JPH11112498A - Control information transmitting method for video conference communication and video conference communication set-up method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a multi-spot video conference only by participating terminals without requiring MCU by allowing each communication terminal to house control information in a channel assigned to its own terminal within a communication frame so as to transmit through a digital communication line. SOLUTION: A frame recommended by CCITT, H.221 is used as the communication frame between terminals. The constitution of a multi-spot video conference system obtained by connecting the terminals in the state of a loop, the change of constitution, the designation of video data to display-output to each terminal, etc., are realized by exchanging control information between a chairman terminal and the other terminals. The area of MLP data is secured on the sub-channel #8 602 of an H.221 frame and plural channels on this area are assigned to each different terminal. Then, each terminal transmits control information by using an assigned channel. An MLP data area is secured by a command on BAS 601.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video conference / telephone terminal, and more particularly to a multi-point video conference communication method in which three or more multi-point video conference / telephone terminals are connected to conduct a conversation or a conference. .

[0002]

2. Description of the Related Art Conventional multipoint video conference systems include CCITT (International Tel).
egrap and Telephone Cons
(ultimate Committee) Recommendation H. 32
The multipoint teleconferencing system proposed in US Pat.

This multipoint video conference system includes a video conference / telephone terminal (hereinafter simply referred to as a "terminal"),
An MCU is provided to realize a multipoint video conference. Then, all terminals participating in the multipoint video conference are connected to the MCU, and the MCU controls the multipoint communication to realize the multipoint video conference.

[0004]

According to the conventional multi-point video conference system, an MCU is provided, and the MCU is connected to all terminals participating in the multi-point video conference to realize the multi-point video conference. However, the following problem occurs.

[0005] 1. The number of terminals that can participate in a multipoint video conference and the communication speed are limited by the capacity of the MCU.

[0006] 2. Even if all terminals participating in the multipoint video conference are in a state where they can participate in the multipoint video conference,
If the MCU is not operating, or if all MCUs
Can not hold a multipoint video conference if is blocked by another group for a multipoint conference.

[0007] 3. When the MCU is located at an apogee from a terminal participating in the multipoint video conference, the communication fee becomes high.

[0008] Therefore, an object of the present invention is to provide a multipoint videoconference communication method capable of realizing a multipoint videoconference only with terminals participating in the multipoint videoconference without requiring an MCU.

[0009]

To achieve the above object,
The present invention includes a digital communication path for transmitting a communication frame, and a plurality of videophone / conference terminals connected in a ring by the digital communication path, wherein the videophone / conference terminal includes the plurality of videophone / conference terminals. A loop formed by a digital communication path connecting a conference terminal and a plurality of videophones / conference terminals, such that the communication frame circulates;
A relay unit for relaying to a videophone / conference terminal located downstream, and storing the generated videophone / conference data in a communication frame relayed by the relay unit, so that other videophone / conference terminals on the loop can be stored. Transmitting means for transmitting the videophone / conference data generated in the videophone / conference terminal, and transmitting means for the videophone / conference terminal stored in the communication frame relayed by the relay means, and the videophone / conference which has been circulated through the loop. And a canceling means for removing the use data.

In order to achieve the above object, the present invention provides a communication frame in which a plurality of communication terminals are connected in a loop via a digital communication line, and a teleconference data storing video conference data in a predetermined direction on the loop. A method of transmitting control information in a video conference communication in which the plurality of communication terminals perform a video conference communication between the plurality of communication terminals, wherein the plurality of communication terminals are included in a communication frame that circulates between the communication terminals connected in a loop. An area for storing control information for control is secured, a plurality of channels in the area are allocated to different communication terminals, and the plurality of channels are allocated to the respective communication terminals. Control in video conference communication, characterized by storing control information in an area allocated to its own terminal and transmitting it via the digital communication line. To provide a method of transmitting information.

[0011]

According to the multipoint video conference system according to the present invention, the video telephone / conference terminal is constituted by a digital communication path connecting the plurality of video telephone / conference terminals and the plurality of video telephone / conference terminals. Loop around the communication frame. Each terminal transmits the generated videophone / conference data to another videophone / conference terminal on the loop by storing the generated videophone / conference data in the relayed communication frame. Also,
By removing the videophone / conference data transmitted by the user from the communication frame that has circulated around the loop, transmission of videophone / conference data twice and unnecessary accumulation of videophone / conference data are eliminated. I do.

According to the present invention, a communication frame is
It circulates on a digital communication line to which terminals are connected (a digital communication line in which a plurality of video conference terminals are connected in a loop). Then, control information for controlling the multipoint video conference is stored in a communication frame circulating on the line. In this way, control information can be exchanged between the video conference terminals constituting the multipoint video conference system.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a multipoint video conference system according to the present invention will be described below.

First, FIG. 1 shows the configuration of a multipoint video conference system according to this embodiment, in which the number of terminals participating in the multipoint video conference is four.

In the figure, 1, 2, 3, and 4 are terminals and 5 is a digital communication network. In this embodiment, the terminal A1 is a chair terminal that functions as a chair of a multipoint video conference. In the present embodiment, as a digital communication network, CCITT, an I
Assume SDN. Further, for the sake of simplicity, it is assumed that each terminal is connected to ISDN by a basic interface of 2B + D.

In this embodiment, each terminal participating in the multipoint video conference is connected in a loop. That is, as shown, terminal A1 connects to terminals D4 and B2 with different B channels, terminal B2 connects to terminals A1 and C3, terminal C3 connects to terminals B2 and D4, Terminal D4 connects to terminal C3 and terminal A1.

Next, FIG. 2 shows a configuration of a terminal according to the present embodiment.

In FIG. 1, reference numeral 200 denotes a video input / output device such as a CRT or a video camera; 201, a video codec for encoding / decoding video information; 202, a video path control unit for multiplexing / demultiplexing video information; 210 is an audio input / output device such as a speaker or a microphone;
Is an audio codec that encodes / decodes audio information, 212 is an audio processing unit that processes audio information, 220 is a conference control unit that controls each unit associated with a multipoint video conference, 230 is a telematic device,
240 is a system control unit for controlling the entire terminal, 25
Reference numeral 0 denotes an end / network signal control unit for performing communication control such as call control with the digital communication network 5, and 260 denotes an H221 described later.
MUX / DMU for framing frames
X and 270 are network interface units that serve as lower layer interfaces with the network. Further, the system control unit includes an end-end signal control unit that handles control data and notification data with other terminals.

Among them, the video input / output device 200,
Video codec 201, audio input / output device 21
0, details of the audio codec 211, the telematic device 230, the system control unit 240, the end / network signal control unit 250, the MUX / DMUX 260, the network interface unit 270, the end / end signal control unit, and the operation in the normal one-to-one communication Is CCITT Recommendation H. 320,
H. 221, H .; 242, H .; 261, the description is omitted, and the following description will focus on points that are different from those in the normal one-to-one communication when a multipoint video conference is performed.

Hereinafter, an outline of the operation of the multipoint video conference system according to the present embodiment will be described.

FIGS. 3, 4 and 5 show terminals A, B, C and D
3 shows video output from the video input / output device 200 and audio output from the audio output device 210 of each terminal when the four terminals are in a multipoint video conference.

The example shown in FIG. 3 is an example in which all terminals output video information transmitted from one terminal. FIG.
A transmits the video information transmitted from terminal B to all terminals A
This shows a case where a BCD is outputting a display. The source terminal of the video information is usually the terminal used by the speaker in the conference, and the source terminal is determined by an instruction from the chair terminal or transmits the highest level of audio information. Is automatically determined by the terminal that is running. FIG. 3B shows a state where the source terminal of the video information is switched from terminal B to terminal C.

On the other hand, the audio output at each terminal is
Regardless of the video information to be output, all audio information received from other terminals participating in the conference is mixed and output. However, audio information transmitted by the own terminal is not output by the own terminal using an echo canceling technique.

That is, in the example shown in FIG. 3, the terminal A outputs the audio information transmitted by the terminals B, C and D, and the terminal B outputs the audio information transmitted by the terminals A, C and D. The terminal C outputs the audio information transmitted by the terminals A, B and D, and the terminal D outputs the audio information transmitted by the terminals A, B and C.

The example shown in FIG. 4 is an example in which all terminals output two pieces of video information transmitted from two different terminals. FIG. 4 shows that all the terminals A, B, C, and D display and output two pieces of video information transmitted from the terminals A and D vertically. Also in this case, the two originating terminals to be displayed and output are determined by the instruction from the chair terminal, or are automatically determined to the two terminals in the order of transmitting the audio information of a large level.

In the case of FIG. 4, as in the case shown in FIG. 3, all audio information received from other terminals participating in the conference is output regardless of the video information to be output. Mix and output.

The example shown in FIG. 5 is an example in which all terminals output four pieces of video information of all terminals participating in a video conference. FIG. 5 shows a state in which the terminals A, B, C, and D display and output the video information of the terminals A, B, C, and D on the screen divided into four.

In the case of FIG. 5, as in the case shown in FIG. 3, all audio information received from other terminals participating in the conference is output regardless of the video information to be output. Mix and output.

When a multipoint video conference is to be carried out with five or more terminals, the four source terminals to be displayed and output are determined according to an instruction from the chair terminal, or transmit a large level of audio information. The four terminals are automatically determined in this order.

Next, a communication frame used for communication between terminals in this embodiment will be described.

In the present embodiment, CCITT, H.264, etc. are used as communication frames between terminals. 221 (referred to as “H.221 frame” in this specification).

FIG. 2 shows a configuration of a 221 frame.

In the figure, reference numeral 600 denotes an FA used for frame synchronization.
S, BA used to transmit commands, terminal capabilities, etc.
S and 602 are subchannels # 8, which are used for transmitting MLP messages and the like. The other area 603 is an area used for transmitting video data, audio data, and data.

The assignment of the area 603 to video data, audio data, and data is specified in the BAS 601 by a command or terminal capability.

The details of the multipoint video conference system according to the present embodiment will be described below.

First, means for realizing video output of the multipoint video conference system shown in FIGS. Now, it is assumed that four terminals A, B, C, and D are connected in a loop as shown in FIG.

First, a transmission frame of video data of each terminal will be described. The video data is obtained by converting the video information captured by the video input / output device 200 into a video codec 2.
01 is data encoded by DCT or the like. Also,
The transmission frame of the video data is stored in the area assigned to the video data in the area 603 of the H221 frame.

In this embodiment, as the transmission frame of the video data, the CCITT, H.264,. H.261 frame (hereinafter referred to as “H.261 frame”) is used.

FIG. 7 shows the H.264 used in this embodiment. 26
1 shows a configuration of one frame.

FIG. 261 frames.

As shown in FIG. 261 frames include PSC 701, TR 702, PTYPE 703, P
EI704, PSPARE705 header part and GOB
It consists of 1 to 12 data parts. PSC 701 indicates synchronization data, and TR 702 indicates a cyclic sequence number of the packet.

One image frame is composed of the video data stored in the GOBs 1 to 12. That is, GOB1 to GOB1
2 stores video data of an image area obtained by dividing one image frame into 12 parts. FIG.
12 shows the relationship between 〜12 and an area in an image frame.

Now, when all terminals display and output the video information from one terminal shown in FIG. 3, the terminal that is the source of the video information displays and outputs the video information captured by the video input / output device 200. At the same time, video data is stored in 261 frames are created and transmitted. Other terminals use the H.264 service. 261 frame is received and displayed for output, and the H.264 frame is transmitted to the next destination terminal. 2
Relay transmission of 61 frames. The originating terminal transmits the H.264 message transmitted by itself. When the 261 frame returns after looping around the communication path connecting the terminal on the loop, this is displayed and output, and the data transmitted earlier by the own terminal is discarded.

FIG. 7B shows the H.264 when all the terminals output the four pieces of video information of all the terminals participating in the video conference shown in FIG. This is an example of using 261 frames. In this example, GOBs 1, 3, and 5 are assigned to terminal A,
2, 4, and 6 to terminal B, and GOBs 7, 9, and 11 to terminal C.
, GOBs 8, 9, and 12 are allocated to terminal D. FIG. 8c
Shows the relationship between the GOB assigned to each terminal and the image area.

Assuming that terminal A is now the chair terminal,
The terminal A encodes video information that has been reduced to 1/4 and captured by the video input / output device 200, stores the video data in GOBs 1, 3, and 5, and stores the video data in H.264. 261 frames are created and transmitted. The terminal B transmits the H.264. H.261 frame is received, and H.261 is received. Video information indicated by video data of GOBs 1 to 12 of 261 frames is displayed and output. In addition, the video input / output device 200 encodes the video information which has been reduced to 1/4 and taken in, and receives the encoded H.264 information. 261 frames of GOB2, 4,
6 stores its own video data and sends it to the next destination terminal. 261 frames are transmitted.

Terminals C and D are also the same as terminal B 26
One frame is received and the video information indicated by the GOB video data is displayed and output. In addition, the video input / output device 200
Encodes the video information captured by reducing it to 1/4,
The received H. The own video data is stored in the GOB to which 261 frames are allocated, and transmitted to the next destination terminal.

The terminal A sends the H.100 message transmitted by itself. If the H.261 frame circulates around the communication path connecting the terminal on the loop and returns, The video information indicated by the 261 frame GOB video data is displayed and output. In addition, the video input / output device 200 encodes the video information which has been reduced to 1/4 and taken in, and receives the encoded H.264 information. GOB1 of 261 frames,
New video data of the self is stored in H.3 and 5, and H.3. The header of the 261 frame is updated and transmitted to the terminal B.

As shown in FIG. 4, all terminals
In the case of outputting two pieces of video information transmitted from two different terminals, GOBs are allocated to the two terminals as transmission sources as shown in FIG. 8B. However, in this case, the terminal that is not the transmission source receives the received H.264. H.261 frame video data display output; Only the relay of 261 frames is performed. If the terminal A is not the source terminal, the frame generation processing, the frame relay processing, Only the 261 frame video data display output is performed.

Now, FIGS. 7C and 7D are the same as those shown in FIG.
H. a case where all terminals output four pieces of video information of all terminals participating in a video conference This is another usage example of the H.261 frame.

FIG. 7C shows that each terminal has not only GOB but also H.264. This is an example in which 261 frames are also allocated. In this case, each terminal transmits the assigned H.264. Its own video data reduced to 1/4 is stored in the assigned GOB of 261 frames, and only the predetermined header is added to the other GOBs without storing the data and transmitted. Also, each terminal receives the received H.264. From the 261 frame, the video data stored in the GOB assigned to the terminal to which the frame is assigned is displayed and output in an area corresponding to the GOB.
In addition, H. When the 261 frame returns around the communication path connecting the terminal on the loop, new video data is stored in the assigned GOB, and the frame header is updated and transmitted as necessary. In addition,
By such an operation, the four H.264s. 1 in 261 frames
This constitutes an image frame.

FIG. 7C shows that, in the example of FIG. This is an example in which 261 frames are omitted.

The received H.264 message is as follows. The relay transmission in which its own video data is stored in the GOB assigned with 261 frames is controlled by the video path control unit 2 of each terminal.
02 (see FIG. 2).

Hereinafter, details of the video path control unit will be described.

First, as shown in FIG. 7B, H.264 in which GOBs are sequentially allocated to different terminals. A first example of a video path control unit that handles 261 frames will be described.

FIG. 9 shows the internal configuration of the video path control unit.

In the figure, reference numeral 201 denotes a video codec;
Denotes a MUX / DMUX, and 202 denotes a video path control unit.

As shown, the video codec 201
Includes a video coder 910, a transmission buffer 911, and a transmission error correct 912 as a transmission system of a terminal, and a reception error collection 932, a reception buffer 93 as a reception system.
1. A video decoder 930 is provided, and a video codec control 920 is provided as a control system.

The video path control unit 202 is provided as a transmission system of the terminal, and includes a video SW 900, a video clock switching control 902, and a signal delay 901.

The MUX / DMUX 260 receives the H.264 received via the network interface 270. H.221 frame
261 frames are received and passed to the receiving system of the video codec 201. The MUX / DMUX 260 is based on H.264. 2
61 frames are created, and H.61 frames are created together with other data. 221
A frame is generated and transmitted via the network interface 270.

The operation of the receiving system is the same as that of the conventional one-to-one communication. The video codec 201 decodes the 261 frames, decodes the video data of the GOBs 1 to 12, and outputs the decoded data to the video input / output device 200.

As described above, the transmission system operates when the video data of the own terminal is stored and transmitted in all the GOBs 1 to 12, when the received GOBs 1 to 12 are transmitted as they are, and when the video data of the own terminal is transmitted. GO assigned data
G stored in B and received from another terminal
There are three types of transmission with OB.

When receiving a notification from the conference control unit 220 that the video data of the own terminal is stored and transmitted in all of the GOBs 1 to 12, the video codec encodes the video information captured by the video input / output device 200. , GOB1
12 stored in H.12. 261 frames are generated and stored in the transmission buffer 911. The video SW 900 selects the data 903 from the transmission buffer 911 of the video codec. 261 frames to be transmitted error correct 912
To the MUX / DMUX 260 via

When the video SW 900 receives a notification from the conference control unit 220 that the received GOBs 1 to 12 are to be transmitted as they are, the video SW 900 selects the data 904 from the receiving system and receives the received H.264 data. The 261 frame is passed to the MUX / DMUX 260 via the transmission error correct 912 as it is.

G to which video data of the own terminal is allocated
The video codec is stored in the OB and transmitted from the conference control unit 220 to the effect that the received other terminal is transmitted together with the GOB that is the transmission source.
00, the video information fetched is reduced to 1/4 and encoded, and stored in the GOB assigned to the own terminal. 26
One frame is generated and stored in the transmission buffer 911.
The GOB assignment is also notified from the conference control unit 220. The video SW 900 switches and outputs data 903 from the transmission buffer 911 of the video codec and data 905 from the reception system delayed by the signal delay 901. Then, the GOB allocated to the own terminal is transmitted from the transmission buffer 911 of the video codec.
03 to the MUX / D via the transmission error collect 912.
MUX 260, and other GOBs and H.264. For the header of the 261 frame, data from the receiving system is passed to the MUX / DMUX 260 via the transmission error correct 912. However, the terminal that has become the chair terminal is the GOB assigned to the own terminal and the H.264 terminal. For the header of the 261 frame, data 9 from the transmission buffer 911 of the video codec is used.
03 to the MUX / D via the transmission error collect 912.
The data is passed to the MUX 260, and the data from the receiving system is transmitted to the other GOBs via the transmission error correct 912.
/ DMUX 260.

Such data 9 of the video SW 900
The video SW clock switching control 902 controls the switching timing between the data SW 03 and the data 905.
The delay by the signal delay 901 is performed to adjust the input of the data 905 to the video SW 900 by the time required for the switching control.

The switching control of the video SW 900 by the video clock switching control 902 will be described in detail.

In this example, each terminal sets PSC and T as end flags at the position immediately after the assigned GOB.
R, and the video clock switching control 902 determines the video SW based on the end flag.
900 switching is controlled. P as the end flag
SC is used because the value of PSC is specified so as not to appear in the video data.

The PSC used for this end flag
And H. In order to distinguish the PSC 701 used for the H.261, a fixed value "11111" is used as a TR immediately after the PSC used as an end flag. And H.
The value of the most significant bit of TR 702 (5 bits) in the header of the 261 frame is fixed at 0. That is,
H. The sequence number of the 261 frame is 1 to 1
Use up to 5.

FIG. 10 shows the internal configuration of the video SW clock switching control 902.

In the figure, 1006 is a data register, 100
1 is end flag detection, 1002 is SW control, 100
5, 1003 and 1004 are SWs.

In this example, the video codec 201
H.264 in which video data obtained by encoding video information reduced to 1/4 is stored in the assigned GOB. 261 frames are stored in the transmission buffer 911, and the end flags PSC and TR are stored immediately after the assigned GOB.

Now, it is assumed that the video SW 900 selects the data 905 from the delayed receiving system, and the data 905 from the delayed receiving system has been transmitted to the transmission error correct 912.

At this time, the SW 1005 selects the data 904 from the receiving system, and monitors the end flag by the data register 1006 and the end flag detection 1001. If the end flag is detected, the end flag is set to SW control 1
002. Upon receiving this notification, the SW control 1002 switches among the SWs 900, 1003, 1004, and 1005. Then, a read clock is transmitted, and if the own terminal is not the chair terminal, the GOB assigned to the own terminal and the end flag added immediately after that, which are stored in the transmission buffer 911, are read. If the own terminal is the chair terminal, H.264 is stored in the transmission buffer 911. 26
The header part of one frame, GOBs 1, 3, and 5 assigned to the terminal which is continuous with the header part and the end flag added immediately thereafter are read out.

The read data 903 replaces the data 905 from the delayed receiving system with the video SW 9
00 is selected and sent to the transmission error correct 912. The delay time of the signal delay 901 is adjusted such that the switching timing of the video SW 900 is such that the start position of the data 903 starts from the start position of the end flag on the data 905 from the delayed receiving system. As a result, the end flag on the data from the receiving system disappears.

By the operation described above, the SW 1005
Selects the data 903 from the transmission buffer 911. This time, the end flag of the data 903 is monitored by the data register 1006 and the end flag detection 1001. If the end flag is detected, this is set to S
Notify W control 1002. The SW control 1002 receives this notification, and switches SW 900, 1003, 1004, 1005
Switch. As a result, the video SW 900 selects the data 905 from the delayed receiving system, and returns to the initial state of transmitting the data 905 from the delayed receiving system to the transmission error correct 912.

As described above, each terminal has a PSC as an end flag at a position immediately after the assigned GOB.
When the transmission is performed by adding the TRB and the TR, the end flag or the like may be stored at the position where the GOB assigned to the terminal at the next position in the loop communication path is stored. . For example, in the terminal B, an end flag or the like may be stored at a position where the GOB 7 assigned to the terminal C is stored.
However, this H. The data transmitted by the terminal C on the H.261 frame has already circulated to the other terminals A, B, and D. This data is updated to new video data at the terminal C receiving the 261 frame. Therefore, no trouble occurs.

Next, GOBs shown in FIG. 7B are sequentially assigned to different terminals. A second example of the video path control unit that handles 261 frames will be described.

FIG. 11 shows the configuration of the video path control unit according to the second example.

In the figure, reference numeral 1100 denotes a memory; 1104, a read address generator for generating a read address of the memory 1100; 1105, a write address generator for generating a write address of the memory 1100; 1103, a SW controller; 1102, a register; 1101 is a GOB comparison unit, 1
Reference numeral 106 denotes a video SW, and 1107 denotes a transmission buffer.

The video codec is a video input / output device 2
00, the video information fetched is reduced to 1/4 and encoded, and stored in the GOB assigned to the own terminal. 26
One frame is generated and stored in the transmission buffer 911.

Data 904 from the receiving system is stored in memory 1100 by read address generating section 1104. The GOB comparison unit 1101 calculates the GO
B is monitored, and the GOB number is assigned to the own terminal.
In the case of B, the writing to the memory 1100 and the increment of the address of the write address generation unit 1104 are stopped, and the stopped address value is stored in the register 1102. If the GOB number of the data 904 is no longer the GOB assigned to the own terminal, the memory 1100
And the write address generation unit 1104 resumes incrementing the address, and writes the data 904 to the memory 1100. However, the chair terminal is H.264. The header part of the 261 frame is handled in the same way as the GOB assigned to the own terminal.

The data stored in the memory 1100 is read by the address generated by the read address generation unit 1105 and transmitted to the transmission error collect 912 via the video SW 1106 and the transmission buffer 1107. The SW control unit 1103 includes a register 1102
Value and read address generation unit 110
4 are compared with each other, and if they match, reading from the memory 1100 and the read address generation unit 11
04, stop incrementing the address
1106, the GOB data 903 assigned to the terminal is read from the transmission buffer 911, and the transmission error correct 91 is transmitted via the transmission buffer 1107.
Send to 2. However, the chair terminal is H.264. 261 frame header part and GOB data 90 assigned to the terminal itself
3 is read and transmitted to the transmission error collect 912. Then, when the reading from the transmission buffer 911 is completed, the increment of the address of the write address generation unit 1104 is restarted, the video SW 1106 is switched, and the reading of the data from the memory 1100 and the transmission to the transmission error correct 912 are restarted.

Incidentally, H. If the encoding by the video codec 201 is not completed when the 261 frame is received, the dummy data is stored in the assigned GOB instead of the video data. The terminal that has received the dummy data ignores the dummy data.

The means for realizing the audio output of the multipoint video conference system shown in FIGS. Now, it is assumed that four terminals A, B, C, and D are connected in a loop as shown in FIG.

The audio data corresponds to the H.264 data shown in FIG. 2
It is stored in an area 603 of 21 frames.

By the way, H. The audio data stored in the area 603 of the 221 frame is data obtained by mixing the audios of all the terminals participating in the multipoint video conference. Each terminal receives audio data that circulates around the loop communication path, cancels and outputs audio data transmitted by the terminal from the received audio data, and outputs the terminal from the received audio data. The newly transmitted audio data is mixed with the canceled audio data and transmitted to the next terminal on the loop.

The audio processing unit 212 realizes such cancellation of the audio data transmitted from the own terminal and mixing of the newly transmitted audio data.

The details of the audio processing section 212 will be described below.

FIG. 12 shows the internal configuration of the audio processing unit 212.

As shown, the audio processing unit 212
Are an echo canceling unit 1200 for canceling audio data transmitted by the terminal itself, and a mixer unit 121 for mixing audio data newly transmitted.
It has 0.

The echo canceling unit 1200 comprises an audio loop delay control 1201, an audio variable delay 1202, an audio subtraction 1203, an output control 1204, a μ / A conversion 1205, a linear conversion 1206, and an audio level detection 1207. The mixer unit 1210 includes a linear converter 1211, an audio adder 1212, and a μ / A converter 112.
213, audio average level identification 1214.

In the echo cancellation section 1200, the audio loop delay control is performed by the system control section 240 by receiving a notification of the delay time from when the audio data is transmitted to when the audio data circulates on the loop and returns. Audio variable delay 1202 is set. The delay time is M
In the UX / DMUX 260, the specific H.264 transmitted is transmitted. 2
The time required for 21 frames to go around the loop and return is measured and reported to the system control unit 240.

The linear conversion 1211 converts the audio data coded by the audio codec 211 according to the μ / A rule into linear data,
Send to The audio variable delay 1202 is
The audio data received from 211 is delayed for a set time and sent to audio addition 1212 and audio subtraction 1203.

On the other hand, the MUX / DMUX 260 Extract audio data from 221 frames,
Send to linear conversion 1206. Linear conversion 1206 is MU
The audio data coded according to the μ / A rule received from the X / DMUX 260 is converted back to linear data and sent to the audio subtraction 1203.

The audio subtraction 1203 performs the linear conversion 1
The audio data from the audio variable delay 1202 is subtracted from the audio data from 206. with this,
Canceling of the audio data transmitted by the own terminal earlier than the received audio data is realized.

In this manner, the audio data in which the audio data transmitted by the own terminal before the received audio data is canceled is sent to the μ / A converter 1205 via the output control 1204, and the μ / A rule is applied. And transmitted to the audio codec 211. The audio codec decodes the received audio data and outputs it to the audio input / output device 210.

The audio data in which the audio data transmitted by the terminal before the received audio data is canceled is sent to the audio addition unit 1212 via the output control 1204. Audio addition 1212
Adds the audio data received from the output control 1204 and the audio data received from the linear conversion 1211. As a result, a mix of newly transmitted audio data is realized, and this data is encoded by the μ / A conversion 1213 according to the μ / A rule, and the MUX / DMUX 26
Send to 0. The MUX / DMUX 260 converts the received audio data into H.264 data. 221 frames and transmit to the next terminal on the loop.

The audio average level discriminator 1214 calculates the level of the audio data received from the linear conversion 1211 and sends it to the conference control 220. The identified level of the audio data is used for the above-described automatic switching of the video data to be displayed based on the audio volume.

The audio level detection 1207 is
The terminal operates when the terminal becomes the chair terminal, and notifies the conference control unit 220 of the level of audio data in which the own terminal has canceled the audio data transmitted earlier than the received audio data. Output control 1204
When receiving an instruction from the conference control unit 220, once
This is a means for setting the audio data output value of the echo canceller unit 1200 to 0. In this embodiment, an existing audio codec that uses data encoded according to the μ / A rule as an interface is assumed as the audio codec 211.
Is a linear data interface, the μ / A conversion 1211 and the μ / A conversion 1205 are unnecessary.

Here, audio average level identification 121
4 will be described in detail.

FIG. 13 shows an audio average level identification 121.
4 shows the internal configuration.

As shown in the figure, the audio average level identification 1214 includes audio addition 1301, write control 1302, memory 1303, counter 1304, counter value comparison 1305, reset control 1306, identification control 1
307, and audio level identification 1308.

When audio data is received from the μ / A converter 1211, the audio addition 1301
03, the added value of the audio data up to the previous time is read out, and the added value is added to the audio data received from the μ / A converter 1211.
Then, the audio data after the addition is written in 3. Memory 13
03 is counted by the counter 1304.

When the number of times of writing to the memory becomes a certain number or more, the identification control 1307 sets the audio level identification 13
08 and the reset control 1306 are notified. Upon receiving the notification, the audio level identification 1308 reads the added value of the audio data up to that point from the memory 1303 and notifies the conference control unit 220.

On the other hand, the reset control 1306 receiving the notification
Resets the contents of the memory 1303 and the count value of the counter.

The details of the multipoint video conference system relating to video data and audio data have been described above.

The details of the multipoint video conference system related to the control required to hold and operate the multipoint video conference will be described below.

In the present embodiment, the configuration of the multipoint video conference system in which the terminals are connected in a loop as shown in FIG. 1, the change of the configuration of the multipoint video conference system accompanying the withdrawal of the terminal from the multipoint video conference, Designation of video data to be displayed and output to each terminal is realized by exchanging control information between the chair terminal and other terminals.

[0109] First, the transmission frame of the control information will be described.

In this embodiment, the control information is stored in H.264 shown in FIG. 221 frame sub-channel # 8 (reference numeral 60)
2) Above, CCITT Recommendation H. M specified in H.221
An area for LP data is secured, and a plurality of channels on this area are allocated to different terminals. Then, each terminal transmits control information using the assigned channel.

FIG. 14 shows channels in the MLP data area.

The MLP data area has a size of 6.4 Kb / s or 4 Kb / s, and can be secured by a command on the BAS (601 in FIG. 6).

FIG. 14A shows a case where the MLP data area is secured at a size of 6.4 Kb / s. In this case, as shown in the figure, a common channel and eight channels Nos. 1 to 7 are formed every 8 bits on the MLP data area. Therefore, the common channel is used as the channel used by the chair terminal, and another channel is allocated to another terminal according to control information on the common channel.

FIG. 14B shows a case where the MLP data area is secured at a size of 4 Kb / s. In this case, as shown in the figure, a common channel and four channels No. 1 to No. 3 are configured every 8 bits on the MLP data area. Therefore, the common channel is used as the channel used by the chair terminal, and another channel is allocated to another terminal according to control information on the common channel.

[0115] Instead of using the MLP data area, the BAS area may be used for transmitting control information.

That is, the H.264 shown in FIG. The BAS area may be extended up to sub-channel # 8 (reference numeral 602) by a command of the BAS area 601 of the 221 frame, and the extended area may be used for transmitting control information of each terminal.

The control information transmitted by each channel is a command and data.

The command and the data are identical to each other as shown in FIG. 221 frame and may be transmitted. Alternatively, as shown in FIG. 221 frames may be divided into channels and stored and transmitted.

Each terminal receives the received H.264. Analyze the MLP data area or BAS area of 221 frames,
The control information transmitted by the own terminal to the destination stored in the area allocated to the own terminal is extracted and the received H.264 information is transmitted. The control information of the MLP data area of the 221 frame or the area other than the area allocated to the own terminal in the BAS area is relayed to the next terminal on the loop as it is.

If there is control information to be newly transmitted, the control information is stored in an area allocated to the terminal itself, and the received H.264 information is transmitted. 2
The information is relayed to the next terminal on the loop together with the control information of the 21-frame MLP data area or the area other than the area allocated to the own terminal in the BAS area.

Next, details of holding and operating a multipoint video conference using control information exchanged between the chair terminal and other terminals will be described.

The control of the multipoint video conference system using the control information is mainly performed by the system control unit 240 and the conference control unit 220 of each terminal.

First, details of the system controller 240 and the conference controller 220 of the chair terminal will be described.

FIG. 16 shows the control processing of the multipoint video conference unique to the terminal serving as the chair terminal. That is, in this embodiment, each terminal has a function of operating as a chair terminal.

First, a case where a video conference is started by the loop video conference system shown in FIG. 1 will be described.

In this case, upon receiving designations of terminals B, C, and D participating in the conference from a keyboard (not shown), system control section 240 controls end network control section 250 and places a call with terminal B. Establish. Next, call termination processing 1613
A command for instructing the terminal B that has established the call to connect to the terminal C is sent to the packet combining transmission control process 162.
Pass to 7. The packet combining / transmission control processing 1627 creates MLP data or BAS data in which the received command is stored in the common channel, performs MUX interface processing 1629, and transfers the data to the MUX / DMUX 260.
MUX / DMUX 260 stores the received MLP data or BAS data in H.264. A 221 frame is created and sent to the terminal B via the network interface 270.

When the terminals C and B are connected, a command for instructing the terminal C to connect to the terminal D is given by:
Send via terminal B. Then, when the terminal D and the terminal C are connected, a command for instructing the connection to the terminal A is sent to the terminal D via the terminals B and C. When the terminals A and D are connected, the loop configuration is completed.

As described above, the terminal which participates in the video conference is sequentially connected by the command instructing the connection to the terminal, and a loop is created.

Next, audio control in a multipoint video conference will be described.

The conference control unit 220 includes the audio processing unit 2
It is determined 1621 whether or not the level notified from the audio level detection 1207 (see FIG. 12) is a silence level for a certain period, that is, is equal to or lower than a predetermined level determined to be silence for a certain period. If it is determined that the sound level is the silence level for a certain period, the output control unit 1204 of the audio processing unit 212 is instructed to temporarily set the audio data to “0”, and the audio output of the echo canceller is temporarily turned off 1620.

As described above, by resetting the audio data level, accumulation of an arithmetic error generated in the audio subtraction 1203 and the audio addition 1212 of the audio processing unit 212 in the audio data is suppressed. Note that the accumulation of the calculation error appears as noise when audio data is output.

Next, switching control of video data displayed on each terminal will be described.

In the present embodiment, it is possible to select whether to switch video data automatically based on the audio data level of each terminal or to switch based on a switching request from each terminal. This selection is made by the automatic manual switching SW 1625.

First, a case where video data is automatically switched based on the audio data level of each terminal will be described.

The MUX / DMUX 260 receives the received H.264.
The MLP data or BAS data in the H.221 frame is passed to the packet decryption transmission control process 1628 via the DMUX interface process 1630. The packet decryption transmission control process 1628 receives the received MLP data or BAS data.
It decodes the S data and passes the data of the audio average level sent from each terminal to the memory write control 1622.
The memory write control 1622 writes this in the memory 1623 for each terminal, compares the level in the comparison processing 1624, and notifies the video path switching instruction processing 1626 which terminal has the maximum audio data level. In the video path switching instruction process, a command for setting the video data to be displayed to the video data of the terminal having the highest audio data level is passed to the packet synthesis transmission control process 1627. Packet synthesis transmission control processing 1627
Is the MLP storing this command in the common channel.
Data or BAS data is created, subjected to MUX interface processing 1629, and passed to the MUX / DMUX 260. MUX / DMUX 260 stores the received MLP data or BAS data in H.264. A 221 frame is created and sent to each terminal on the loop via the network interface 270.

Next, a case will be described in which video data to be displayed and output to each terminal is switched based on a switching request from each terminal.

The MUX / DMUX 260 receives the received H.264.
The MLP data or BAS data in the H.221 frame is passed to the packet decryption transmission control process 1628 via the DMUX interface process 1630. The packet decryption transmission control process 1628 receives the received MLP data or BAS data.
The S data is decoded, and if there is a switch request command, this command is passed to the switch request processing 1611.
The switching request processing 1611 transfers the content of the switching request to the character superimposition processing when a command indicating the switching request is received or when a switching request is instructed from the keyboard, and converts the content of the switching request into a video as shown in FIG. The output is superimposed on the display output screen of the input / output device 299.

Then, the request input processing 1610 notifies the video path switching instruction processing 1626 of the terminal transmitting the video data whose switching request requests display. In the video path switching instruction processing, a command for setting the video data to be displayed to the video data of the notified terminal is passed to the packet synthesis transmission control processing 1627. The packet synthesis / transmission control processing 1627 creates MLP data or BAS data in which the command is stored in the common channel, performs MUX interface processing 1629, and
Pass to UX / DMUX 260. Also, MUX / DMUX
H. 260 stores the received MLP data or BAS data. A 221 frame is created and sent to each terminal on the loop via the network interface 270.

Next, a case will be described in which any terminal leaves or a new terminal participates in the video conference by the video conference in the loop video conference system shown in FIG.

The MUX / DMUX 260 receives the received H.264.
The MLP data or BAS data in the H.221 frame is passed to the packet decryption transmission control process 1628 via the DMUX interface process 1630. The packet decryption transmission control process 1628 receives the received MLP data or BAS data.
The S data is decoded, and if there is an exit request command, this command is passed to the midway exit / intermediate participation process 1614.
When receiving a command to exit from the room or join in the middle 1614 or a request to leave the room, or when a request to leave or join in the middle is instructed from the keyboard, the contents of the request are passed to the character superimposition process 1601 and a switching request is made as shown in FIG. 1602 is superimposed on the display output screen of the video input / output device 299 and output.

Then, the request input processing 1621 notifies the call termination control processing 1613 of the contents of the request. The call termination control process 1613 generates a termination command and a call command according to the contents of the request,
627. The end-call command instructs the exiting terminal to disconnect the two terminals adjacent to the loop from the exiting terminal, or a connection between two terminals connected on the loop at a position close to the participating terminal. Is a command for instructing to disconnect. The call command is a command for instructing connection between terminals that have been connected to a terminal that has exited or for forming a loop including terminals that participate. Specifically, when the terminal C in FIG. 1 requests the leaving, the disconnection command between the terminal C and the terminal D is instructed by the end command, and the disconnection between the terminal C and the terminal B is indicated by the end command. The terminal B is instructed to connect to the terminal D by a call command. When the terminal E joins between the terminal B and the terminal C shown in FIG. When a connection is instructed and the terminal E is connected to the terminal B, the terminal E is instructed to connect to the terminal C by a call command.

The packet combining / transmission control processing 1627 creates MLP data or BAS data in which the command received from the call termination control processing 1613 is stored in the common channel, performs MUX interface processing 1629, and passes it to the MUX / DMUX 260. . Also, MUX / D
The MUX 260 receives the received MLP data or BAS
H. which stored data. A 221 frame is created and sent to each terminal on the loop via the network interface 270.

Next, control processing of a multipoint video conference by a terminal other than the chair terminal will be described.

FIG. 19 shows a control process of a multipoint video conference of a terminal other than the chair terminal.

First, the case where the chair terminal instructs connection or disconnection with another terminal will be described.

The MUX / DMUX 260 receives the received H.264. The MLP data or BAS data in the H.221 frame is passed to a packet decoding / transmission control process (not shown) via a DMUX interface process 1909. The packet decoding / transmission control process decodes the received MLP data or BAS data, and outputs a common channel (FIG. 14). If there is an outgoing call command or an end-of-call command, the command is passed to the system control unit 240. System control unit 240
Controls the end network control unit 250 to connect to or disconnect from the terminal specified by the command.

Next, a case where the chair terminal instructs to switch the video data to be displayed will be described.

The MUX / DMUX 260 receives the received H.264. The MLP data or the BAS data in the 221 frame is passed to a packet decoding / transmission control process (not shown) via a DMUX interface process 1909. The packet decoding / transmission control process decodes the received MLP data or BAS data and displays the data on a common channel. If there is a command for switching video data, the command is passed to the conversation control unit 240.

The conference controller control unit processing 1907 of the conference control system control unit 240 responds to the notified command by
H. It is determined whether the video data of the own terminal is stored and transmitted in the 261 frame. When the video data of the own terminal is stored and transmitted, the size of the video information transmitted by the own terminal and the GOB storing the video data are determined. decide. And
The determined contents are notified to the video codec 201 and the video path control unit 202. The video codec 201 and the video path control unit 202 operate based on this notification as described above.

Next, the process of transmitting the average audio level to the chair terminal will be described.

Conference controller control processing 190 of conference controller 240
7 receives the notification of the audio average level from the audio average level identification 1214 of the audio processing unit 212 as described above, and passes this data to a packet synthesis transmission control process (not shown). The packet combining and sending control process creates MLP data or BAS data in which this data is stored in a channel assigned to the terminal itself,
X interface processing 1908 is performed, and MUX / DMU
Hand over to X260. Further, the MUX / DMUX 260 stores the received MLP data or BAS data in the H.264. 221 frame is created and the network interface 270 is created.
Via the loop to the chair terminal.

Next, a process for transmitting a video switching request, a midway exit request, or a transmission request for telematic terminal data to the chair terminal will be described.

When these requests are input from a keyboard or the like (not shown), the input capture processing of the system control unit 240 captures the requests and passes them to the main control 1906. The main control 1906 generates a command according to the passed request and passes it to the conference master control processing 1907. Conference master control processing 1
907 passes this command to a packet synthesis transmission control process (not shown). The packet combining and sending control process creates MLP data or BAS data in which this command is stored in the channel allocated to the terminal itself, performs MUX interface processing 1908, and performs MUX / DMUX 26
Pass to 0. Further, the MUX / DMUX 260 stores the received MLP data or BAS data in the H.264. 22
One frame is created and sent to the chair terminal on the loop via the network interface 270.

The character superimposition 1905 is performed by the main control 190.
Under the control of 6, the command and data received from the chair terminal are superimposed and displayed on the screen of the video input / output device.

By the way, in the above embodiment, H. 2
The means for storing video data transmitted by four terminals in 61 frames (FIG. 7) has been shown.

The video codec 201 of each terminal transmits the received H.264 code. The video data stored in the 261 frame is decoded and output to the video input / output device 200 for display.

However, H. When the video data transmitted from four terminals is stored in the 261 frame, the video data transmitted from each terminal is mutually independent. Therefore, the video codec 201 can handle the video data transmitted from each terminal independently. it can.

Therefore, in this embodiment, the video codec 201 displays and outputs the decoded video data when the decoding of the video data transmitted from each terminal is completed.

FIG. 20 shows a configuration around a video coder of a video codec.

In the figure, 2005 is a decoder, 2001 is a decoding memory, 2000 and 2007 are display memories of a double buffer configuration, 2008 is a receiving memory, and 200 is a video input / output device. When the display memories 2000 and 2007 having the double buffer configuration operate for writing the decoded data, the display memories 2000 and 2007 use the video input / output device 200
It works for reading and displaying data to

The decoder 2005 includes a receiving memory 2008
Read out the received video data from the
The decoding is performed with reference to the decoded data of the previous frame stored in 005. The decrypted data is written to the decryption memory 2005 as a reference for decrypting the next frame,
Further, the data is written to the display memory 2000 which is currently operating for writing the decrypted data. When the decoding of the video data for the 1/4 image area transmitted from one terminal is completed, the display memory 2000 and 2007 are switched, and the display memory 2000 is read out from the display memory 20 for reading out the display.
07 is used for writing the decrypted data.

By the way, the display memory and the decoding memory are 1
Memory can be shared.

In FIG. 21, the display memory and the decoding memory are 1
The configuration when two memories are shared is shown.

In the figure, 2105 is a decoder, 2101 and 2105
Reference numeral 102 denotes a memory having a double buffer configuration commonly used as a decoding memory and a display memory, 200 denotes a video input / output device, and 2008 denotes a reception memory. When one of the memories 2101 and 2102 of the double buffer configuration operates as a decoding memory for reading reference data and a display memory for display reading, the other memory serves as a decoding memory for writing decoded data and a display memory. Operate as memory.

The decoder 2105 has a receiving memory 2008
Memory 210 which reads out the received video data and operates as a decoding memory for reading out reference data.
The decoding is performed with reference to the decoded data of the previous frame read from 0. In parallel with the reading from the memory 2102 for reference, the decoded data in the memory 2102 is read for display and sent to the video input / output device 200. The data decoded by the decoder 2105 is written to a memory 2101 operating as a decoding memory for writing the decoded data for reference of decoding the next frame. When the decoding of the video data of the 1/4 image area transmitted from one terminal is completed, the memory 210 operating as the decoding memory for reading the reference data
From 2, the decoded data of the area other than the quarter area where decoding has been completed this time is transferred to the memory 2101, and
And 2101 are switched.

[0166] Hereinafter, similarly, 1 is transmitted from one terminal.
The video data is transferred to the memory 2101 every time decoding of video data for the 画像 image area is completed, and the roles of the memories 2100 and 2101 are switched.

In the above embodiment, as shown in FIG. 1, each terminal is connected by one B channel to form a loop multipoint video conference system.

However, since one B channel is two transmission paths in different transmission directions, if each terminal is connected in a loop by one B channel, two loop communication paths are actually formed. In the above description, a case has been described in which only one of the two loop communication paths is used. However, by simultaneously using these two loop communication paths, the communication capacity between terminals can be increased. That is, for example, video data is transferred to one of two loop communication paths, H.264. 221 frames, and the audio data is transmitted by the other H.221 frame. 22
Distribution such as transmission in one frame becomes possible.

In this case, CCITT, H. 221
H. shown in FIG. 221
By utilizing the frame, H.264 is used. 221 frames can also be extended. That is, one of the two loop communication paths is set to H.264. 221 as a first channel,
The other is H. 221 is used as an additional channel.

In the above embodiment, each terminal is connected by one B channel as shown in FIG. 1 to form a loop-shaped multipoint video conference system. But,
As described above, one B channel is two transmission paths in different transmission directions. Therefore, even in a configuration in which terminals are sequentially connected by one B channel as shown in FIG. The H.221 frame is transmitted in a loop, and terminals other than both ends receive H.221 frames in any one transmission direction.
By transmitting the 221 frame transparently to the next terminal, a loop communication path can be formed. And
Even if a loop communication path is configured in this way,
This embodiment can be similarly applied.

In the above embodiment, the digital communication network shown in FIG. 1 is assumed to be CCITT, ISDN defined by the I series recommendation, and each terminal
And 2B + D basic interface.

However, in this embodiment, ISDN and 2B + D
In addition to the basic interface described above, the present invention can be similarly applied to a case where a terminal is connected to an ISDN by a primary rate interface. Further, in this case, when a plurality of B channels in the primary rate interface are used, H.264 using the additional channel is used. 221 frames can be used.

[0173]

As described above, according to the present invention, the MCU
And a multipoint videoconference communication method capable of realizing a multipoint videoconference with only the terminals participating in the multipoint videoconference without requiring the terminal.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a multipoint video conference system according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a multipoint videophone / conference terminal according to one embodiment of the present invention.

FIG. 3 is an explanatory diagram showing an operation of the multipoint video conference system according to one embodiment of the present invention.

FIG. 4 is an explanatory diagram showing an operation of the multipoint video conference system according to one embodiment of the present invention.

FIG. 5 is an explanatory diagram showing an operation of the multipoint video conference system according to one embodiment of the present invention.

FIG. 6: CCITT, H .; 221 is an explanatory diagram illustrating a frame configuration defined in Recommendation 221. FIG.

FIG. 7: CCITT, H .; 261 is an explanatory diagram illustrating an example of use of a frame defined in Recommendation 261 according to an embodiment of the present invention. FIG.

FIG. 8: CCITT, H .; FIG. 3 is an explanatory diagram showing a relationship between GOB and video data defined in Recommendation H.261 according to an embodiment of the present invention.

FIG. 9 is a block diagram illustrating a first configuration example of a video path control unit according to one embodiment of the present invention.

FIG. 10 is a block diagram showing a configuration of video SW clock switching control according to one embodiment of the present invention.

FIG. 11 is a block diagram illustrating a configuration of an audio processing unit according to an embodiment of the present invention.

FIG. 12 is a block diagram illustrating audio average level identification according to an embodiment of the present invention.

FIG. 13 is a block diagram showing a second configuration example of the video path control unit according to one embodiment of the present invention.

FIG. 14 is an explanatory diagram illustrating a control information transmission method according to an embodiment of the present invention.

FIG. 15 is an explanatory diagram illustrating a control information transmission method according to an embodiment of the present invention.

FIG. 16 is a block diagram showing a configuration of a control system of a chair terminal according to an embodiment of the present invention.

FIG. 17 is an explanatory diagram showing a display example of control information in the chair terminal according to one embodiment of the present invention.

FIG. 18 is an explanatory diagram showing a display example of control information on the chair terminal according to one embodiment of the present invention.

FIG. 19 is a block diagram illustrating a configuration of a control system of a terminal according to an embodiment of the present invention.

FIG. 20 is a block diagram showing a first configuration example around a video decoder according to an embodiment of the present invention.

FIG. 21 is a block diagram showing a second configuration example around a video decoder according to one embodiment of the present invention.

FIG. 22. CCITT, H .; 221 is an explanatory diagram illustrating a frame configuration using an additional channel defined in the Recommendation 221. FIG.

FIG. 23 is a block diagram showing a second configuration example of the multipoint video conference system according to one embodiment of the present invention.

[Explanation of symbols]

 1, 2, 3, 4 terminal 5 digital communication network 200 video input / output device 201 video codec 202 video path control unit 210 audio input / output device 211 audio codec 212 audio processing unit 220 conference control unit 230 telematic device 240 system control unit 250 End / network signal control unit 260 MUX / DMUX 270 network interface unit

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[Procedure amendment]

[Submission date] August 10, 1998

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

Claims (5)

[Claims] A plurality of communication terminals connected in a loop via a digital communication line, and a communication frame storing video conference data is circulated in a predetermined direction on said loop to allow communication between said plurality of communication terminals. And transmitting control information for controlling the plurality of communication terminals in a communication frame circulating between the communication terminals connected in a loop. Securing an area, allocating a plurality of channels in the area to different communication terminals, allocating the plurality of channels to each of the communication terminals, and allocating each of the communication terminals to an area allocated to its own terminal. A method of transmitting control information in video conference communication, comprising storing control information and transmitting the control information via the digital communication line. 2. The method for transmitting control information in video conference communication according to claim 1, wherein each of said communication terminals is provided first in a channel allocated to its own communication terminal in a received communication frame. In a video conference communication, the control information stored in a channel allocated to a communication terminal other than itself is extracted by extracting control information stored by itself and transmitted to the next communication terminal on the loop as it is. Transmission method of control information. 3. The method for transmitting control information in video conference communication according to claim 1 or 2, wherein the communication frame is H.264 of CCITT. 221 using a communication frame specified in H.221. 22
A method for transmitting control information in video conference communication, wherein the control information is stored in an MLP data area in one frame. 4. The method for transmitting control information in video conference communication according to claim 1 or 2, wherein the communication frame is H.264 or CC. 221 using a communication frame specified in H.221. 22
A method for transmitting control information in video conference communication, wherein the control information is stored in a BAS area in one frame. 5. A video conference communication setting method for performing a video conference communication between a plurality of communication terminals via a digital communication line, wherein a plurality of communication terminals participating in the conference communication are specified in a first communication terminal. Then, the first communication terminal sets up a call with the second communication terminal based on the designation, and the second communication terminal communicates with the third communication terminal via the digital communication line. Transmitting information, the second communication terminal sets a call with a third communication terminal based on the information transmitted from the first terminal, the first communication terminal, Secondly, transmitting the information of the next connection destination terminal to the third communication terminal via the communication terminal, the communication of the next connection destination based on the information transmitted by the third communication terminal By setting up a call with a terminal, the communication terminals Setting the video conference communication, characterized by connecting.