JPH04132387A - Pictorial communication equipment - Google Patents

Abstract

PURPOSE:To prevent the stop of an animation at the time of transmitting a still picture by dividing one still picture into blocks in order to prepare plural block picture signals, and time-division multiplexing both the picture signals and an one screen signal at the animation in order to transmit them on one communication line. CONSTITUTION:A block address generating part 23 generates both an address for storing a still picture signal and a reading address for reading out a signal from the stored still picture signal at every block. A selector 25 switches the transmission of the block picture signal transmitted from a still picture frame memory 21 to an encoder 26 into the transmission of the one screen signal transmitted from an animation frame memory 22 to the encoder 26 in a prescribed timing, based on a timing signal from a time-division controlling part 27. That is the time division multiplexing processing by which the block picture signal and the one screen signal are alternately combined is operated. Thus, the request for reducing a cost can be granted, and a failure that the animation is stopped while transmitting the still picture can be canceled.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image communication device that handles both moving images and still images as communication images, and is used, for example, in a video conference system.

'r and its i.

2. Description of the Related Art Video conferencing systems have conventionally been known that use telephone lines, public lines such as 15DN, or private lines to send and receive images to improve the efficiency of communication. This type of video conference system is, for example, shown in Figure 7 (
As shown in a), dedicated codecs are provided for still images and moving images, and both still images and moving images are sent and received separately through two lines. However, such a configuration requires dedicated codecs for moving images and still images, and also requires two lines for moving images and still images, resulting in high costs.

On the other hand, as a solution to this drawback, the method shown in the same figure (b
) has been proposed. This system uses one line and one codec for video and still images; if video is required, a switching device is operated to send and receive video; If a still image is required, a switching device is operated to send and receive still images.

However, such a switching system cannot transmit both a moving image and a still image at the same time, resulting in the inconvenience that the moving image stops while the still image is being transmitted.

In view of the above circumstances, it is an object of the present invention to provide an image communication device that satisfies the demand for cost reduction and eliminates the above-mentioned drawback, that is, the inconvenience that a moving image stops during still image transmission. The purpose is

In order to solve the above-mentioned problem, the image communication device according to the invention of claim 1 for transmitting images is an image communication device that handles both moving images and still images as communication images, and divides two still images into blocks. and means for time-division multiplexing the block image signal in the still image and the one-screen signal in the moving image and transmitting the same on one communication line. .

The image communication device according to the invention of claim 2 is an image communication device that handles both moving images and still images as communication images.
means for separating a time-division multiplexed signal into a one-screen signal for a moving image and a block image signal for a still image; a means for generating a moving image from the separated one-screen signal group; and a means for generating a moving image from the separated block image signal group; The invention is characterized in that it has a means for generating an image.

According to the above configuration, only one line is used, which satisfies the need for cost reduction. Still images are not transmitted all at once, but are transmitted in parts as block image signals. That is, the n-th one-screen signal in the video and the n
Basically, one block image signal will be interposed between the +1st single-screen signal, but since the block image signal is minute in time, the video will stop even if a still image is transmitted. It never appears that way.

An embodiment of the present invention will be described below with reference to FIGS. 1 to 6.

FIG. 1 is a block diagram showing a schematic configuration of an image communication device of the present invention, and FIG. 2 is an explanatory diagram showing a video conference system using the image communication device.

In FIG. 1, 11 is a line control section, 14 is an audio signal processing section, 15a is a microphone, 15b is a speaker, 16 is a transmission video signal processing section, 17a is a still image television camera, 17
b is a video television camera; 20 is a received video signal processing unit;
18a is, for example, a CRT (Cathode Ray Tube).
be) or L CD (Liquid Cr1sta
A still image display consisting of
18b is a moving image display made of the same CRT or LCD.

The line control unit 11 is configured to control the connection between the line and each part within the device, send out a calling signal, and detect an incoming signal. Further, the audio signal processing section 14 includes an audio amplifier (not shown) and the like, and is configured to amplify the audio signal input from the microphone 15a and drive the speaker 15b.

As shown in FIG. 3(a), the transmission video signal processing section 16 includes a still image frame memory 21 and a moving image frame memory 2.
2, a block address generation section 23, a moving image address generation section 24, a selector 25, an encoder 26, a time division control section 27, and a moving image state storage section 28.

Still image frame memory 21 stores still image signals sent from television camera 17a. Then, the block address generating section 23 generates the address for storing the still image signal and a subsequent address for reading out a signal for each block (block image signal) from the stored still image signal. Here, the still image signal for one screen is not outputted to the selector 25 at once, but is outputted sequentially for each block image signal. In this embodiment, the still image is divided into blocks, for example, in the form of folds, as shown in FIG. Furthermore, one block here does not mean a processing unit block of orthogonal transform (DCT, etc.) encoding or vector quantization encoding.

The video frame memory 22 stores video signals sent from the television camera 17b. Then, the moving image address generating section 24 generates successive addresses for reading out the image signal for each frame (hereinafter referred to as one-screen signal) from the above-mentioned address for storing the moving image signal and the stored image signal.

The selector 25 sends the block image signal sent from the still image frame memory 21 to the encoder 26 and the one-screen signal sent from the video frame memory 22 based on the timing signal from the time division control unit 27. encoder 2 of
6 is switched at a predetermined timing. That is, by passing through the selector 25, as shown in FIG. 4(a), time division multiplexing processing is performed in which the block image signal and the one-screen signal are alternately combined.

Note that (d) in the same figure shows the signal arrangement form of a single moving image for comparison. Figure (a) showing time-sharing processing of still images.
Although the frames are dropped by about 1/2 compared to the video only (d) in the same figure, it is possible to prevent the video from disappearing during still image transmission.

Note that the frame numbers in FIG. 4 indicate the number of frames, and the same frame number does not indicate the same frame image.

The encoder 26 encodes the time-division multiplexed image signal,
It performs predetermined encoding processing. In this case, the same encoding algorithm may be used for moving images and still images, but in this embodiment, while still images are directly encoded, for moving images, the difference between frames is Interframe encoding processing is performed to encode the data.

In interframe encoding, in order to encode the difference component, the state of the encoder 26 that encoded the previous frame is stored in the moving image state storage section 28.

A brief explanation of the code processing is as follows. That is, as shown in FIG. 6(a), the encoder 26 encodes one screen signal of the moving image (S 1 ), and then the state of the encoder 26 at this time is stored in the moving image state storage section 28. Store (S2). Next, one still image block is encoded (33), and then the state of the encoder 26 is reproduced based on the stored contents of the moving image state storage section 28 (S4), and the difference component from the next one screen signal is is encoded (Sl),
This series of actions is repeated. The video signal encoded by the encoder 26 is sent to the other party through a communication line.

The received video signal processing section 20 has the same configuration as the aforementioned transmission video signal processing section 16, as shown in FIG. 3(b). The difference in configuration is that a demultiplexer 25' is provided in place of the selector 25, and a decoder 261 is provided in place of the encoder 26. A brief explanation of the decoding process is as follows. That is, Fig. 6(b
), the decoder 26'' decodes one screen signal in the moving image (Sll), and then the state of the decoder 26° at this time is stored in the moving image state storage unit 28 (Sll).
12). Next, one block of still images is decoded (31
3), after that, the state of the decoder 26 is reproduced based on the stored contents of the video state storage unit 28 (314), and the difference component from the next one-screen signal is decoded (Sll), and this series repeating the action. And the decoder 26"
The video signal decoded by the demultiplexer 25"
The video signal and still image signal are separated into a video signal and a still image signal, and each is temporarily stored in the frame memories 21 and 22.The video signal is stored in the stored one-screen signal group, and the video signal is stored in the stored block image signal group. Still images are generated, read out sequentially, and displayed on the displays 18a and 18b, respectively.

According to the above configuration, only one line is used, and the demand for cost reduction can be satisfied. Still images are not transmitted all at once, but are transmitted in parts as block image signals. That is, the n-th one-screen signal in the video and the n
Basically, one block image signal will be interposed between the +1st single-screen signal, but since the block image signal is minute in time, the video will stop even if a still image is transmitted. It never appears that way.

Note that even if the encoding/decoding process is the same for moving images and still images, the encoding parameters may be different for moving images and still images. For example, the optimal Huffman tables for Huffman encoding are used for moving images and still images.

Also, as mentioned earlier, the processing unit for video is one frame,
A still image is one block, and the encoded data thereof is transmitted in an alternating time division manner, so there is no particular need to provide header information or the like to distinguish between the moving image part and the still image part of the transmission data. In other words, if it is known whether the first signal sent is a video signal or a still image signal, the decoding side can determine that the point at which one screen signal or one block of still images has been decoded is the boundary between the video and still images. Therefore, the moving image portion and the still image portion can be distinguished in this decoding process.

Note that by time-divisionally transmitting moving images and still images, the image quality of the moving images is degraded compared to the case where only moving images are transmitted. That is, since no moving image is transmitted during still image transmission, frame drop occurs.

To reduce the rate of dropping frames, for example,
As shown in Figure (b), the amount of encoded data for still images is reduced. To achieve this, the still image is divided into smaller blocks to make the unit blocks smaller.

Further, as shown in FIG. 2(c), the amount of encoded data of one screen signal of a moving image may be reduced. To achieve this, it is necessary to highly compress the single-screen signal while allowing the image quality of the single-screen signal to deteriorate.
If pixels are thinned out or DCT is used for compression, the quantization step may be increased. Of course, both of FIGS. 4(b) and 4(C) may be combined.

In general, the finer the block division of a still image and the smaller the amount of encoded data in one block, the better the video quality (image quality and frame drop rate of one screen signal), but the longer the transmission time for one still image. Become. Conversely, the larger the block division of a still image and the larger the amount of encoded data in one block, the more
Although the image quality of the moving image deteriorates, the transmission time for one still image can be shortened.

By controlling these relationships with parameters,
It may also be possible to make adjustments according to the user's preferences and situations.

In addition, although the above method uses a method of reducing the block size in order to reduce the amount of encoded data for one block of still images, another method is to allow deterioration in the image quality of still images and to reduce the amount of encoded data for one block of still images. It is also possible to increase the compression power and reduce the amount of encoded data for l block of still images. Furthermore, in the above embodiment, one screen data of a moving image and one block data of a still image are arranged alternately.
Alternatively, it is also possible to adopt a configuration in which multiple screen data groups and still image or multiple block data groups are arranged alternately.

According to the present invention as described above, it is possible to reliably eliminate the problem that a moving image stops during still image transmission, while satisfying the demand for cost reduction.

[Brief explanation of the drawing]

1 to 6 show an embodiment of the present invention, in which FIG. 1 is a block diagram showing a schematic configuration of an image communication device, and FIG. 2 shows a video conference system using the image communication device. 3(a) is a block diagram showing a transmission video signal processing section, FIG. 3(b) is a block diagram showing a receiving video signal processing section, and FIG. 4(a) is an explanation showing a time division multiplexed signal. figure,
Figure (b) is an explanatory diagram showing a time division multiplexed signal with a reduced amount of encoded data for still images, and (C) is an explanatory diagram showing a time division multiplexed signal with a decreased amount of coded data for moving images. d
) is an explanatory diagram showing the signal arrangement form of a single video, FIG. 5 is an explanatory diagram of block division, FIG. 6(a) is a flowchart showing code side processing, and FIG. FIGS. 7(a) and 7(b) are explanatory diagrams each showing a video conference system using a conventional image communication device. 11... Line control unit, 16... Transmission video signal processing unit, 17a, 17b-television camera, 18a, 18b...
・Display, 20... Reception video signal processing section, 21
. . . W% still image frame memory 22 . . . Video frame memory, 23 . . . Block address generation section, 24.
...Video address generation section, 25...Selector, 25
'... Demultiplexer, 26... Encoder, 26'
. . . Decoder, 27 . . . Time division control section, 28 . . . Moving image state storage section. Patent applicant: Murata Machinery Co., Ltd. 7th (a) (b) Allowance & motion 1゜(a) 6th (b)

Claims (2)

[Claims] (1) In an image communication device that handles both moving images and still images as communication images, a means for dividing one still image into blocks to generate a plurality of block image signals, and a block image signal for the still image and one for the moving image are provided. 1. An image communication device comprising means for time-division multiplexing a screen signal and transmitting the multiplexed screen signal onto one communication line. (2) In an image communication device that handles both moving images and still images as communication images, a means for separating a time division multiplexed signal into a single screen signal for moving images and a block image signal for still images, and a group of separated single screen signals. What is claimed is: 1. An image communication device comprising means for generating a moving image using a group of separated block image signals, and means for generating a still image using a group of separated block image signals.