JPS62105588A - Video conference system between multispots - Google Patents

Abstract

PURPOSE:To carry out a communication conference simultaneously between conference terminals by using a speed variable video encoder and decoder in the conference terminal and a conference controller and multiplexing, separating and transmitting through a variable allocation of a time slot. CONSTITUTION:A video signal from terminals 1a, 1a' has a redundancy between frames compressed by the encoder/decoders 2a, 2a', multiplexed by the multiplexing/separating device 3a and transmitted to the multiplexing/separating device 4a. The separated signal is decoded to a chrominance separating signal by the encoder/decoders 5a, 5a' and transmitted to a video conference controller 6 between multispots. The video signals of a terminal 1a, a terminal 1c and a terminal 1e' are similarly transmitted to the controller 6. Further, before the conference, conference information is delivered between the terminal 1 and the controller 6, from the terminal, the speed of the device 2 and the allocation of the time slot of the device 3 are instructed and the controller 6 controls the allocation of the time slot of the device 4 and the speed of the device 5. Thus, the terminal 1a displays the pictures of the terminals 1a, 1e on respective monitors and the terminal 1b can change over the pictures of the terminal 1a or 1c and display.

Description

[Detailed description of the invention] [Technical field to which the invention pertains] The present invention relates to a multi-point communication system that connects a plurality of video conference terminals on a tamatori via a video conference control device, and performs multipoint communication between these video conference terminals. This relates to a video conferencing system.

[Conventional technology]

As a conventional multipoint video conference, there is a method in which video conference terminals installed at multiple locations are connected to a multipoint video conference control device, and screens from each location are combined or switched for display. In addition, there is a field multiplexing method as a method for displaying screens of multiple stations on multiple monitors. In this system, the video signals of each station are multiplexed for each field in a time-division manner, and a frame of 3.2 Mb/s is created. It is transmitted using the inner encoding method (Sawada et al., Tokyo Multi-Point Television Conference Δ Method I Laboratory Report Vol. 33, No. 3 (/ri rIlt)).

[Problem that the invention seeks to solve]

However, the transmission distance between the terminal and the conference control device is 100Kr.
For long distances longer than n, in order to be economical, usually
/JMb/s An 8-degree interframe transmission path is used (
Kuroda and others for East TV conference 1! Mb/s interframe coding device〃, Kenjitsuho volume 33//issue (/rir≠9゜In this interframe transmission path, redundancy is suppressed by using the correlation of frames of video signals with little movement. If a signal with no correlation is applied between consecutive frames (for example, a signal in which images from different points are field-multiplexed for each field),
Because the buffer memory in the interframe encoding device overflows, it cannot be transmitted.As a result, video signals from multiple points cannot be multiplexed and transmitted to a remote terminal.
The drawback was that screens from multiple locations could not be displayed simultaneously.

[Means to solve problems]

In order to solve the drawbacks of the conventional system, the present invention uses an encoding/decoding device (for example, AjMb/s or 7
Transmission rate of A t Kb/s) (T, , Koga
.

et, al:%5UB-T/RATE MOTION
VIDEO0ODECFOR
E #, IOC! By multiplexing and transmitting this using Ir, t2, it is possible to simultaneously display screens from multiple locations using transmission lines with the same speed, and it is possible to grasp the conference situation at each location in a long point-to-point conference. Make it.

The present invention uses a variable speed encoding/decoding device for a video conference terminal and a point-to-point conference control device, and selects the encoding speed corresponding to the number of points as a transmission path between them, and uses variable time slot allocation. Performs demultiplexing to enable transmission of video signals from multiple locations. Note that in the conventional transmission method between a terminal and a control device, video signals are exchanged at a fixed speed.

〔Example〕

FIG. 1 shows an embodiment of a three-point conference according to the present invention.

/a + /a + /b + /c r /c is a video conference terminal, 2ap, 2a l jb t, 2c I
, 2C is a variable speed video encoding/decoding device, 3a, 3
c + IIa + tAc is a demultiplexer, ja *
ja.

, rb J tcl JC is a variable speed video encoding/decoding device, and B is a multipoint video conference control device. In the figure, video signals from terminals /a and /a are 2
a! -2a encoder/decoder compresses the redundancy between frames and converts each frame to a transmission rate of 7 Ar Kb/s. (For example, /a sends out a human image, /
(a) sends out a written image) This signal is sent to t! by the demultiplexer 3a. The signal is multiplexed at a speed of Mb/s and transmitted to a demultiplexer at 4a. Separated by ja, yua and ja
The signal is decoded into a digital color-separated video signal by the encoding/decoding device of t, and transmitted to the multipoint video conference control device of t.

Also, from the terminal /b, the encoding/decoding device 2b transmits /,! The signal is converted into a digital signal of Mb/s, decoded by a 1.5 TB encoding/decoding device, and transmitted to the control device of Party B in the form of a color-separated video signal. Furthermore, /c.

The video signal of the terminal /e' is sent to the control device of Party B using the 2c + , 2C' and tc/jC' encoding/decoding devices 1.3CTIAc demultiplexing device in the same way as the /ap/a' terminal. transmitted.

Note that, in reality, a transmission device, a switching device, etc. are installed between the encoding/decoding devices 3 and ≠, but they are omitted in this figure. Furthermore, multiplex transmission in the opposite direction to that described above is performed from the conference control device of Party B to the terminals /a and /a', thereby performing two-way video communication.

Furthermore, prior to the conference, conference information (number of points, 9 display monitors, etc.) is exchanged between the terminal at / and the conference control device at 2 using a signal channel (indicated by the broken line in Figure 7), and the terminal In addition to specifying the speed of the encoder/decoder of , the time slot allocation of the demultiplexer of 3, and the time slot allocation of the demultiplexer of ! control the speed of the encoding/decoding device. (Indicated by the dashed line in FIG. 1) In this way, the /a terminal displays the /b and IC screens on each monitor, and the /b terminal switches to display the /a or IC screens.

FIG. 2 KA shows an example of the configuration of a multi-point conference controller. //at //a, //be //c,
//c' is the video signal input terminal, /za + /comi'
r/−2b l/jc! /JC' u video signal output terminal, #a + /3a'+ 7.3b t /
3c t /ic' is the control information input terminal from the terminal, /
4La l #a'l /! 1tb'l/4tCl
/4tC' is a demultiplexer and code/decoder control information output terminal, /ja + /ja', /jb + /c r /! c is the audio information input terminal, /, gal #
a', /Ab + #e + #c' are audio information output terminals, /7a t /7a + /7b r /7c
+ /7c is 7V-,! Memory, / is a state switching circuit, / is a level comparison circuit, and O is an audio addition/loss insertion circuit. Here a.

a t b HC) C corresponds to FIG. In the figure, the video signal from // is once stored in the frame memory of /7, and then outputted one after another using the same clock phase signal and synchronized. This signal is / Which video switching circuit /
Also, the desired terrestrial video signal is set in the video designation signal from the terminal 3 and sent to the output terminal 2. #a
+ /4'a', /4(b + /4'c+ /lA
C' is a control terminal for allocating time slots for the demultiplexer and specifying the speed for the encoder/decoder in response to urgent information from the terminal. On the other hand, the audio signal from the terminal is /
After being input from the terminal of j, the level is compared at /9 to detect a channel with a pot-sized level, and the signal is added at 20, a loss is inserted to prevent howling, and the signal is sent to the output terminal of /6.

In this way, the desired ground signal is extracted from the video signals from each terminal and sent to each terminal.

Also, the transmission path between each terminal and the conference control device is /,jMb
The speed is constant at a speed of /s, and it is possible to exchange co-channel information with the terminal of A and C and proceed with the meeting while viewing images of all destinations. In addition, in this example, we explained the case of multiplexing the Kochaneto, but if the movement of the video is small, it is possible to multiplex transmission of an even larger number of channels. is also applicable.

〔Effect of the invention〕

As explained above, according to the present invention, by multiplexing transmission using a variable speed video encoding/decoding device for a conference terminal and a mold control device, screens at multiple points can be displayed even at a terminal in a remote location. Since they can be displayed simultaneously, it is possible to grasp the conference status at each destination in a long point-to-point conference, which has the advantage of increasing its effectiveness.

[Brief explanation of drawings]

Figure 1 Example of the Miike Point Conference/a + /a + /b + /c + /c ・・
・Video conference terminal! a, coa H, 2b lcoc,
2c... Variable speed video encoding/decoding device 3a r 3c r ≠ a r lAc ``' Demultiplexing device! a・ta・jb h !c + !c'... Variable speed video encoding code Multipoint video conference control device 2. Figure 2 Configuration example of multipoint video conference control device //a + //a
+71b //c r //c'...Video signal input terminal /2a r /2a'+ /, 2b t Dc *
/2c'"Video signal output terminal /3a l /3t
1'T /3b l /3Cl /3C'""Control information input terminal /lAa * /4ta'+ #br /
4tc + /lAc'``'Demultiplexer and encoder/decoder control information output terminal /ja・#a + #b + 15c r /yoC'・
・・Audio information input terminal /&a + #a + /Ah
+ lAc p /AC' =・Audio information output terminal/7
a y /7a + /7b + /7c + /7c
---7L/-A) Mori/r...Video switching circuit, /P...Level ratio soft circuit, 20.
...Audio addition/loss insertion circuit.

Claims (1)

[Scope of Claims] In a multipoint video conference in which a video conference terminal installed at three or more points and a multipoint video conference control device are connected, and a communication conference is simultaneously held between the video conference terminals, the video terminal In addition to having a plurality of encoding/decoding means that can change the transmission speed according to the set number of monitors to be displayed, the method also includes means for multiplexing and demultiplexing transmission by variable allocation of time slots. The control device side is equipped with a plurality of encoding/decoding means for varying the speed based on the control information transmitted from the video conference terminal, and a means for demultiplexing and transmitting. comprising means for adjusting the phase of video signals, means for switching and distributing each video signal, and means for adding audio signals from each of the terminals, and connecting between each of the video conference terminals and the multipoint video conference controller. A multipoint video conferencing system characterized by transmitting video signals by changing the multiplexing method depending on the conference.