JPH0269088A - Multilocation picture communication system - Google Patents

Abstract

PURPOSE:To eliminate the necessity of providing coding and decoding devices to each location by causing the coding device of each location to multiplex coding controlling information and video requesting data with each coding data by switching inter-frame coding data and other coding data to each other at every picture. CONSTITUTION:A multilocation picture communication controller 4 performs switching of picture data sent from plural locations from the data of video pictures on which no inter-frame coding is performed based on the data detected by a detecting means 4A. Moreover, the controller 4 sends data requesting picture freezing to the decoding device 2 at the same location as that of a coding device 1 by means of a picture freezing requesting means 4C during the data discontinuing time created by video data switching. Video data and picture freezing requesting signals from each location are selectively outputted to the decoding device 2 at the same location as that of the coding device 1 through a selector 4D. Therefore, necessity of providing coding and decoding devices in a multilocation picture communication controller to each location is eliminated.

Description

[Detailed description of the invention] [Table of contents] Overview Industrial field of application Prior art (Figures 9 and 10) Means for solving the problem to be solved by the invention (Figures 1 to 3) Function (1st
3) Embodiment (FIGS. 4 to 8) Effects of the invention [Summary] Regarding a multipoint image communication system that performs image communication between multiple points via a multipoint image communication control device, the base of transmission path code data is The purpose is to make it possible to perform video switching processing at each point, thereby eliminating the need for encoding and decoding devices for each point in a multipoint image communication control device. The multipoint image communication control device is configured to switch between encoded data and other encoded data on a screen-by-screen basis, and to multiplex interframe encoded control information and video request data with each encoded data. is detected and the image data from multiple points is switched from the non-interframe encoded data of the newly selected image after one screen worth of data of the previously selected image is completed. The decoding device at each location switches the decoded data on a screen-by-screen basis and freezes the screen upon receiving a one-screen freeze request. Configure.

[Industrial Field of Application] The present invention relates to a multipoint image communication system that performs image communication between multiple points via a multipoint image communication control device, and particularly relates to a multipoint image communication system that is suitable for use in image conference communication between multiple points. Regarding point image communication system.

[Prior Art] Conventionally, as a multipoint image communication system, encoding devices and decoding devices located at multiple points are connected to a multipoint image communication control device, and video data sent from each point is transmitted. The multi-point image communication control device decodes the signal once and restores it to the original video signal, and then selects one screen from among the video signals from other locations by requesting video selection from each location or by comparing the audio levels of each location. There are some things that are transmitted to each location.

FIG. 9 is a block diagram showing such a conventional example, and in this FIG. 9, there are three points P-1 to
P-3 includes an encoding device 101 that encodes image input and outputs a video switching request signal, and a decoding device 10 that decodes encoded data from another point and outputs an image output.
2 is provided.

Further, a multi-point image communication control bag [104] is provided on the transmission line 103 connecting each of these points. This multipoint image communication control device 104 includes the decoding device 1
05. Encoding device 106, video switching device 1072, phase adjustment device [108] are provided at each location.

Here, the decryption bag! E105 is the encoding device 1 at each point.
Decode the data from 01 and phase adjust the 1 image data! While outputting to 108, the video selection signal is separated and
Video switching bag [Output to 107, decoding device 10
6 decodes signal point data from the video switching device 107 and outputs it to the decoding bag [102] of the corresponding point.

The video switching device 107 outputs data from a desired point in response to a video selection signal from the decoding device 105. The 1-phase adjustment device 108 is used to prevent synchronization from being lost when switching videos. belongs to.

By the way, each point and multipoint image communication control device 104
Encoding devices 101, 106 and decoding devices 102, 105 provided in the above are configured for variable encoding and variable decoding as one of the predictive encoding methods, respectively, as shown in FIG. . That is, first, the encoding device [101 (106) includes the quantization unit 201. Frame memory 202° subtraction unit 203. Addition unit 204. The decoding device 102 (105) includes a variable encoding section 205, a buffer memory 206, and a frame memory 207. Addition unit 208. The circuit configuration includes a variable decoding section 209 and a buffer memory 210, and these circuit configurations are known as a circuit for predictive encoding.

Therefore, in the encoding bag [101 (106)], the subtraction unit 203 takes the difference value between frames, which is the change between the previous screen stored in the frame memory 202 and the video input (current screen), to make the video signal redundant. This difference value is variably encoded in the variable encoder 205 to perform high-efficiency encoding so that it can be transmitted at a low transmission rate, and the decoding bag [10
The variable length decoding unit 209 of No. 5 (102) performs variable decoding to obtain the original video signal.

Since high-efficiency code transmission using variable encoding is performed in this way, the multi-point image communication control device 104 has an encoding device 105 and a decoding device 106 at each point, as shown in FIG. Only the number is required. This is because even if there is encoded video data for one screen sent to the transmission path 103, it is a difference from the previous screen, so the video signal cannot be reproduced unless there is data from the previous screen. Therefore, in order to switch and transmit video using the multipoint image communication control device 104, the video data sent from each location must be decoded once, returned to the original video signal, switched, and encoded again. This is because it is necessary.

With such a configuration, the video input at each point is variably encoded by the encoding device 101, and the multi-point image communication control device! 1104 through transmission line 3. In the multi-point image communication control device 104, the sent video data is variably decoded by the decoding device 105 to return to the original video, and the video signal is switched to the video corresponding to another point via the phase adjustment device 108. While being input to the device 107, the video selection signal is input to the video switching device 107 corresponding to this point. For example, considering a video transmitted to point P-1, in this example, the video signal is transmitted to another point P-2,
The video selection signal is input to the video switching device 1.7 corresponding to point P-3, while the video selection signal is input to the video switching device 1.7 corresponding to point P-1! !
1078 are input.

Now, for example, if point P-1 requests a video signal from point P-2, the video switching device 1107 corresponding to point P-1 outputs the video signal from point P-2, and By being encoded by the encoding device 106 and further decoded by the decoding bag @102 of the point P-1, the point P-
2 is monitored at point P-1.

Note that video signals are transmitted and captured in the same manner for the other points P-2 and P-3.

Furthermore, as a high-efficiency encoding (including decoding) technique, in addition to the variable encoding technique, a vector quantization technique and a transform encoding technique can also be used.

[Problem to be solved by the invention]

However, such conventional multi-point image borrowing methods do not directly perform PCM transmission, but instead employ highly efficient coding and transmission methods that use variable coding, vector quantization, and transform coding. Therefore, it is necessary to install encoding devices and decoding devices for the number of points in the multipoint image communication control device, and as the number of points increases, the circuit configuration of the multipoint image communication control device becomes large-scale. There is a problem of becoming

The present invention was made in view of these problems, and
By making it possible to perform video switching processing based on transmission line code data, it is not necessary to provide a multipoint image communication control device with an encoding device and a decoding device corresponding to each point. The purpose is to provide a multipoint image communication system.

[Means for Solving the Problems] The present invention also provides, as shown in FIG.
-2, . By providing a multi-point image communication control bag W4 with data requesting the capture of an image from the point desired to be received from the encoding device 1 at an arbitrary point, images from the point desired to be received are selected. This is a multi-point image communication system that allows this image to be taken into the decoding device 2 at the arbitrary point.

By the way, the principle block diagram of the encoding device 1 and the decoding bag [2 at each point P-i (i=1.2...N) is shown in Figure 2, and multi-point image communication control Device 4
A block diagram of the principle is shown in Fig. 3.

First, as shown in FIG. 2, the encoding device 1 provided at each location includes a first encoding means 1A that performs interframe encoding, and a second encoding means 1A that performs encoding other than interframe encoding. encoding means 18, encoded data switching means IC for switching between the data interframe encoded by the first encoding means 1A and the data encoded by the second encoding means 18 on a screen-by-screen basis, and each screen The apparatus includes a multiplexing means 1D that multiplexes and transmits the encoded data of , data indicating that the screen is not subjected to interframe encoding, and data requesting video from a point desired to be received.

Further, the decoding device 2 provided at each location is also a second decoding device 2.
As shown in the figure, the first decoding means 2A performs interframe decoding, the second decoding means 2B performs decoding other than interframe decoding, and the first decoding means 2A performs interframe decoding. encoded data and second decoding means 2
A screen freeze request is received from a decoded data switching means 2C that switches the data decoded by B on a screen-by-screen basis, and a screen freeze request means 4G (described later) in the multipoint image communication control device 4, via a detection means 2D. The screen freezing means 2E is configured to freeze the screen.

Furthermore, as shown in FIG. 3, the multipoint image communication control device 4 receives data indicating that the beginning of the screen and the screen is not subjected to interframe coding from the data transmitted from the encoding device 1. A detection means 4A detects data requesting an image from a desired point, and based on the data detected by this detection means 4A, switching of image data sent from multiple points is performed. After data for one screen of the previously selected video is completed, the video data switching means 4B performs decoding from the data of the screen that has not been interframe encoded for the newly selected video, and decodes the video data during free time during video data switching. For device 2.

It is composed of a screen freeze requesting means 4C that sends data requesting screen freezing, and a selector 4D that selectively outputs video data from each point and a screen freeze request signal, and these detecting means 4A, video Switching means 4B, screen freeze requesting means 4C and selector 4D
are provided for the number of points, N, respectively.

[Operation] With such a configuration, in the encoding device 1, the first encoding means 1A performs interframe encoding, while the second encoding means 18 performs interframe encoding between the interframe encodings. Encoding other than interframe encoding is performed, and furthermore, the encoded data switching means IC transfers the interframe encoded data by the first encoding means 1A and the second encoding means 18.
The encoded data is switched on a screen-by-screen basis and output. In addition, in this encoding device 1, the encoded data of each screen includes data indicating that the screen is not subjected to interframe encoding and data requesting video from a desired point to be received by the multiplexing means 1D. It is multiplexed and transmitted to the multipoint image communication control device 4.

Then, in the multipoint image communication control device 4, the detection means 4A receives from the data transmitted from the encoding device 1 data indicating that the screen is not encoded between the beginning of the screen and the frames. Based on the data detected by the detection means 4A.

Switching between image data sent from multiple points starts with data from a newly selected screen that has not been interframe encoded, after one screen of data from the previously selected video has been completed. During the free time for video data switching, the screen freeze requesting means 4C sends data requesting screen freezing to the decoding device 2 located at the same location as the encoding device [1]. The video data and screen freeze request signal from each point are sent to the selector 4D.
is selectively output to the decoding bag [2] located at the same location as the encoding device 1.

Also, a decoding device 2 located at the same location as the encoding device 1
Then, while interframe encoded data is coming, the first decoding means 2A performs interframe decoding, and while encoded data other than interframe encoded data is coming, the second decoding means 2A performs interframe decoding. The decoding means 2B performs decoding other than interframe decoding, and the decoded data switching means 2C performs the first
The data decoded between frames by the second decoding means 2A and the data decoded by the second decoding means 2B are switched on a screen-by-screen basis. Incidentally, when a screen freeze request is received from the screen freeze request means 4C in the multipoint image communication control device 4 via the detection means 2D, the screen is frozen by the screen freeze means 2E.

[Example code] Hereinafter, the present invention will be described in detail with reference to the drawings.

In the case of this embodiment, as shown in FIG. 4, for example, an encoding device 1 and a decoding device are located at three points P-1, P-2, and P-3. 2 are provided in pairs, and a multipoint image communication control device 4 is installed on the transmission path 3 connecting these points.
By providing data requesting the capture of an image from the point desired to be received from the encoding device [1 at an arbitrary point to the multipoint image communication control device 4, the image from the point desired to be received is selected. This is about a multi-point image communication system that allows this image to be taken into the decoding device 2 at any point, and the encoding device at each point P-i (i=1.2.3) 1 and decoding bag W2 are shown in FIG. 5, and a block diagram of the multipoint image communication control device 4 is shown in FIG.

First, the encoding device 1 provided at each location includes a frame memory 10, a one-clock delay unit 11, and
．． Subtraction section 12. Addition unit 13. Quantization unit 14. Selector 1
5. Variable length encoder 16° encoder 17. Multiplexing section 18
．． It is configured with a buffer memory 19.

Here, since the frame memory 10 can store one previous screen, it is provided for performing interframe encoding. The one-clock delay unit 11 delays image information by one clock, and is provided to perform intra-frame encoding as encoding other than inter-frame encoding.

The subtraction unit 12 is for calculating the difference between the previous video input and the current video input, and the addition unit 13 is for adding the input/output information of the frame memory 1o or the 1-clock delay unit 11.
The quantization unit 14 quantizes the difference information between the previous video input and the current video input, and these components include a first encoding means that performs interframe encoding and a code other than interframe encoding. This constitutes a second encoding means that performs encoding (intraframe encoding).

The selector 15 selectively outputs either the output of the frame memory 10 or the output of the 1-clock delay section 11, and this switching is performed based on the interframe encoding control signal.
Intraframe encoding is performed once for every M times of interframe encoding (M is a natural number). That is, this selector 1
Reference numeral 5 constitutes an encoded data switching means that switches between the data interframe encoded by the first encoding means and the data encoded by the second encoding means on a screen-by-screen basis.

The variable length encoding unit 16 performs variable length encoding in order to perform high efficiency encoding.

The encoding unit 17 encodes an interframe encoding control signal having information indicating that the screen is not subjected to interframe encoding, and a video request signal as data requesting video from a point to be received. A multiplexing unit (multiplexing means) 18 multiplexes an interframe encoding control signal and a video request signal with encoded data of each screen, and a buffer memory 19 multiplexes this data when transmitting this multiplexed data. can be temporarily stored.

Further, the decoding device 2 provided at each location is also the fifth decoding device 2.
As shown in the figure, buffer memory 20° variable decoding section 2
12 Screen freeze request detection unit 22° interframe encoding control information detection unit 232 Screen freeze unit 24. selector 25
．． Addition unit 26. Frame memory 27, 1 clock delay unit 28. It is configured with a selector 29.

Here, the buffer memory 20 can temporarily store received data, and the variable decoding section 21 is provided corresponding to the variable length encoding section 16 to perform variable length decoding. be.

The screen freeze request detection unit 22 detects a screen freeze request instruction from a screen freeze instruction unit 45 (described later) in the multipoint image communication control device 4, and the interframe encoding control information detection unit 23 detects interframe encoded data. This is to detect whether the data is true or not.

The screen freeze section 24 stores required dummy data (for example, 0)
, and then freeze the screen as it was at that time.

The selector 25 outputs the signal from the variable decoding unit 21 while the screen freeze request detection unit 22 does not detect the screen freeze request instruction from the screen freeze instruction unit 45, and the screen freeze request detection unit 22 outputs the signal from the variable decoding unit 21. When a screen freeze request instruction from the instruction section 45 is detected, a signal is issued from the screen freeze section 24.

The adder 26 adds the input signal and the previous information during decoding.

The frame memory 27 can store the previous screen for one screen, and is therefore provided for performing interframe decoding.

The one-clock delay unit 28 delays image information by one clock, and is provided to perform intra-frame decoding as decoding other than inter-frame encoding.

Therefore, these members 21, 26 to 28 constitute a first decoding means that performs interframe decoding and a second decoding means that performs decoding other than interframe decoding.

The selector 29 includes an interframe coding control information detection unit 23
While detecting interframe encoded data, the output from the frame memory 27 is selected, and when no interframe encoded data is detected, the output from the 1-clock delay section 28 is selected. That is, this sector 29 constitutes decoded data switching means that switches between the data decoded between frames by the first decoding means and the data decoded by the second decoding means on a screen-by-screen basis. .

Furthermore, a multipoint image communication control bag! ! As shown in FIG. 6, I4 is a leading data detection section 41. Interframe coding control information detection unit 42. Request video information detection unit 43. Switching signal generator 44. A freeze instruction section 45 and a selector 46 are each provided with the number of points (three in this example).

Here, the leading data detector 41 detects the leading data of the screen from the data transmitted from the encoding device 1, and the interframe encoding control information detector 42 detects the interframe encoding control signal. The requested video information detecting section 43 detects a video request signal as data requesting a video from a desired point, and the detection results from the leading data detecting section 41 and the interframe coding control information detecting section 42 are as follows. , and the detection result from the requested video information detection section 43 is input to the switching signal generation section 44 for points corresponding to the own point.

The switching signal generating section 44 receives the detection results from the leading data detecting section 41 and the interframe coding control information detecting section 42 for points corresponding to points other than its own point, and the request video information detecting section 43 for its own point. In response to the detection result, the selector 46 is switched and the freeze instruction section 45 is controlled.
4, and receive the control signal from 4, during the free time for video data switching.

The selector 46 constitutes a screen freeze requesting means for sending data requesting screen freezing to the decoding device 2, and the selector 46 receives a control signal from the switching signal generating section 44, and
Interframe encoded data and intraframe encoded data from other points are alternatively output. This allows switching of image data sent from multiple points other than the own point, and interframe encoding of the newly selected image after one screen worth of data of the previously selected image is completed. This can now be done from screen data that has not yet been updated.

With the above-described configuration, the encoding device 1 at each point P-1 to P-3 switches the selector 15 every M frames to stop interframe encoding and perform intraframe encoding. As a result, interframe encoded data is transmitted from each point to the multipoint image communication control device 4 for 1M frames, and intraframe encoded data is transmitted every M frames. Note that at this time, the interframe encoding control signal and the video request signal are multiplexed and transmitted at the beginning of the encoded data.

In the multi-point image communication control device 4, the leading data detection section 41 corresponding to each point detects the beginning of the encoded data, and the interframe encoding control information detection section 42 detects the interframe code that is continuously transmitted for M frames. The requested video information detection unit 43 detects the video information to be captured by detecting the encoding information and the intra-frame encoding information transmitted every M frames.

Then, the start information of the encoded data detected by the start data detection unit 41 and the interframe coding control information detection unit 4
The interframe coding control information detected in step 2 is sent to the switching signal generation unit 44 for other points, and the video information to be captured detected by the requested video information detection unit 43 is sent to the switching signal for the own point. The signal is sent to the generating section 44.

Then, from each switching signal generation section 44, the freeze instruction section 4
5 and the selector 46, the switching control of the transmission data in the switching signal generating section 44 is performed at the point P.
To explain the switching control of transmission data to -1 as an example,
It will look like Figure 7.

That is, first, in step S1, the requested video information detection section 43
Based on the detection signal of point P-1, it is determined which point the image of the point P-1 is desired to be captured. In this flow, when Sa is O, an image of point P-2 is requested, and when Sa is 1, an image of point P-3 is requested.

Then, if there is a video switching request at point P-1,
That is, when Sa changes from O to 1 or from 1 to 0,
In the next step S2, the content of the request is checked1. For example,
If the video from point P-2 is requested (if Sa=O), it is determined in step S3 whether the data for point P-3 has been sent to the end. This determination is made based on whether or not the leading data is detected from the leading data detection unit 41 for point P-3. In this flow, when 5e=O, it means that the first data has been detected, and when 5e=1, it means that the first data has not been detected.

When 5e=O is detected in this step S3.

Assuming that the data for point P-3 has been sent to the end, it is determined in step S4 whether 5c=O and 5b=1. Here, Sc is the leading data detection unit 4 for point P-2.
Indicates the presence/absence information of the leading data of the video from point P-2 obtained in step 1, 5c = 0 indicates presence of leading data, 5c = 1 indicates absence of leading data, and sb is the information for point P-2. Point P-2 obtained by interframe encoded control information detection unit 42
indicates interframe coding control information from sb=.

5b=1 means interframe coding, and 5b=1 means intraframe coding. Therefore, the first data from point P-2 is detected (5c=O), and the encoded data sent from point P-2 is intra-frame encoded data (
Sb = 1), the selector 46 is switched to the image of point P-2 (step 55), while S c = O
, and if 5b=1 is not satisfied, freeze instruction information is sent (step S6).

Also, if you request video from point P-2 (S a
= 1), it is determined in step S7 whether the data for point P-2 has been sent to the end. This judgment is
It is determined whether the first data is detected from the first data detection unit 41 for point P-2 (whether SC=O or not).

When 5c=O is detected in this step S7.

Assuming that the data for point P-2 has been sent to the end, it is determined in step S8 whether 5e=Q and 5d=1. Here, Sd indicates interframe coding control information from point P-3 obtained by interframe coding control information detection unit 42 for point P-3, 5d=O indicates interframe coding, 5d =1 means intraframe encoding. Therefore, the first data from point P-3 should be detected (5e=O)
.

In addition, when the encoded data sent from point P-3 is intra-frame encoded data (Sd=1), the selector 46 is switched to the image of point P-3 (step 59), while 5e If 5d=O5 and 5d=1 are not satisfied, freeze instruction information is sent (step 5IO).

Note that switching control of transmission data to other points P-2 and P-3 is performed in the same manner.

In this way, the multipoint image communication control device 4 detects the data indicating the beginning of one screen from the transmitted data, generates a signal indicating the position of the leading data, and uses the screen without interframe coding to detect the data indicating the beginning of one screen from the transmitted data. detecting data indicating a screen without interframe coding, and generating a signal indicating a screen that is not interframe encoded;
From these signals, it detects data indicating the video you want to receive.

The encoded data from each point is switched on a screen-by-screen basis, and the encoded data of the newly switched video starts from the intra-frame encoded data, and the requested video data is transmitted to each point. During free time, data instructing to freeze the screen and dummy data unrelated to decoding are multiplexed and transmitted.

The time chart at this time is shown in Figure 8.
Figures (a) to (a) relate to point P-1, where Figure 8 (a) is encoded data of point P-1, Figure 8 (b) is a signal indicating the beginning of screen data, and Figure 8 (b) is a signal indicating the beginning of screen data. Figure (Q) is a signal indicating interframe coding control information, and Figure 8 (d) is point P-1.
8(e) is the transmission data to point P-1, and FIG. 8(f) to (j) are the signals indicating the requested video of point P-2.
8(f) shows the encoded data at point P-2, FIG. 8(g) shows the signal indicating the beginning of the screen data, and FIG. 8(h) shows the interframe coding control information. The signal, FIG. 8(i) is a signal indicating the requested video of point P-2, FIG. 8(j) is the transmission data to point P-2, and FIG.
) to (o) are related to point P-3, and Fig. 8(k)
is the encoded data of point P-3, FIG. 8(Q) is a signal indicating the beginning of screen data, FIG. 8(m) is a signal indicating interframe coding control information, and FIG. 8(n) is the point The signal indicating the requested video of P-3, FIG. 8(o), is the data transmitted to point P-3.

In FIG. 8, FS is data indicating the top of the screen, and FR is freeze instruction information (however.

CM is interframe coding control information, RP is video request information, D is coded video data, FS is pseudo screen top information transmitted during switching free time, FR The skewer is freeze instruction information transmitted during the switching free time, and Du+*my Data is dummy data that does not affect the reproduced video.

As described above, encoded data is sent from the multipoint image communication control device 4 to the decoding bag ff1i2 at each point. Detects the control information, decodes the video data, and freezes the screen during the switching free time, while otherwise.

The decoded data is subjected to interframe decoding or intraframe decoding. At this time, the switching timing of the selectors 25 and 29 is determined by the switching signal generation unit 4 of the multipoint image communication control device 4.
It is synchronized with the switching timing in 4.

In this way, while inter-frame encoding is mainly performed as encoding in the encoding device 11 at each point, intra-frame encoding is performed periodically (every M frames) without using previous screen data. Switching of video data in the point image communication control device 4 can be performed after the encoded data of the previous image has been completed, but before the interframe encoding of the newly switched video is performed, so that the encoded data remains as it is. It is something that can be handled. Therefore, there is no need to provide a multipoint image communication control device with encoding devices and decoding devices for the number of points, unlike in the past, and this prevents the hardware scale of the multipoint image communication control device from increasing. However, multipoint image conferencing can be realized.

Also, since the bit length of encoded data for one screen changes depending on the input screen, the encoded data sent from each point is always sent to the selector 46 with the leading data of the screen aligned with the encoded data from other points. Although input is not possible, the receiving side freezes the screen until the beginning of the next screen arrives, so there is no disturbance on the screen during the switching transition.

Note that in the above embodiment, intraframe encoding was performed as encoding other than interframe encoding, but vector quantization or transform encoding may be performed in addition to that.

Furthermore, it goes without saying that the present invention can be similarly applied to systems using multi-point image communication control devices for four or more points.

[Effects of the Invention] As detailed above, according to the multipoint image communication system of the present invention, the encoding device at each point performs interframe encoding and interframe encoding that does not use previous screen data. In addition, switching of video data in the multipoint image communication control device can be performed after the encoded data of the previous image has been completed, without interframe encoding of the newly switched video. Therefore, the encoded data can be handled as is, and there is no need to provide encoding devices and decoding devices for the number of points in the multipoint image communication control device as in the conventional method. The advantage is that multipoint image conferencing can be realized without increasing the size of the hardware.

[Brief explanation of the drawing]

1 to 3 are block diagrams of the principles of the present invention, and FIG. 4 is a block diagram showing the overall configuration of an embodiment of the present invention. FIG. 5 is a block diagram of the encoding device and decoding device at each point, FIG. 6 is a block diagram of the multipoint image communication control device, and FIG. 7 is a flowchart explaining the operation of an embodiment of the present invention. FIG. 8 is a time chart explaining the operation of an embodiment of the present invention, FIG. 9 is a block diagram showing a conventional example, and FIG. 10 is a block diagram of a conventional encoding device and decoding device. In the figure, 1 is an encoding device, and 1A is a first encoding means. 18 is a second encoding means, 1C is an encoded data switching means, 1D is a multiplexing means, and 2 is a decoding device. 2A is a first decoding means, 2B is a second decoding means, 2C is a decoded data switching means, and 2D is a detection means. 2E is a screen freezing means, 3 is a transmission line, 4 is a multipoint image communication control device, and 4A is a detection means. 4B is a video switching means, and 4C is a screen freeze requesting means. 4D is a selector. 10 is a frame memory, 11 is a 1-clock delay section, and 12 is a subtraction section. t3 is an adder, 14 is a quantizer, 15 is a selector, and 3-11 is a variable length encoder. 17 is an encoding section, 18 is a multiplexing section, 19.20 is a buffer memory, 21 is a variable decoding section, 22 is a screen freeze request detection section, 23 is an interframe coding control information detection section, 24 is a screen freezing section , 25 is a selector, 26 is an adder, 27 is a frame memory, 28 is a 1-clock delay unit, and 29 is a selector. 41 is a leading data detection unit. 42 is an interframe coding control information detection section, 43 is a requested video information detection section, 44 is a switching signal generation section, 45 is a freeze instruction section, and 46 is a selector. P-i is a point. 111 encoding system 1 2-m-decoding device This invention's original factory front diagram Figure 2 4-11 Of course, the video image is rapidly advanced control 11 branches! Principle 7 of the invention
0717 Figure 3 --- Figure 3 shows the overall structure of the monocyst flI of the present invention. Examples and illustrations 1/7 Figure 9

Claims (1)

[Claims] Pairs of encoding devices (1) and decoding devices (2) are provided at a plurality of points (P-i), and multiple points are provided on a transmission path (3) connecting these points. A point image communication control device (4) is provided, and the encoding device (1) at an arbitrary point is provided.
By supplying the multi-point image communication control device (4) with data requesting the capture of an image from a point that you want to receive, the image from the point you want to receive is selected, and this image is sent to the desired point. In a multi-point image communication system that can be input to the decoding device (2), the encoding device (1) includes a first encoding means (1A) that performs interframe encoding; a second encoding means (18) that performs encoding other than encoding; and a second encoding means (18) that encodes data interframe encoded by the first encoding means (1A) and encodes it by the second encoding means (1B). encoded data switching means (1C) that switches the encoded data on a screen-by-screen basis, and the encoded data of each screen, data indicating that the screen is not interframe encoded, and the video from the point desired to be received. A multiplexing means for multiplexing and transmitting requested data (
1D), and the multipoint image communication control device (4) does not perform inter-frame encoding from the beginning of the screen on the data transmitted from the encoding device (1). a detection means (4A) that detects data indicating that the image is received and data requesting images from the point to be received; and image data sent from multiple points based on the data detected by the detection means (4A). After the data for one screen of the previously selected video is completed,
A request is made to the video data switching means (4B), which starts from screen data that has not been interframe encoded in the newly selected video, and to the decoding device (2), during the idle time of video data switching. The decoding device (2) includes a first decoding means (2A) that performs interframe decoding, and a screen freeze request means (4C) for sending data to A second decoding means (2B) that performs decoding, data decoded between frames by the first decoding means (2A), and data decoded by the second decoding means (2B). decoded data switching means (2C) for switching on a screen-by-screen basis; and screen freezing means for freezing the screen in response to a screen freeze request from the screen freeze request means (4C) in the multipoint image communication control device (4). (2E) A multipoint image communication system comprising: