JPH06339139A - Data transmission equipment - Google Patents

Abstract

PURPOSE:To send picture data efficiently by switching number of inserted restart marker codes depending on a line state to reduce number of inserted restart marker codes when the line quality is excellent. CONSTITUTION:In a data transmission equipment 1 sending continuous data D2 to a desired transmission object, a marker code is inserted to the continuous data D2 for a predetermined period and the result is sent to a transmission object, and when a re-transmission request is sent from the transmission object, the data D2 delimited by the marker codes corresponding to the re-transmission request are sent again to the transmission object and the period inserting the marker code is switched in response to the state of a line with the transmission object. When the data D2 delimited by the marker code corresponding to the re-transmission request are sent again to the transmission object in this manner, the number insertion of the marker codes is reduced and data are sent efficiently when the line quality is excellent by selecting the period for inserting the marker code depending on the line state with the transmission object.

Description

Detailed Description of the Invention

[0001]

[Table of Contents] The present invention will be described in the following order. Field of Industrial Application Conventional Technology Problem to be Solved by the Invention Means for Solving the Problem (FIGS. 5, 7, and 8) Action (FIGS. 5, 7, and 8) Example (1) Overall Configuration (FIG. 1) (1-1) Processor (FIGS. 2 to 6) (1-2) Transmission of still image (FIGS. 5, 7 and 8) (2) Effect of embodiment (3) Other embodiment The invention's effect

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data transmission device,
For example, the present invention can be applied to a video conference device that compresses image data and transmits the data together with audio data.

[0003]

2. Description of the Related Art Conventionally, in a video conference apparatus, by transmitting and receiving audio data, image data and the like with a desired transmission target, it is possible to achieve communication with a communication target at a remote place. Has been done
-245889 publication).

That is, this type of video conference apparatus obtains a picked-up image of a person who attends a conference through a predetermined image pickup apparatus, fetches the picked-up image, compresses the data, and then sends the image to a call target. Further, the video conference device sends the voice signal of the attendee together to the call target, and at the same time, expands the image data coming from the call target and displays it on a predetermined display device.

Further, the video conference apparatus sends line drawing data input via a tablet or the like to a call target in response to a user's operation, and instead, a still image input via an image scanner or the like is sent. Send to the call target. For this reason, the conventional video conferencing apparatus is installed in a dedicated video conferencing room or the like and is used by connecting a line such as an optical fiber with a call target so that a large amount of data can be transmitted and received. Was there.

[0006]

By the way, when a still image is transmitted by this type of video conference apparatus, after the image data of this still image is encoded, it is transmitted by inserting a restart marker code at a predetermined cycle. It is done like this. This restart marker code represents the delimiter of this continuous image data, and in the transmission target, it is judged whether or not the image data could be correctly transmitted in units of the image data delimited by this restart marker code, and A resend request is issued for image data that could not be transmitted.

In response to this, when the resending request is issued, the video conference device resends the corresponding image data to the transmission object, so that the image data is surely transmitted even if the line condition is bad. It is designed to be able to do.

By the way, in the case of transmitting image data by inserting the restart marker code in this way, if no retransmission request is issued, the image data cannot be transmitted efficiently because of the insertion of the restart marker code. . On the other hand, if the frequency of insertion of the restart marker code is low, even if an error occurs in part of the image data delimited by the restart marker code, all the image data delimited by this restart marker code will be deleted. By resending, once a resending request is issued, conversely the transmission efficiency deteriorates.

That is, with respect to this restart marker code, if the line quality is good, it is possible to improve the transmission efficiency as a whole by decreasing the frequency of insertion, whereas if the line quality is poor, the frequency of insertion is increased. Has a feature that the time required for retransmission can be shortened and the transmission efficiency can be improved as a whole. Therefore, when transmitting this kind of still image, it is necessary to set the number of restart marker codes to be inserted so that the image data can be transmitted most efficiently.

However, the line quality may change depending on the transmission target, and even if the lines are connected to the same transmission target, for example, there is a feature that it changes according to the time zone. Furthermore, not only during the time of day, but also when the line is congested, the line may be connected in a detoured manner, and in this case also the line quality has a characteristic that it changes significantly. To do.

The present invention has been made in consideration of the above points, and when transmitting data by inserting a marker code of this kind, it is possible to efficiently transmit desired data. It is intended to propose a device.

[0012]

In order to solve such a problem, according to the present invention, in a data transmission device 1 for transmitting continuous data D2 to a desired transmission target, a marker code is inserted into continuous data D2 at a predetermined cycle. When the retransmission request is transmitted from the transmission target after being inserted, the data D separated by the marker code corresponding to the retransmission request is transmitted.
2 is retransmitted to the transmission target, and the cycle for inserting the marker code is switched according to the condition of the line between the transmission target and the transmission target.

Further, in the second invention, the data transmission device 1 stores the issuance frequency of the resend request transmitted from the transmission object in a predetermined storage means, and the issue frequency stored in the storage means is used as a reference. Determine the situation.

Further, in the third invention, the continuous data D2 is formed by encoding image data.

[0015]

When the data D2 delimited by the marker code in response to the resend request is retransmitted to the transmission target, if the cycle of inserting the marker code is switched according to the status of the line with the transmission target, the line If the quality is good, the marker code insertion frequency can be reduced to efficiently transmit data, and if the line quality is poor, the marker code insertion frequency can be increased to reduce the time required for retransmission.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

(1) Overall Structure In FIG. 1, reference numeral 1 denotes a video conference apparatus as a whole,
The processor 3 is stored in a predetermined storage base 2, the monitor device 4 is disposed on the storage base 2, and the imaging unit 5 is disposed on the monitor device 4. As a result, the video conference apparatus 1 images the attendees of the conference lined up in front of the monitor apparatus 4 by the image pickup unit 5, processes the video signal obtained by the image pickup by the processor 3, and sends the video signal to the call target in the form of a moving image. Further, the image data of the moving image transmitted from the call target is received by the processor 3 and displayed on the monitor device 4.

Further, the video conference apparatus 1 includes a processor 3
A printer is connected to the printer so as to be able to output the image transmitted from the call target, and the image scanner and the document image pickup device are further connected to the processor 3 to input a binary image (hereinafter referred to as a binary image). A document image) and a color still image (hereinafter referred to as a natural image) can be sent to the call target. Further, as in the case of image data, the video conference device 1 modulates / demodulates an audio signal via the processor 3 and transmits / receives it to / from a call target,
The audio signal is directly input / output to / from an external device, and the audio signal is transmitted / received between the image pickup unit 5 and the remote commander 6.

The audio signal transmitted / received between the image pickup section 5 and the remote commander 6 is transmitted / received via the infrared ray L1.
A microphone 8 is connected to the microphone 8 to collect the voice of the attendees of the conference, and the voice of the call target can be monitored via the speaker provided in the remote commander 6. Further, the video conference device 1 transmits and receives a remote control signal for the processor 3 and the image pickup unit 5 between the image pickup unit 5 and the remote commander 6 in addition to this audio signal, thereby operating the remote commander 6 to operate the monitor unit 4. By selecting the menu displayed on the lower part of the display screen, the entire operation mode, the magnification of the image pickup unit 5, and the like can be switched. As a result, the video conference apparatus 1 can switch the operation mode and the like by a simple operation, and can improve the overall usability.

Further, in this embodiment, the remote commander 6 is adapted to be able to connect a tablet, and sends the two-dimensional coordinate data inputted via this tablet to the image pickup section 5, and the image pickup section 5 receives this coordinate data. Is output to the processor 3. As a result, the video conference device 1 can send the line drawing data input by operating the tablet to the call target and can monitor the line drawing data as needed.

(1-1) Processor As shown in FIG. 2, the processor 3 inputs the video signal SV input through the image pickup section 5 to the image input / output section 10,
Here, the video signal SV is converted into a digital signal to generate a digital video signal, and the digital video signal is compressed by the encoder / decoder unit 11. In this process, the encoder / decoder unit 11 uses the CCIT
T (comite consultaif international telegraphique
et telephoniqe), H. This digital video signal is data-compressed according to the format specified in H.261.
The image data D1 obtained as a result is output to the main processing unit 12. As a result, the video conference apparatus 1 can efficiently transmit the image pickup result of the image pickup unit 5 in the form of a moving image.

On the other hand, among the image data transmitted from the call target through the line L, CCITT, H. 261
The image data D1 of the moving image compressed according to the format specified in the
The data is input to the decoder unit 11, subjected to data decompression processing here, converted into a video signal SVO by the image input / output unit 10, and output to the monitor device 4.

On the other hand, when a document image is captured by the document image capturing device 13 and the captured image is transmitted, the processor 3
After the video signal output from the document image pickup device 13 is converted into a digital video signal by the image input / output unit 10, the image data processing unit 14 compresses the data and sends it from the main processing unit 12 to the call target. As a result, the video conference device 1 can input a natural image through the document image capturing device 13 and can transmit the natural image to the call target as necessary.

At this time, the image data processing unit 14 compresses the natural image acquired by applying the data compression method (JPEG: joint photgraphic experts group) of a predetermined format defined for the still image, and the result is obtained. The image data D2 is sent to the call target via the main processing unit 12.

On the other hand, the processor 3 inputs the image data of the document image to the image data processing unit 14 when transmitting the document image input via the image scanner 15 to the object of communication, and here, regarding the facsimile, Data compression is performed according to the specified processing procedure.
Furthermore, the video conference apparatus 1 sends the compressed image data D2 to the call target through the main processing unit 12, so that the video conference apparatus 1 can efficiently transmit the document image as well. There is.

On the other hand, the image data processing unit 14 receives the image data D2 via the main processing unit 12 when the image data of the natural image and the document image is transmitted from the communication object, and decompresses the original data. After reproducing the image, the image is output to the printer 16 in response to the user's operation, and is also converted into a digital video signal and output to the image input / output unit 10, where it is converted into a video signal and output to the monitor device 4. To do. As a result, the video conference device 1 can monitor the natural image and the document image transmitted in the form of a still image from the call target on the monitor device 4 instead of or in addition to the video of the call target, Further, it can be outputted to the printer 16 as required.

In addition, in a series of processing in which a natural image and a document image are captured and data is compressed, the image data processing unit 14 monitors the natural image and the document image via the image input / output unit 10 in a series of processes. The video conferencing apparatus 1 can monitor the natural image and the document image captured as needed. Further, when the monitor device 4 monitors the natural image and the document image transmitted / received to / from the call target, the image data processing unit 14
The image of the line drawing input via the tablet 17 can be displayed so as to be superimposed on the natural image and the document image, whereby processing such as drawing can be executed on the display screen of the document image and the natural image. ing.

That is, the main processing section 12 connects the tablet 17 to the remote commander 6 so that the transmitting / receiving section 1
The coordinate data can be taken in through 9. Further, the main processing unit 12 sends this coordinate data to the call target in the form of line drawing data DW. Furthermore, the main processing unit 1
2 reproduces the image of the line drawing input by the user on the tablet 17 based on this line drawing data DW, and then outputs this image data from the image data processing unit 14 to the image input / output unit 10 in the form of a digital video signal, Here, it is superimposed on the natural image and the document image and displayed on the monitor device 4.

As a result, the video conferencing apparatus 1 can monitor the same document image or natural image as the call target and input line drawings or the like on the document image or natural image to perform communication. (That is, telewriting)

Further, in the processor 3, the audio processing unit 18 processes an audio signal directly input / output with an external device and an audio signal input / output with the transmission / reception unit 19. That is, the video conference apparatus 1 receives the infrared ray L1 transmitted from the remote commander 6 by the transmission / reception unit 19 built in the imaging unit 5, and demodulates the audio signal and the control command here.
The audio processing unit 18 inputs the audio signal SA received by the transmitting / receiving unit 19 and the audio signal directly input from the external device in the digital signal format, and the CCITT, G. 7
11 and G.I. The data is compressed according to the format defined in 722 and then output to the main processing unit 12.

Further, the audio processing unit 18 inputs the audio data transmitted from the callee side via the main processing unit 12, expands the data here, and outputs it to the transmitting / receiving unit 19 and directly to an external device. As a result, in the video conference apparatus 1, the microphone 8 can be simply connected to the remote commander 6 to talk with the call target without connecting a cable to the processor 3 one by one.

The main processing unit 12 processes the image data and audio data input in this manner as CCITT, H.264, H.264, and H.264 data. Two
The data transmitted according to the format specified in No. 21 to the call object and the data transmitted from the call object according to the format are separated into image data, audio data, etc., and output to each circuit block. That is, in this embodiment, the processor 3 has a connector for optical fiber connection and a connector for connection of the integrated service digital communication network on the back surface, which allows 384 [kb] through the optical fiber.
ps] lines (ie, consisting of H ₀ channels) up to 2
Connected to a line, and a line of 1536 [kbps] or 1920 [kbps] (that is, H ₁₁ and H ₁₂ channels)
INS network 64 (information network system net 64)
) 64 [kbps] lines can be connected at the same time within a range from 2 lines to a maximum of 6 lines to make a call.

The main processing unit 12 inputs / outputs data to / from a communication target through the line L, and at the same time, the transmission / reception unit 19
A control command is output to the bus BUS in response to a control command input from the control unit and a control command DC transmitted from the call target, whereby the operation of each circuit block can be switched as needed. That is, the encoder / decoder unit 11, the image data processing unit 14, and the audio processing unit 18 switch their operations in response to a control command output from the main processing unit 12 via the bus BUS, whereby the video conference apparatus 1 is The display image on the monitor device 4 can be switched as necessary, and the type of data to be transmitted to the call target can be switched.

In response to the transmission of this control command, the processor 3 includes the main processing unit 12 and the encoder / decoder unit 1.
1. Image data and audio data input / output to / from the image data processing unit 14 and the audio processing unit 18 are input / output via a dedicated connection line, thereby performing a series of data compression at a high speed. It can be processed.

(1-1-1) Image Input / Output Unit As shown in FIG. 3, the image input / output unit 10 inputs the video signal SVI of the NTSC system from the image pickup unit 5 and the document image pickup device 13 to the decoder 20. Here, it is converted into a luminance signal and a color difference signal. Analog digital conversion circuit (A / D) 2
1 converts the luminance signal and the color difference signal into a digital signal, and then, through a matrix circuit 22, an encoder /
It is output to the decoder unit 11 or the image data processing unit 14.
As a result, the image input / output unit 10 causes the image pickup unit 5 to operate as necessary.
The image data of a moving image can be captured from the image capturing device 13 and the image data of a natural image can be captured from the document image capturing device 13.

Further, the image input / output unit 10 receives from the encoder / decoder unit 11 the image data D _{V of the} moving image and the image data D _ME of the menu to be displayed on the monitor device 4 from the encoder / decoder unit 11 to the matrix circuit 22. The image data D _MA output from the image data processing unit 14 is received by the matrix circuit 22, and the output data of this matrix circuit 22 is converted into a digital analog conversion circuit (D / A) 2
Output to 3. In this case the matrix circuit 22, the image data D _V in response to operation of the user, D _ME, and selects and outputs the D _MA, and these image data D _V, D _ME, selectively synthesized to output D _MA To do.

The digital-analog conversion circuit 23 converts the image data into a luminance signal and a color difference signal which are analog signals, and the luminance signal and the color difference signal are encoded by the encoder 25.
Then, it is converted into an NTSC video signal SVO and output to the monitor device 4. Accordingly, the image input / output unit 10 can display attendees and the like of the call together with the menu when the image data D _{V of the} moving image and the image data D _{ME of the} menu transmitted by the matrix circuit 22 are selected. It is done like this.

Alternatively, in the matrix circuit 22, when the image data D _MA output from the image data processing unit 14 is selected together with the image data D _ME , the image input / output unit 10 causes the image input / output unit 10 to transmit the natural data transmitted from the call target. The image, the document image, and the natural image and the document image captured by the video conference apparatus 1 can be displayed together with the menu, and the document image can be displayed together with the line drawing image as required. .

Further, when the user selects the sub-screen display mode, the matrix circuit 22 outputs the image data selected for the sub-screen to the digital-analog conversion circuit 23 via the sub-screen creating circuit (PINP) 24. As a result, the video conference apparatus 1 can display a small child screen on the main display screen as needed to monitor, for example, a moving image and a document image, or a moving image and a natural image at the same time. .

Alternatively, the image input / output unit 10 selects the image data D _ME by the matrix circuit 22 at the time of rising after the power is turned on, so that the initial screen is displayed and the selectable menu is displayed. Has been done. In this embodiment, the image input / output unit 10 includes the decoder 2
The video signal input to 0 can be directly output to the monitor device 4, so that the imaging result of the imaging unit 5 can also be monitored.

(1-1-2) Encoder / Decoder Section and Audio Processing Section As shown in FIG. After being converted into a digital signal, the audio data processing circuit 28 performs CCITT, G.D. 711 and G.I. The data is compressed according to the format defined in 722 and output to the main processing unit 12. Further, the audio processing unit 18 receives the audio data DA output from the main processing unit 12 in the audio data processing circuit 28, where the audio data DA is decompressed to restore the original audio data, and the echo data DA is restored. The signal is converted into an analog signal via the cera 27 and output.

At this time, the echo canceller 27 temporarily stores the audio data to be transmitted to the call target in a predetermined data storage means and delays it, and subtracts it from the audio data coming from the call target. As a result, the echo generated when transmitting and receiving a voice signal using a geostationary satellite is reduced.

On the other hand, the encoder / decoder section 11
Receives the image data D _V of the moving image picked up by the image pickup unit 5 into the image conversion circuit 29 via the image input / output unit 10, and performs image conversion processing here. In this image conversion processing, the image conversion circuit 29 converts the image data D _V formed in the format of the luminance signal and the color difference signal at the horizontal scanning line number and frame frequency of NTSC format into the horizontal scanning line number 280.
Book, image data D whose basic frame frequency is 30 [Hz]
_It is converted to _CIF, and _H.264 The image data D _CIF to be processed defined by _H.261 is generated. On the other hand, the encoder / decoder 30 sends this image data D _CIF to H.264.
Data is compressed according to the format defined by H.261, and the resulting image data is output to the error correction circuit 31 to which an error correction code is added and then output to the main processing unit 12.

As a result, the video conference unit 1 has the image pickup unit 5
CCI for moving image data input via
The H.264 standard specified in the TT recommendation. Data is compressed according to the H.261 format. Further, the error correction circuit 31 receives the image data D1 sent from the call target from the main processing unit 12, performs error correction processing, and outputs it to the encoder / decoder 30, and the encoder / decoder 30 outputs this image data D _CIF as data. Image conversion circuit 29 by expanding
Output to.

The image conversion circuit 29 receives the image data D
By interpolating the _CIF , the number of horizontal scanning lines and the frame frequency of this image data D _CIF is set to N contrary to the time of transmission.
The number of horizontal scanning lines and the frame frequency of the TSC format are converted and output to the image input / output unit 10. As a result, the video conference device 1 is set to H.264. Image data of a moving image transmitted according to the H.261 format can be monitored.

The menu plane 32 is formed by a memory circuit that stores image data, and is connected from the main processing unit 12 to the bus B.
The stored image data D _ME is selectively output to the image input / output unit 10 in response to a control command input via the US, whereby the video conference device 1 displays the display screen of the monitor device 4 as necessary. A selectable menu can be displayed on the remote commander 6.

(1-1-3) Image Data Processing Unit As shown in FIG. 5, the image data processing unit 14 connects the local bus LBU to the bus BUS via the bus controller 35.
S is connected, and the processor 3 connects the main processing unit 12 to this bus BUS. On the other hand, the image data processing unit 14
On the local bus LBUS, a still image processing circuit 36, a binary image processing circuit 37, an image interface circuit (image I
The F circuit) 38 and the interface circuit (IF) 39 are connected.

As a result, the image data processing unit 14 disconnects the local bus LBUS from the bus BUS when a control command is input to the local bus LBUS from the main processing unit 12 via the bus controller 35, and thereby the still image processing is performed. Circuit 36, binary image processing circuit 37, image interface circuit 38, interface circuit 39
Can independently access the arithmetic memory 40 and execute predetermined data processing.

That is, the interface circuit 39 uses the S
The data input / output circuit is a CSI (small computer system interface) system, and image data of a document image input via the image scanner 15 is sequentially input and stored in the arithmetic memory 40 and stored in the arithmetic memory 40. Image data such as a document image is output to the printer 16.

The binary image processing circuit 37 includes the controller 4
By driving 1 to access the arithmetic memory 40, the image data of the document image stored in the arithmetic memory 40 is data-compressed according to the format specified for the facsimile and the resulting image data is the image interface circuit. Output to 38.

On the contrary, the binary image processing circuit 37
Sequentially fetches the image data of the call target side output from the image interface circuit 38 and decompresses the data, thereby decompressing the image data of the document image that is data-compressed and transmitted, and calculates the decompressed image data. It is stored in the memory 40.

On the other hand, the still image processing circuit 36 compresses the image data of the natural image stored in the arithmetic memory 40 by applying the data compression method defined for the natural image, and the result is obtained. The image data is output to the image interface circuit 38. On the contrary, the still image processing circuit 36 takes in the image data of the call target from the image interface circuit 38, decompresses the data, and thereby restores the compressed image data of the transmitted natural image and calculates it. It is stored in the memory 40.

As a result, the video conference apparatus 1 uses the arithmetic memory 40 by switching between the natural image and the document image, and compresses and decompresses the natural image and the document image.

The image interface circuit 38 inputs / outputs image data D2 of a natural image and a document image between the still image processing circuit 36, the binary image processing circuit 37 and the main processing section 12, and at this time, the communication procedure By inputting / outputting the image data D2 according to the protocol, the image data D2 is retransmitted in response to the retransmission request sent from the call target. Further, the image interface circuit 38 adds the restart marker code or the like necessary for the determination of the resend request to the main processing unit 12 with the image data D2 added, and further, regarding the image data D2 coming from the call target, This restart marker code is detected and a retransmission request is output if necessary.

The controller 41 includes the still image processing circuit 3
6, the operation memory 4 according to the request of the binary image processing circuit 37
0 is controlled so that desired image data can be input / output between the still image processing circuit 36, the binary image processing circuit 37 and the arithmetic memory 40. Further, the controller 41 switches the operation in response to a control command input from the main processing unit 12 via the bus BUS, whereby the image data of the arithmetic memory 40 is converted into an image FIFO (first in first out) 42 formed by a memory circuit. A natural image, a document image or the like, which is output to the image input / output unit 10 via the, and stored in the arithmetic memory 40, can be monitored.

The image input / output unit 1 receives this document image and the like.
When outputting to 0, the memory controller 41 switches the address data in response to the control command output from the main processing unit 12 to generate the desired data such as the document image stored in the arithmetic memory 40. Is displayed at a magnification of 1, and further scrolled and rotated to be displayed on the monitor device 4. As a result, the video conference apparatus 1 can freely switch the display of the document image and the like in response to the control command transmitted from the call target and further in response to the operation of the remote commander 6 by the user.

The image input / output unit 1 displays the document image and the like.
When outputting to 0, the image FIFO 42 outputs image data via the matrix circuit 43, and the matrix circuit 43 outputs the image data of the line drawing stored in the drawing plane 44 in the operation mode of telewriting and the image FIFO 42 from this image FIFO 42. The output image data is added and output. As a result, the video conference apparatus 1 can display a line drawing image on a natural image and a document image together.

That is, this drawing plane 44
Is based on the line drawing data input via the tablet and the line drawing data transmitted from the call target.
2 writes the image data to store the line drawing image. As a result, the video conference device 1 can perform telewriting on the document image and the natural image.

Further, the controller 41 uses the image FIFO.
By switching the operation of 42, the image input / output unit 10
Captured by the document image capturing device 13 via the image FIFO 42 sequentially into the arithmetic memory 40,
As a result, this image data can be compressed by the still image processing circuit 36 and transmitted.

(1-1-4) Main Processing Unit As shown in FIG. 6, the main processing unit 12 executes the processing procedure stored in the memory circuit 45 by the system controller 46 to control the overall operation of the video conference apparatus 1. To do. That is, the system controller 46 uses the interface circuit (I
F) By detecting the operation of the remote commander 6 via 47, the line interface circuit (line IF) 48 is driven in response to the user's selection operation, and thereby the line to the desired call target is established. Connecting.

That is, the line interface circuit 48
Is connected to a connector arranged on the back surface of the processor 3 so that desired data can be transmitted and received to and from the call target. Further, in this state, the system controller 46 sets a format of data to be transmitted by executing a predetermined communication protocol with the call target, and subsequently, the encoder / decoder unit 11, the image data processing unit 14, and the audio processing unit 18 Etc. to issue a control command to start a call.

At this time, the system controller 46 activates the multiplexing circuit 49, whereby the image data D1 and D2 output from the encoder / decoder section 11, the image data processing section 14, and the audio processing section 18 are set.
The audio data DA is converted into H.264 by the multiplexing circuit 49. 221 is multiplexed according to the format of 221 to generate multiplexed data DMU, and this multiplexed data DMU is sent to the call target via the line interface circuit 48. On the contrary, the multiplexing circuit 49 inputs the multiplexed data DMU transmitted from the communication object via the line interface circuit 48, separates the multiplexed data DMU into the image data D1, D2, and the audio data DA. Output to circuit block.

Further, the system controller 46, when the user specifies the switching of the operation mode during the call with the call target, the multiplexed data D coming from the call target again.
When the operation mode is switched on the call target side by monitoring the MU, the encoder / decoder unit 1 responds to this switching.
1. The operations of the image data processing unit 14 and the audio processing unit 18 are switched so that a natural image or the like can be transmitted instead of a moving image, and line drawing data or the like can be transmitted and received as necessary. Has been done.

Therefore, the system controller 46 controls the entire operation and takes in the two-dimensional coordinate data input by operating the tablet 17 at a predetermined cycle, so that the coordinate data is continuously drawn as a line drawing. The line drawing data DW is output to the image data processing unit 14 to be displayed on the monitor device 4 and output to the multiplexing circuit 49. As a result, the video conference device 1
The line drawing data DW can be assigned to a part of the multiplexed data DMU and can be transmitted and received.

In this embodiment, the main processing unit 12
Is an external bus interface circuit (external bus IF) 5
By connecting an external device of RS232C interface via 0, the whole operation can be controlled via this external device, whereby the video conferencing apparatus 1 connects a separate controller as necessary. The whole operation can be controlled.

(1-2) Transmission of still image In this embodiment, the system controller 46 operates the mouse connected to the remote commander 6 by the user,
When a natural image transmission mode is selected on the display screen, and when a control command for switching to the natural image transmission mode is input from the transmission target, the entire operation mode is switched to the natural image transmission mode, and the arithmetic memory 40 The image data of the natural image stored in is transmitted to the transmission target.

That is, the system controller 46 issues a control code to the controller 41 to activate the still image processing circuit 36 and the image interface circuit 38, thereby causing the still image processing circuit 36 to display a still image. After the data is compressed and encoded, a restart marker code is added and output through the image interface circuit 38. At this time, the image interface circuit 38 controls the still image processing circuit 36 to retransmit the corresponding image data when the retransmission request is sent from the transmission target corresponding to the restart marker code, and thereby the corresponding image data is retransmitted. Even if the line condition deteriorates, the image data D2 can be surely transmitted.

At this time, the system controller 46 refers to the statistical information table shown in FIG. 7 to set the number of restart marker codes to be inserted, and the still image processing circuit 36 outputs the control output from the controller 41. The number of interleaved restart marker codes is switched based on the code.

That is, in this statistical information table, the number of restart marker codes to be inserted in one still image can be selected on the basis of the number of retransmission requests generated during the transmission of two consecutive still images. In this case, for example, when the retransmission request is input twice in the transmission of the past still image and the retransmission request is input twice in the transmission of the subsequent still image, the next still image is transmitted. The number of restart marker codes to be inserted is selected as 3 times. Thus, while the controller 41 outputs the number of resend requests to the system controller 46 every time the image interface circuit 38 transmits one still image, the system controller 46 uses the number of resend requests as a reference. The number of insertions of the restart marker code can be set for the subsequent still image.

As a result, in the video conference apparatus 1,
After starting transmission, it is possible to judge the status of the line and switch the number of times the restart marker code is inserted.
As a result, if the line quality is good, the number of restart marker code insertions is reduced to improve transmission efficiency, and if the line quality is poor, the number of restart marker code insertions is increased and retransmission is performed. The required reduction in efficiency can be effectively avoided. In addition, not only when still images are continuously transmitted, but also the number of restart marker codes to be inserted can be switched in the same manner according to the line status when transmitted in the past. The image data can be transmitted.

At this time, in the video conference apparatus 1, by setting the number of the restart marker codes to be inserted based on the previous and previous error counts, if the number of retransmission requests increases even once, it immediately continues. When transmitting a still image, the number of restart marker codes to be inserted can be increased, so that image data can be transmitted reliably and efficiently. On the other hand, when the number of retransmission requests twice consecutively decreases, the number of interleaved restart marker codes can be reduced in the video conference apparatus 1, and thus the transmission quality is temporarily improved. However, the number of restart marker codes to be inserted can be reduced by reliably waiting for the recovery of the transmission quality.

Here, the video conferencing apparatus 1 is configured to be able to register 40 transmission targets in advance, and the system controller 46 stores the number of past retransmission requests for each transmission target and registers this statistical information table in this registration. It is designed to refer to each part. As a result, the video conference device 1
The line status can be judged for each transmission target to switch the number of restart marker code insertions, and the number of restart marker code insertions can be finely switched to efficiently transmit image data. .

Further, the system controller 46 sets the communication time zone from 0:00 to 4:00, 4:00 to 8:00, 8:00 to 12:00, 12:00 to.
It is divided into six time zones of 16:00, 16:00 to 20:00, and 20:00 to 24:00, and stores the number of retransmission requests for each time zone, and refers to this statistical information table for each time zone. There is.
As a result, the video conference apparatus 1 can switch the number of the restart marker codes to be inserted by judging the line status depending on the time zone, so that the still image data can be efficiently transmitted. Has been done. That is, when transmitting image data etc. using this kind of line,
There is a feature that the line quality changes according to the time zone, and this change also has a feature that it changes according to the area of the transmission target.

As a result, the video conference apparatus 1 refers to the statistical information table according to the time zone for each transmission object and switches the number of restart marker codes to be inserted.
Finely switch the number of restart marker codes to be inserted,
As a result, still image data can be efficiently transmitted.

The still image processing circuit 36 processes the image data of the still image by executing the processing procedure shown in FIG. 8 for each still image, and at this time, it is set by referring to this statistical information table. The restart marker code is inserted in a predetermined cycle according to the number of inserted restart marker codes. That is, the still image processing circuit 36 shifts from step SP1 to step SP2, outputs the SOS code indicating the start of the image data here, and then outputs the header at the subsequent step SP3.

Subsequently, the still image processing circuit 36 stores image data for 8 lines (hereinafter referred to as 1 block line) arranged in the horizontal scanning direction in units of 8 × 8 pixels (hereinafter referred to as MCU) as an arithmetic memory. After reading from 40 (that is, by block line control), a reference level such as a DC level required for processing is set to an initial value in the subsequent step SP5. Further, the still image processing circuit 36 follows the subsequent step SP.
In step 6, the image data of the MCU is processed by discrete cosine processing, requantization and data compression, and then in step SP7, variable length coding processing is performed and output.

Further, the still picture processing circuit 36 judges whether or not the processing of the image data for the MCU is completed in the subsequent step SP8 (that is, in the present embodiment, the processing of the image data in the form of the luminance signal and the color difference signal is carried out). It is necessary to repeat this process for one MCU), and if a negative result is obtained here, step SP6
Return to. As a result, the still image processing circuit 36 is
When the processing of the image data for U is completed, step S
When an affirmative result is obtained in P8, the process proceeds to step SP9, where it is determined whether the image data processing for one block line has been completed.

When a negative result is obtained here, the still image processing circuit 36 returns to step SP5 and repeats the processing of the image data for the subsequent MCU, whereas when the processing of the image data for one block line is completed, the step SP9 A positive result is obtained in step SP1
Move to 0. Here, the still image processing circuit 36 converts the image data into byte boundary data by inserting a stat bit if necessary, and then determines in step SP11 whether the data processing for one page is completed.

If a negative result is obtained here, the still image processing circuit 36 returns to step SP4 to start image data processing for the next block line, whereas when data processing for one page is completed, step SP11 When an affirmative result is obtained in step S12, the process proceeds to step SP12 and this process is completed.

In this series of processing, the still image processing circuit 3
6 is adapted to add a restart marker code in step SP10 in accordance with the number of restart marker codes inserted via the controller 41, so that the video conference apparatus 1 can respond to the line condition in the video conference apparatus 1. Switches the number of restart marker codes to be inserted.

(2) Effects of the Embodiments According to the above configuration, the number of restart marker codes to be inserted is switched in accordance with the line status so that the number of restart marker codes to be inserted can be changed when the line quality is good. Image data can be efficiently transmitted by reducing the number, and if the line quality is poor, the number of restart marker codes to be inserted can be increased to reduce the time required for retransmission. Can be transmitted.

(3) Other Embodiments In the above embodiment, the case where the number of interleaved restart marker codes is switched depending on the transmission target and time zone has been described, but the present invention is not limited to this. The switching depending on the transmission target or the time zone may be omitted if necessary.

Further, in the above-mentioned embodiment, the case of transmitting the image data of the still image has been described, but the present invention is not limited to this, and is widely used in the case of transmitting various continuous data by inserting the marker code. Can be applied.

[0084]

As described above, according to the present invention, the data transmission apparatus capable of efficiently transmitting image data according to the line status by switching the number of marker codes to be inserted according to the line status. Can be obtained.

[Brief description of drawings]

FIG. 1 is a front view showing a video conference apparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram showing the overall configuration.

FIG. 3 is a block diagram showing an image input / output unit.

FIG. 4 is a block diagram showing an encoder / decoder unit.

FIG. 5 is a block diagram showing an image data processing unit.

FIG. 6 is a block diagram showing a main processing unit.

FIG. 7 is a schematic diagram showing a statistical information table.

FIG. 8 is a flow chart used for the explanation.

[Explanation of symbols]

1 ... Video conferencing device, 3 ... Processor, 4 ... Monitor device, 6 ... Remote commander, 10 ... Image input / output unit, 11 ... Encoder / decoder unit, 12 ... Main processing unit, 14 ... Image data processing unit, 18 ... Audio data processing unit, 36 ... Still image processing circuit, 40 ... Operation memory, 41 ... Controller, 46 ... System controller.

Claims (3)

[Claims] 1. A data transmission device for transmitting continuous data to a desired transmission target, wherein a marker code is inserted into the continuous data at a predetermined cycle to transmit to the transmission target, and a retransmission request is transmitted from the transmission target. Then, in response to the retransmission request, the data delimited by the marker code is retransmitted to the transmission target, and the cycle for inserting the marker code is switched according to the state of the line with the transmission target. A data transmission device characterized by the above. 2. The data transmission device stores the issuance frequency of the retransmission request transmitted from the transmission target in a predetermined storage means, and the line frequency of the line is determined based on the issuance frequency stored in the storage means. The data transmission device according to claim 1, wherein a condition is determined. 3. The data transmission device according to claim 1, wherein the continuous data is formed by encoding image data.