JPS63115482A - Interpoint video conference system - Google Patents

Abstract

PURPOSE:To reduce the numbers of band compression decoders and coders compared with a conventional system by permitting each terminal to compress and decode the frequency bands of plural input picture signals subjected to analog multiplex and band compression, and band-compressing and outputting the signal after at least one of the picture signals is replaced with another signal. CONSTITUTION:Conference terminals 110, 115 and 120 are connected in a loop, and a conference is controlled descentralizedly. A screen synthesizing circuit 103 in the terminal 120 synthesizes new picture signal a'1, which bisects the screen and displays videos B and C, from its own picture signal c2 and a picture signal b2 from a screen separator circuit 127, and transmits the synthetic signal as a picture signal a'2 to the terminal 110. It decodes the signal a'2, displays the signal on a display device 112, and isolates picture signals b2 (b2: the video of the terminal 115) and c2 with the aid of a screen separator circuit 125. A screen synthesizing circuit 101 in the terminal 110 bisects the screen with the aid of its own picture signal a2 and the picture signal c2, instead of the signal b2, synthesizes a new picture signal b'1 displaying videos C and A, and transmits it as a picture signal b'2 to the terminal 115 through a band compression coder 113. The same holds of the terminal 115. The videos B and C about conference rooms other than self-one are displayed on the same screen of a display device 112 for the terminal 110, for instance.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a multipoint video conference system.

(Prior Art) Generally, each terminal in a multipoint video conference system transmits its own video to other terminals and receives a plurality of image signals from other terminals.

An example of such a multipoint video conference system is Kishino et al.'s "Multipoint video teleco.
ferencing system using fi
eld/frame time division
multiplexing technique''I
international conference
nce Symposium April 37-4, 19B4
The one described on page 4 is known.

Furthermore, the image signal has a band of 4 MHz, and the PC
When M encoding is performed, the signal speed reaches 60 Mb/s or more. For this reason, it is necessary to perform band compression in order to transmit image signals through a high-speed digital dedicated line of 384 Kb/s or 1.5 Mb/s.

As such a band compression device, for example, NEC Corporation
NETEC-XV manufactured by the company is known.

FIG. 3 shows a first example of a conventional multipoint video conference device.

According to FIG. 3, the multipoint video conference device 300 includes screen synthesis circuits 301 , 302 , 303 , band compression encoders 304 , 305 , 306 and band compression decoder 30 .
7, 308.

309, the terminal 310 is the television camera 3.
11. Display device 312. Band compression encoder 313. By the band compression decoder 314, the terminal 315
16. Display device 317. Band compression encoder 318. The band compression decoder 319 further allows the terminal 320 to output a television camera 3219 display device 322 . Band compression encoder 323. They are each configured by a band compression decoder 324.

In FIG. 3, an analog image signal from a television camera 311 of a terminal 310 is converted into a digital signal by a band compression encoder 313 and subjected to band compression, resulting in a digital image signal a of, for example, 1.5 Mb/s.

Similarly, digital image signals bt l C1 are output from the terminals 315 and 320 and sent to the multipoint video conference device 300. This digital image signal aly
bt e c, respectively, are band compression decoders 307 , 308 , 30 in the multipoint video conference device 300 .
9 by analog image signal "* r b, l cm
is converted to In this way, 2 of the screen composition circuit 301
Analog image signals S, C, and C are applied to the two inputs, and the screen synthesis circuit 301 divides one screen into two from the two analog image signals b1 and ram and displays two images B and C. analog image signal a°□
Compose and output. The analog image signal a' is further converted into a digital signal by a band compression encoder 304, subjected to band compression, and sent to the terminal 310 as a 1.5 Mb/s digital image signal a1, for example.

This digital image signal a+2 is converted into an analog signal by the band compression decoder 314 of the terminal 310 and can be displayed on the display device 312.

Similarly, screen synthesis circuits 302 and 303 output analog image signals Cm e am and 8!, respectively. *t)
! A new analog image signal "1 m "1 is synthesized from 1), and this analog image signal 1)'1 + c+1 is further digitally encoded and subjected to band compression by band compression encoders 305 and 306, for example, 1.5 Mb/s. The digital image signals of "1 +C-" are sent to the terminals 315, respectively.
, 320.

In this way, for example, on the display device 312 of the terminal 310, images B and C of conference rooms other than one's own are simultaneously displayed on the same screen.

FIG. 4 shows a second example of a conventional multipoint video conference device.

In FIG. 4, the same numbers as in FIG. 3 indicate the same components as in FIG. 3, respectively.

The multipoint video conference bag shown in Figure 4 [300 has a third
Field multiplexing circuits 400, 401, 40 replace the screen synthesis circuits 301, 302, 303 shown in the figure.
2 is provided. Furthermore, terminals 310, 315, 3
20 have field separation circuits 403 and 404, respectively.
, 405 and - pairs of display devices (406, 407
), (40B.

409), (410, 411) are provided.

In FIG. 3, the band-compressed digital image signal "I" output from each terminal 310, 315, 320 is
+ 1) I sc is the band compression decoder 307 , 308 , 30 of the multipoint video conference device 300, respectively.
9 respectively the analog image signal "* r bl
r Converted to Cm.

In this way, the analog image signal b* r cm is applied to the two inputs of the field multiplexing circuit 400, which causes the field multiplexing circuit 400 to insert the image signal C2 into the first field and the image signal C2 into the second field. A new analog image signal a'1 is generated and output. The analog image signal a'1 is further converted into a digital signal by a band compression encoder 304, subjected to band compression, and sent to the terminal 310 as a 1.5 Mb/s digital image signal a1, for example.

This digital image signal a- is converted into an analog signal by the band compression decoder 314 of the terminal 310, and then separated into two analog image signals by the field separation circuit 403 and displayed on two display devices 406 and 407, respectively.

Similarly, field multiplex circuits 401 and 402 each receive an analog image signal c! +8! and am r
By field multiplexing bl, new analog image signals b+ and CI□ are created, and this analog image signal "1 r C+1 is further passed through a band compression encoder 3.
05, 306, digitally encoded and band-compressed the digital image signal b" of, for example, 1.5 Mb/s.
t + C't as terminals 315 and 320, respectively.
It can be sent to.

In this way, for example, the two display devices 40 of the terminal 310
6, 407 shows video B of other conference rooms except for your own.

C is displayed simultaneously.

(Problems to be Solved by the Invention) In the multipoint video conference device 300 shown in FIG.
, 315 and 320, respectively. These two image signals are image signal 1
For example, in the multipoint video conferencing device 300 shown in FIG. 3 for transmitting over a transmission line of 1.5 Mb/s, for example, a screen synthesis circuit 301 converts two analog image signals S, C, and C into a screen. A new analog image signal a°1 is synthesized by the division. However, since it is difficult to perform such screen synthesis directly from band-compressed digital image signals bl and CI, the third
The multipoint video conference device 300 shown in the figure is equipped with band compression decoders 307, 308, 309 to perform altbl+C1 decoding of digital image signals, and band compression encoders 304, 305, 306, which are newly added. Combined analog image signal "1 * "1 e
Digital encoding and band compression of e'l are performed.

That is, the multipoint video conference device 300 shown in FIG.
Band compression decoders 307 , 308 , 309 and encoders 304 , 305 correspond to each terminal 310 , 315 , 320 .

306, making the multipoint video conference device 300 extremely expensive.

In the multipoint video conference device 300 shown in FIG. 4, the digital image signal is similarly band-compressed.
Direct field multiplexing of 1*bll at is difficult and requires band compression encoders 304 , 305 , 306 and band compression decoders 307 , 308 , 309 for each terminal 310 , 315 , 320 .

An object of the present invention is to provide an inexpensive multipoint video conference system that does not require a large number of band compression decoders and encoders.

(Means for Solving the Problems) According to the present invention, in each terminal of a multipoint video conference network configured by connecting video conference terminals having input terminals and output terminals in a loop, band-compressing and decoding the plurality of image signals subjected to analog multiplexing and band-compression, and replacing at least one of the plurality of image signals with another image signal, and then subjecting it to band-compression again and sending it as an output. A multipoint video conference system featuring the following features can be obtained.

(Function) In the present invention, by connecting each video conference terminal in a loop, control of a multipoint video conference is performed in a decentralized manner. This is an attempt to omit the compression encoder and decoder.

That is, in the present invention, each video conference terminal decodes a plurality of analog-multiplexed, digitally encoded, and band-compressed image signals applied to its input, and at the same time decodes a plurality of analog multiplexed, digitally encoded, and band-compressed image signals that are input to other video conference terminals that are read directly to the output. Instead of unnecessary image signals, the own video is analog multiplexed, digitally encoded and band compressed again, and sent to other video conference terminals connected to the output.

In this way, each video conference terminal can simultaneously display images of multiple conference rooms other than its own, and the number of band compression encoders and decoders can be halved compared to conventional multipoint video conference systems. Can be done.

(Example) Next, embodiments of the invention will be described with reference to the drawings.

FIG. 1 shows a first embodiment of the invention.

A first embodiment of the present invention shown in FIG. 1 differs from the prior art multipoint videoconferencing system shown in FIGS. The control function of the video conference is provided by the video conference terminals 310 and 31.
5,320 distributed.

According to FIG. 1, the first embodiment of the present invention is constructed by connecting teleconference terminals 310, 315, and 320 in a loop, and the terminal 110 includes a screen composition circuit 101, a television camera 1119, a display device 112. band compression encoder'
113, band compression decoder 1149 screen separation circuit 125
Accordingly, the terminal 115 uses the screen composition circuit 102. TV camera 116, display device 117. Band compression encoder 118.
The terminal 120 is further connected to the screen synthesis circuit 103 by the band compression decoder 1192 and the screen separation circuit 126. TV camera 12
11 display device 122. Band compression encoder 123. Each of them includes a band compression decoder 124 and a screen separation circuit 127.

The screen composition circuit 103 of the terminal 120 shown in FIG. The band compression encoder 123 synthesizes a new analog image signal a′ that displays C.
Add to the input. The band compression encoder 123 digitally encodes and band-compresses this analog image signal, and outputs it to the terminal 1 as a 1.5 Mb/s digital image signal a-, for example.
Send on 10.

In the terminal 110, the band compression decoder 114 decodes this digital image No. 2 a1 into an analog signal and displays it on the display device 112, and the screen separation circuit 125 converts the digital image No. 2 a1 into two analog image signals b! Separate into e c.

Here, the analog image signal S is unnecessary for the terminal 115 because it is its own image. For this reason, the screen synthesis circuit of the terminal 110 uses an analog image signal from the television camera 111 and a screen separation circuit 125 instead of an analog image signal.
A new analog image signal S which divides one screen into two and displays two images C and A is synthesized from the analog image signal C1 from , and is digitally encoded and band compressed by a band compression encoder 113. It is sent to the terminal 115 as a .5 Mb/s digital image signal b'2.

Similarly, in the terminal 115, the analog image signal c1
Instead, an analog image signal a-) from the television camera 116 and an analog image signal a-) from the screen separation circuit 126 are used.
A new analog image signal c'1 is synthesized, digitally encoded and band-compressed by a band compression encoder 118, and sent to a terminal 120 as a digital image signal C-.

In this way, for example, on the display device 112 of the terminal 110, images B and C of conference rooms other than one's own are simultaneously displayed on the same screen.

FIG. 2 shows a second embodiment of the present invention. In FIG. 2, the same numbers as in FIG. 1 indicate the same components as in FIG.

In a second embodiment of the present invention shown in FIG. 2, field separation circuits 203, 204, 205 and field separation circuits 203, 204, 205 and field Multiplex circuits 200, 201, and 202 are provided, and terminals 100, 115, and 120 each have a set of display devices (206, 207), (20
8,209) and (210,211) are provided.

Field multiplex circuit 202 of terminal 120 shown in FIG.
is the analog image signal b! from the field separation circuit 205 in the first field. TV camera 1 in the second field
A new analog image signal a'1 is generated into which the analog image signals from 21 are inserted. This analog image signal 8''□ is subjected to digital encoding and band compression by a band compression encoder 123, and is sent to the terminal 110 as a 1.5 Mb/s digital image signal a', for example.

In the terminal 110, this digital image signal 8'2 is decoded into an analog signal by a band compression decoder 114, and then separated by a field separation circuit 203 into two analog image signals, i, t, and c, which are respectively displayed on two display devices 206, 207. to be displayed.

Here, the analog image signal S is unnecessary for the terminal 115 because it is its own image.

For this reason, the field multiplexing circuit 200 of the terminal 110 inserts the analog image signal C8 from the field separation circuit 203 into the first field and the analog image signal from the television camera 111 into the second field instead of the analog image signal Sukura. A new analog image signal b' is generated.

This analog image signal b'1 is further processed by a band compression encoder 11.
Digital encoding and band compression are performed by 1.
It is sent to the terminal 115 as a 5 Mb/s digital image signal.

Similarly, in the terminal 115, the analog image signal from the field separation circuit 204 is applied to the first field, and the analog image signal from the field separation circuit 204 is applied to the first field.
TV camera 1 instead of analog image signal in the field
A band compression encoder 118 generates a new analog image signal C°□ into which the analog image signal S from 16 has been inserted.
The digital image signal C1 is digitally encoded and band-compressed and sent to the terminal 120 as a digital image signal C1.

In this way, for example, the display device 206゜2 of the terminal 110
07, images B and C of other conference rooms except for one's own are simultaneously displayed on the same screen.

(Effects of the Invention) As described above, in the first and second embodiments of the present invention shown in FIGS. 1 and 2, the multi-point television according to the prior art shown in FIGS. Band compression encoder 304 required for terminal support in conference device 300
, 305 , 306 and band compression decoders 307 , 3
08 and 309 can be omitted.

That is, according to the present invention, the number of expensive band compression encoders and decoders can be reduced by half, and an inexpensive multipoint video conference system can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a first embodiment of the present invention;
Figure 3 is a block diagram showing a second embodiment of the present invention, Figure 3 is a block diagram showing a first example of a conventional multi-point video conference device, and Figure 4 is a conventional multi-point video conference system. FIG. 3 is a block diagram showing a second example of the device. In the figure, 101 , 102 , 103 , 301 ,
302, 303 are screen composition circuits, 113, 118
, 123 , 304 , 305 , 306 . 313, 318, 323 are band compression encoders, 114
, 119. 124, 307, 308, 309, 314,
319, 324 are band compression decoders, 125, 126
, 127 is a screen separation circuit, 400° 401, 402
Field multiplexing circuits 403, 404, and 405 represent field separation circuits, respectively.

Claims (3)

[Claims] (1) Analog multiplexing and band compression applied to the input at each terminal of a multipoint video conference network configured by connecting video conference terminals having input terminals and output terminals in a loop. A multi-point video conference system, characterized in that the image signals of the plurality of image signals are band-compressed and decoded, at least one of the plurality of image signals is replaced with another image signal, and then band-compressed is again applied and sent as an output. (2) The multipoint video conference system according to claim 1, wherein analog multiplexing is performed by a split screen. (3) The multipoint video conference system according to claim 1, wherein analog multiplexing is performed by field or frame multiplexing.