JPH04291892A - Multi-point video conference controller - Google Patents

Abstract

PURPOSE:To prevent image data to be useless in switching from being generated or to prevent a picture from being distorted concerning the multi-point video conference controller to switch image data among respective points one and another at a multi-point video conference system. CONSTITUTION:A multiple separating means 11 is provided to separate image data and audio data, a switching control means 12 is provided to output a switching control signal based on the audio data, an image data switching means 13 is provided to switch the output destination of the image data corresponding to the respective points according to the switching control signal, a multiplexing means 14 is provided to multiplex and transmit the image data and the audio data, an image frame phase control means 15 is provided to fetch the respective image data, to detect the phases of respective image frames, to control the leading phase of each image frame and to output a leading phase control signal, and a switch control means 16 is provided to control the output timing of the switch control signal corresponding to the leading phase control signal.

Description

[Detailed description of the invention]

0001

[Industrial Field of Application] The present invention relates to a multipoint television conference system in which a plurality of points are connected to each other by bidirectional video lines and audio lines, in which image data is switched between each point. The present invention relates to a conference control device.

0002

2. Description of the Related Art FIG. 3 is a block diagram showing the configuration of a conventional multipoint video conference system. In the figure, codecs 41, 42, and 43 corresponding to each location are connected to a multipoint video conference control device 30. Note that the codecs at each location are shown separately on the transmitting side and receiving side in the figure for convenience. The image data and audio data transmitted from each codec are processed by a demultiplexing circuit (D
MUX) 311 to 313 and are separated into image data and audio data. Each image data is sent to an image data switching section 32, and each audio data is sent to a switching control section 33 and a multiplexing circuit (MUX) 34. In the image data switching section 32, based on the audio data corresponding to each point detected by the switching control section 33, image data of another point is assigned to the speaker's location, and image data of the speaker is assigned to locations other than the speaker. Select and output. The image data output for each point is multiplexed with audio data by multiplexing circuits 341 to 343, and then sent to the codecs 41 and 42 of the corresponding point.
, 43.

0003

[Problems to be Solved by the Invention] In the conventional multi-point video conference control device 30, image data is switched by distinguishing between speakers and non-speakers according to the audio state of each point detected by the switching control section 33. , is configured to change the screen displayed at each location. By the way, image data is usually transmitted and received in blocks as entropy-encoded image frames, but the switching timing of image data is performed based on audio data regardless of the image frame. Therefore, switching may occur in the middle of an image frame, in which case image data processing becomes discontinuous on the receiving side, some of the image data that had been sent up to that point is wasted, and frame synchronization is lost. Furthermore, the word synchronization for the error correction code is lost, resulting in an error correction error. In addition, in order to prevent the screen from becoming distorted in such a case, a freeze process that maintains the screen for a predetermined period of time has become essential.

SUMMARY OF THE INVENTION An object of the present invention is to provide a multipoint video conference control device that can switch image data in units of image frames and avoid generating wasteful image data and disrupting the screen during switching. do.

[0005]

[Means for Solving the Problems] FIG. 1 is a block diagram showing the basic configuration of the present invention. In the figure, the invention according to claim 1 includes a multiplexing and demultiplexing means 11 that separates input image data and audio data corresponding to each point, and a speaker is separated based on the separated audio data corresponding to each point. a switching control means 12 that outputs a switching control signal that distinguishes between a location where the image is displayed and a location other than the location and which switches image data;
an image data switching means 13 for switching the output destination of the image data corresponding to each point in accordance with the switching control signal; and a multiplexing means 14 for multiplexing and transmitting the image data and the audio data to be output for each point. In a multipoint video conference control device equipped with the above, each image data separated by the demultiplexing means 11 is taken in, the phase of each image frame is detected, the leading phase of each image frame is controlled, and the leading phase control signal is transmitted. The image frame phase control means 15 includes an output image frame phase control means 15, and a switching timing control means 16 that controls the output timing of the switching control signal output from the switching control means 12 according to the leading phase control signal of each image frame. It is characterized by

The invention as set forth in claim 2 provides a multi-point video conference control device as set forth in claim 1, in which the image data outputted from the image data switching means 13 corresponding to each point is taken in, and a predetermined error correction code is applied. The present invention is characterized in that it includes an error correction encoding means 17 that performs an encoding process.

[0007]

[Operation] According to the invention described in claim 1, the image frame phase control means 15 provided corresponding to each point adjusts the leading phase of each image frame and outputs it to the image data switching means 13, and the switching timing control means By controlling the output timing of a switching control signal that controls switching of image data according to the audio data via 16, switching of image data can be performed in units of image frames. Therefore, image data that is wasted during switching can be eliminated.

According to the second aspect of the invention, since the error correction encoding means 17 performs error correction encoding after image data is switched in units of image frames, the receiving side performs error correction due to image switching. Errors and out-of-sync can be avoided.

[0009]

Embodiment FIG. 2 is a block diagram showing the configuration of an embodiment of the present invention. Components corresponding to the conventional multipoint video conference control device shown in FIG. 3 are designated by the same reference numerals and will not be described. In the figure, the image frame phase control means 15 is
In this embodiment, an error correction circuit 21 that corrects errors in image data input for each channel, a unique word detection circuit 22 that detects a unique word of an image frame to detect the beginning of the image frame, and The memory 23 stores the information, and the memory control circuit 24 controls the leading phase of the image frame in accordance with the detection of the unique word. Further, the memory control circuit 24 controls the read timing of the memory 23 according to the leading phase of the image frame, and also controls the operation of the switching control section 25 that controls switching of the image data switching section 32.

Furthermore, between the image data switching section 32 and multiplexing circuits (MUX) 341 to 343, error correction coding is performed on the image data output from the image data switching section 32, and parity bits are added. Error correction encoding circuits 261 to 263 are provided. In the multipoint video conference control device having such a configuration, the unique word detection circuit 22 and the memory control circuit 24 detect the unique word of the image frame for each channel, identify its leading phase, and store image data. Controls the read timing of the memory 23. Furthermore, the switching control unit 25 detects the speaker based on the audio data, and furthermore, the timing of the switching control signal sent to the image data switching unit 32 in accordance with the leading phase control signal of the image frame output from the memory control circuit 24. Adjust. Therefore, the image data switching unit 32 can switch image data for each channel in units of image frames.

Note that the image data switching section 32 allows switching in units of image frames, so it is possible to easily perform an operation of sequentially transmitting image signals of a plurality of channels to one channel. That is, on the receiving side, images from multiple locations can be displayed simultaneously. In addition, in the error correction encoding circuit 26, error correction encoding is performed for each channel after image data is switched in image frame units, so the codec on the receiving side reliably ensures that errors occur in synchronization with image switching. Correction processing can be performed.

0012

[Effects of the Invention] As explained above, the present invention switches image data in units of image frames in a multipoint video conference system, so that it is possible to avoid sending unnecessary image data at the time of switching. Can be done. Furthermore, since error correction encoding is performed after switching image data, it is possible to avoid error correction errors and loss of synchronization caused by switching.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the principle configuration of the present invention.

FIG. 2 is a block diagram showing the configuration of an embodiment of the present invention.

FIG. 3 is a block diagram showing the configuration of a conventional multipoint video conference system.

[Explanation of symbols]

11 Demultiplexing means 12 Switching control means 13 Image data switching means 14 Multiplexing means 15 Image frame phase control means 16 Switching timing control means 17 Error correction encoding means 21 Error correction circuit 22 Unique word detection circuit 23 Memory 24 Memory control circuit 25 Switching control circuit 26 Error correction encoding circuit 31 Demultiplexing circuit (DMUX) 32 Image data switching circuit 33 Switching control circuit 34 Multiplexing circuit (MUX)

Claims (2)

[Claims] Claim 1: Multiplexing and demultiplexing means (11) for separating input image data and audio data corresponding to each point, and based on the separated audio data corresponding to each point, identifying the location where the speaker is a switching control means (12) for outputting a switching control signal for distinguishing points from other points and switching image data; and an image data switching means for switching an output destination of image data corresponding to each point in accordance with the switching control signal. (1
3), and a multiplexing means (14) for multiplexing and transmitting the image data and the audio data to be output corresponding to each point, the multiplexing and demultiplexing means (11) an image frame phase control means (15) that captures each separated image data, detects the phase of each image frame, controls the leading phase of each image frame, and outputs the leading phase control signal; A multipoint video conference control device comprising: switching timing control means (16) for controlling the output timing of the switching control signal output from the switching control means (12) according to the leading phase control signal. . 2. The multipoint video conference control device according to claim 1, wherein the image data output from the image data switching means (13) for each point is taken in and subjected to predetermined error correction encoding processing. Correction encoding means (1
7) A multipoint video conference control device comprising: