2 (FIG. 18C) for processing video data is reproduced.

The timing reference signal 1 generated by the reference signal generator 1602b2 of the source device 1503
608b2 (FIG. 19C) is output to the second data output unit 1012 outside the system. Then, in the second data output unit (camera) 1012, the imaging process is performed in synchronization with the timing reference signal 1608b2 from the source device 1503, and the video data 1606 obtained by the imaging process is output to the source device 1503. (Fig. 19
(d)).

Then, the controller 1601b2 of the source device 1503 holds the video data 1606 from the data output unit 1012. Thereafter, the controller 1601b2 stores the video data 1606 as isochronous data in the isochronous data packet 1704a, and when the data transmission right is acquired by the arbitration process, the transmission path 1500b as shown in FIG. A process of transmitting an isochronous data packet 1704a having video data 1606 stored thereon is performed. This isochronous data packet 1704a is transmitted to the sink device 1501 via the transmission line 1500b, the first source device 1502, and the transmission line 1500a.

When the isochronous data packets 1703a and 1704a are received by the sink device 1501, the controller 1601a sends the received data packet 1
Isochronous data included in 703a and 1704a (FIG. 19)
(f), (g)) 1604a1 and 1604a2 are converted to video data 1605, 1605 from source devices 1502 and 1503, respectively.
As 606, processing for outputting to the video synthesizing apparatus 1020 is performed. Since these two types of video data are input from the first and second data output units to the first and second source devices 1502 and 1503 in a state where frame synchronization is established, the sink device 1501 , The frame synchronization of the two types of video data is established.

As described above, in the third embodiment, the sink device 1501 that receives video data (isochronous data)
And first and second source devices 1 for transmitting video data
In the data transmission system 30 having only the devices 502 and 1503 and having acquired the data transmission right by arbitration, and performing the data transmission by the packet,
It is assumed that the sink device 1501 stores synchronization information serving as a processing reference of the received isochronous data in an asynchronous data packet and transmits the same, and synchronizes the source device with the synchronization information included in the asynchronous data packet from the sink device. Since the isochronous data is transmitted at the same time, the sink device receiving a plurality of isochronous data can obtain, for example, a plurality of isochronous data in which the processing timing for each frame is synchronized, and It is possible to eliminate the need for a buffer for absorbing the noise.

In the third embodiment, the data transmission system stores synchronization information in an asynchronous data packet and transmits it. However, the data transmission system stores synchronization information in an isochronous data packet. May be transmitted. In the third embodiment,
As the data transmission system, the one in which the sink device 1501 transmits the synchronization information to the source devices 1502 and 1503 has been described. In the data transmission system, one source device transmits the synchronization information to the sink device and the other source devices. May be used.

In the third embodiment, the data transmission system is described in which the synchronization information is transmitted from the sink device 1501 to the second source device via the first source device. In the data transmission system, one of a plurality of devices included in the system may directly transmit synchronization information to another device. In this case, each device also uses the synchronization information based on the synchronization information. It is possible to generate a timing reference signal whose cycle and timing match.

Further, in the third embodiment, the case where the sink device and the source device constituting the data transmission system perform data transmission based on one piece of synchronization information has been described. A plurality of data transmission devices (i.e., a plurality of sink devices and a plurality of source devices) are divided into a plurality of groups, and the data transmission devices belonging to each group perform data transmission based on different synchronization information for each group. It may be.

Further, in the third embodiment, the case where the timing reference signal used in the data transmission system is a frame synchronization signal indicating the head of each video frame (that is, indicating the timing at which signal processing for each video frame is started) As described above, the timing reference signal is a signal (block synchronization signal) indicating the timing of signal processing for each block when signal processing for each video frame is performed for each block dividing the video frame.
It may be. The timing reference signal may be a signal (channel synchronization signal) indicating the timing of signal processing for each of the left and right channels of the audio signal.

Also, in the third embodiment, a case has been described in which a camera is connected to each source device as a data output unit outside the system, and a video synthesizing device is connected to the sink device as a device outside the system. However, the data output unit outside the system connected to the source device is a VTR
And a device outside the system connected to the sink device may be a display device such as a monitor or a navigation system, or a video recording device. Also,
In the third embodiment, the specific configuration of the transmission path constituting the data transmission system is not shown, but an optical fiber may be used as the transmission path.

(Embodiment 4) FIG. 20 shows Embodiment 4 of the present invention.
Is a diagram for explaining a data transmission system according to
1 shows a configuration of a sink device that constitutes the system.
The data transmission system according to the fourth embodiment is different from the sink device 150 in the data transmission system 30 according to the third embodiment.
1 and the isochronous data 160 from the source devices 1502 and 1503 together with the processing of the sink device 1501.
A sink device 2001 for performing a process of detecting a phase difference of 51606 is provided.

The sink device 2001 is connected to the transmission line 150
Of receiving transmission data Td from transmission line 150, transmission line 150
0a, a controller 2001a for performing a process of controlling the video synthesizing device 1020 outside the system, and an arbitration process for data transmission (arbitration), and synchronization information included in the received transmission data Td. A reference signal generator 2002a for generating a reference signal 2008a based on the Is
01a to video data 2004a1 and 2004aa
2, each of the source devices 1502 and 150
And a phase detector 2010 for detecting a phase difference (phase shift) between the isochronous data 1605 and 1606 from FIG. 3 and outputting phase difference information Ipd.

Here, the reference signal 2008a is a frame synchronization signal for determining the timing at which the video synthesizing device 1020 synthesizes isochronous data for each frame. The reception process of the controller 2001a is a process of receiving the transmission data Td from the transmission path 1500a and outputting the isochronous data 1605 and 1606 included in the data as video data 2004a1 and 2004a2 to the video synthesizing device 1020 outside the system. is there.

The transmission processing of the controller 2001a is performed in accordance with the synchronization information 2007 from the video synthesizing apparatus 1020.
is stored in the asynchronous data packet and the transmission path 1500a
And a process of storing the phase difference information Ipd from the phase detector 2010 in an isochronous data packet or an asynchronous data packet and transmitting the same to the transmission path 1500a. This synchronization information 2007a is a frame synchronization signal indicating the timing at which the video synthesizing device 1020 synthesizes a plurality of isochronous data for each frame. Further, the control process of the controller 2001a is a process of transmitting and receiving asynchronous data 2003a such as a command for controlling the video composition device 1020 to and from the video composition device 1020. The arbitration process of the controller 2001a performs data transmission between the data transmission devices connected via the transmission paths 1500a to 1500c, that is, the sink device 2001, the first and second source devices 1502 and 1503, and the data transmission device 1504. This is a process for acquiring a right.

In the data transmission system according to the fourth embodiment, source devices 1502 and 1503 are output from sink device 2001 to video synthesizing device 1020.
Based on the phase difference information Ipd, the phase difference Pd between the two video data 2004a1 and 2004a2 is eliminated.
Processing for shifting the timing reference signal is performed.

In the data transmission system of the fourth embodiment, since the sink device 2001 outputs the synchronization information of the data transmission system, the synchronization information Is included in the transmission data Td received by the controller 2001a. Is output to the reference signal generator 2002a, and the reference signal generator 2002a does not perform the operation of generating the reference signal 2008a based on the synchronization information Is. However, when a source device other than the sink device 2001 of the data transmission system generates the synchronization information of the data transmission system, the synchronization information output process in the controller 2001a and the generation operation of the reference signal 2008a in the reference signal generator 2002a are performed. Will be performed. Other configurations of the data transmission system according to the fourth embodiment are exactly the same as those of the data transmission system 30 according to the third embodiment.

FIG. 21 is a diagram showing input / output signals for the sink device and the source device in the data transmission system of this embodiment. Data 200 shown in FIG.
4a1 is the sync device 2001 to the video synthesizing device 1
020, which is video data 1605 supplied from the first data output unit 1011 to the source device 1502. Video data 2004a2 shown in FIG. 21B is video data output from the sink device 2001 to the video synthesizing device 1020, and is video data 1606 supplied from the second data output unit 1012 to the source device 1503. Here, a phase difference Pd occurs between the video data 2004a2 and the video data 2004a1.

The data 1606 shown in FIG.
Is video data input from the second data output unit 1012 to the second source device 1503 in synchronization with the frame synchronization signal 1608b2 shown in FIG. Also,
Data 1606c illustrated in FIG. 21F is video data input from the second data output unit 1012 to the second source device 1503 in synchronization with the frame synchronization signal 1608c2 illustrated in FIG. Here, the frame synchronization signal 1608c2 shown in FIG. 21E is the frame synchronization signal 16608 shown in FIG.
08b2 is advanced in phase.

Next, the operation will be described. In the data transmission system according to the fourth embodiment, the sink device 2001
Video data 2004a1 and 200a output from the controller 2001a of the
When the phase shift of 4a2 does not occur, the data transmission process exactly the same as that of the third embodiment is performed.

When the two video data 2004a1 and 2004a2 are out of phase, information Ipd indicating the phase difference detected by the phase detector 2010 of the sink device 2001 is transmitted from the sink device to each source device. In a predetermined source device, the sink device 200
The processing of shifting the timing reference signal is performed so that the phase difference Pd between the two pieces of video data 2004a1 and 2004a2 output from No. 1 to the video synthesizing apparatus 1020 disappears.

That is, when the controller 2001a of the sink device 2001 receives the first and second isochronous data 1605 and 1606 from the transmission line 1500a,
A process of outputting the first and second isochronous data 1605 and 1606 as video data 2004a1 and 2004a2 to the video synthesizing device 1020 is performed. At this time, the phase detector 2010 detects a phase shift between the video data 2004a1 and 2004a2 output to the video synthesizing device 1020, and outputs information (phase difference information) Ipd indicating the detected phase shift Pd to the controller 2001a. .
Then, in the controller 2001a, the phase detector 20
10 stores the phase difference information Ipd input from 10 in an isochronous data packet or an asynchronous data packet,
A process of transmitting the data to the source device via the device 500a is performed.

When each of the source devices 1502 and 1503 receives an isochronous data packet or an asynchronous data packet storing the phase difference information Ipd from the sink device 2001, the controllers 1601b1 and 1601b2 respond to the phase difference information Ipd. The reference signal generator 160
The timing reference signal generated based on the synchronization information in 2b1 and 1602b2 is the video data 2004a
Processing is performed to control the reference signal generator so that the reference signal generator is shifted by a phase amount corresponding to the phase difference Pd between 1 and 2004a2. However, the video data 2004a1 and 200a
In order to eliminate the phase difference Pd of 4a2, it is only necessary to advance or delay one phase of the video data.
Normally, the process of shifting the timing reference signal is performed in one of the source devices 1502 and 1503.

For example, a case where the process of shifting the timing reference signal is performed by the second source device 1503 will be briefly described. In the reference signal generator 1602b2 of the second source device 1503, the controller 1601b2
Reference signal 16 based on the synchronization information Is from
08b2 (FIG. 21C) is performed, and the phase of the timing reference signal 1608b2 is converted to the phase difference information Ipd from the controller 1601b2.
, A phase adjustment process for advancing by a phase amount corresponding to the phase difference Pd indicated by the information is performed. As a result, the reference signal generator 1602b2 outputs the timing reference signal 1
A timing reference signal 1606c (FIG. 21 (f)) whose phase is advanced by a phase amount Pd from 608b2 (FIG. 21 (c)) is
The data is output to the second data output unit 1012. Thereby, the video data 1606 based on the timing reference signal 1608c2 is output from the second data output unit 1012.
c is the phase amount P from the timing at which the video data 1606 based on the timing reference signal 1608b2 is output.
It is output at a timing earlier by a time corresponding to d. As a result, from the sink device 2001, as the video data from the first and second source devices 1502 and 1503, the synchronized and phase-matched isochronous data 2 is established.
004b1 and 2004b2 are the video compositing devices 1020
Will be output.

As described above, in the fourth embodiment, the sink device 15 in the data transmission system of the third embodiment is used.
01, along with the processing of the sink device 1501,
Isochronous data 16 from source devices 1502 and 1503
05, 1606, and performs a process of outputting phase difference information Ipd indicating the phase difference.
1, the source device 1503 and the sink device 2001
Since the timing reference signal is shifted based on the phase difference information Ipd so that the phase difference Pd between the two video data 2004a1 and 2004a2 output from the to the video synthesizing device 1020 disappears, the sink device
Synchronized and in-phase video data can be output to the video compositing device 1020 as video data from the two source devices.

In the fourth embodiment, as a data transmission system, information on phase shift (phase difference information)
Although the Ipd is stored in an asynchronous data packet or an isochronous data packet and transmitted, the phase difference information Ipd may be stored in a cycle start packet 1701 and transmitted. In the fourth embodiment, the data transmission system detects the phase difference between the isochronous data 1605 and 1606 from the source devices 1502 and 1503 instead of the sink device 1501 in the data transmission system of the third embodiment. Phase difference information Ip
Although the sink device 2001 for performing the phase detection process for outputting the d is provided, and the source devices 1502 and 1503 perform the process of shifting the timing reference signal based on the phase difference information Ipd, the data transmission system has Device 1 in the data transmission system 10 according to the first embodiment.
01 or in place of the sink device 701 in the data transmission system 20 of the second embodiment, a sink device for performing the phase detection processing in addition to the processing in these sink devices is provided. The shift processing of the timing reference signal may be performed. In this case, for example, the phase difference information
And the special frame header 401 in Embodiment 2 or the special transmission / reception designation packet 1001a1 in Embodiment 2 for transmission.

(Embodiment 5) FIG. 22 is a block diagram illustrating a data transmission system according to Embodiment 5 of the present invention. The data transmission system 50 according to the fifth embodiment includes first and second
(Hereinafter simply referred to as a transmission system) 50a and 50b. Here, each of the transmission systems 50a and 50b has the same configuration as the data transmission system 10 of the first embodiment.

That is, the first transmission system 50a
Is a first data output unit 1 such as a camera outside the system.
051, a first source device 2203 for receiving real-time data 2205a such as audio data or video data and transmitting the data as isochronous data Dt1, and a second data output from a camera or the like external to the system. Receiving data 2206a having a high real-time property such as audio data or video data from the unit 1052,
A second source device 2204 for transmitting the data as isochronous data Dt2.

The transmission system 50a receives the isochronous data Dt1 and Dt2 transmitted from each of the source devices 2203 and 2204, and outputs the data to a video synthesizing device 1050 external to the first sink device 2201. ,
A first transmission line 2200a for transmitting data between the sink device 2201 and the first source device 2203, and a second transmission line 2200a for transmitting data between the first and second source devices 2203 and 2204. Transmission line 2200b,
A third transmission path 2200c for transmitting data between the second source device 2204 and the sink device 2201 is provided. In the data transmission system 50a, the sink device 2201, the first and second source devices 2202 and 2203, and the first to third transmission paths 22
One ring-shaped data transmission path is formed by 00a to 2200c.

Further, the second transmission system 50b
Third data output unit 105 such as a camera outside the system
3 which receives data 2207a having a high real-time property such as audio data or video data and transmits the data as isochronous data Dt3.
05 and a fourth source for receiving data 2208a having high real-time properties such as audio data or video data from a fourth data output unit 1054 such as a camera outside the system, and transmitting the data as isochronous data Dt4. Device 2206.

The transmission system 50b receives the isochronous data Dt3 and Dt4 transmitted from each of the source devices 2205 and 2206 and outputs the data to the video synthesizing device 1050 outside the system. ,
The second sink device 2202 and the third source device 22
Transmission line 2200d for transmitting data between the first transmission line 05 and the second transmission line
And the third and fourth source devices 2205 and 220
Transmission path 2200 for transmitting data between
e, the fourth source device 2206 and the second sink device 2
Sixth transmission path 2 for transmitting data to / from the
200f. And this transmission system 5
0b, one ring-shaped data transmission path is formed by the sink device 2202, the third and fourth source devices 2205 and 2206, and the fourth to sixth transmission lines 2200d to 22000f. In the data transmission system 50, the devices 2201 to 2206 operate with the same system clock, that is, the operation clock of one of the devices 2201 to 2206 (for example, the sink device 2201) Equipment 2
The operation clocks of 202 to 2206 are synchronized.

Here, the first and second sink devices 2
201 and 2202 have exactly the same configuration as the sink device 101 of the first embodiment. That is, the sink device 2201 transmits the synchronization information 2211 from the video synthesizing device 1050 to each of the source devices 2203 and 2204, receives the video data transmitted from each of the source devices 2203 and 2204, and outputs the video data to the video synthesizing device. Is performed. Also, the sink device 2202
Performs a process of transmitting the synchronization information 2211 from the video synthesis device 1050 to each of the source devices 2205 and 2206, and a process of receiving video data transmitted from each of the source devices 2205 and 2206 and outputting the video data to the video synthesis device. It is.

In addition, the first and third source devices 220
Reference numeral 3 2205 denotes the sink device 102 according to the first embodiment.
It has exactly the same configuration as. That is, the source device 2
203 and 2205 are timing reference signals 220 based on synchronization information 2211 from the first and second sink devices.
8b1 and 2208b3 to be generated and output to the first and third data output units 1051 and 1053, and video data 2 output from the first and third data output units based on the timing reference signals 2208b1 and 2082b3.
205a and 2207a, and receives the transmission path 2200b,
2200e.

In addition, the second and fourth source devices 220
4, 2206 are the source device 103 of the first embodiment.
It has exactly the same configuration as. That is, the source device 2
204 and 2206 are timing reference signals 220 based on synchronization information 2211 from the first and second sink devices.
8b2, 2208b4 to generate and output to the second and fourth data output units 1052, 1054, and video data 2 output from the second and fourth data output units based on the timing reference signals 2208b2, 2208b4.
206a and 2208a, and receives the transmission path 2200c,
2200f.

In FIG. 22, asynchronous data such as control commands accessed between the first and second sink devices 2201 and 2202 and the video synthesizing device 1050, and from the sink device 2201 to the video synthesizing device 1050. The output reference signal is not shown. In FIG. 22,
Asynchronous data such as control commands accessed between the first to fourth source devices 2203 to 2206 and the first to fourth data output units 1051 to 1054;
From the fourth data output units 1051 to 1054 to the first to fourth
The synchronization information output to the source devices 2203 to 2206 is not shown.

Next, the operation will be described. In the first and second transmission systems 50a and 50b constituting the data transmission system 50 according to the fifth embodiment, data transmission processing is performed in exactly the same manner as the data transmission system 10 according to the first embodiment.

First, the data transmission of the first transmission system 50a will be described. When the synchronization information 2211 from the video synthesizing device 1050 is input to the sink device 2201 of the first transmission system 50a, the sink device 2201 stores the synchronization information in a special frame header of a predetermined transmission frame and transmits it. The process of sending to the road 2200a is performed. When the special frame header from the transmission line 2200a is input to the first source device 2203, the first source device 2203 generates a timing reference signal 2208b1 based on the synchronization information included in the special frame header, and The signal is output to the first data output unit 105
1 is performed.

The video data 2205 output from the first data output unit 1051 based on the timing reference signal
a is received by the first source device 2203, the first
In the source device 2203, a process of inserting the video data 2205a into the isochronous data slot of a predetermined transmission frame and transmitting it to the transmission path 2200b is performed.

When the predetermined special frame header from the transmission path 2200b is input to the second source device 2204, the second source device 2204 generates the timing reference signal just like the first source device 2203. 220
8b2 and outputs the same to the second data output unit 1052, and the video data 22 output from the second data output unit 1052 based on the timing reference signal.
06a to the transmission line 2200c.
In the first sink device 2201, video data 2205a and 2206 from each source device are transmitted from the transmission path 2200c.
When a is received, a process of copying the data and outputting it to the video compositing device 1050 is performed.

Next, data transmission of the second transmission system 50b will be described. When the synchronization information 2211 from the video synthesizing device 1050 is input to the sink device 2202 of the second transmission system 50b, the synchronization device 2202 stores the synchronization information in a special frame header of a predetermined transmission frame and transmits it. The process of sending to the road 2200d is performed. When the special frame header from the transmission path 2200d is input to the third source device 2205, the third source device 2205 generates a timing reference signal 2208b3 based on the synchronization information included in the special frame header, and The signal is output to the third data output unit 105
3 is performed.

The video data 2207 output from the third data output unit 1053 based on the timing reference signal
a is received by the third source device 2205, the third
The source device 2205 performs a process of inserting the video data 2207a into the isochronous data slot of a predetermined transmission frame and transmitting the video data 2207a to the transmission path 2200e.

When the predetermined special frame header from the transmission path 2200e is input to the fourth source device 2206, the fourth source device 2206 outputs the timing reference signal just like the third source device 2205. 220
8b4 to be output to the fourth data output unit 1054, and the video data 22 output from the fourth data output unit 1054 based on the timing reference signal.
08a to the transmission line 2200f.
Then, in the second sink device 2202, the transmission path 220
Video data 2207 from each source device via 0f
When a and 2208a are received, a process of copying the data and outputting it to the video compositing apparatus 1050 is performed.

As a result, the source devices 2203 and 2204 belonging to the first transmission system, and the source devices 22 belonging to a second transmission system different from the first transmission system.
05 and 2206, video data for which frame synchronization has been established from each corresponding data output unit is transmitted from the transmission line 22.
00c and 2200f, and the video synthesizing device 1050 uses the video data from the transmission paths 2200c and 2200f to output these video data 22
The synthesis processing of 05a to 2208a is performed.

As described above, the data transmission system according to the fifth embodiment includes the first sink device 2201 and the first and second source devices 2203 and 2204, and the first and second source devices 2203 and 2204. The video data 2205a and 2206a transmitted from the
1, the first transmission system 50a, the second sink device 2202, and the third and fourth source devices 2205, 2
206, and the third and fourth source devices 2205, 2
Video data 2207a, 220 transmitted from 206
8a at the second sink device 2202, and a second transmission system 50b.
b, the data transmission is performed based on the synchronization information from the video synthesizing device 1050. Therefore, the video data 2205a and 2206a transmitted from the first transmission system 50a to the video synthesizing device 1050, and the second transmission system The video data 2207a and 2208a transmitted from the video 50b to the video synthesizing device 1050 are video data for which frame synchronization has been established, and the video synthesizing device 1050 converts video data input from the transmission lines 2200c and 2200f of each transmission system. On the other hand, direct synthesis processing can be performed.

In the fifth embodiment, as a data transmission system having a plurality of independent individual transmission systems, an individual transmission system constituting the system has the same configuration as the data transmission system of the first embodiment. Although shown, the individual transmission system may have the same configuration as the data transmission system of the second embodiment, the data transmission system of the third embodiment, or the data transmission system of the fourth embodiment. For example, when a plurality of individual transmission systems constituting the data transmission system have the same configuration as the data transmission system of the second embodiment, in each individual transmission system, the synchronization information is stored in a special transmission / reception designation packet and transmitted. The Rukoto. When the plurality of individual transmission systems constituting the data transmission system have the same configuration as the data transmission system of the third embodiment, in each individual transmission system, the synchronization information is an asynchronous data packet or an isochronous data packet. And transmitted.
Further, when the plurality of individual transmission systems constituting the data transmission system have the same configuration as the data transmission system of the fourth embodiment, the sink devices 2201 and 2202
A phase detector for detecting a phase shift of a plurality of received isochronous data is provided, and information on the phase shift detected by the phase detector is stored in an asynchronous data packet or an isochronous data packet, and the sink device 2201, 2202 to the source devices 2203 to 2206.
Each source device corrects the reproduction timing of the frame reference signal based on the received information on the phase shift.

In the fifth embodiment, the individual transmission system in the data transmission system is a ring-type connection type in which a plurality of data transmission devices (sink device and source device) constituting the system are connected in a ring. However, the individual transmission system in the data transmission system may be a bus-type connection type in which a plurality of data transmission devices constituting the system are bus-connected, or a plurality of data transmission devices constituting the system may be implemented. As shown in Embodiment 3, a tree-type connection type in which another data transmission device is connected to one data transmission device may be used. Further, in the fifth embodiment, as each individual transmission system constituting the data transmission system, 1
Although one sink device and two source devices are connected via a transmission line, the individual transmission system in the data transmission system has one sink device and one source device in a one-to-one relationship. They may be connected.

(Embodiment 6) FIG. 23 is a block diagram for explaining a data transmission system according to Embodiment 6 of the present invention. Data transmission system 60 of the sixth embodiment
Are the first and the first, which independently transmit video data.
It is composed of second individual transmission systems 60a and 60b. Here, in each of the individual transmission systems 60a and 60b, two data transmission devices constituting the systems are connected one-to-one.

That is, the first individual transmission system 60
a is a first source that receives data 2321 having high real-time properties such as audio data or video data from a first data output unit 1011 such as a camera outside the system, and transmits the data as isochronous data Dt1. It has a device 2312 and a first sink device 2310 that receives the isochronous data Dt1 transmitted from the source device 2312 and outputs it to the video synthesizing device 1020 outside the system. Further, the individual transmission system 60a includes first and second transmission paths 2300, 2300 for transmitting data between the first sink device 2310 and the first source device 2312.
301.

The first transmission line 2300 is a transmission line for transmitting data from the first sink device 2310 to the first source device 2312, and is a low-speed transmission line on which high-speed data transmission is not possible. It is. Therefore, the data transmission unit of the first sink device 2310 and the first source device 23
Twelve data receiving units are adapted to low-speed data transmission. The second transmission path 2301 is connected between the first source device 2312 and the first sink device 2310.
This is a transmission path for transmitting data to the STA, and is a high-speed transmission path capable of high-speed data transmission. Therefore, the data receiving unit of the first sink device 2310 and the data transmitting unit of the first source device 2312 correspond to high-speed data transmission.

The second individual transmission system 60b
Is a second data output unit 1 such as a camera outside the system.
012, which receives data 2323 having high real-time properties such as audio data or video data and transmits the data as isochronous data Dt2.
313 and a second sink device 2311 that receives the isochronous data Dt2 transmitted from the source device 2313 and outputs the data to the video synthesizing device 1020 outside the system. The individual transmission system 60b includes third and fourth transmission paths 2302 and 23 for transmitting data between the second sink device 2311 and the second source device 2313.
03.

Here, the third transmission line 2302 is a transmission line for transmitting data from the second sink device 2311 to the second source device 2313, and is a low-speed transmission that cannot perform high-speed data transmission. Road. Therefore, the data transmission unit of the second sink device 2311 and the second source device 2
The data receiving unit 313 is compatible with low-speed data transmission. The fourth transmission path 2303 is:
From the second source device 2313 to the second sink device 231
1 is a transmission path for transmitting data to the H.1, and is a high-speed transmission path capable of high-speed data transmission. Therefore, the data receiving unit of the second sink device 2311 and the data transmitting unit of the second source device 2313 are compatible with high-speed data transmission.

That is, the low-speed transmission lines 2300 and 23
02, and the maximum data transmission rate Y (Mbp) of the high-speed transmission paths 2301 and 2303.
The relationship with s) is X <Y. For example, the transmission speed X is 5 Mbps and the transmission speed Y is 50 Mbps. further,
The first and second sink devices 2310 and 2311
Has exactly the same configuration as the sink device 101 of the first embodiment. That is, the sink devices 2310 and 2
Reference numeral 311 denotes synchronization information 233 from the video synthesizing device 1020.
0 is stored in the special frame header, and the transmission path 2300,
The processing of transmitting the video data to the video synthesizing apparatus 1020 is performed.

In addition, the first and second source devices 231
Reference numeral 2213 denotes the source device 102 according to the first embodiment.
It has exactly the same configuration as. That is, the source device 2
312 and 2313 are timing reference signals 2320, 2320 based on synchronization information from the first and second sink devices.
22 to generate the first and second data output units 1011 and 1
012 and the timing reference signal 232
0, 2322, receiving video data 2321, 232 output from the first and second data output units, storing the data in an isochronous data slot, and outputting the data to transmission paths 2301, 2303. Is what you do.

FIG. 24 is a diagram showing the data structure (transmission frame format) of the transmission data transmitted on the transmission paths 2300 to 2303. As shown in FIG.
In each of the above transmission lines, the transmission frames (# 1),
Td1 (# 2) Td2, (# 3) Td3,... Are transmitted.

In the low-speed transmission paths 2300 and 2302, as shown in FIG. 24B, an asynchronous data slot 2402 storing asynchronous data 2404 is transmitted following a frame header 2401 for detecting the head of a transmission frame. You. Note that this asynchronous data slot 2402
Can be assigned in advance to a device (first or second sink device) that transmits asynchronous data, and if necessary, each device (first and second sink devices) It is also possible to use a slot 2402.

In the high-speed transmission paths 2301 and 2303, as shown in FIG. 24 (c), an isochronous data slot storing isochronous data 2405 follows a frame header 2401 for detecting the head of a transmission frame. An asynchronous data slot 2402 storing the asynchronous data 2403 and the asynchronous data 2404 is transmitted. The isochronous data slot 2403 is a source device 23 for transmitting isochronous data.
12, 2313 are assigned in advance. The asynchronous data 2404 is a response signal (ACK, NACK, etc.) to a control command from the sink device to the source device or a control command from the source device to the sink device.
And status data (data indicating the state of each device). The isochronous data 2405 is video data or the like from a data output unit.

As described above, the data transmission system 60 according to the sixth embodiment can only transmit asynchronous data from the sink device to the source device, and can transmit isochronous data and asynchronous data from the source device to the sink device. Transmission is possible. That is, the data structure of the transmission frame used in this data transmission system is basically the same as that in the first embodiment, but the sixth embodiment is applicable to the data transmission from the sink device 2310 to the source device 2312. The transmission frame used for transmission and the transmission frame used for data transmission from the sink device 2311 to the source device 2313 include:
The difference from the first embodiment is that the isochronous data slot 2403 is not included.

Since the data transmission speed is different between the low-speed transmission line and the high-speed transmission line, the size of the frame header 2401, the asynchronous data slot 2402, and the asynchronous data 2404 of the transmission frame corresponding to the high-speed transmission line on the time axis Are the frame header 2401 of the transmission frame corresponding to the low-speed transmission path, the slot 240 for the asynchronous data,
2, and the size of the asynchronous data 2404 on the time axis. As described above, in the data transmission system 60 according to the sixth embodiment, by utilizing the speed difference between the transmission speed from the source device to the sink device and the transmission speed from the sink device to the source device, the transmission from the source device to the sink device is performed. In the transmission frame, a period for transmitting isochronous data from the source device to the sink device is secured, and the period of the transmission frame from the sink device to the source device and the period of the transmission frame from the source device to the sink device are determined. They are the same.

Next, the operation will be described. Each transmission system 6 in the data transmission system 60 of the sixth embodiment
In 0a and 60b, transmission of synchronization information from the sink devices 2310 and 2311 to the source devices 2312 and 2313 is performed using the low-speed transmission paths 2300 and 2302, and the sink devices 2310 and 231 are transmitted from the source devices 2312 and 2313.
1 is transmitted using the high-speed transmission paths 2301 and 2303.

That is, the synchronization information 2330 from the video synthesizing apparatus 1020 is used for the first and second individual transmission systems 60.
a and 60b, the sync devices 2310 and 2311 send the synchronization information to the frame header 24 of a predetermined transmission frame.
A process of inserting the data into the asynchronous data slot 2402 following the 01 and transmitting it to the low-speed transmission paths 2300 and 2302 is performed. The synchronization information from the transmission lines 2300 and 2302 is
When input to the second source devices 2312 and 2313,
In each of the source devices 2312 and 2313, based on the synchronization information, the timing reference signal 232 having the same period and phase is used.
0, 2322, and the timing reference signal is
Processing for outputting to the second data output units 1011 and 1012 is performed. Here, the timing reference signals 2320, 2
322 has the same period and phase,
Specifically, it is a frame synchronization signal indicating the start timing of the processing for each video frame.

The first and second data output units 1011 and 1011
From 1012, in synchronization with the timing reference signal,
Video data (isochronous data) 2321 and 23 respectively
23 are output and input to the first and second source devices 2312 and 2313 in a state where frame synchronization is established.

The first source device 2312 holds the input isochronous data 2321 and thereafter inserts the isochronous data 2321 into the isochronous data slot 2403 following the frame header 2401 of a predetermined transmission frame. Then, the synchronization information 2404 from the sink device is transferred to the asynchronous data slot 24 following the isochronous data slot 2403.
02 to transmit the isochronous data and the synchronization information to the high-speed transmission path 2301. That is, in the source device 2312, the video data 2321 is transferred to the first sink device 2310, and the received synchronization information 2404 is returned to the first sink device 2310.

Similarly, in the second source device 2313,
The input isochronous data 2323 is retained, and thereafter,
The isochronous data 2323 is stored in an isochronous data slot 2403 following a frame header 2401 of a predetermined transmission frame.
, The synchronization information 2404 from the sink device is inserted into the asynchronous data slot 2402 following the isochronous data slot 2403, and the process of transmitting the isochronous data and the synchronization information to the high-speed transmission path 2303 is performed. . That is, in the second source device 2313, the video data 2323 is transferred to the second sink device 2311, and the received synchronization information 2404 is returned to the second sink device 2311.

The first and second sink devices 231
0, 2311, the high-speed transmission paths 2301, 23, respectively.
Isochronous data 2405 stored in the isochronous data slot 2403 of the transmission frame received via the transmission
Are output to the video compositing apparatus 1020 as the respective video data 2331 and 2333. Since the video data 2331 and 2333 are input from the first and second data output units to the first and second source devices 2312 and 2313 in a state where frame synchronization is established, The output timing from 2311 is also
The frame synchronization is established.

Note that the video data 2405 received by the sink devices 2310 and 2311
The data is discarded after reception at 0, 2311 and is not transferred to the source devices 2312, 2313 via the low-speed transmission path. The asynchronous data 2404 returned from the source devices 2312 and 2313 to the sink devices 2310 and 2311
Also, as with the video data 2405, the sink device 2310,
After being received at 2311, they are discarded.

As described above, the data transmission system 60 according to the sixth embodiment has the first sink device 2310 and the first source device 2312, and these devices are connected to the two transmission paths 2300, 2300 having different transmission speeds. A first individual transmission system 60a connected one-to-one by 2302, a second sink device 2311 and a second source device 2313,
These devices are connected to two transmission paths 230 having different transmission speeds.
A second individual transmission system 60b connected in a one-to-one relationship with each of the individual transmission systems 60a, 603;
0b, the data transmission is performed based on the synchronization information from the video synthesizing device 1020. Therefore, the video data 2331 transmitted to the video synthesizing device 1020 by the first individual transmission system 60a and the second individual transmission system 6
The video data 2333 transmitted to the video synthesizing device 1020 by Ob is video data for which frame synchronization has been established, and the video synthesizing device 1020 performs direct synthesizing processing on the video data transmitted by each transmission system. be able to. Further, a buffer for absorbing a timing difference between two video data transmitted by each transmission system can be eliminated.

In each of the individual transmission systems, as a transmission line used for data transmission from the sink device to the source device, the transmission speed is determined by the transmission line used for data transmission from the source device to the sink device. Since a transmission speed lower than the transmission speed is used, an inexpensive member is used for a transmission path for performing data transmission from the sink device to the source device, and data transmission from the sink device to the source device is performed. Inexpensive transmission / reception units can be used, and low-cost and efficient data transmission can be performed.

In the sixth embodiment, as a data transmission system, the source devices 2312 and 2313 receive the synchronization information 2404 received from the sink devices 2310 and 2311.
To the asynchronous data slot 240 of the high-speed transmission frame.
In the data transmission system, the low-speed transmission path is terminated at the source devices 2312 and 2313, and the received synchronization information 2404 is returned to the sink device. It may not be.

In the sixth embodiment, the data transmission system stores synchronization information in an asynchronous data slot and transmits it.
The synchronization information may be stored and transmitted in an isochronous data slot provided in a transmission frame for performing data transmission from the sink device to the source device. Further, the data transmission system may transmit the synchronization information to each of the source devices 2312 and 2313 using the special frame header as described in the first embodiment.

Further, in the sixth embodiment, the case where the timing reference signal used in the data transmission system is a frame synchronization signal indicating the head of each video frame (that is, indicating the timing at which signal processing for each video frame is started) However, the timing reference signal is a signal (block synchronization signal) indicating the timing of signal processing for each block when signal processing for each video frame is performed for each block that divides the video frame.
It may be.

In the sixth embodiment, a case has been described in which a camera is connected to each source device as a data output unit outside the system, and a video synthesizing device is connected to the sink device as a device outside the system. However, the data output unit outside the system connected to the source device is a VTR
And a device outside the system connected to the sink device may be a display device such as a monitor or a navigation system, or a video recording device.

In Embodiment 6, specific members constituting the transmission lines in the data transmission system are not specifically shown, but all the transmission lines 2300 to 23
An optical fiber may be used for 03. Also, a low-speed transmission path 2 for performing data transmission from the sink device to the source device.
Metal wires (electric wires) may be used for 300 and 2302, and optical fibers may be used for high-speed transmission paths 2301 and 2303 for transmitting data from the source device to the sink device.

The data transmission system according to the sixth embodiment is different from the data transmission system according to the fourth embodiment in that the sink device 2
310 and 2311 are provided with a phase detector for detecting a phase shift of a plurality of received isochronous data, and information on the phase shift detected by the phase detector is output as asynchronous data or isochronous data by the sink device 2310 and 2311
, To the source devices 2312 and 2313. In this case, the source device corrects the reproduction timing of the reference signal on the basis of the received information on the phase shift, so that the sink devices 2310 and 231
In 1, the isochronous data in which synchronization is established can be obtained even when the phase shift of the isochronous data from the two source devices occurs due to the data delay in the transmission path.

(Embodiment 7) FIG. 25 is a block diagram for explaining a data transmission system according to Embodiment 7 of the present invention. Data transmission system 70 of the seventh embodiment
Is composed of first and second individual transmission systems 70a and 70b that independently transmit video data, similarly to the data transmission system 60 of the sixth embodiment.
Here, in each of the individual transmission systems 70a and 70b, two data transmission devices constituting the systems are connected one-to-one.

That is, the first individual transmission system 70
a first source device 2512 which receives data 2521 having high real-time properties such as audio data or video data from a first data output unit 1011 outside the system and transmits the data as isochronous data Dt1; ,
Isochronous data D transmitted from the source device 2512
a first sink device 2510 that receives t1 and outputs it to the video synthesizing device 1020 outside the system. In addition, the individual transmission system 70a includes the first sink device 251
A first transmission path (low-speed transmission path) 2500 for transmitting data from the first source apparatus 2512 to the first source apparatus 2512 at a low speed, and the first source apparatus 2512 to the first sink apparatus 2510.
And a second transmission path (high-speed transmission path) 2501 for transmitting data at high speed. Therefore, the data transmission unit of the first sink device 2510 and the first source device 2
The data receiving unit 512 is compatible with low-speed data transmission. Also, the first sink device 2510
And the data transmission unit of the first source device 2512 are adapted for high-speed data transmission.

Also, the second individual transmission system 70b
A second source device 2513 that receives highly real-time data 2523 such as audio data or video data from a second data output unit 1012 outside the system and transmits the data as isochronous data Dt2; Isochronous data Dt transmitted from the source device 2513
2 and a second sink device 2511 that receives the signal 2 and outputs it to the video synthesizing device 1020 outside the system. The individual transmission system 70b includes a second sink device 2511
A second transmission line (low-speed transmission line) 2502 for transmitting data from the second source device 2513 to the second source device 2513 at a low speed;
And a fourth transmission line (high-speed transmission line) 2503 for transmitting data at high speed from the source device 2513 to the second sink device 2511. Accordingly, the data transmission unit of the second sink device 2511 and the second source device 25
Thirteen data receiving units are compatible with low-speed data transmission. The data receiving unit of the second sink device 2511 and the data transmitting unit of the second source device 2513 correspond to high-speed data transmission.

That is, the low-speed transmission paths 2500 and 25
02 and the maximum data transmission rate Y (Mbp) of the high-speed transmission paths 2501 and 2503.
The relationship with s) is X <Y. For example, the transmission speed X is 5 Mbps and the transmission speed Y is 50 Mbps. And
In the seventh embodiment, the first and second sink devices 2
510, 2511 and first and second source devices 251
Reference numeral 2,2513 denotes a sink device 701 of the second embodiment.
As in the case of the source device 702 or 703, data transmission is performed using packets.

That is, the first and second sink devices 2510
And 2511 store the synchronization information 2530 from the video synthesizing device 1020 in a data packet, and
0, 2502, and a process of receiving video data transmitted from the first and second source devices 2512 and 2513 and outputting the video data to the video synthesizing device 1020.

Also, the first and second source devices 251
2 and 2513 generate timing reference signals 2520 and 2522 based on synchronization information from the first and second sink devices, and generate the first and second data output units 1011 and 1012.
And the timing reference signal 2520,2
522, receives video data 2521 and 2523 output from the first and second data output units, stores the data in data packets, and
03 is performed. As described above, the data transmission system 70 according to the seventh embodiment is different from the data transmission system 60 according to the sixth embodiment in that data transmission is performed using packets.

FIG. 26 is a diagram showing the data structure (transmission frame format) of the transmission data transmitted on the transmission paths 2500 to 2503. FIG. 26A shows the sink device 2
Low-speed transmission paths 2500, 2502 for transmitting data from 510, 2511 to source devices 2512, 2513
2 shows a data structure of a transmission frame in FIG. FIG.
6 (b) shows a data structure of a transmission frame in a high-speed transmission path for transmitting data from the source devices 2512 and 2513 to the sink devices 2510 and 2511.

As shown in FIG. 26, in each of the individual transmission systems 70a and 70b, the transmission / reception designation packets 2601 to 2603 are always output to the transmission line at regular intervals by the sink device or the source device. Therefore, on each transmission path 2500 to 2503 of the data transmission system 70,
The transmission / reception designation packet is transmitted in the same cycle. The transmission / reception designation packets 2601 to 2603 include transmission / reception designation information for designating a device that receives data stored in a data packet immediately thereafter and a device that transmits the data.

For example, the transmission / reception designation packet 2601
2603, the transmission / reception designation packet 2601 contains information instructing the transmission of asynchronous data from the sink device to the source device.
Reference numeral 2603 includes information for instructing transmission of isochronous data from the source device to the sink device. By storing information instructing the transmission of asynchronous data from the source device to the sink device in the transmission / reception designation packets 2601 to 2603, it is also possible to transmit the asynchronous data from the source device to the sink device.

A data packet 2611 following the transmission / reception designation packet 2601 is the first sink device 25.
10 or a data packet containing asynchronous data transmitted by the second sink device 2511. As the asynchronous data, a control command from the sink device to the source device, a response signal (ACK, NACK, etc.) to the control command from the source device to the sink device, or status data (data indicating the state of each device) is transmitted. . Data packets 2612 and 2613 following the transmission / reception designation packets 2602 and 2603 include isochronous data transmitted by the first source device 2512 or the second source device 2513. The data packet including the isochronous data is transmitted only from the source device to the sink device.

Thus, in the data transmission system 70 according to the seventh embodiment, asynchronous data is transmitted from the sink device to the source device, and the asynchronous data is transmitted from the source device to the sink device.
Isochronous data and asynchronous data are transmitted. Although the data structure of the transmission frame in the data transmission system 70 is basically the same as the data structure of the transmission frame in the data transmission system 20 of the second embodiment, the data transmission system 70 of the seventh embodiment has , Isochronous data are source devices 2512, 2513
The data transmission system 20 according to the second embodiment differs from the data transmission system 20 according to the second embodiment in that the data is transmitted only in one direction to the sink devices 2510 and 2511.
Is different. In the seventh embodiment, as in the sixth embodiment, since the data transmission speed on the high-speed transmission line is higher than the data transmission speed on the low-speed transmission line, the size of each packet on the high-speed transmission line is It is smaller than the size of the corresponding packet.

Next, the operation will be described. Each transmission system 7 in the data transmission system 70 of the seventh embodiment
0a, 70b, the first and second sink devices 2510,
2511 to the first and second source devices 2512 and 251
3 is transmitted to the low-speed transmission paths 2500 and 2502.
And the first and second source devices 2512, 252
513 to the first and second sink devices 2510 and 2511
Of video data (isochronous data) is transmitted using the high-speed transmission paths 2501 and 2503.

That is, in the first and second individual transmission systems 70a and 70b of the data transmission system 70, transmission / reception designation packets are transmitted from the first and second sink devices 2510 and 2511 at a fixed period, respectively. Is transmitted to the source devices 2512 and 2513. In this state, the synchronization information 2530 from the video synthesizing device 1020 is output.
Is input to the first and second sink devices 2510 and 2511 of the first and second individual transmission systems 70a and 70b, the first sink device 2510 outputs the transmission / reception designation packet 2601 and the synchronization information. Is transmitted via the low-speed transmission path 2500. At the same time, the second sink device 25
In step 11, a process of transmitting, via the low-speed transmission path 2502, the data packet 2611 storing the synchronization information following the transmission / reception designation packet 2601 is performed. At this time, the transmission / reception designation packet 2601 stores information specifying the sink device as the supply source of the synchronization information stored in the data packet subsequent thereto, and specifying the source device as the supply destination of the synchronization information. . Here, the synchronization information is a frame synchronization signal of video data received by each sink device or information for generating the frame synchronization signal.

Thereafter, in the first individual transmission system 70a, a process of repeatedly transmitting a transmission / reception designation packet from the first sink device 2510 to the first sink device 2512 via the low-speed transmission path 2500 at regular intervals is performed. Done. For example, in the transmission system 70a, after transmitting the transmission / reception designation packet 2601, the transmission / reception designation packets 2602 and 2603 are transmitted. Note that these transmission / reception specifying packets 2602 and 2603 include information specifying the source device 2512 as the supply source of the video data stored in the data packet immediately following it, and specifying the sink device 2510 as the supply destination.

Also, in the second individual transmission system 70b, after the data packet 2611 is transmitted, the transmission / reception designation packet is transmitted via the low-speed transmission path 2502 in the same manner as in the first individual transmission system 70a. A process of repeatedly transmitting data from the second sink device 2511 to the second source device 2513 at regular intervals is performed. For example, in the transmission system 70b, the transmission / reception designation packet 260
1 after transmission of the transmission / reception designation packet 2602 and 260
3 is transmitted. These transmission / reception designation packets 26
02 and 2603 include information that specifies the second source device 2513 as a supply source of video data stored in a data packet immediately following the second data source, and specifies the second sink device 2511 as a supply destination thereof.

On the other hand, the individual transmission systems 70a, 70
0b of the source devices 2512 and 2513 from the sink devices 2510 and 2511,
When the data packet 2611 is received, the timing reference signals 2520 and 2522 are reproduced based on the synchronization information included in the data packet 2611, and the timing reference signals 2520 and 2522 are reproduced by the first and second data output units 1011 and 1011. Output to 1012. The timing reference signal 2520 and the timing reference signal 2522 have the same period and phase. Then, the video data 2 output from the first and second data output units 1011 and 1012 based on the timing reference signal is output.
521 and 2523 are input to the source devices 2512 and 2513 and are held. Frame synchronization is established between the video data 2521 and the video data 2523.

In the first source device 2512 of the first individual transmission system 70a, the first sink device 251
A process of returning the transmission / reception designation packet 2601 and the data packet 2611 from 0 to the first sink device via the high-speed transmission path 2501 is performed. In the first sink device 2510, the transmission / reception designation packet 2601 and the data packet 26 transmitted from the first source device 2512 are returned.
11 is discarded. Similarly, the second individual transmission system 7
In the second source device 2513 of 0b, a process of returning the transmission / reception designation packet 2601 and the data packet 2611 from the second sink device 2511 to the second sink device via the high-speed transmission path 2503 is performed. In the second sink device 2511, the transmission / reception designation packet 2601 and the data packet 2611 returned from the second source device 2513 are discarded.

Thereafter, in the first source device 2512 of the first individual transmission system 70a, every time a transmission / reception designation packet 2602, 2603 is received via the low-speed transmission path 2500, transmission / reception from the first sink device 2510 is performed. The designated packets 2602 and 2603 are returned to the sink device, and the transmission / reception designated packets 2602 and 2603 are followed by the video data 2521 from the first data output unit 1011.
Is stored in the data packets 2612 and 2613 and transmitted to the first sink device 2510 via the high-speed transmission path 2501. Similarly, in the second source device 2513 of the second individual transmission system 70b, the low-speed transmission path 2
The transmission / reception designation packets 2602 and 2603 via the communication 502
Every time is received, the transmission / reception designation packets 2602 and 2603 from the second sink device 2511 are returned to the second sink device, and after the transmission / reception designation packets 2602 and 2603, the second data output unit 1012 Is stored in the data packets 2612 and 2613 and transmitted to the second sink device 2511 via the high-speed transmission path 2503.

Then, the first and second sink devices 251
0, 2511, the high-speed transmission paths 2501, 25
03 transmission / reception designation packet 2602
2603 is discarded. Further, in the first and second sink devices 2510 and 2511, when the data packets 2612 and 2613 storing the video data are received, the received video data is output data 2531,
It is output to the video synthesizing device 1020 as 2533.

The video data 2531 and 2533 are
In a state where frame synchronization has been established with the first and second source devices 2512 and 2513, the first and second data output units 10
11 and 1012, the first,
The synchronization of the video frames has been established even at the time of output from the second sink devices 2510 and 2511. Since the data packets 2612 and 2613 are discarded after being received by the sink devices 2510 and 2511, they are not re-transferred to the source devices 2512 and 2513.

As described above, the data transmission system 70 according to the seventh embodiment has the first sink device 2510 and the first source device 2512, and these devices are connected by the low-speed transmission path 2500 and the high-speed transmission path 2501. It has a first individual transmission system 70a connected one-to-one, a second sink device 2511 and a second source device 2513, and these devices are connected one-to-one by a low-speed transmission path 2502 and a high-speed transmission path 2503. And a second individual transmission system 70b connected to the first transmission system. Each of the individual transmission systems 70a and 70b performs data transmission using a packet based on the synchronization information from the video synthesizing device 1020. Data 2531 transmitted to the video synthesizing device 1020 by the transmission system 70a of FIG.
The video data 2533 transmitted to the video synthesizing device 1020 by Ob is video data for which frame synchronization has been established, and the video synthesizing device 1020 performs direct synthesizing processing on the video data transmitted by each transmission system. be able to. Further, a buffer for absorbing a timing difference between two video data transmitted by each transmission system can be eliminated.

In each of the individual transmission systems, the transmission speed used for data transmission from the sink device to the source device depends on the transmission speed used for data transmission from the source device to the sink device. Since a transmission speed lower than the transmission speed is used, an inexpensive member is used for a transmission path for performing data transmission from the sink device to the source device, and data transmission from the sink device to the source device is performed. Inexpensive transmission / reception units can be used, and low-cost and efficient data transmission can be performed.

In the seventh embodiment, a data packet 2611 including asynchronous data transmitted from the sink devices 2510 and 2511 to the source devices 2512 and 2513 is used as a data transmission system in the source device 251.
2 and 2513, the data transmission system returns from the sink devices 2510 and 2511 to the source devices 2512 and 2511.
13 may not be sent back to the sink device.

FIG. 27 shows the sink devices 2510 and 2511.
14 shows a data structure of a transmission frame in a data transmission system that does not return a data packet 2611 from the to the source devices 2512 and 2513 to the sink device. FIG.
7A shows a data structure of a transmission frame in a low-speed transmission path from the sink devices 2510 and 2511 to the source devices 2512 and 2513, and FIG.
2 shows a data structure of a transmission frame in a high-speed transmission path from the communication device 22513 to the sink device 2510 2511.

In this data transmission system, after the transmission / reception designation packet 2701 is received by the source devices 2512 and 2513 from the sink devices 2510 and 2511 via the low-speed transmission path, the transmission / reception designation packet 2701 is transmitted from the source device at the high speed. The data is returned to the sink device via the transmission path. Here, the transmission / reception designation packet 2701 from the sink device to the source device transmitting this low-speed transmission path specifies the sink device as a source of information such as asynchronous data included in the data packet 2702 that follows the packet, As the source device. On the other hand, the transmission / reception designation packet 2701 from the source device to the sink device transmitting the high-speed transmission path designates the source device as the transmission source of information such as video data included in the data packet 2703 that follows, and designates the source device as the supply destination. Contains information specifying the sink device.

A data packet 270 containing asynchronous data transmitted from the sink devices 2510 and 2511
2 is received by the source devices 2512 and 2513 and then disappears at the source device at the end of the transmission path. Further, a data packet including video data transmitted from the source devices 2512 and 2513 is
After being received at 0, 2511, it disappears at the sink device at the end of the transmission path. In such a data transmission system, there is no need to return a data packet containing asynchronous data or video data from the receiving device to the transmitting device.

As described above, in a data transmission system in which data packets storing asynchronous data and isochronous data are deleted on the receiving side and are not returned to the transmitting side, transmission for data transmission from the sink device to the source device is performed. Only a data packet 2702 storing asynchronous data exists in a frame, and only a data packet 2703 storing isochronous data exists in a transmission frame for data transmission from a source device to a sink device.

Also, in the seventh embodiment, as the transmission / reception designation packet, a device for transmitting a data packet immediately after that and a device for receiving this data packet are designated. A channel and a reception channel may be allocated, and the transmission / reception designation packet may designate a transmission channel of a device that transmits a data packet and a reception channel of a device that receives a data packet. Also, in the seventh embodiment, the data transmission system stores synchronization information as asynchronous data in a data packet and transmits the data. However, the synchronization information is stored as isochronous data in a data packet and transmitted. You may do so.

In the seventh embodiment, the data transmission system has been described in which the synchronous information is stored as asynchronous data in the data packet and transmitted. However, the data transmission system is as shown in the second embodiment. In addition, the sink devices 2510 and 2511 multiplex the synchronization information serving as a reference of the processing timing of the isochronous data into another packet by using a special transmission / reception designation packet, and the source devices 2512 and 211.
513. Again,
The source devices of the first and second individual transmission systems constituting the data transmission system can reproduce the same frame synchronization signal (timing reference signal) based on the synchronization information from the sink device.

Also, in the seventh embodiment, the data transmission system has been described in which the transmission / reception designation packet is transmitted at regular time intervals. However, the data transmission system transmits / receives the transmission / reception designation packet at an arbitrary time interval. In this case, the same effects as those of the data transmission system according to the seventh embodiment can be obtained. In the seventh embodiment,
The case has been described where the timing reference signal used in the data transmission system is a frame synchronization signal indicating the beginning of each video frame (that is, indicating a timing at which signal processing for each video frame is started). The signal (block synchronization signal) indicating the timing of the signal processing for each block when the signal processing for the video frame is performed for each block that divides the video frame may be used.

In the seventh embodiment, a case has been described in which a camera is connected to each source device as a data output unit outside the system, and a video synthesizing device is connected to the sink device as a device outside the system. However, the data output unit outside the system connected to the source device is a VTR
And a device outside the system connected to the sink device may be a display device such as a monitor or a navigation system, or a video recording device.

[0307] Also, in Embodiment 7, specific members constituting the low-speed transmission line and the high-speed transmission line in the data transmission system are not specifically shown, but optical members are used as both the low-speed transmission line and the high-speed transmission line. Fibers may be used, metal wires (electric wires) may be used for the low-speed transmission lines 2500 and 2502, and optical fibers may be used for the high-speed transmission lines 2501 and 2503. In this case, the data transmission system according to the seventh embodiment is also used. A data transmission system similar to that described above can be realized.

Further, as shown in the fourth embodiment, the data transmission system according to the seventh embodiment
510, 2511 are provided with a phase detector for detecting a phase shift of a plurality of received isochronous data, and information on the phase shift detected by the phase detector is output as asynchronous data or isochronous data as a sink device 2510, The configuration may be such that transmission is performed from 2511 to the source devices 2512 and 2513. In this case, the source device corrects the reproduction timing of the reference signal based on the received information on the phase shift, thereby causing a phase shift of the isochronous data from the two source devices due to data delay in the transmission path. Even in this case, the sync devices 2510 and 2511 can obtain isochronous data in which synchronization has been established.

In each of the first to seventh embodiments, the data transmission system has been described in which the sink device transmits the synchronization information to the source device. However, in the data transmission system, the source device uses the synchronization information and the video data. Causes
The multiplexed data obtained by multiplexing the synchronization information and the video data may be transmitted as isochronous data.

[0310] A case will be described below where the source device transmits multiplexed signals obtained by multiplexing video data and synchronization information as isochronous data. FIG. 28 is a diagram illustrating a process of performing data transmission using the multiplexed signal. In the source device in the data transmission system, a process of multiplexing the timing reference signal 2801 (FIG. 28A) and the video data 2802 (FIG. 28B) is performed.
The multiplexing process results in a multiplexed signal 2803 (FIG. 28 (c)).
Is generated. Here, the multiplexed signal 2803 includes synchronization information 28 for reproducing the timing reference signal 2801.
01a is included. The synchronization information 2801a is based on the timing reference signal 280 for the system operation clock (that is, the operation clock of one of the sink device, the source device, the data output unit, and the video synthesizing device).
1 represents a phase, and includes, for example, a frame number, a line number, or a block number of video data. When such a multiplexed signal 2803 is received by the sink device, the multiplexed signal 2803 is received by the sink device.
803, the timing reference signal 2
804 (FIG. 28 (d)) and video data 2805 (FIG.
8 (e)) is generated.

As described above, in the data transmission systems of the first to seventh embodiments, the video data 280 is transmitted between the sink device and the source device or between the source devices.
2 (FIG. 28 (b)) instead of transmitting
The multiplexed signal 2803 (FIG. 28 (c)) obtained by multiplexing the video data and the synchronization information may be transmitted as isochronous data. (FIG. 28 (e)) 2805 and a reference signal 2804 synchronized with video data (FIG. 28 (d))
Can be easily reproduced.

(Eighth Embodiment) FIG. 29 is a block diagram for explaining a data transmission apparatus according to an eighth embodiment of the present invention. This data transmission apparatus is, for example, a data transmission system according to the first embodiment. It is used as a sink device or a source device. FIG. 29A shows a general configuration of a data transmission device used as a sink device or a source device in the data transmission system 10 according to the first embodiment, for example.

The data transmission apparatus 2910 receives the transmission data Td from the input transmission path 2900b, transmits the transmission data Td to the output transmission path 2900a, and accesses the data processing apparatus 2900 outside the system. And a controller 2901a that performs a process of outputting the synchronization information Is received as the transmission data Td, and a reference signal generator 2902a that outputs a timing reference signal 2908a to the data processing device 2900 based on the synchronization information. are doing.

Here, the transmission data Td includes isochronous data such as video data and asynchronous data such as control commands and status data. Further, the data access process of the controller 2901a includes a process of receiving the synchronization information 2907a from the data processing device 2900 and transmitting it as transmission data to the transmission side transmission line 2900a, and a process of transmitting video data to the data processing device 2900 at the same time. And input / output processing of asynchronous data 2905a such as a control command for the data processing device 2900.

When the data processing device 2900 is a data output unit such as a camera or a video reproducing device, the data transmission device 2910 operates as the source device of the first embodiment. Also, this data transmission device 2910
When the data processing device 2900 is a device using a plurality of isochronous data, such as the video synthesizing device 1020, the device operates as the sink device of the first embodiment.

FIG. 29B shows a camera (hereinafter referred to as a camera device) 2920 equipped with a network control function, which is used as a source device in the data transmission system 10 according to the first embodiment, for example. This camera device 2920 performs an imaging process based on a frame synchronization signal 2908b and outputs video data 2906b, an imaging unit 2903b, a process of receiving transmission data Td from an input transmission line 2900b, and transmission to an output transmission line 2900a. Processing for transmitting data Td, the imaging unit 2903b
Access processing of the data and transmission data T
a controller 2901b that performs a process of outputting the synchronization information Is received as d, and a reference signal generator 2902 that outputs a frame synchronization signal to the imaging unit 2903b as a timing reference signal 2908b based on the synchronization information Is.
b.

[0317] Here, the transmission data Td includes isochronous data such as video data and asynchronous data such as control commands and status data. The data access process of the controller 2901b is performed by the imaging unit 2
Isochronous data 290 such as video data from 903b
6b, transmitting the isochronous data 2906b to the output-side transmission path 2900a, and inputting / outputting asynchronous data 2905b such as a control command to the imaging unit 2903b.

When the camera device 2920 provides synchronization information to the system, the controller 29
The data access process 01b includes a process of transmitting the frame synchronization signal 2907b from the imaging unit 2903b as synchronization information to the output-side transmission path 2900a. In this camera device 2920, the imaging unit 2903b operates in the same manner as, for example, the data output unit 1011 in the data transmission system 10 of the first embodiment, and the controller 2901b and the reference signal generator 2902b are the same as those of the first embodiment. 1, for example, the controller 201b1 of the first source device 102 and the reference signal generator 202b1
Works the same as.

In the camera device 2920 having such a configuration, the image pickup unit 2903 synchronizes with the reference signal (that is, the frame synchronization signal) unique to the isochronous data reproduced from the synchronization information Is by the reference signal generator 2902b. Video data will be output. For this reason, in a data transmission system having a plurality of camera devices 2920b, video data output from each of the plurality of camera devices 2920 has frame synchronization established, and receives a plurality of video data in the data transmission system. The data transmission device (sink device) can acquire a plurality of video data for which frame synchronization has been established.

FIG. 29C shows a camera (camera device) 2930 having a network control function, which is used as a source device in the data transmission system 10 according to the first embodiment, for example.

This camera device 2930 is different from the camera device 2920 shown in FIG.
Video compression unit 29 that compresses video data 2906b output from 3b and outputs compressed video data 2906c.
31. Therefore, this camera 2930
In the controller 2901b, the process of transmitting the compressed video data 2906c instead of the video data 2906b to the output side transmission line 2900a is performed as the process of transmitting the isochronous data.

The data transmission device 2 shown in FIG.
In the camera device 910, the camera device 2920 shown in FIG. 29B, and the camera device 2930 shown in FIG. 29C, the asynchronous data received from the input-side transmission path 2900b is input to the controllers 2901a and 2901b. Data transmission device 2910, camera device 29
20 and 2930 can be controlled.

In the data transmission device 2910 and the camera devices 2920 and 2930, the controller 290
1a and 2901b, the status signal indicating the state of the device is transmitted as asynchronous data to the output side transmission line 2900a, so that the data transmission device 2910 and the camera device 2
In 920 and 2930, it is possible to detect the operation state of another device constituting the data transmission system.

[0324]

As described above, according to the data transmission system of the present invention (claim 1), a plurality of isochronous data that are processed at a timing synchronized with a reference signal having a fixed period are transmitted to a transmission line. A source device, and one or more sink devices for receiving a plurality of isochronous data transmitted to the transmission path, the specific device being one of the sink device and the plurality of source devices, It is assumed that reference signal information for reproducing a predetermined reference signal serving as a reference for processing timing of isochronous data is transmitted to a transmission line, and a plurality of source devices other than the specific device are transmitted to the transmission line. The reference signal information is received, the predetermined reference signal is obtained, and the isochronous data synchronized with the reference signal is output, so that the sink device receiving a plurality of isochronous data performs data synchronization. Established Could be obtained a plurality of isochronous data, there is an effect that it is possible to eliminate a buffer to absorb the phase shift data isochronous supplied from a plurality of source devices.

According to the present invention (claim 2), in the data transmission system according to claim 1, data transmission on the transmission path is repeated for each transmission frame which is a unit of transmission data. The transmission frame shall have a frame header for storing information indicating the head of each transmission frame, and an isochronous data slot for storing the isochronous data. In the existing data transmission method using a transmission frame having a frame header and an isochronous data slot, the reference signal from the specific device is not changed without changing the data structure in the transmission frame. Transmission of information can be performed.

According to the present invention (claim 3), in the data transmission system according to claim 2, the specific device periodically transmits the special frame header including the reference signal information. In a source device other than the specific device, reference signal information can be acquired at regular intervals, and isochronous data constantly synchronized with a correct reference signal can be generated.

According to the present invention (claim 4), in the data transmission system according to claim 1, data transmission on the transmission path is performed for each transmission frame which is a unit of transmission data. The frame has a frame header that stores information indicating the head of each transmission frame, an isochronous data slot that stores the isochronous data, and an asynchronous data slot that stores the asynchronous data. Since the apparatus stores the reference signal information in the isochronous data slot or the asynchronous data slot and transmits the same, the reference signal information can be multiplexed with the isochronous data or the asynchronous data and transmitted.

According to the present invention (claim 5), in the data transmission system according to claim 1, the specific device includes a source device that is a transmission source of the isochronous data, and a transmission device that transmits the isochronous data. Since a transmission / reception designation packet storing information designating the preceding sink device is transmitted to the transmission path, and a specific transmission / reception designation packet transmitted from the specific device includes the reference signal information. ,
In the existing packet transmission method using the transmission / reception designation packet, the reference signal information can be transmitted from the specific device without changing the data structure of the packet transmission.

According to the present invention (claim 6), in the data transmission system according to claim 5, the specific device periodically transmits a specific transmission / reception designation packet including the reference signal information. Therefore, in the source devices other than the specific device, the reference signal information can be acquired at regular intervals, and isochronous data constantly synchronized with the correct reference signal can be generated.

According to the present invention (claim 7), in the data transmission system according to claim 1, the specific device is a source device that is a source of the isochronous data, and a destination device that is a destination of the isochronous data. A transmission / reception designation packet storing information for designating a sink device serving as a source and a sink device or a source device serving as a source and a destination of the asynchronous data is transmitted to the transmission path, and the reference signal information is transmitted in the isochronous manner. Since the data is transmitted in the form of data or asynchronous data, the reference signal information can be multiplexed with isochronous data or asynchronous data and transmitted.

According to the present invention (claim 8), in the data transmission system according to claim 1, a plurality of sink devices and source devices that transmit data packets in each transmission cycle during a unit transmission process are provided. An arbitration for acquiring a transmission right to transmit a data packet is performed, and a packet is transmitted between a transmission source device that has acquired the transmission right of the data packet by the arbitration and a transmission destination device corresponding to the transmission source device. Data shall be transmitted, and the specific device shall be
A cycle start packet indicating a start timing of a transmission cycle, which is a period of the unit transmission process, is transmitted at regular intervals, and the reference signal information is included in isochronous data or asynchronous data and transmitted to the transmission path. Therefore, even in an existing packet transmission method that performs arbitration for acquiring a transmission right to transmit a data packet, the reference signal information is transmitted from the specific device without changing the data structure of the packet transmission. Can be.

According to the present invention (claim 9), in the data transmission system according to claim 1, a plurality of individual transmission systems each including at least one source device and at least one sink device are formed. One specific device among the plurality of devices constituting the individual transmission system, the reference signal information shall be sent to another device in the individual transmission system to which the specific device belongs, and each of the individual transmission systems, Since the devices other than the specified device receive the reference signal information sent from the specified device and reproduce the reference signal unique to each individual transmission system, the sink device and the source device constituting the system are individually configured. Even if the transmission system is divided into multiple groups,
In a device that uses isochronous data transmitted from the source device of the individual transmission system, as a plurality of isochronous data,
Synchronous established isochronous data can be obtained.

According to the present invention (claim 10), claim 1
In the data transmission system described above, the sink device, comprises a phase detector for detecting the amount of phase shift of the plurality of received isochronous data, the phase difference information indicating the amount of phase shift detected by the phase detector It is assumed that at least one of the plurality of source devices is synchronized with a timing at which a reference signal is reproduced from the reference signal information based on the phase difference information transmitted from the sink device. Since the correction is made so that the phase shift amount is reduced, even when the phase shift of the isochronous data from the two source devices occurs due to the data delay in the transmission path, the synchronization is established even when Sex data can be obtained.

[0334] According to the data transmission system of the present invention (claim 11), a source device for transmitting isochronous data processed at a timing synchronized with a reference signal having a fixed period, and a source device for transmitting isochronous data transmitted from the source device. A sink device for receiving isochronous data, wherein the sink device transmits reference signal information for reproducing a predetermined reference signal serving as a reference for processing timing of the isochronous data to a first transmission path. And a signal reproduction process for receiving the reference signal information from the sink device and reproducing the predetermined reference signal from the received reference signal information. And performing a data transmission process of transmitting the isochronous data to the sink device via a second transmission path in synchronization with the reproduced predetermined reference signal. Since the transmission rate of the isochronous data in the second transmission path is higher than the transmission rate of the reference signal information in the first transmission path, the transmission of the isochronous data using a plurality of systems is performed. In a device that receives isochronous data, isochronous data with frame synchronization established can be obtained as a plurality of isochronous data, and isochronous data supplied from a plurality of source devices can be obtained. This has the effect of eliminating the need for a buffer that absorbs the phase shift. Further, an inexpensive member is used for a transmission path for performing data transmission from the sink device to the source device, and an inexpensive transmission / reception unit for performing data transmission from the sink device to the source device. Can be used, and efficient data transmission can be performed at low cost.

According to the present invention (claim 12), claim 1
1. The data transmission system according to 1, wherein the data transmission from the sink device to the source device includes a frame header indicating a head of each transmission frame and an asynchronous data slot for storing asynchronous data processed at an arbitrary timing. The data transmission from the source device to the sink device is performed in units of a first transmission frame, and the data transmission from the source device to the sink device includes the frame header, the isochronous data slot storing the isochronous data, and the asynchronous data slot. Since the sink device transmits the reference signal information while including the reference signal information in the frame header of the first transmission frame, the frame device and the isochronous data slot In the existing data transmission method using the transmission frame having the Without changing the data structure, it is possible to perform the transmission of the reference signal information.

According to the present invention (claim 13), claim 1
2. In the data transmission system according to 2, since the sink device transmits the frame header including the reference signal information at a constant period, the source device can acquire the reference signal information at a constant period, Isochronous data synchronized with a correct reference signal can always be generated.

According to the present invention (claim 14), claim 1
1. The data transmission system according to 1, wherein the data transmission from the sink device to the source device includes a frame header indicating a head of each transmission frame and an asynchronous data slot for storing asynchronous data processed at an arbitrary timing. The data transmission from the source device to the sink device is performed in units of a first transmission frame, and the data transmission from the source device to the sink device includes the frame header, the isochronous data slot storing the isochronous data, and the asynchronous data slot. And the sink device transmits the reference signal information while including the reference signal information in the asynchronous data, so that the reference signal information is multiplexed into isochronous data or asynchronous data. Can be transmitted.

According to the present invention (claim 15), claim 1
1. The data transmission system according to 1, wherein the sink device stores information specifying a device as a transmission source of the isochronous data and a device as a transmission destination of the isochronous data in a transmission / reception designation packet. Since the specific transmission / reception designation packet transmitted from the sink device includes the reference signal information, the existing packet transmission method using the transmission / reception designation packet requires the packet transmission. The reference signal information can be transmitted from the specific device without changing the data structure to be performed.

According to the present invention (claim 16), claim 1
5. In the data transmission system according to item 5, since the sink device periodically transmits a specific transmission / reception designation packet including the reference signal information, the source device transmits the reference signal information at regular intervals. Isochronous data that can be acquired and always synchronized with a correct reference signal can be generated.

According to the present invention (claim 17), claim 1
1. The data transmission system according to 1, wherein the sink device performs a process of storing the reference signal information in a required asynchronous data packet among asynchronous data packets including asynchronous data and transmitting the reference signal information to a first transmission path. Since the source device performs transmission / reception processing of asynchronous data processed at an arbitrary timing and transmits an isochronous data packet storing the isochronous data to the second transmission line, Signal information can be multiplexed on asynchronous data and transmitted. .

According to the present invention (claim 18), claim 1
In the data transmission system according to the eleventh aspect, since the transmission path is configured using an optical fiber, data transmission can be performed at high speed.

According to the present invention (claim 19), claim 1
In the data transmission system described above, the sink device and the source device transmit and receive data as an optical signal, and the transmission path has a plurality of input terminals and a plurality of output terminals, and any one of the input terminals An optical star coupler that outputs the supplied optical signal from all output terminals, an output-side optical fiber that connects the output terminals of the sink device and the source device to the input terminals of the optical star coupler, Since it consists of an input terminal and an input-side optical fiber that connects the output terminal of the optical star coupler,
Even when data communication is interrupted on one transmission path, data transmission can be performed via another transmission path, and the reliability of data transmission can be improved.

According to the present invention (claim 20), claim 1
2. The data transmission system according to claim 1, wherein a first transmission path for transmitting data from the sink device to the source device is configured by a conductor that propagates an electric signal, and transmits data from the source device to the sink device. The second transmission line for transmitting data is constituted by an optical fiber for transmitting an optical signal, so that transmission of data having a small data amount is performed by the first transmission line and transmission of data having a large data amount is performed by the second transmission line. Thus, an inexpensive data transmission system with good transmission efficiency can be realized.

According to the present invention (claim 21), claim 1
Or the data transmission system according to 11, wherein the source device is connected to a video data output unit having an imaging unit that performs an imaging process or a video playback unit that performs a playback process of video data, and is output from the video data output unit. The video data is transmitted to the transmission path as isochronous data, and the sink device is connected to a video processing device that synthesizes or records a plurality of video data, and is transmitted as isochronous data from the plurality of source devices. Since the plurality of pieces of video data are received and supplied to the video processing device, a navigation system using actual video in a car or the like, a drive recorder in a car or the like, or a surveillance camera system can be realized.

According to the present invention (claim 22), claim 2
2. The data transmission system according to claim 1, further comprising: a video compression unit that compresses the video data supplied from the video data output unit and outputs compressed video data, wherein the source device is configured to output the compressed video data to the isochronous data. Therefore, the amount of isochronous data sent from the source device can be reduced.

According to the present invention (claim 23), claim 1
12. The data transmission system according to 11, wherein the source device is a source device and a transmission line connecting the source device is mounted on a vehicle, and the source device is an imaging unit that performs an imaging process or reproduces video data. Connected to a vehicle-mounted video data output unit having a video playback unit for performing processing, and transmitting the video data output from the video data output unit to the transmission path as isochronous data; and It is connected to an on-board video processing device that synthesizes or records video data, receives a plurality of video data transmitted as isochronous data from the plurality of source devices, and supplies the video data to the video processing device. , The sink device, the source device, and the transmission path constitute a network for transmitting video data in the vehicle. According vehicle navigation system or car drive recorder, it can be realized.

[0347] According to the data transmission method of the present invention (claim 24), reference signal information for reproducing a predetermined reference signal serving as a reference of processing timing of isochronous data processed at a fixed timing is provided. A data transmission step of transmitting from the specific device among one of a sink device receiving isochronous data and a plurality of source devices transmitting isochronous data to the transmission path; And a signal reproduction step of receiving the reference signal information sent to the path and reproducing the reference signal. Data can be obtained, and there is an effect that a buffer for absorbing a phase shift of isochronous data supplied from a plurality of source devices is not required.

According to the data transmission method of the present invention (claim 25), the isochronous data processed at the timing synchronized with the reference signal having a fixed period is transmitted to the source device which is the transmission source of the isochronous data. From, connected to the source device in a one-to-one correspondence relationship, when transmitting to the sink device that is the destination of the isochronous data, the sink device, the reference of the processing timing of the isochronous data A reference signal information for reproducing a predetermined reference signal is transmitted to a source device via a first transmission path. The source device receives the reference signal information from the sink device and transmits the predetermined reference signal to the source device. And the isochronous data is transmitted to the sink device via the second transmission path in synchronization with the reproduced predetermined reference signal, so that a system having the isochronous data and the source device is duplicated. When transmitting isochronous data by using, the device that receives isochronous data can obtain isochronous data with frame synchronization established as a plurality of isochronous data. This has the effect of eliminating the need for a buffer for absorbing the phase shift of isochronous data supplied from the source device. Further, since the transmission rate of the isochronous data in the second transmission path is higher than the transmission rate of the reference signal information in the first transmission path, data transmission from the sink device to the source device is performed. An inexpensive member is used for the transmission path for performing the transmission, and an inexpensive transmission / reception unit for transmitting data from the sink device to the source device can be used. Transmission can take place.

According to the data transmission apparatus of the present invention (claim 26), transmission and reception of isochronous data processed at a timing synchronized with a reference signal having a fixed period and asynchronous data processed at an arbitrary timing And a reference signal for reproducing the reference signal based on reference signal information for reproducing a predetermined reference signal received as the asynchronous data and serving as a reference for processing timing of the isochronous data. A generator for receiving a plurality of isochronous data, a plurality of synchronized isochronous data can be obtained, and a plurality of isochronous data supplied from a plurality of data transmission sources can be obtained. This eliminates the need for a buffer for absorbing the phase shift.

[0350] According to the data transmission apparatus of the present invention (claim 27), in the data transmission apparatus of claim 26, there is provided an image pickup section for performing image pickup processing and outputting video data. The video data is output in synchronization with the reference signal reproduced by the reference signal generator, and the controller sends the video data output from the imaging unit to the transmission path as the isochronous data. Therefore, an apparatus that receives a plurality of video data has the effect of being able to obtain a plurality of video data with synchronization established.

[0351] According to the data transmission apparatus of the present invention (claim 28), in the data transmission apparatus of claim 27, a video compression section for compressing video data from the imaging section and outputting compressed video data is provided. Since the controller transmits the compressed video data as the isochronous data, the amount of isochronous data transmitted from the source of the video data can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a data transmission system according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a sink device (FIG. 1A) and a first source device (FIG. 2A) included in the data transmission system according to the first embodiment;
(b)) and the configuration of the second source device (FIG. (c)).

FIG. 3 is a diagram showing a data structure (transmission frame format) of transmission data propagating through a transmission path of the data transmission system according to the first embodiment.

FIG. 4 is a data structure of transmission data propagating through a transmission path of the data transmission system according to the first embodiment (FIG. 4A), and reproduced by first and second source devices in the data transmission system; The timing reference signal (FIG. (B), FIG. (C)) is shown.

FIG. 5 is a diagram for explaining processing of transmission data in the data transmission system according to the first embodiment, and includes a timing reference signal from the first and second source devices (FIG.
(c)), video data to the first and second source devices (FIG.
(b), (d)), transmission data Td on the transmission line ((e)),
And video data (FIGS. (F) and (g)) from the sink device.

FIG. 6 is a diagram for explaining a case where synchronization information is transmitted using an isochronous data slot in the data transmission system according to the first embodiment, and illustrates transmission paths 100a and 100;
0b, 100c, the transmission frame of the data
(a), FIG. (b) and FIG. (c)).

FIG. 7 is a diagram showing a data transmission system according to a second embodiment of the present invention.

FIG. 8 is a diagram illustrating a sink device (FIG. 8A) and a first source device (FIG. 7A) that constitute the data transmission system according to the second embodiment;
(b)) and a second source device (FIG. (c)).

FIG. 9 is a diagram showing a data structure (transmission frame format) of transmission data propagating through a transmission path of the data transmission system according to the second embodiment.

FIG. 10 shows a data structure of transmission data propagating through a transmission line of the data transmission system according to the second embodiment (FIG. 10A), and data reproduced by first and second source devices in the data transmission system; Timing reference signal (Figure (b), Figure (c))
Is shown.

FIG. 11 is a diagram for explaining processing of transmission data in the data transmission system according to the second embodiment;
Timing reference signal from the source device (Figure (a), Figure
(c)), video data to the first and second source devices (FIG.
(b), (d)), transmission data Td on the transmission line ((e)),
And video data (FIGS. (F) and (g)) from the sink device.

FIG. 12 is a diagram illustrating an example of a system in a case where the connection configuration of each device in the data transmission system according to the second embodiment is changed from a ring connection to a bus connection.

FIG. 13 shows a connection configuration of each device in the data transmission system according to the second embodiment, using a multi-input multi-output signal distributor, and using a data input side transmission line of a sink device and first and second source devices. FIG. 2 is a diagram illustrating a system in which the data output side and the data output side are separated from each other, and each device is replaced with a connection configuration in which a bus connection is made.

FIG. 14 is a diagram showing a connection configuration of each device in the data transmission system according to the second embodiment, using a multi-input multi-output signal distributor, and using the data transmission device groups of the first, second, and third groups. FIG. 11 is a diagram illustrating a system in which an input-side transmission line and a data output-side output are separated, and each group is replaced with a connection configuration in which a bus connection is made.

FIG. 15 is a diagram showing a data transmission system according to a third embodiment of the present invention.

FIG. 16 shows a sink device (FIG. (A)), a first source device (FIG. (B)), and a second source device (FIG. (C)) constituting the data transmission system according to the third embodiment. FIG.

FIG. 17 is a diagram showing a data structure (transmission frame format) of transmission data propagating through a transmission path of the data transmission system according to the third embodiment.

FIG. 18 shows a data structure of transmission data propagating through a transmission path of the data transmission system according to the third embodiment (FIG. 13A), and reproduced by the first and second source devices in the data transmission system. Timing reference signal (Figure (b), Figure (c))
FIG.

FIG. 19 is a diagram for explaining processing on transmission data in the data transmission system according to the third embodiment, and illustrates timing reference signals (FIGS. (A) and (c)) from first and second source devices. ), Video data to the first and second source devices (FIGS. (B) and (d)), and transmission data Td on the transmission path.
(Figure (e)) and video data from the sink device (Figure
(f) and Fig. (g)).

FIG. 20 is a diagram showing a sink device constituting a data transmission system according to the fourth embodiment.

FIG. 21 is a diagram showing input / output signals to / from each device of the data transmission system according to the fourth embodiment, in which video data (FIGS. (A) and (b)) from a sink device and to a second source device; (FIG. (D), FIG. (F)) and a frame synchronization signal (FIG. (C), FIG. (E)) corresponding to the video data.

FIG. 22 is a diagram showing a data transmission system according to a fifth embodiment of the present invention.

FIG. 23 is a diagram illustrating a data transmission system according to a sixth embodiment of the present invention.

FIG. 24 shows each transmission frame (FIG. 24) of transmission data propagating through the transmission path of the data transmission system according to the sixth embodiment.
(a)), a transmission frame on a low-speed transmission path (FIG. (b)), and a transmission frame on a high-speed transmission path (FIG. (c)).

FIG. 25 is a diagram showing a data transmission system according to a seventh embodiment of the present invention.

FIG. 26 shows an example of a transmission frame on a low-speed transmission line of the data transmission system according to the seventh embodiment (FIG. 12A),
FIG. 2 is a diagram showing an example of a transmission frame on a high-speed transmission line of the system (FIG. 2B).

FIG. 27 shows another example of the transmission frame on the low-speed transmission line of the data transmission system according to the seventh embodiment (FIG.
(a)) and another example (FIG. (b)) of a transmission frame on the high-speed transmission line of the system.

FIG. 28 is a diagram illustrating a process of transmitting a multiplexed signal as isochronous data in the data transmission system according to each of the embodiments of the present invention, and illustrates a timing reference signal (FIG.
(D), video data ((b) and (e)), and a multiplexed signal ((c)).

FIG. 29 is a diagram illustrating a data transmission device according to an eighth embodiment of the present invention, in which a data transmission device (FIG. (A)) as a sink device or a source device, and a camera device (FIG. (B)) as a source device. ) And a camera device having a compression unit (FIG. (C)).

FIG. 30 is a diagram showing a conventional data transmission system.

[Explanation of symbols]

10, 20, 20a, 20b, 20c, 30, 50, 6
0, 70 data transmission system 50a, 60a, 70a first individual transmission system 50b, 60b, 70b second individual transmission system 100a to 100c, 700a to 700c, 1200,
1301a to 1303a, 1301b to 1303b, 1
401a to 1403a, 1401b to 1403b, 14
01c, 1402c, 1401d, 1500a to 150
0c, 2200a to 2200f, 2900a, 2900
b transmission line 101,701,1201,1301,1401,15
01 Sink device 102, 702, 1202, 1302, 1404, 14
06,1502,2203,2312,2512 1st
Source devices 103, 703, 1203, 1303, 1406, 15
03, 2204, 2313, 2513 Second source device 201a, 201b1, 201b2, 801a, 801
b1, 801b2, 1601a, 1601b1, 160
1b2, 2001a, 2901a, 2921b Controllers 202a, 202b1, 202b2, 802a, 802
b1, 802b2, 1602a, 1602b1, 160
2b2, 2002a, 2902a, 2902b Reference signal generator 203a, 203b1, 203b2, 602, 803
a, 803b1, 803b2, 1603a, 1603b
1,1603b2, 2003a, 2404, 2905
a, 2905b Asynchronous data 204a1, 204a2, 205, 206, 804a
1,804a2,805,806,1604a1,1
604a2, 1605, 1606, 2004a1, 20
04a2, 2204a1-2204a4, 2205-2
208,2321,2323,2331,233,2
405, 2521, 2523, 2531, 2533, 2
802, 2805, 2906a, 2906b Video data (isochronous data) 207a, 207b1, 207b2, 807a, 807
b1, 807b2, 1607a, 1607b1, 160
7b2, 2007a, 2211, 230, 2908
a, 2908b Synchronization information 208a, 208b1, 208b2, 808a, 808
b1, 808b2, 1608a, 1608b1, 160
8b2, 2008a, 2208b1-2208b4, 2
320, 2322, 2801, 2804, 2907a,
2907b Timing reference signal (frame synchronization signal) 301 Frame header 302, 2403 Isochronous data slot 302a1, 302a2, 302a3, 302am Individual data slot 303, 2402a, 2402b Asynchronous data slot 401 Special frame header 402, 2401a, 2401b Frame header 601 , 603, 604 Isochronous data 809a, 809b1, 809b2 Selection switches 901a1, 901a2, 901a3, 901an, 1
001a1, 1001a2, 1001a3, 1101a
1,1101a2, 2601-2603, 2701 Transmission / reception designation packet 902a1, 902a2, 1002a1, 1002a
2, 1102a1, 1102a2, 2612, 261
3,2702,2703 Data packet 903,1710 Transmission frame 1011,1051 First data output unit 1012,1052 Second data output unit 1053 Third data output unit 1054 Fourth data output unit 1020,1050 Video combining device 1030 Data processing device 1310 Distributor 1402, 2045 Third source device 1405, 2046 Fourth source device 1504 Data transmission device 1701 Cycle start packet 1703, 1703a, 1704, 1704a Isochronous data packet 1705, 1705a, 2611 Asynchronous data Packet 2010 Phase detector 2201, 310, 2510 First sink device 2202, 2311, 2511 Second sink device 2300, 2302, 2500, 2502 Low-speed transmission path 2301, 2303, 2501, 2503 High-speed transmission path 2803 Multiplexed signal 2900 Data processing device 2903a, 2903b Imaging unit 2906c Compressed video data 2910 Data transmission device 2920, 2930 Camera device 2931 Video compression unit Ap Arbitration period Cs0 to Cs32 Control signal Ipd Phase difference information Is Synchronization information Od0 to Od2 Output data Pd Phase shift T1a, T1b First and second input terminals T2 Output terminal Td Transmission data Td1, Td2, Td3, Tdn Transmission frame

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) H04N 5/073 H04L 11/00 330

Claims (28)

[Claims] 1. A transmission path for transmitting isochronous data processed at a timing synchronized with a reference signal having a fixed period and asynchronous data processed at an arbitrary timing, and transmitting the isochronous data. A data transmission system comprising: a plurality of source devices for transmitting to a transmission line; and one or more sink devices for receiving a plurality of isochronous data transmitted to the transmission line. And transmitting the reference signal information for reproducing a predetermined reference signal serving as a reference of the processing timing of the isochronous data to the transmission line. The plurality of source devices receive the reference signal information transmitted to the transmission path, acquire the predetermined reference signal, and output isochronous data synchronized with the reference signal. Data transmission system to be. 2. The data transmission system according to claim 1, wherein the data transmission on the transmission path is repeatedly performed for each transmission frame that is a unit of transmission data, and the transmission frame is a transmission frame of each transmission frame. A frame header for storing information indicating the head, and an isochronous data slot for storing the isochronous data, wherein the specific device transmits the reference signal information by including the reference signal information in the frame header. A data transmission system, characterized in that: 3. The data transmission system according to claim 2, wherein said specific device periodically transmits a special frame header including said reference signal information. 4. The data transmission system according to claim 1, wherein the data transmission on the transmission path is performed for each transmission frame that is a unit of transmission data, and the transmission frame is a head of each transmission frame. A frame header for storing information indicating the same, an isochronous data slot for storing the isochronous data, and an asynchronous data slot for storing the asynchronous data. The source device performs the process of transmitting and receiving the asynchronous data in addition to the process of receiving data. The source device performs the process of transmitting and receiving the asynchronous data in addition to the process of transmitting the isochronous data. Wherein the specific device transmits the reference signal information stored in the isochronous data slot or the asynchronous data slot. Data transmission system, characterized in that there. 5. The data transmission system according to claim 1, wherein the specific device specifies a source device as a transmission source of the isochronous data and a sink device as a transmission destination of the isochronous data. A transmission / reception designation packet storing information is transmitted to the transmission path. A specific transmission / reception designation packet transmitted from the specific device includes the reference signal information. . 6. The data transmission system according to claim 5, wherein the specific device periodically transmits a specific transmission / reception designation packet including the reference signal information. 7. The data transmission system according to claim 1, wherein the sink device and the source device perform a process of transmitting and receiving a data packet storing the isochronous data or the asynchronous data. A source device that is a source of the isochronous data, a sink device that is a destination of the isochronous data,
And transmitting a transmission / reception designation packet storing information designating a sink device or a source device as a transmission source and a transmission destination of the asynchronous data to the transmission path, and converting the reference signal information into the isochronous data or the asynchronous data. A data transmission system characterized in that the data transmission system includes and transmits the data. 8. The data transmission system according to claim 1, wherein the sink device and the source device perform a process of transmitting and receiving a data packet storing the isochronous data or the asynchronous data. In the data transmission, a unit transmission process for transmitting data within a certain period of time is repeatedly performed. A sink device and a source device that transmit a data packet in each transmission cycle which is a period of the unit transmission process include a data packet. Arbitration for acquiring the transmission right to transmit the data packet, and the transmission of the data packet is performed between the transmission source device that has acquired the transmission right of the data packet by the arbitration and the transmission destination device corresponding to the transmission source device. The above-mentioned specific device performs cycle transmission indicating a start timing of a transmission cycle which is a period of the unit transmission process. Data transmission system, characterized in that sending bets packets at predetermined time intervals, and including the reference signal information in the isochronous data or asynchronous data is to transmitted to the transmission path. 9. The data transmission system according to claim 1, wherein a plurality of individual transmission systems each including at least one source device and at least one sink device are formed, and a plurality of individual transmission systems constituting each of the individual transmission systems are provided. One of the devices transmits the reference signal information to another device in the individual transmission system to which the specific device belongs. The device other than the specific device in each of the individual transmission systems Is a data transmission system for receiving reference signal information sent from the specific device and reproducing a reference signal unique to each individual transmission system. 10. The data transmission system according to claim 1, wherein the sink device includes a phase detector for detecting a phase shift amount of the received plurality of isochronous data, and the phase detected by the phase detector. At least one source device of the plurality of source devices reproduces a reference signal from the reference signal information based on the phase difference information transmitted from the sink device. A data transmission system for correcting the timing of the data transfer so that the amount of phase shift in the sink device is reduced. 11. A source device for transmitting isochronous data processed at a timing synchronized with a reference signal having a fixed period, a sink device for receiving isochronous data transmitted from the source device, and the source device A data transmission system having first and second transmission paths in which data transmission directions are different from each other, connecting the device and the sink device such that they have a one-to-one correspondence. The source device transmits reference signal information for reproducing a predetermined reference signal serving as a reference for processing timing of temporal data to the source device via the first transmission path; Receives the reference signal information from the sink device, a signal reproduction process of reproducing the predetermined reference signal from the received reference signal information, and the reproduced predetermined reference signal Thereby synchronize, the isochronous data and performs data transmission processing to be transmitted to the sink device via the second transmission path, the transmission speed of isochronous data in the second transmission line is,
A data transmission system, wherein the transmission speed is higher than the transmission speed of the reference signal information in the first transmission path. 12. The data transmission system according to claim 11, wherein the sink device and the source device perform transmission / reception processing of asynchronous data processed at an arbitrary timing. The data transmission from the sink device to the source device is performed for each transmission frame, which is a unit of transmission data, and includes a frame header indicating the beginning of each transmission frame, and asynchronous data processed at an arbitrary timing. The data transmission from the source device to the sink device is performed in units of a first transmission frame having an asynchronous data slot for storing the frame header and the isochronous data. A second transmission frame having a temporal data slot and the asynchronous data slot is performed in units of a unit. The data transmission system, wherein the sink device transmits the reference signal information while including the reference signal information in a frame header of the first transmission frame. 13. The data transmission system according to claim 12, wherein the sink device transmits a frame header including the reference signal information at a constant period. 14. The data transmission system according to claim 11, wherein the sink device and the source device perform transmission / reception processing of asynchronous data processed at an arbitrary timing. Is performed for each first transmission frame that is a unit of transmission data. The data transmission from the sink device to the source device is processed at an arbitrary timing with a frame header indicating the head of each transmission frame. The transmission is performed in units of a transmission frame having an asynchronous data slot for storing asynchronous data. The data transmission from the source device to the sink device includes storing the frame header and the isochronous data. A second transmission frame having a temporal data slot and the asynchronous data slot is performed in units of a unit. The data transmission system, wherein the sink device transmits the reference signal information while including the reference signal information in the asynchronous data. 15. The data transmission system according to claim 11, wherein the sink device transmits information that specifies a device that is a source of the isochronous data and a device that is a destination of the isochronous data. A data transmission / reception designation packet stored in a transmission / reception designation packet and transmitted to a first transmission path, wherein the specific transmission / reception designation packet transmitted from the sink device includes the reference signal information; system. 16. The data transmission system according to claim 15, wherein the sink device periodically transmits a specific transmission / reception designation packet including the reference signal information. 17. The data transmission system according to claim 11, wherein said sink device performs transmission / reception processing of asynchronous data processed at an arbitrary timing, and is a transmission source of said isochronous data or asynchronous data. And information specifying a device to which the isochronous data or the asynchronous data is to be transmitted is stored in a transmission / reception specifying packet and transmitted to the first transmission path, and the reference signal information is transmitted to the asynchronous data including the asynchronous data. The source device performs a process of storing the packet in a required asynchronous data packet among the packets and sending the packet to the first transmission path. The source device performs a process of transmitting and receiving asynchronous data processed at an arbitrary timing, A data transmission system for transmitting an isochronous data packet storing temporal data to a second transmission path. Beam. 18. The data transmission system according to claim 1, wherein the transmission path is configured using an optical fiber. 19. The data transmission system according to claim 1, wherein the sink device and the source device transmit and receive data as an optical signal, and the transmission path includes a plurality of input terminals and a plurality of output terminals. An optical star coupler that outputs an optical signal supplied to any one of the input terminals from all output terminals, and an output-side optical fiber that connects the output terminals of the sink device and the source device to the input terminals of the optical star coupler. A data transmission system comprising: an input-side optical fiber that connects input terminals of the sink device and the source device to an output terminal of the optical star coupler. 20. The data transmission system according to claim 11, wherein the sink device transmits the output data as an electric signal,
Receiving the input data as an optical signal, the source device transmitting the output data as an optical signal, receiving the input data as an electric signal, and transmitting the data from the sink device to the source device. The first transmission line is formed by a conductor that transmits an electric signal, and the second transmission line for transmitting data from the source device to the sink device is formed by an optical fiber that transmits an optical signal. A data transmission system characterized by comprising. 21. The data transmission system according to claim 1, wherein the source device is connected to a video data output unit having an imaging unit that performs an imaging process or a video playback unit that performs a playback process of video data. The video data output from the video data output unit is transmitted as isochronous data to a transmission path. The sink device is connected to a video processing device that synthesizes or records a plurality of video data, A data transmission system for receiving a plurality of video data transmitted as isochronous data from a source device and supplying the video data to the video processing device. 22. The data transmission system according to claim 21, wherein the source device includes a video compression unit that compresses video data supplied from the video data output unit and outputs compressed video data. A data transmission system for transmitting data as the isochronous data. 23. The data transmission system according to claim 1, wherein the sink device, the source device, and a transmission line connecting the sink device and the source device are mounted on a vehicle, and the source device performs an imaging process. The video data output unit is connected to an in-vehicle video data output unit having an imaging unit for performing video data playback processing and a video playback unit for performing video data playback processing, and transmits video data output from the video data output unit to a transmission path as isochronous data. Yes, the sink device is connected to an on-board video processing device that synthesizes or records a plurality of video data, receives a plurality of video data transmitted as isochronous data from the plurality of source devices, The sink device, the source device, and the transmission path are connected to the network for transmitting video data in the vehicle. Data transmission system, characterized by constituting the workpiece. 24. A method of transmitting isochronous data processed at a timing synchronized with a reference signal having a fixed period and asynchronous data processed at an arbitrary timing to a plurality of source devices as transmission sources of the isochronous data. A data transmission method for transmitting the isochronous data to one or more sink devices via a transmission path, wherein a predetermined reference signal serving as a reference for processing timing of the isochronous data is reproduced. Transmitting a reference signal information to the transmission path from the specific device of the sink device and the plurality of source devices to the transmission line; and transmitting the reference signal information to the transmission line by the plurality of source devices. A signal reproducing step of receiving reference signal information and reproducing the reference signal. 25. Isochronous data processed at a timing synchronized with a reference signal having a fixed period is changed from a source device that is a source of isochronous data to a one-to-one correspondence with the source device. A data transmission method for transmitting to a connected sink device to which the isochronous data is transmitted, wherein reference signal information for reproducing a predetermined reference signal serving as a reference for processing timing of the isochronous data is provided. Transmitting the reference signal information from the sink device to the source device via the first transmission path; and receiving the reference signal information from the sink device at the source device to reproduce the predetermined reference signal. A signal reproducing step; and a data transmitting step of transmitting the isochronous data to the sink device via a second transmission path in synchronization with the reproduced predetermined reference signal. Transmission speed of isochronous data in the second transmission line is,
A data transmission method, which is faster than the transmission speed of the reference signal information in the first transmission path. 26. Isochronous data connected to a transmission path and processed at a timing synchronized with a reference signal having a fixed period, and asynchronous data processed at an arbitrary timing are transmitted or transmitted via the transmission path. A data transmission device for receiving, comprising: a controller that controls transmission and reception of the isochronous data and asynchronous data; and a predetermined reference signal that is received as the asynchronous data and serves as a reference for processing timing of the isochronous data. A data transmission device comprising: a reference signal generator that reproduces the reference signal based on reference signal information to be reproduced. 27. The data transmission apparatus according to claim 26, further comprising: an imaging unit that performs imaging processing and outputs video data, wherein the imaging unit converts the video data into a reference signal reproduced by the reference signal generator. A data transmission device for outputting in synchronization with a signal, wherein the controller transmits the video data output from the imaging unit to the transmission path as the isochronous data. 28. The data transmission device according to claim 27, further comprising: a video compression unit that compresses video data from the imaging unit and outputs compressed video data, wherein the controller performs the isochronous compression of the compressed video data. A data transmission device for transmitting as sex data.