JPS62108690A - Inter-multiple points video conference system - Google Patents

Abstract

PURPOSE:To economize a transmission line, and to display the screens of plural points against a high performance terminal at a remote place by bracketing and using a spatial multiplexing and a time multiplexing at every transmission section. CONSTITUTION:Inter-multiple points video conference controllers 5a and 5b are equipped with the reduction and synthesizing function and the magnifying function of a screen, and at the controller 5a, video signals from terminals 1a and 1b are reduced to a half and are synthesized, and sent to the inter- multiple points video conference controller 5b through the transmission line of an inter-frame encoding device 3a. At the controller 5b, the reduced and synthesized signal is magnified and interpolated, and also, it is converted to a field multiple signal to be sent to a video conference terminal 1c or 1d. Adversely, the video signals from the terminals 1c and 1d are reduced and synthesized at the controller 5b, then being sent to the controller 5a.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field to which the Invention Pertains) The present invention connects three or more video conference terminals via two or more video conference control devices, and performs communication between these multiple video conference terminals. This relates to a multipoint video conferencing system.

(Prior art) As a conventional multipoint video conference system, a multipoint video conference is configured by connecting video conference terminals installed at multiple locations and video conference control devices between each location, and There is a method of displaying the screens by combining or switching them.

FIG. 4 is a diagram showing an example of the configuration of a conventional multipoint video conference.

In the figure, la, Ib, lc, and Id are video conference terminals, 2a and 2b are broadband exchanges, and 3a and 3b are
4 is an interframe encoding device, and 4 is a multipoint video conference control device.

The video conference terminal 1a is connected to an exchange by dialing, and the exchange connects the video conference terminals lb, lc, which are communication partners.
1. d and each point-to-point video conference control device 4 are connected via a transmission path.

Normally, a transmission capacity of about 100 Mb'/s is required to transmit a video signal, but in order to be economical on long-distance transmission lines, interframe coding equipment 38 g3b [2
1 suppresses redundant variation between frames and achieves 1.5 Mb/s.
Compress the bandwidth to a speed of about

However, if the field multiplexing method [1], which multiplexes video signals at each point in the time axis direction, is applied to the interframe transmission path, the difference information between frames is so large that the buffer memory overflows and cannot be transmitted. For this reason,
It is not possible to multiplex transmission from the control device 4 to the remote terminals of the video conference terminals 1c and ld, and only screens at specific points can be switched and displayed.

On the other hand, since the interframe transmission path is not applied from the control device 4 to the high-performance terminals of the video conference terminals 1a, ], and b,
Multiple screens can be displayed by separating the field multiplexed signals on the terminal side, and the disadvantage is that the screen display method differs depending on the location where the terminal is installed. In other words, in the conventional method, multiple transmission lines are required to connect from the terminal to the conference control device using individual transmission lines, which is not economical.Also, since the information is engraved on a terminal in a remote location and transmitted between frames, The drawback was that multiplexed transmission was not possible, and the screen display method differed depending on the area where the terminal was installed.

[11 Sawada et al. Teleconference method 2”, Research report 33
Vol. 11, No. 11 (1984) [2] Kuroda et al. “1.5 Mb/s interframe coding device for video conferencing”, Kenjitsuho Vol. 33, No. 11 (1,984)
(Object of the Invention) In order to solve the drawbacks of the conventional system, the present invention suppresses the transmission capacity by installing a plurality of point-to-point video conferencing control devices and interconnecting the transmission lines between them with a single transmission line. The aim is to provide long point-to-point video conferencing services economically and under the same conditions regardless of region.The drawings will be explained in detail below.

(Structure of the Invention) The present invention adds screen reduction/synthesis functions and enlargement functions to a control device for a long point-to-point video conferencing service. distribution function only), control devices are directly connected to each other, and spatial multiplexing and temporal multiplexing are used separately for each transmission section, and video signals from each terminal are spatially multiplexed on the interframe transmission path. It is characterized by making the transmission path more economical by performing digital transmission, and also by making it possible to display screens at multiple points even on high-performance terminals (having multiple monitors) in remote locations.

(Example) FIG. 1 is a diagram showing a configuration example of a video conference between important points according to the present invention, and is an example in which a video conference is held between four points.

The difference from FIG. 4 is that the point-to-long point video conference control device 5a,
5b and the interframe coding bag+13b.

Compared to the control device 4, the point-to-long point video conference control devices 5a and 5b have screen reduction/combining functions and enlargement functions. In the same figure, the control device Ft5a thins out the video signals from the terminals 1 and 1b to 172 pixels in both the vertical and horizontal directions, reduces them, and synthesizes them. Control device 5b
Send to.

The control device 5b enlarges and interpolates this reduced composite signal, converts it into a field multiplexed signal, and transmits it to the video conference terminal 1.
Send to c or 1d.

On the other hand, conversely, the video signals from the video conference terminals 1c and 1d are reduced and combined by the control device 5b, and transmitted to the control device 5a using the interframe transmission path between the interframe coding devices 38.

The control device 5a expands this signal, performs field multiplex conversion, and displays it on the video conference terminal 1a or 1b.

Next, an outline of the operation of the point-to-long point video conference control devices 5a, 5b will be explained. FIG. 2 shows an example of the device configuration.

In the figure, lla, llb, lie, and lid are video signal input terminals, 12a, 1.2b, ], 2c, and 12d are audio signal input terminals, and 13a, 13b.

1.3c, 13d are video signal output terminals, 14a, 14b
, 14c, 14d are audio signal output terminals, 15a, 15b
, 15c, 15d are frame memories, 16a, 16b,
16c and 16d are screen reduction circuits, 17 is a screen synthesis/switching circuit, 18a, 18b, 18c, and 18d are field multiplexing circuits, 19a, 19b, 19c, and 19d are screen enlargement circuits, 20 is a switching circuit, and 21 is a level comparison circuit. , 22
is an audio addition/loss insertion circuit.

In this configuration, video signals from each point are temporarily stored in frame memo 5a, 15b, i5c, and 15d.
By reading with the same clock, the phases of the video signals can be matched. Also, screen reduction circuits 16a and 16b.

In steps 16c and 16d, pixels are thinned out by 172 in the vertical and horizontal directions. The latter video signal is sent to the screen synthesis/switching circuit 1.
7, the screens are combined into a single screen, and the screen is further switched to the normal screen, and the screen at each point is processed as is, or the screen at each point is processed field by field by field multiplexing circuits 18a, 181), 18c, and 1lld, or the screen is enlarged. 19a
, 19b, ], 9c, and 1.9d, pixels are interpolated and enlarged vertically and in the aqueous direction.

On the other hand, the audio signals are compared in a level comparison circuit 21, and the audio signals at each point are added together in an audio addition/loss insertion circuit 22, and further a loss is inserted to prevent howling.

As a result, the video signals from each point are reduced and combined and spatially multiplexed by the video conferencing control device between each point, making it possible to transmit them even on the frame-to-frame transmission path, and transmitting this signal to multiple points on the receiving side. Zoom in with video conferencing control equipment,
By field multiplexing and sending to the terminal side,
High-performance terminals can separate fields and display multiple screens.

On the other hand, if the terminal has only one monitor, screens at each location are displayed by switching.

FIG. 3 shows the video signals transmitted and received on the interframe coding transmission path, FIG. 3(a) shows the video signals transmitted from the control device 5a to 5b, and FIG. Indicates the video signal to be transmitted.

In this way, the video conferencing control device between each point performs screen reduction, compositing, and expansion, and the frame-to-frame transmission path is spatially multiplexed to make the transmission path more economical. By performing conversion, it becomes possible to display screens from multiple locations simultaneously on a high-performance terminal with multiple monitors.

Note that although the above explanation has been given using the case of four points as an example, the same method can be applied to other points as well.

(Effects of the Invention) As explained above, according to the present invention, the video conferencing control devices between each point with screen reduction/combining and enlargement functions are interconnected, and the normal transmission path is connected to the time division multiplexing method (field By selectively using space-division multiplexing (screen reduction/combining) for the inter-frame transmission path, it is possible to reduce transmission capacity and achieve economic efficiency, and it is also possible to reach high-performance terminals in remote locations. Since it is possible to display multiple points on screen, it has the advantage of being able to provide a variety of point-to-point video conferencing services at low cost.

[Brief explanation of drawings]

FIG. 1 shows an example of the configuration of a video conference between points according to the present invention, and FIG.
The figure shows an example of the configuration of an inter-point video conference control device, FIG. 3 shows a video signal transmitted and received on an inter-frame transmission path, and FIG. 4 shows an example of the configuration of a conventional inter-point video conference. Ia, lb,],]c, 1d--video conference terminal 2a,
2b... Broadband switch, 3a, 3b... Interframe coding device, 4...
・Each point-to-point video conference control device, 5a, 5b...Each point-to-point video conference control device, 11
a, llb, llc,]]Id-video signal input terminal 12
a, 12b, 12c, 12d - audio signal input terminal, ]]
3a, 13b, 13c, 13d - video signal output terminal 14
a, 14b, 14c, 14d - audio signal output terminal, 15
a, 15b, 15c, 15d - frame memory, 16
a, 16b, 16c, 16d - screen reduction circuit, 17...
-Screen synthesis/switching circuit, 18a, 18b, 18c, 18d -Feed multiplexing circuit, 19a, 19b, 19c, 19d...Screen enlargement circuit, 20...Switching circuit, 21...Level comparison circuit, 22- ...Audio addition/loss insertion circuit.

Claims (1)

[Scope of Claims] In a multipoint video conference in which video conference terminals installed at three or more locations are connected to video conference control devices between each location, and a communication conference is simultaneously held between the terminals, the video conference control device Now, we need a means to reduce the video signals from each point and combine them into one double-sided image, a means to enlarge this reduced composite screen and play it back to the original size screen, and a means to directly convert the enlarged screen to one screen or to the screens of multiple points. It has a means for field multiplexing and transmitting it to a terminal, and a means for adding audio signals from each terminal, and interconnects a plurality of the video conference control devices via a transmission path to perform mutual communication between the plurality of terminals. A multipoint video conferencing system that is characterized by: