JPH089349A - Video signal multiplexer, video signal demultiplexer and video signal multiplex transmission system - Google Patents

Abstract

PURPOSE:To reduce the number of transmission lines for receiving simultaneous video transmission from plural video signal sources and to reduce transmission charging. CONSTITUTION:A video signal multiplexer 1 multiplexes the video signals transmitted from the respective video signal sources at plural points P1-P4 while adding a signal for synchronism establishment. In that case, the signal for synchronism establishment is added as a transmission source identifier showing the respective transmission video sources and transmitted through one transmission line 3 and on the reception side, the video signals are demultiplexed for each video signal source based on this signal for synchronism establishment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal multiplexer and a video signal demultiplexer suitable for simultaneously transmitting video between a plurality of points such as a video conference, a videophone or a remote multipoint monitor. The present invention relates to a video signal multiplex transmission system using them.

[0002]

2. Description of the Related Art For example, there is a system using a multipoint control device as a conventional example of transmitting video simultaneously between a plurality of points such as a video conference. This multipoint control device is usually provided with a plurality of input transmission lines and a plurality of output transmission lines, and the plurality of input / output transmission lines are logically connected in the multipoint control device. , It is configured so that video can be simultaneously transmitted between a plurality of points.

FIG. 6 is a diagram showing a flow of video data when simultaneous video transmission between n points, in this example, four points, is performed by using such a conventional multipoint control device. A video signal transmitted from a video signal source (not shown) at each of the points P1 to P4 is distributed in the multipoint control device 20 via an input-side transmission path connecting each of the points P1 to P4 and the multipoint control device 20. Then, the multipoint control device 20 and the multipoint control device 20 are distributed via an independent output-side transmission line that connects a point other than the transmission point.

FIG. 7 is a block diagram representatively showing the video transmission / reception device 21 at the point P1 among the video transmission / reception devices arranged at the respective points P1 to P4. The same applies to the respective points P1 to P4. The video transmission / reception device having the above configuration is arranged.

The video transmission / reception device 21 includes a video signal transmission device 22 as a video signal source, a transmission framing device 23 for adding a bit for establishing synchronization, and a multipoint control device 20.
From the three synchronization establishment devices 24 _{2 to} 24 ₄ respectively receiving the video data distributed from the respective independent transmission paths,
It is composed of three video receiving devices 25 _{2 to} 25 ₄ which respectively receive the video signals from the respective synchronization establishing devices 24 _{2 to} 24 ₄ .

In FIG. 7, since the video transmission / reception device 21 at the point P1 is shown, each synchronization establishment device 24 ₂ ...
Video data from each of the points P2 to P4 is given to the channel 24 ₄ via the multipoint control device 20.

As shown in FIG. 8, the transmission framing device 23 inserts the synchronization establishment bits (S1, S2, S3 ... Sn) one bit at the beginning of the time-divided video data and transmits it. , The synchronization establishment device on the receiving side detects whether or not the above-mentioned synchronization establishment bit has been received as specified, determines that synchronization has been established because it has been received as specified, and outputs the video signal from the transmitted video data. Extract.

As described above, even when the conventional multipoint control device 20 is used, it is possible to simultaneously perform video transmission of a plurality of points.

[0009]

However, in such a conventional example, the transmission framing device 23 of the video transmitting / receiving device 21 at each of the points P1 to P4 transmits the video data independently of the other points. In addition, the transmission path itself for transmitting the transmission-framed video data is completely independent of other points.

Therefore, in order to receive the simultaneous video transmission from a plurality of points at an arbitrary point, a plurality of transmission lines for independently receiving the video data transmitted from the plurality of points are secured at the point. However, a plurality of synchronization establishing devices are required for each of these transmission paths.

Therefore, a user who wants to perform multipoint video transmission with a plurality of points needs to pull in the transmission paths for the plurality of points and pay the transmission charge for the plurality of points.

The present invention has been made in view of the above points, and it is an object of the present invention to reduce the number of transmission paths for receiving simultaneous video transmissions from a plurality of video signal sources and to reduce transmission charges. And

[0013]

In order to achieve the above-mentioned object, the present invention is constructed as follows.

That is, the video signal multiplexing apparatus of the present invention according to claim 1 is a video signal multiplexing apparatus for adding a synchronization establishing signal to a video signal transmitted from a plurality of video signal sources and multiplexing the signal. A multiplexing control unit for adding the synchronization establishment signal as a transmission source identifier indicating each video signal source is provided.

The video signal separating apparatus according to the present invention of claim 2 is
A video signal separating device for separating a multiplexed video signal by adding a synchronization establishment signal to a video signal transmitted from a plurality of video signal sources, wherein each video signal is based on the synchronization establishment signal. A separation control unit that separates the video signal for each source is provided.

A video signal multiplex transmission system according to a third aspect of the present invention comprises the video signal multiplex apparatus according to the first aspect and the video signal demultiplexing apparatus according to the second aspect.

[0017]

According to the video signal multiplexing apparatus of claim 1, for example, when the synchronization signal is added to the video signals transmitted from the video signal sources respectively arranged at a plurality of points and the signals are multiplexed, Since the establishment signal is added as a transmission source identifier indicating each video signal source, the video signals from a plurality of points can be multiplexed and transmitted in a state where each transmission point can be identified by one transmission path.

According to the video signal separating apparatus of the second aspect, for example, a multiplexed video signal in which a synchronization establishment signal is added to the video signals transmitted from the video signal sources respectively arranged at a plurality of points and multiplexed. Is separated into video signals of each transmission point based on the signal for establishing synchronization, so that the multiplexed video signal transmitted by one transmission line can be separated into video signals of each transmission point on the receiving side. Become.

According to the video signal multiplex transmission system of the third aspect, the video signal multiplex apparatus of the first aspect and the video signal demultiplexing apparatus of the second aspect are provided. The video signals transmitted from the video signal source are multiplexed and transmitted through one transmission path, and the multiplex-transmitted video signal can be separated at the reception side into the video signals at each transmission point.

[0020]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a diagram showing a flow of video data when simultaneous video transmission between n points, in this embodiment, four points is performed by using a video signal multiplexing apparatus according to an embodiment of the present invention. It is a figure corresponding to the prior art example of FIG.

The video signals emitted from the point P1 to P4 is via the input transmission path ₂₁ to ₂₄ connecting the video signal multiplexing units each point P1 to P4, the video signal multiplexing apparatus 1 , The synchronization establishment bit is used as a transmission point identifier as will be described later, and is multiplexed on one transmission line 3. The video data multiplexed on one transmission path 3 is output from the video signal multiplexer 1 and the same signal is distributed to four points P1 to P4.

FIG. 2 is a block diagram showing the detailed structure of the video signal multiplexing apparatus. The video signals transmitted from the points P1 to P4 are stored in a plurality of buffers 4 ₁ to 4 ₄ , respectively, and the points P 1 to P ₄ are stored in accordance with the counter value of the counter 5.
The video signals from 1 to P4 are sequentially selected by the data selection unit 6 and given to the multiplexing control unit 7. On the other hand, based on the counter value, a synchronization establishment bit is generated from the synchronization bit generator 8 and given to the multiplexing controller 7. The multiplexing control unit 7 adds a bit for establishing synchronization as a transmission point identifier to the selected video signal and outputs it as multiplexed video data.

FIG. 3 is a diagram showing the structure of this multiplexed video data. Bits for establishing synchronization (S1, S2, S3 ... S
n) is inserted and multiplexed one bit at a time for each head of the video signal selected by the data selection unit 6. At this time,
The synchronization establishment bits are individually associated with each origin point to form the origin point identifier. That is, in this embodiment, the synchronization establishment bit S1 is added to the video signal from the transmission point P1, the synchronization establishment bit S2 is added to the video signal from the transmission point P2, and the synchronization establishment bit S2 is added from the transmission point P3. A bit S3 for establishing synchronization is added to the video signal, and the transmission point P
A synchronization establishment bit S4 is added to the video signal from No. 4.

The bit for establishing synchronization is, for example,
CCITT Recommendation H. The transmission / reception synchronization bit 261 can be used. This CCITT recommendation H.264. According to H.261, an error correction code (parity) is added to a serial bit string (data) obtained by encoding a video signal, and transmission / reception synchronization bit (SYN) is added to the data.
C) is added, and the bit at the time of transmission / reception synchronization is defined as (00011011). Therefore, it is possible to identify up to 8 points from this bit sequence.

For example, in this embodiment, the transmission / reception synchronization bit "0" is the point P1, the next bit "0" is the point P2, the next bit "0" is the point P3, and the next bit is the point P3. “1” is the point P4, the next bit “1” is the point P1, the next bit “0” is the point P2, the next bit “1” is the point P3, and the next bit “1” is the point P4. It corresponds to.

FIG. 4 is a block diagram of an embodiment of a video transmitter / receiver 9 which is provided at each of the points P1 to P4 and which transmits a video signal to the video signal multiplexer 1 and receives multiplexed video data. FIG. 4, and in this FIG.
The video transmission / reception device 9 at the point P1 is representatively shown.

The video signal transmitter / receiver 9 transmits the video signal transmitter 10 as a video signal source for transmitting the video signal to the video signal multiplexer 1 and the multiplexed video signal from the video signal multiplexer 1 as described later. Video signal separation device 1
1 and four video receiving devices 12 _{1 to} 12 ₄ which respectively receive the separated video signals. The video signal separation device 11 performs a process corresponding to a conventional synchronization establishment device and a process of separating a video signal using the synchronization establishment bit as a transmission point identifier.

FIG. 5 is a block diagram showing the detailed structure of the video signal separating apparatus 11.

The multiplexed video data from the video signal multiplexer 1 is given to a synchronizer 13, which synchronizes with a predetermined synchronization condition, such as CCITT Recommendation H.264.
When the synchronization by the transmission / reception synchronization bit of H.261 is satisfied, the synchronization establishment signal is output to the counter 14 and the synchronization bit removing unit 15. The counter 14 generates a counter value which is a signal for specifying the transmission points P1 to P4 by the synchronization establishment signal. The sync bit removing unit 15 removes the sync bit from the multiplexed video data. Separation control unit 16
Separates the video data into the reception data corresponding to each of the transmission points P1 to P4 from the data from which the synchronization bit is removed and the counter value.

The received data for each of the transmission points P1 to P4 is given to each of the video receivers 12 _{1 to} 12 ₄ in FIG.

As described above, the video signals from the four points P1 to P4 are multiplexed and each point P1 is transmitted through one transmission line.
To P4, it is possible to reduce the number of transmission paths and transmission charges, and the video transmission / reception devices arranged at each of the points P1 to P4 may be provided with one synchronization establishment device, respectively. The number of devices can be reduced as compared with the conventional example.

In this embodiment, the points P1 to P4 are set.
Since the video signal from is transmitted by time division multiplexing, the data amount of the video signal that can be transmitted is 1/4 compared to the conventional example. Therefore, for example, transmit it as a 1/4 screen of the conventional screen. You can do this.

In the above embodiment, the four video signal sources are
Although it is arranged at each of four different points, the present invention can of course be applied to a case where different video signal sources are arranged at the same point.

As another embodiment of the present invention, the scramble processing for multipoint video transmission is performed by changing the spot identifier according to a certain rule during transmission and reception without predetermining the spot identifier. It may be configured as follows.

Although the above-described embodiment is applied to video transmission at four points, the present invention can of course be applied to video transmission at any number of points.

[0037]

As described above, according to the present invention, when a synchronization establishing signal is added to a video signal transmitted from a plurality of video signal sources and the signals are multiplexed, the synchronization establishing signal is supplied to each video signal source. Is added as a transmission source identifier to be transmitted, and on the receiving side, it can be separated into video signals of each video signal source based on this synchronization establishment signal. Further, the video signals transmitted from the respective video signal sources can be multiplexed and transmitted by one transmission line, so that the transmission line can be reduced and the transmission charge can be reduced as compared with the conventional example.

[Brief description of drawings]

FIG. 1 is a diagram showing a flow of video data according to an embodiment of the present invention.

FIG. 2 is a block diagram of the video signal multiplexer of FIG.

FIG. 3 is a diagram showing a structure of multiplexed video data.

FIG. 4 is a block diagram of a video transmission / reception device of the present invention.

5 is a block diagram of the video signal separation device of FIG.

FIG. 6 is a diagram showing a flow of video data in a conventional example.

FIG. 7 is a block diagram of a conventional video transmission / reception device.

FIG. 8 is a configuration diagram of video data of a conventional example.

[Explanation of symbols]

 1 Video Signal Multiplexing Device 7 Multiplexing Control Unit 9 Video Transmitting / Receiving Device 11 Video Signal Separating Device 16 Separation Control Unit

Claims (3)

[Claims] 1. A video signal multiplexer for adding a synchronization establishment signal to a video signal transmitted from a plurality of video signal sources and multiplexing the signal, wherein the synchronization establishment signal is transmitted to each video signal source. A video signal multiplexing apparatus comprising a multiplexing control unit added as a source identifier. 2. A video signal demultiplexing device for demultiplexing a multiplexed video signal by adding signals for synchronization establishment to video signals transmitted from a plurality of video signal sources, the video signal demultiplexer being based on the signals for synchronization establishment. And a video signal separation device for separating video signals for each video signal source. 3. A video signal multiplexer according to claim 1 and claim 2.
Video signal multiplex transmission system including the video signal separation device of.