JPS62199185A - Graphic display device - Google Patents

Abstract

PURPOSE:To reduce the turbulence in a reproducing picture to a future by providing a means for decoding animation data in an animation decoding part, a means for detecting an initial picture display signal and a reference and initial picture frame memory or the like. CONSTITUTION:When the decoding unit 371 disposed in an animation decoding part decides that a picture steering in the transmitted animation data goes to 01, it transmits the initial picture display signal SW-SIGR to a selector 379. The selector 379 feeds the contents of the initial picture frame memory 378 to the reference frame memory 377 and this data is added to the present frame by an adder 376, fed to an output processing unit 374 and displayed on a graphic display part through the frame memory part. Since an initial picture transfer instructing signal is periodically generated from a control part and the initial picture is periodically displayed, the turbulence in the picture to the future due to a line error is reduced. Thus, by providing the unit 371 or the like, the turbulence in the reproducing picture to the future can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an electronic conference system and the like for holding a conference between remote points, and particularly to a graphic display device that periodically displays an initial image stored in advance.

[Technical Background of the Invention] Conventionally, there has been something called an electronic conference system, such as the one shown in FIG. 7, for example. As shown in the figure, this electronic conference system includes a microphone 1, a speaker 2, a television camera 3 for projecting an image of the conference hall, a television camera 4 for copying a manuscript, a television monitor 5, a facsimile device 6, and a hard copy device as a printer. 7. Audio unit 8 that encodes and decodes audio signals from the microphone 1 and speaker 2; Image unit 9 that encodes and decodes image signals; Control unit 10 that controls the image unit; Instructions for control unit 10; It is comprised of an operation unit 11 for inputting information, and a transmission unit 12 for transmitting and receiving audio signals and image signals.

In such conventional electronic conference systems, video data is transmitted using a narrowband transmission path, and when a high-level data link (HDLC) procedure is used, a playback request is issued when a line error occurs. I was trying to get the correct compressed image data.

[Problems with the background technology] However, when using a narrow band transmission path as described above, moving image data is much smaller than the current image due to spatial compression (one screen), temporal compression (between frames), etc. Since the amount of information is small, there is a problem that if a bit error occurs in the transmitted data due to a line error or the like, this error will affect the future, and as a result, the reproduced image on the receiving side will be distorted. Further, requesting retransmission using an HDLC procedure or the like, obtaining correct compressed moving image data, and decoding it lacks real-time performance, and in this case as well, there is a problem that a kind of blurring of the reproduced image occurs.

[Object of the Invention] The present invention has been made to solve the above-mentioned problems, and its purpose is to provide a graphic display device in which reproduced images are less blurred in the future.

[Summary of the Invention] In order to achieve the above object, the present invention provides a video decoding unit that decodes input video data, a frame memory unit that stores the decoded video data, and a frame memory unit that stores the decoded video data. In a graphic display device having a display unit that displays video data stored in the video data, the video decoding unit includes a decoding unit that decodes the video data, and detecting an initial image display signal from the input video data. a reference frame memory that stores frame data to be referred to for frame data to be processed, an initial image frame memory that stores initial image data input in an initial state, and video data that is normally input. and an output section that performs arithmetic processing based on the contents of the reference frame memory and outputs the data after decoding the reference frame memory, and outputs the contents stored in the initial image frame memory when an initial image display signal is detected. Features.

[Embodiments of the Invention] Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 1 is a block diagram showing a conference unit system according to an embodiment of the electronic conference system of the present invention.

The control device 900 is connected to drawing, still image, moving image, and audio input devices, and to the control device 900 is connected to soft copy, hard copy, and audio output devices. Signals from these input devices and signals to output devices are subjected to processing such as selection and multiplexing according to several control information signals, and are then transmitted.

The input devices include a plurality of drawing input devices 100 for inputting handwritten characters and figures, a still image input device 200 for inputting documents before or during the meeting, and a still image input device 200 for inputting documents for meeting participants and the background of the conference hall. Video input device 300 for inputting images and audio input device 400 for inputting audio
is connected.

In addition, the output devices include a plurality of flat display devices 150 and graphic display devices (1) 160 for displaying input information of the own terminal and transmitted drawing type and still image type, and graphic display device (1) 1.
A hard copy device 260 for making a copy of 60, a graphic display device (2>350) for displaying the own terminal and the transmitted video input information, and an audio output device 450 for outputting the transmitted audio input information are connected. has been done.

The above input information is determined by signals from devices such as the operation input device 8501, the state detection device 800 that detects when conference participants leave or sit, and the speaker identification device 510 that determines the speaker from the voice of the conversational person. controlled.

FIG. 2 is a block diagram showing an example of the video input device 300.

This moving image input device 300 images a speaker using a plurality of television cameras, selects a predetermined television camera among the cameras, and sends the image information shown to the control device 900.

This video input device 300 includes a plurality of video input units 310a.
, 310b, 310c, 3'lOd, and the control device 900
a video selector unit 320 that selects one video input unit from the plurality of video input units based on a speaker switching signal (PID) from the speaker; and a video encoder unit 320 that compresses and encodes the selected video input signal (PIN). section 330, and a frame identifier adding section 340 to the encoded video data (PSD).
It consists of

The operation of this moving image input section @300 will be explained below.

, Multiple video input units 310a, 310b, 310G, and 310d are used to increase videos of meeting attendees, meeting i, and the background of the event.
The signal is converted into an electrical signal and sent to the video selector section 320.

Considering that the transmission capacity of the line is 64 kbps and data such as audio must also be transmitted over this line, it is impossible to input multiple moving images at the same time. Therefore, the video selector unit 320 uses the speaker switching signal (PID) of the control device 900.
) to select one video input section that captures the caller, and send this video input signal (PID) to the video encoding section 3.
Send to 00.

Note that the video input section of a person who leaves the meeting during the meeting can be disconnected by using the speaker switching signal (PID).

The video encoding unit 330 converts the video input signal (PIN) into 32 kb S by sampling processing using a frame drop method, predictive encoding processing using an interframe encoding method, direct exchange encoding processing using a cosine transform encoding method, etc. The identifier addition unit 340 compresses and encodes the data and outputs it as video data (PSD).
Send to.

The identifier adding unit 340 includes a frame identifier (FID) indicating that the data is video data, and a speaker switching signal (P
ID) is added to the video data (PSD) and sent to the control device 900 as transmission data (SXD).

Next, the video encoding section 330 will be explained.

An embodiment of the video encoding section 330 is shown in FIG.

This video encoding section 330 includes an input processing unit 331,
Transmission memory unit 332 and cosine transformation unit 3
33, an encoding unit 334, and a reference memory section 335
and σ adder 336.

The reference memory section 335 is a reference frame memory 337.
, an initial image frame memory 338 and a selector 339. The reference frame memory 337 stores replaced data one frame before the frame to be processed, and the initial image frame memory 338 stores frame data of the first image.

The operation of this video encoding section 330 will be explained below.

First, the video input signal (PIN) selected by the video selector section 320 is sent to the input processing unit 331, and after color burst and synchronization signals are removed from the video input signal, A/DS conversion is performed in 8 bits. . Furthermore, a digital filter (not shown) reduces the number of pixels in each frame to 25.
From 6x25& to 128x128, the frame frequency is also reduced from 30 frames/sec to 10 frames/sec.

Next, the input processed data of each frame is sent to the transmission memory unit 332 and stored in a current frame memory (not shown). The data of the previous reinterpreted frame is stored in the reference frame memory 337.
The current frame and reference frame are compared in units of 8×8 pixel blocks, and the block to be rewritten is determined. The adder 336 calculates the difference between the current frame and the reference frame, and the portion of the current frame that differs from the reference frame is input to the cosine transform unit 333, and is also input to the reference frame memory 337 via the selector 339, where it is input to the reference frame memory 337. The contents of will be rewritten.

The initial image frame memory 338 is for storing moving image data immediately after the power is turned on.

Further, the cosine transform unit 333 removes correlation between pixels by two-dimensional cosine transform, and sends the obtained transform coefficients to the encoding unit 334.

Since many of these transform coefficients take zero, they are compressed by run-length encoding instead of sending a long string of O bits.

Encoding unit 334 then selects the actual code in the Huffman coding table according to the prediction of the local energy of the image for the transform coefficients. It also encodes information about the block.

This encoded data enters a transmission buffer (not shown), and is sent from there as video data (PSD) to the identifier adding section 340 at a predetermined transmission rate.

Furthermore, the encoding unit 334 performs transmission rate control to prevent overflow and underflow of transmission data.

In this way, the video encoding unit 330 combines three types of compression: spectral, spatial, and temporal.

In other words, on the spectrum, subsampling in both horizontal and vertical directions and two-dimensional cosine transform encoding to remove correlation between pixels is performed on the redundancy of color components, and on the temporal scale, redundancy in values between frames is performed. Frame skipping, interpolation, and conditional rewriting are performed for each frame.

When the initial image transmission instruction signal (hereinafter referred to as instruction signal) SW-3IGT is input from the control device 900, this instruction signal 5W
-3IGT is a selector 339 and an encoding unit 334
is input. FIG. 6 is a format diagram of the transmission data output from the video encoding section 330, which includes the flag pattern F, frame identifier FID, and device address SA.
D, image data steering DS, video data D, and frame check sequence FC3. If the image data steering wheel DS is "00", it means a normal image display, and if it is "01", it means an initial image display.

When the instruction signal 5W-8IGT is input to the encoding unit 334, the encoding unit 334 converts the data from the flag pattern F in the transmission frame shown in FIG. 6 to the image data steering DS that is "01" as video data PSD. Send. Further, the selector 339 to which the instruction signal 5W-3IGT is input transfers the contents of the initial image frame memory 338 to the reference frame memory 337. Then, as mentioned above, the reference frame and current frame are compared,
The reference frame 337 at this time is the initial image frame. When the instruction signal 5W-3IGT is input from the control device 900 in this way, the video encoding section 330
The image data steerfling DS of the frame data output from the frame data becomes "01".

FIG. 4 is a block diagram showing an embodiment of the graphic display device (2) 350.

This graphic display device (2>350 is a device that displays the own terminal and the transmitted video input information, and the received data output from the control device 900 (RXD> to the device address (
SAD), an identifier detection unit 360 for detecting a frame identifier (FID) and a speaker switching signal (PID).
and a video decoding unit 370a that decodes video data (PRD).

370b, a frame memory unit 380 for temporarily storing and synthesizing decoded video signals (POlJT>), a display control unit 385 for controlling display of a plurality of videos and a still video in multiple divisions, and a graphic for displaying a video. Display device 390
It consists of

The operation of this graphic display device (2>350') will be explained below.

The received data (RXD) sent from the control device 900 is composed of control information and image information, and the control information includes a frame identifier (FID), a device address (SAD), a speaker switching signal (PID), etc. The image information is only video data.

First, the identifier detection unit 360 detects this frame identifier (FI
D) detects that it is video data, then detects the device address (SAD), and determines whether the own terminal is the other party's terminal. Furthermore, it is determined from which video input unit the video data is coming from based on the speaker switching signal (PID).

Next, the frame identifier (FID) and the identifier detection section 360
device address (SAD) and talker switching signal (PI
The moving image data (PRD) from which D) has been removed is sent to a moving image decoding section 370a or 370b, where the moving image data is compressed and encoded to 32 kbps.

These moving image decoding units 370a and 370b have the device address (
In response to SAD>, two systems with the same configuration are provided in order to correctly decode without delay even if the local terminal and the other terminal or the other terminal and the other terminal input simultaneously.

This decoded video signal (POUT) is temporarily stored in a predetermined area of the frame memory section 380, and a display screen is synthesized.

Note that the device address (S
AD) and speaker switching signal (PID) are transmitted by the display control unit 3.
85, and display control is performed on the frame memory unit 380 to display a plurality of moving images of the own terminal and any two terminals of the other terminal, and a still moving image in a plurality of sections on the same screen.

The moving image signal is then read from the frame memory section 380 at predetermined cycles and displayed on the graphic display section 390.

Next, the video decoding section 370a (370b) will be explained.

A first embodiment of the video decoding unit 370a (370b)
Shown in Figure 0.

The video decoding unit 370a includes a decoding unit 371 that decodes video data block by block, an inverse cosine transform unit 372 that performs inverse cosine transform on the decoded transform coefficients, and a current frame memory and a reference frame memory. The output processing unit 74 outputs moving image frames from the current frame memory and reference frame memory, a reference memory section 375, and an adder 376. The reference memory unit 375 includes a reference frame memory 377, an initial image frame memory 378, and a selector 379. Reference frame memory 3
77 stores the frame data that has been rearranged immediately before the frame data to be processed, and the initial image frame memory 378 stores the frame data of the first image that is inputted immediately after the power is manually turned on, etc. Ru. And reception memory 373, adder 376, output processing unit 37
4 constitutes an output section 381.

The operation of this video decoding section 370a will be explained below.

First, the video data (P
RD) is put into a reception buffer (not shown) of the decoding unit 371. Next, the block information is decoded,
The decoding step size is determined to obtain transform coefficients using roughly the same table as the Huffman encoding table.

Next, the inverse cosine transform unit 372 performs two-dimensional inverse cosine transform on the transform coefficients reproduced by the decoding unit 371, and outputs data in units of blocks.

Then, the receiving memory unit 373 rewrites the corresponding area in the current frame memory (not shown) in units of 8x8 pixel blocks based on the position information of the block to be rewritten.

The frame data immediately before the rewriting performance is stored in the reference frame memory 377, and the current frame in the data format of the difference amount and the contents of the reference frame memory 377 are added by the adder 376 and output processing unit 3
74 and input to the reference frame memory 377 via the selector 379.
The contents of will be rewritten.

Roughly the output processing unit 374 is the reception memory unit 3
Using the 73 current frame memory and reference frame memory, the frame frequency can be returned from 10 frames/second to 30 frames/second, and the pixel level in the reproduced frame can change smoothly over time. Frame interpolation is performed by Keiki as follows.

Finally, the video signal processed by the output processing unit 374 (
POUT) is sent to the frame memory section 380.

When the decoding unit 371 determines that the image data steering DS in the transmitted data is "01", the decoding unit 371 selects the selector 379.
An initial image display signal (hereinafter referred to as display signal) SW-3IGR is sent to. Then, the selector 379 sends the contents of the initial image frame memory 378 to the reference frame memory 377, and this data is added to the current frame by an adder 376 and sent to the output processing unit 374, and thereafter is displayed graphically via the frame memory section 380. It is displayed in section 39O.

When the image data steering DS is input as "01", the initial image stored in the initial image frame memory 378 is displayed on the graphic display section 390.

Since the control device 900 periodically generates the instruction signal 5W-3IGT, the graphic display device 350 periodically displays the initial image. Also, in the electronic conference system, since there are few changes in the image, there will be less blurring of the image in the future due to line errors. Furthermore, this embodiment has the advantage of being real-time since no error reproduction request is made.

[Effects of the Invention] As described above in detail, according to the present invention, it is possible to reduce blurring of reproduced images in the future.

[Brief explanation of drawings]

Figure 1 is a block diagram of the electronic conference system, Figure 2 is a block diagram of the video input device, Figure 3 is a block diagram of the video encoder, Figure 4 is a block diagram of the graphic display device (2), and Figure 5 is a block diagram of the video encoding unit.
FIG. 6 is a block diagram of a video decoding unit, FIG. 6 is a data frame format diagram, and FIG. 7 is a block diagram of a conventional electronic conference system. 100......Drawing input device 150.
......Flat display device 300...
......Video input device 350...
...Graphic display devices 370a, 370b...Video decoding section 371...Decoding unit 3
72......Inverse cosine transformation unit 375...Reference memory section 380.
...... Frame memory section 381...
......Output section 390...
・Graphic Display Department Representative Patent Attorney Nori Chika Ken Takao Sanno - Figure 1

Claims (1)

[Claims] (1) A video decoding unit that decodes input video data, a frame memory unit that stores the decoded video data, and a display unit that displays the video data stored in the frame memory unit. In a graphic display device having
The video decoding unit includes a decoding unit that decodes video data, a detection unit that detects an initial image display signal from input video data, and a reference that stores frame data to be referred to with respect to frame data to be processed. a frame memory; an initial image frame memory that stores initial image data input in an initial state; and after decoding video data that is normally input, performs arithmetic processing based on the contents of the reference frame memory and outputs it; A graphic display device comprising: an output section that outputs the contents stored in the initial image frame memory when an initial image display signal is detected.