JP2001069483A - Image distribution system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To unitarily manage a distribution amount of image data by allowing a single device (image distribution device) to distribute the image data to an asynchronous network by means of multicast. SOLUTION: The image distribution system is provided with a plurality of image display devices 50 that are accommodated in an asynchronous network 4 and with an image distributor 40 that distributes image data to the image display devices 50 through the asynchronous network 4 by means of multicast, the image distributor 40 distributes an image data distribution table through multicast, and when the image display devices 50 make a request for reception of the image data on the basis of the distribution table, periodically inform the image distributor 40 of prescribed information through multicast, the image distributor 40 manages the distribution state of the image data managed unitarily at present by means of a management table on the basis of the prescribed information from the image display devices 50 and transmits the image data requested by the image display devices 50 at a bit rate condition by which the image data can normally be distributed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image distribution system for distributing image data to a plurality of image display devices accommodated in an asynchronous network. The present invention relates to an image distribution system capable of distributing image data.

[0002]

2. Description of the Related Art In recent years, various products for distributing image data to an image display device (viewer) via a network have appeared on the market with the advance of image distribution technology. Among them, various companies have announced an image distribution system using a LAN (local area network) as an asynchronous network (IP network).

In such an image distribution system,
In order to distribute a large amount of image data over a LAN,
Many collisions (collisions) of image data occur on the LAN, resulting in an increase in traffic. Large capacity high-speed L
The emergence of ANs and switching hubs has also been born behind the introduction of such image distribution systems.

The rise in traffic naturally affects the image data distribution rate. Even when image data is distributed on a high-traffic LAN, the image display device cannot efficiently capture the image data, and the image data is not reproduced. A problem has arisen that is causing problems.

In a conventional image distribution system, in order to distribute a plurality of image data over a LAN, a plurality of cameras and a personal computer (P) corresponding to these cameras are used.
In general, the configuration C) is connected to a LAN as an image distribution device. In this system configuration, since a plurality of image data distribution sources exist in one network, that is, a LAN, collision of transmission image data is likely to occur. In addition, since the distribution rate cannot be managed, the problem of the collision becomes remarkable especially when high-rate image data distribution is considered.

In order to distribute a plurality of image data to many client terminals (image display devices) via a LAN, a connectionless transmission IP (Internet Protocol) multicast transmission method such as UDP / IP is used. Is effective, and has recently been used as a TV broadcast type transmission method.

[0007]

In the above-described conventional image distribution system, collision between image data on the LAN is liable to occur, and there is no method for collectively managing the amount of image data to be distributed. , That is, stable image data distribution was impossible.

For example, if a system configuration of connection-type transmission such as TCP / IP is adopted to cope with a malfunction of image data reproduction from the image display device, the reliability is improved, but it becomes a load on the network and the efficiency of the LAN is improved. Good use is not possible.

[0009] An object of the present invention is to provide an image distribution system capable of centrally managing the distribution amount of image data by performing image data distributed by multicast to an asynchronous network from a single device (image distribution device). To provide.

Another object of the present invention is to control the distribution status by multicast distribution and by dynamically controlling the bit rate of image data distribution, thereby further suppressing the occurrence of collision of image data on the asynchronous network, and Another object of the present invention is to provide an image distribution system capable of performing stable image data distribution.

[0011]

In order to solve the above-mentioned problems, an image distribution system according to the present invention comprises: a plurality of image display devices accommodated in an asynchronous network; and image data transmitted to the image display devices through the asynchronous network. An image distribution device for performing multicast distribution; wherein the image distribution device distributes an image data distribution table by multicast, and the image display device requests reception of the image data based on the distribution table. Regularly notifies predetermined information by multicast to the image distribution device manages the distribution status of the image data that is currently centrally managed based on the predetermined information from the image display device in a management table, The image data requested by the image display device is transmitted under a bit rate condition that allows normal distribution.

In this image distribution system, when there is a request for distribution of new image data from the image display device to the image distribution device, transmission and reception are performed between the image distribution device and the asynchronous network using a test multicast address. Then, the condition of the asynchronous network is tested in advance to determine a distributable bit rate.

[0013] Here, when the image distribution device determines that the reception is abnormal and the image display device notifies the reception abnormality,
The connection segment is determined based on the device's own IP address information in the notification information, and when the image display device limited to the unique asynchronous network has a reception error, the distribution of the connection segment is stopped or the connection is stopped. Adjust to a bit rate that does not cause reception errors in the segment.

Further, the image distribution apparatus has an image data selection table for selecting an image, and automatically judges the image selection to adjust the traffic of the asynchronous network. In this configuration, the image distribution apparatus requests the preceding apparatus having a coding conversion function to change the bit rate of the image data, and the preceding apparatus changes the bit rate to change the bit rate of the same stream image data. Automatically adjust the rate.

[0015] Further, in the image distribution device, a received image data stream from a preceding device having a coding conversion function is switched to an image data stream having a different bit rate, and the image data stream is distributed to the same channel of the asynchronous network. Adjust automatically.

[0016]

Next, embodiments of the present invention will be described with reference to the drawings. [Schematic Configuration of Image Distribution System] Referring to FIG. 1 showing the configuration of an image distribution system according to an embodiment of the present invention, this system 1 includes a plurality of image encoding devices 10 as image distribution sources. Each of these image encoding devices 10 receives a video signal of a moving image to be monitored from the camera 20 as analog image data APD, and compresses and encodes the analog image data APD based on a predetermined moving image encoding method. And sends it to the digital line 2 as digital image data DPD.

In this example, the image encoding device 10 is an MPEG standard which is one of the standards for efficiently encoding a moving image.
No. 2 is adopted in the moving picture coding method. Therefore,
The digital image data DPD may be referred to as MPEG data. MPEG is Moving Picture
e Coding Experts Group (moving picture coding expert group), and MPEG2 is an ISO / IEC13818 created by this standardization group.
Standard. The MPEG2 standard is an encoding method mainly applied to high-quality moving images and high-quality audio.

The digital line 2 transmits the MPEG data transmitted from the image encoding device 10 to ITU-T Recommendation G. 70
The transmission is performed according to the protocol of No. 3. Image distribution system 1
, Each of which includes a plurality of digital lines (G.703 lines) 2,
The MPEG data transmitted from the image encoding device 10 is received. Further, each of the coding conversion devices 30 performs bit rate conversion of the received MPEG2 data and coding conversion to low-speed image data, and sends the data to the wideband bus 3.

The broadband bus 3 transmits data in a synchronous or asynchronous mode according to IEEE1394. The image distribution device 40 constituting the image distribution system 1 converts various image data received through the broadband bus 3 into a network interface, and transmits (distributes) the data to the asynchronous network 4 by multicast.

The asynchronous network 4 is an IP (Internet Protocol) network, and can be constituted by a LAN (local area network) or a WAN (wide area network). In this example, a case where the asynchronous network 4 is configured by a LAN will be described below.

Multicast for distributing image data to the LAN 4 is a technology for implementing point-to-multipoint (point-to-multipoint) communication on an IP network, and is strictly called IP multicast. According to this multicast, data is distributed only to a plurality of terminals belonging to a specific group, here, only to the image display device.
The IP address indicating the multicast group is class D.

Each of the image display devices 50 accommodated in the LAN 4 is a viewer such as a television, and selects image data from a plurality of channels distributed by the image distribution device 40 in a multicast manner. And ITU-T Recommendation H. The 320 low-speed image data is decoded and displayed.

[Detailed Configuration of Image Encoding Apparatus] Next, FIG.
Image encoding device 10 in the image distribution system 1 shown in FIG.
Referring to FIG. 2 showing a detailed configuration of the video input unit 11, the video input unit 11 receives a video signal of a moving image to be monitored from the camera 20 as analog image data APD. The image data encoding unit 12 receives the analog image data AP from the video input unit 11
D is compressed and coded based on a predetermined moving picture coding method. In this example, the image data encoding unit 12 employs a moving image encoding method of MPEG2, which is one of the standards for efficiently encoding moving images.

The data transmission unit 13 is an image data encoding unit 1
The digital image data (MPEG data) DPD encoded in step 2 is transmitted to the digital line 2 through the line interface unit 14.

[Detailed Configuration of Encoding and Conversion Apparatus] Referring to FIG. 3 showing the detailed configuration of the encoding and conversion apparatus 30 in the image distribution system 1 shown in FIG. MPE sent from
G data according to ITU-T Recommendation G. A digital line (G.703 line) 2 for transmission according to the protocol of G.703 is accommodated. The MPEG data received by the line interface unit 31 is used when encoding conversion is not necessary.
The data is input to the isochronous data transmission unit 32 and transmitted to the IEEE1394 broadband bus 3 through the bus interface unit 33.

The MPEG data received by the line interface unit 31 is once decoded by the MPEG data decoding unit 34 and then input to the MPEG data encoding unit 35 if the bit rate needs to be converted. . MPE
The G data encoding unit 35 encodes and converts the MPEG data input from the MPEG data decoding unit 34 into a different bit rate and inputs the encoded data to the isochronous data transmission unit 32.

Further, if the MPEG data received by the line interface unit 31 needs to be converted into low-speed image data, it is once decoded by the MPEG data decoding unit 34, 320 is input to the data encoding unit 36.
H. The H.320 data encoding unit 36 converts the MPEG data input from the MPEG data decoding unit 34 into the H.320 data. The data is encoded and converted into low-speed image data in accordance with 320 and input to the isochronous data transmission unit 32.

The image data which has been subjected to the bit rate conversion and the encoding conversion to the low-speed image data and input to the isochronous data transmission section 32 is transmitted to the wideband bus 3 through the bus interface section 33.

Requests such as bit rate conversion of image data, encoding conversion to low-speed image data, and start of data distribution are made from the image distribution device 40 through the wideband bus 3. These requests from the image distribution device 40 are received by the asynchronous data transmission / reception unit 37 through the bus interface unit 33, and then transmitted to the asynchronous data analysis unit 3.
The processing is performed as determined in step S8.

[Detailed Configuration of Wideband Bus] Referring to FIG. 4 showing the image configuration of the wideband bus 3 in the image distribution system 1 shown in FIG. 1, the wideband bus 3 is a synchronous network, and image data is compliant with IEEE1394. The DPD and the notification message data MSG are transmitted in a synchronous or asynchronous mode. The image data DPD is transmitted in an isochronous (synchronous) channel 30 of the broadband bus 3 while securing a band. The communication band of the notification message data MSG uses an asynchronous (asynchronous) channel 31. The image data DPDA, DPDB, and DPDC have different data streams.

[Detailed Configuration of Image Distribution Apparatus] Next, referring to FIG. 5 showing a detailed configuration of the image distribution apparatus 40 in the image distribution system 1 shown in FIG. Various image data DPD transmitted to the broadband bus 3 is received through the bus interface unit 401. Asynchronous data forming section 404 generates notification message data MSG to coding conversion apparatus 30, and outputs asynchronous message transmitting / receiving section 4.
03 through the bus interface unit 401.

The image data management unit 405 receives the image data DP received by the isochronous data reception unit 402 according to the conditions indicated in the image data selection table 406.
D is transferred (LAN distribution). Image data management unit 40
5 is distributed from the multicast data distribution unit 407 through the network interface unit 408 to the LAN 4 which is an asynchronous network.

The channel information, which is image information, is created by the image data management unit 405 and sent from the multicast data distribution unit 409 to the network interface unit 408.
Is transmitted to the LAN 4 through the LAN.

The periodic notification message MSG transmitted from the image display device 50 to the LAN 4 is received by the multicast data receiving unit 410 through the network interface unit 408, and is stored in the connection terminal management table 412 by the connection terminal management unit 411. It is held as information.

[Detailed Configuration of Image Display Apparatus] Referring to FIG. 6 showing the detailed configuration of the image display apparatus 50 in the image distribution system 1 shown in FIG. 1, each of the plurality of image display apparatuses 50 is a television housed in the LAN 4. It is a viewer such as John. The network interface unit 51 stores the image data DP transmitted from the image distribution device 40 to the LAN 4.
D and channel information CH are input to a multicast data receiving unit 52 for image data and a multicast data receiving unit 53 for channel information, respectively.

The data reception status monitoring unit 54 outputs the image data D
The reception status of the PD is monitored, and the reception status is periodically transmitted to the image distribution device 40 from the multicast data transmission unit 55 through the network interface unit 51 by the notification message MSG.

The data reception status monitor 54 receives the image data DPD received by the multicast data receiver 52.
Is identified based on the channel information CH from the multicast data receiving unit 53. As a result of identification, MPEG
If it is data, it is decoded by the MPEG data decoding unit 56 and If the data is H.320 data, The data is decoded by the 320 data decoding unit 57.

The display section 58 visually displays the decoded image data from the decoding sections 56 and 57. The display unit 58 can perform overlay display and external monitor display. [Operation of Image Distribution System] Next, the operation of the image distribution system 1 according to the embodiment of the present invention shown in FIG. 1 will be described.
Among the drawings referred to in the following description of the operation, FIG. 7 shows a processing execution sequence at the start of image data distribution, and shows a method of determining a distribution bit rate. FIG. 8 shows a processing sequence when an abnormality is detected. Here, packet loss during abnormal delivery (considered data amount overflow in LAN)
Is described. FIG. 9 is an example of a processing sequence when an error occurs.

FIG. 10 shows the connection terminal management table 4 in FIG.
12 shows a detailed example. In this example, each image display device 50
More regularly (for example, every 5 seconds) the image distribution device 40
Is sent a notification message MSG. The image distribution device 40 manages the information for each image channel, processes at the time of error shown in FIG.
The N-side transmission bit rate can be managed.

FIG. 11 shows a detailed example of the image data selection table 406 in FIG. A table is arranged for each LAN channel currently being distributed (channel information is being provided).
This is a table for setting which image data from the broadband bus 3 is to be allocated to the LAN channel, and what kind of change to the bit rate is required for the encoding conversion device 30.

FIG. 12 is a diagram for explaining an operation management example. Referring to the drawings, the image distribution system 1 employs multicast distribution for distribution status management, and calculates a distribution bit rate in advance by monitoring distribution status. That is, when performing multicast distribution on the LAN 4 which is an asynchronous network, the image distribution system 1 grasps the bit rate of image data that can be normally distributed on the LAN, and selects and distributes image data conditions according to the rate. . In this image distribution, the distribution status of the image data on the LAN 4 is grasped and controlled.

For this purpose, the image distribution device 40 distributes the processable image information by a program (image data) distribution table by multicast. When the image display device 50 requests the reception of image data, the image display device 50 sends the image data to the image distribution device 40 by multicast using the own terminal number, reception rank, received image channel number, image reception status, and own IP.
The address is notified periodically by a notification message MSG.

On the image distribution device 40 side, the current image distribution device 4 is set based on the information of the notified message MSG.
The distribution status of the image data centrally managed by 0 is managed in the connection terminal management table 412, and the image data requested by the image display device 50 is transmitted under the bit rate condition that can be normally distributed.

As a result, LAN traffic is reduced as compared with a connection-type procedure such as TCP / IP, and it is particularly possible to cope with an increase in the number of image display devices 50 as connection terminals. In addition, it is possible to determine in advance from the distribution status that distribution is possible for the centrally managed distribution image from the image distribution device 40.

In the image distribution system 1, the bit rate of the LAN 4 is tested in advance. In other words, when a new distribution becomes necessary during the distribution operation, not only the above-described determination is made in the connection terminal management table 412, but also the distribution is actually performed to the test multicast address, and the image display device 50 already receiving Of the current LAN4
The distribution speed is determined by actually measuring the distribution bit rate suitable for.

As a result, it is possible to actually know in advance the network load in the LAN 4 generated from a device other than the image distribution device 40, and to secure an optimum bit rate for the LAN 4.

In the image distribution system 1, an error avoiding process is performed in consideration of the connection network of the image display device 50, that is, the LAN 4. Therefore, at the time of the reception abnormality notification from the image display device 50, the connection segment is determined from the information of the own IP address of the image display device 50, and based on the ratio of all the connected terminals (image display devices), the stable distribution only within the own segment is performed. Consider whether it is a rate or a stable distribution rate to other segments. To stop the distribution of other segments, the image distribution device 40 uses the TTL (Time To Li
ves) is changed.

That is, when the image distribution apparatus 40 is notified of the reception abnormality, the image distribution apparatus 40 determines the connection segment, and determines the unique LA.
If the image display device 50 limited to N4 has a reception error, the distribution of the corresponding segment is stopped or the bit rate is adjusted to a value that does not cause a reception error in the segment.

If a judgment is made for all the networks in the LAN 4, an excessive rate judgment may be made. It may also affect network operations in other segments. Therefore, by judging and responding to the connection segments, more flexible image transmission becomes possible.

The image distribution system 1 automatically adjusts the procedure for avoiding data abnormalities by using the image data selection table 406. That is, the image distribution device 40 determines whether or not the transfer image bit rate is over (a packet loss occurs in the LAN 4), or if the rate still has a margin.
In order to be able to perform image adjustment flexibly, an image data selection table 406 is provided, and the overall delivery conditions of the image distribution device 40 are dynamically changed in accordance with the above determination to adjust network traffic.

Thus, image data can be transmitted and received within the LAN 4 by adapting to the load. Also,
In this image distribution system 1, digital image data D
Operation management is performed using the same stream bit rate conversion of MPEG data as PD. That is, the image distribution device 40 requests the encoding conversion device 30 to change the bit rate of the MPEG data, and in the same stream,
By demodulating and re-encoding the EG data, the bit rate of the image data is converted to a desired bit rate and distributed.

As a result, the MPEG data can be efficiently used by using the encoding conversion device 30. In the image distribution system 1, operation management using bit rate conversion by switching received images in the image distribution device 40 is performed. That is, in the image distribution device 40, the encoding conversion device 3
By switching the received image stream from 0 to an image stream of a different bit rate and distributing it to the same LAN channel, the stream is converted to a desired bit rate and distributed.

Thus, the MPEG data can be efficiently used only by switching the received image without using the encoding conversion device 30. More specifically, in the image distribution system 1, the analog image data APD transmitted from the camera 20 is encoded by the image encoding device 10 into MPEG data DPD of digital image data.
Recommendation G. It is transmitted to the digital line 2 conforming to 703.

The encoding conversion device 30 is connected to the digital line 2
When the encoding conversion is not necessary, the MPEG data input through is transmitted to the IEEE1394 wideband bus 3 via the isochronous data transmission unit 32. Further, the coding conversion device 30 performs bit rate conversion or coding conversion to low-speed image data according to the setting, and then transmits predetermined image data, that is, MPEG data via the data transmission unit 32.
Data and H.264 320 data to the broadband bus 3.
This setting request can be controlled based on a notification message MSG from the image distribution device 40 in addition to the setting change in the conversion device.

The image distribution device 40 is connected to the encoding / conversion device 30 via the broadband bus 3 and communicates with the own distribution device by asynchronous communication of the notification message MSG and isochronous communication of a plurality of types of image data DPD. Import the image data DPD. The image distribution device 40 creates channel information CH based on the captured image information and transmits the channel information CH to the LAN 4 accommodating the plurality of image display devices 50.
P multicast transmission.

The image display device 50 selects an image to be received based on the channel information CH transmitted from the image distribution device 40 through the LAN 4, and transmits an image data reception status notification to the IP multicast address. The image distribution device 40 receives the notification and performs distribution to the LAN 4 side. The image display device 50 receives the distributed image data DP.
By receiving and decoding D, visual display of the image is possible.

As shown in FIG. 10, notification of the image data reception status from the image display device 50 to the image distribution device 40 is made by a notification message MSG including a terminal number, a reception rank, a reception channel number, a reception status, and an own IP address. Done. The image distribution device 40 manages the connection terminal information in the connection terminal management table 412 based on the notification message MSG.

The image display device 50 detects an abnormality based on the error processing sequence shown in FIG.
Notify 0. According to the error processing sequence, the image distribution device 40 determines the location of the image display device 50 being received,
In other words, it is possible to determine whether the processing is within the own network or another network of the LAN 4, the viewing condition, and the error status, and determine the processing.

As to the bit rate control method in this error processing sequence, the bit rate can be adjusted based on the image data selection table 406 shown in FIG. Converting the bit rate means that as shown in the operation management example (bit rate conversion example) in FIG. There is a method in which a bit rate change request is sent to the encoding / conversion device 30 by asynchronous communication, the encoding / conversion device 30 decodes the encoded data once, re-encodes the encoded data at a desired bit rate, and distributes the data to distribute the bit rate.

As shown in the operation management example (reception image switching example) of FIG. 12, all images at the same point at different bit rates are received by the wideband bus 3 and the image By selecting (1), a method of changing the bit rate as viewed from the LAN 4 side can be adopted. In any case, bit rate down selection information is stored in the image data selection table 406 shown in FIG.

The image data to be newly distributed after the state in which the image data has already been distributed is LAN data
4 by taking into account the traffic in FIG.
4 can be reduced.

[0062]

As described above, according to the present invention,
An image data distribution service to an asynchronous network such as an existing LAN can be stably performed, and dynamic image data supply control can be performed according to traffic in the asynchronous network.

Further, according to the present invention, by distributing image data at an appropriate bit rate, more reliable image data can be distributed, and the stability of image data distribution in an existing asynchronous network environment can be improved. The contribution is great.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an image distribution system according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a detailed configuration of an image encoding device.

FIG. 3 is a block diagram showing a detailed configuration of a coding conversion apparatus.

FIG. 4 is a block diagram showing a detailed configuration of a wideband bus.

FIG. 5 is a block diagram showing a detailed configuration of the image distribution device.

FIG. 6 is a block diagram showing a detailed configuration of the image display device.

FIG. 7 is a processing execution sequence at the start of image data distribution.

FIG. 8 is a bit rate adjustment sequence.

FIG. 9 shows an error processing sequence.

FIG. 10 is a diagram showing a detailed configuration of a connection terminal management table.

FIG. 11 is a diagram showing a detailed configuration of an image data selection table.

FIG. 12 is a diagram showing an operation management example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image distribution system 2 Digital line 3 Broadband bus 4 Asynchronous network (LAN) 10 Image encoder 20 Camera 30 Encoding converter 40 Image distributor 50 Image display

Continuation of the front page (72) Inventor Mitsuse Hasegawa 4-1-1, Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa F-term in Fujitsu Limited (reference) 5C064 BA01 BB05 BC18 BD02 BD08 BD14

Claims (6)

[Claims] A plurality of image display devices accommodated in an asynchronous network; and an image distribution device for multicasting image data to the image display devices through the asynchronous network.
The image distribution device distributes an image data distribution table by multicast, and the image display device periodically transmits predetermined information to the image distribution device by multicast when requesting reception of the image data based on the distribution table. Notify,
The image distribution device manages, in a management table, a distribution status of the image data that is currently centrally managed based on the predetermined information from the image display device, and manages the image data requested by the image display device. An image distribution system for transmitting under a bit rate condition that can be normally distributed. 2. When a request for distribution of new image data is sent from the image display device to the image distribution device, transmission / reception is performed between the image distribution device and the asynchronous network using a test multicast address. 2. The image distribution system according to claim 1, wherein a state of the network is tested in advance to determine a distributable bit rate. 3. When the image distribution apparatus determines that there is an abnormality, and when the image display apparatus notifies the reception abnormality, the connection segment is determined based on the apparatus's own IP address information in the notification information, and the unique asynchronous network is established. The method according to claim 2, wherein when the limited image display device has a reception error, the distribution of the corresponding connection segment is stopped or the bit rate is adjusted to a value that does not cause a reception error in the connection segment. Image distribution system. 4. The image distribution apparatus according to claim 2, wherein the image distribution device has an image data selection table for selecting an image, and automatically determines the image selection to adjust the traffic of the asynchronous network. Image distribution system. 5. The image distribution device requests a preceding device having a coding conversion function to change the bit rate of the image data, and the preceding device changes the bit rate to change the bit rate of the same stream image data. The image distribution system according to claim 4, wherein the bit rate is automatically adjusted. 6. The image distribution apparatus switches an image data stream received from a preceding apparatus having a coding conversion function to an image data stream having a different bit rate, distributes the image data stream to the same channel of the asynchronous network, and adjusts the bit rate. 5. The image distribution system according to claim 4, wherein the image distribution is automatically adjusted.