JPH0723355A - Picture communication terminal equipment and freeze control method - Google Patents

Abstract

PURPOSE:To indicate a transmission condition from the receiving side to the transmitting side by setting up an individual command by means of an escape table value defined by a bit rate allocating value with frame structure based upon CCITT recommendation H221. CONSTITUTION:When a condition to be frozen is set up in normal receiving, the picture receiving side operates an operation device 36 to generate a freeze request command from an individual command generating means 40 in a system control circuit 34. The command generated from the means 40 is transmitted to a terminal on the picture transmitting side through a separating/multiplexing circuit 32, a line interface 30 and a communication line. When the transmitting side terminal receives the individual command, an individual command discriminating means 42 in the circuit 34 decodes the meaning of the individual command. When the command is a freeze request command, a freeze control means 44 is instructed to freeze a transmitting picture.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image communication terminal device and a freeze control method, and more particularly to a moving image communication terminal device and a freeze control method in a videophone device and a video conference system.

[0002]

2. Description of the Related Art Regarding the image communication of a video telephone device and a terminal device of a video conference system, CCITT Recommendation H.264. 261 and H.264. There is 221.

CCITT Recommendation H.264 A freeze request command (BAS value (010)) is defined in the bit allocation signal (BAS) in the frame structure of H. 221 and CCITT Recommendation H.264. The freeze release request command is defined in the third bit of the type information 261. These commands are used by the image transmitting side to notify the image receiving side of freeze or unfreeze of the transmitted image. As a result, the disturbance of the transmitted image at the time of scene change or switching of the video source can be prevented from being displayed on the receiving side.

Further, during image communication, the image receiving side may desire to give priority to image quality over smoothness of motion or to prioritize smoothness of motion over image quality. In the conventional example, in such a case, the request is transmitted from the image receiving side to the image transmitting side by telephone, and the user of the image transmitting side is allowed to change the transmission condition so as to meet the wish.

[0005]

Even if the image receiving side desires the image transmitting side to temporarily suspend and resume the image transmission, CCITT Recommendation H.264. 261 and H.261. The command is not prepared in 221.

The present invention is based on CCITT Recommendation H.264. 261 and H.261. It is an object of the present invention to present an image communication terminal device that satisfies this requirement while complying with 221.

Further, in the conventional example, in response to a freeze request, the sending side terminal immediately stops the transmission, so that the freeze image displayed on the image receiving side becomes blurred and distorted. There is. For example, this is a case where a freeze request is issued during movement or scaling of the camera of the image transmission side terminal.

An object of the present invention is to provide a freeze control method that eliminates such an adverse effect.

Further, in the conventional example based on CCITT,
The image receiving side could not change and control the transmission condition of the image transmitting side, which was very inconvenient.

It is another object of the present invention to present an image communication terminal device which eliminates such inconvenience.

[0011]

The image communication terminal device according to the present invention is CCITT Recommendation H.264. 261 and Recommendation H.264. 22
1. An image communication terminal device conforming to CCITT Recommendation H.264. It is characterized in that the original command is set by using the escape table value defined by the bit rate allocation signal value of the frame structure 221. The original command is
For example, a freeze request command and a freeze release request command from the image receiving side to the image transmitting side, and a transmission condition control command from the image receiving side to the image transmitting side.

A freeze control method according to the present invention is characterized in that, in response to a freeze request, after transmitting a predetermined number of frames of moving images, the moving image transmission is stopped. In response to the freeze request, the moving image is transmitted until the difference value between the frames becomes less than the predetermined value δ, and the transmission of the image is stopped when the difference value between the frames becomes less than the predetermined value.
Further, it is characterized in that one frame is intra-coded and transmitted in response to a freeze request.

[0013]

With the above means, the image receiving side can issue a freeze request and a freeze release request to the image transmitting side, and a change in the transmission condition can be requested.

By the above freeze control method, a freeze image can be obtained in a good image quality state.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a schematic block diagram of an embodiment of the present invention. Reference numeral 10 is a camera for photographing materials such as callers and drawings, 12 is an image input interface for converting the output of the camera 10 into a predetermined internal format, 14 is a monitor for displaying an image, and 16 is a monitor 14 for supplying an image signal. It is an image output interface. Reference numeral 18 denotes an image memory for selectively synthesizing an input image and a received image from the image input interface 12 and outputting the image to the image output interface 16.

The monitor 14 may be a single image display device or a plurality of image display devices. Further, the single image display device can display a plurality of images in different windows by the window display system. May be.

An image coding / decoding circuit 22 is composed of an image coding circuit 22a for coding the image signal to be transmitted and an image decoding circuit 22b for decoding the received coded image signal.

Reference numeral 24 is a handset consisting of a microphone and a speaker, and 26 is an audio input / output interface for the handset 24, which is an echo canceling process for canceling echoes when the handset 24 is used, and dial tone, ring tone, busy tone. And a tone generation process such as a ring tone.

Reference numeral 28 is a voice encoding / decoding circuit comprising a voice encoding circuit 28a for encoding the voice signal to be transmitted and a voice decoding circuit 28b for decoding the received encoded voice signal. In this embodiment, 64 Kbps PCM
A-law, 64Kbps PCM μ-law, 64K
bps / 56Kbps / 48Kbps SB-ADPC
M, 32 Kbps ADPCM, 16 Kbps (for example, APC-AB), or an audio signal is encoded / decoded according to an audio encoding / decoding algorithm such as 8 Kbps.

30 is a communication line (for example, ISDN line)
Line interface 32 of the image coding circuit 22
a and the coded information to be transmitted from the voice coding circuit 28a are multiplexed and supplied to the line interface 30, and the coded image information and the coded voice information of the received information from the line interface 30 are separated to obtain the respective images. It is a demultiplexing and multiplexing circuit that supplies the decoding circuit 22b and the speech decoding circuit 28b.

Reference numeral 34 is a system control circuit for controlling the whole,
Reference numeral 36 is an operating device (for example, a ten-key, a keyboard, a touch panel, etc.) for the user to input a predetermined instruction to the system control circuit 34. System control circuit 34
Supplies the control command for the communication partner terminal to the demultiplexing and multiplexing circuit 32, and receives the control command from the communication partner terminal from the demultiplexing and multiplexing circuit 32.

In this embodiment, CCITT Recommendation H.264 is used. 221
Bit rate allocation signal value (BAS in the frame structure of
Escape table value (11)
Using 1), the freeze request command and freeze release command supplied from the image receiving side to the image transmitting side are allocated as the non-CCITT standard unique commands.

Then, in the system control circuit 34, a unique command generating means 40 for generating these unique commands when it becomes the image receiving side, a unique command identifying means 42 for identifying the received unique command, and CCIT
A freeze controller 44 is provided which controls freeze in accordance with a freeze request command and a freeze release command which are T-compliant or unique. These means 4
0, 42, and 44 are installed as hardware or software.

The flow of image signals and audio signals in the embodiment shown in FIG. 1 will be briefly described. The image input by the camera 10 is the image input interface 12 and the image memory 1.
The encoding circuit 22a of the image encoding / decoding circuit 22 via
Applied to. The image encoding circuit 22 a encodes the input image signal with the encoding method and the compression rate designated by the system control circuit 34, and outputs it to the demultiplexing and multiplexing circuit 32.

On the other hand, the input voice signal from the microphone of the handset 24 is input to the voice encoding circuit 28a of the voice encoding / decoding circuit 28 via the voice input / output interface 26, is encoded, and is encoded into the demultiplexing / multiplexing circuit 32. Is applied.

The demultiplexing and multiplexing circuit 32 is the coding circuit 2
Coded signals from 2a and 28a and system control circuit 3
Command from 4 is multiplexed, line interface 3
Output to 0. The line interface 30 outputs the signal from the demultiplexing and multiplexing circuit 32 to the connected communication line.

The signal received from the communication line is input from the line interface 30 to the demultiplexing / multiplexing circuit 32.
The separation / multiplexing circuit 32 separates the encoded image signal, encoded audio signal and command of the received signal and applies them to the image decoding circuit 22b, the audio decoding circuit 28b and the system control circuit 34, respectively.

The image decoding circuit 22b decodes the coded image signal from the circuit 32, and the decoded received image is temporarily stored in the image memory 18. The image memory 18 selectively combines the image input by the camera 10 and the image received from the image decoding circuit 22b and outputs the image to the image output interface 16. For example, picture-in
For example, there is a fitting to a picture or a corresponding window in a window display system. The monitor 14 displays the image signal from the image output interface 16 as an image.
As a result, the input image and / or the received image is displayed on the monitor 14.
Is displayed on the screen.

The received voice signal decoded by the voice encoding circuit 28b is applied to the speaker of the handset 24 via the voice input / output interface 26. As a result, the voice from the communication partner can be heard.

The command received from the other party is separated from the image information and the audio information by the separation / multiplexing circuit 32 and supplied to the system control circuit 34.

Next, the operation in the case of using the unique command to make a freeze request from the image receiving side to the image transmitting side will be described. It is assumed that both the image transmission side terminal and the image reception side terminal have the configuration of FIG. 2 is a flowchart of the image receiving side, and FIG. 3 is a flowchart of the image transmitting side.

On the image receiving side, during normal communication (S1), when a situation is desired to freeze (S2), the operator operates the operating device 36 to issue an original command from the original command generating means 40 of the system control circuit 34. A certain freeze request command is generated (S3). The command generated by the unique command generating means 40 is the demultiplexing and multiplexing circuit 3
2, transmitted to the image transmission side terminal through the line interface 30 and the communication line.

On the other hand, when the image transmitting side terminal receives the unique command from the image receiving side terminal during normal communication (S11), the unique command identifying means of the system control circuit 34 decodes the meaning of the unique command. If it is a freeze request command (S12), the freeze control means 44 is instructed to freeze the transmitted image (S13). For example, as will be described in detail later, the freeze control unit 44, after inputting the freeze request signal, transmits images for several frames and then stops transmission. The image transmitting side freezes the received image in the image memory 18 during the transmission of these several frames,
A still image is displayed on the monitor 14 (S4).

Needless to say, theoretically, the image freeze is considered to be either a case of freezing in the image memory 18 of the image transmitting side terminal or a case of freezing in the image memory 18 of the image receiving side terminal. The embodiment can be applied to both of them. The latter is more flexible, but the former has the advantage that it can be used even when the image receiving side terminal is not equipped with an image memory.

When the image receiving side terminal wants to release the freeze of the received image, the operator operates the operating device 36 to make the unique command generating means 40 of the system control circuit 34.
Generates a freeze release command, which is an original command (S15). Similarly to the freeze request command, this freeze release command is also transmitted to the image transmitting side terminal through the demultiplexing and multiplexing circuit 32, the line interface 30, and the communication line.

When the image transmitting side terminal receives the freeze release command of the unique command from the image receiving side terminal, the unique command identifying means of the system control circuit 34 decodes the meaning of the unique command. If it is a freeze cancel command (S14), the freeze control means 44 is instructed to cancel the freeze of the transmitted image (S15).

By releasing the freeze of the transmitted image on the image transmitting side (S13), a continuous moving image is displayed on the monitor 14 on the image receiving side (S6).

In the above embodiment, the image receiving side can request the image transmitting side to freeze and release the transmitted image while complying with CCITT.

Next, an embodiment of the present invention relating to freeze control will be described. Freeze control means 44 of the image transmission side terminal
Executes the freeze of the transmission image as shown in FIG. 4, FIG. 5 or FIG. 6 in response to a freeze request command from the image receiving side terminal or a freeze request from the operating device 36 of the image transmitting side terminal.

FIG. 4 shows a control flow chart of the first embodiment. When a freeze request occurs, the input source of the transmitted image (camera 10 in the embodiment of FIG. 1) is fixed (S2).
1). This is usually a physical fixation of the camera 10 (movement of the camera 10 stopped during panning and tilting, stop of zooming during zooming of the zoom). If the video tape recorder or video disk reproducing device is originally fixed, the fixed instruction is ignored.

With the image input source fixed, a moving image
The frame is transmitted (S22, 23), and the transmission of the moving image is stopped (S24). The number n of frames to be transmitted is determined according to the image input source by simulation or the like.

Since the image input source is fixed in this way,
The image to be transmitted becomes stable, so that the image can be transmitted with a relatively high image quality even by encoding (for example, interframe predictive encoding). Further, since the image transmission is continued for several frames after the freeze request, there is a time margin for freezing the image data in the image memory 18.

FIG. 5 shows a control flowchart of the second embodiment of freeze control. When a freeze request occurs, the input source of the transmission image is fixed as in the case of FIG. 4 (S3).
1). With the image input source fixed, the moving image is transmitted (S32) until the difference value between frames (cumulative value or average value of the entire screen) becomes less than the predetermined value δ (S33).
S32 and S33 correspond to confirming the stability of the transmitted image. When the difference value between frames becomes less than δ (S
33), the transmission of the image is stopped (S34).

In the second embodiment, since the image input source is fixed, the image to be transmitted becomes stable, and S32, 33
After confirming the stability of the transmitted image with, stop the transmission. Therefore, it is possible to transmit an image with a relatively high image quality even by encoding (for example, interframe predictive encoding). Of course, there is a time margin for freezing the image data in the image memory 18.

FIG. 6 shows a control flowchart of the third embodiment of freeze control. When the freeze request is generated, the input source of the transmission image is fixed as in the case of FIGS. 4 and 5 (S41). With the image input source fixed, one frame of the image to be transmitted is encoded in the intra-frame encoding mode and transmitted (S42), and thereafter the image transmission is stopped (S43).

In the third embodiment, since the image input source is fixed, the image to be transmitted becomes stable. Since the stable image is encoded by the intra-frame encoding in which the block distortion is relatively free from blurring, the image can be transmitted with a relatively high image quality.

Next, an embodiment of the present invention in which the transmission conditions can be controlled from the image receiving side will be described. The functional block diagram is the same as in FIG. Here, CCITT Recommendation H.264 is used. Using the escape table value (111) defined by the bit rate allocation signal value (BAS value) in the frame structure of 221, the control command of the transmission condition is allocated as a unique command of the non-CCITT standard.
For example, the number of frames per second, the number of quantization steps, and the designation or switching of CIF / QCIF.

Next, the operation of controlling the transmission conditions from the image receiving side to the image transmitting side using the unique command will be described. It is assumed that both the image transmission side terminal and the image reception side terminal have the configuration of FIG. FIG. 7 shows a flowchart on the image receiving side, and FIG. 8 shows a flowchart on the image transmitting side.

When the operator on the image receiving side wants to adjust the received image during normal communication (S51) (S52),
The operating device 36 is operated to specify transmission conditions, for example, the number of frames per second, the number of quantization steps, CIF / QCIF switching designation, and the system control circuit 34 designates the designated transmission condition. The command is sent from the unique command generating means 40 as a unique command, that is, the above-mentioned H. It is generated using the escape table value (111) defined by the bit rate allocation signal value (BAS value) in the frame structure of 221 (S53). The command generated by the unique command generating means 40 is transmitted to the image transmitting side terminal through the demultiplexing and multiplexing circuit 32, the line interface 30 and the communication line.

On the other hand, when the image transmitting side terminal receives the unique command from the image receiving side terminal during normal communication (S61), the unique command identifying means of the system control circuit 34 decodes the meaning of the unique command. If it is a transmission control command (S62), the image transmission condition is changed to the transmission condition designated by the transmission control command (S63).

The image receiving side terminal receives the image whose transmission condition is adjusted by the transmission control command (S54), and if it is satisfied (S55), stops the transmission of the transmission control command and must be satisfied. If (S55), the remote control of the transmission condition by the transmission control command is continued (S5).
3, 54).

In the above embodiment, the image receiving side can control the transmission condition of the image transmitting side while complying with CCITT.

[0054]

As can be easily understood from the above description, according to the present invention, the image receiving side can make a freeze request and a freeze release request to the image transmitting side. Further, the image receiving side can control the transmission condition of the image transmitting side. Furthermore, it is possible to obtain a frozen image with a good image quality.

[Brief description of drawings]

FIG. 1 is a schematic block diagram of an embodiment of the present invention.

FIG. 2 is an operation flowchart on the image receiving side of freeze control from the image receiving side.

FIG. 3 is an operation flowchart on the image transmission side of freeze control from the image reception side.

FIG. 4 is a flowchart of a first embodiment regarding freeze control.

FIG. 5 is a flowchart of a second embodiment relating to freeze control.

FIG. 6 is a flowchart of a third embodiment relating to freeze control.

FIG. 7 is an operation flowchart on the image receiving side of transmission condition control from the image receiving side.

FIG. 8 is an operation flowchart on the image transmission side of transmission condition control from the image reception side.

[Explanation of symbols]

10: camera 12: image input interface 1
4: Monitor 16: Image output interface 18:
Image memory 22: Image encoding / decoding circuit 22a: Image encoding circuit 22b: Image decoding circuit 24: Handset 26: Audio input / output interface 28: Audio encoding / decoding circuit 28a: Audio encoding circuit 28
b: voice decoding circuit 30: line interface 3
2: Separation and multiplexing circuit 34: System control circuit 3
6: Operating device 40: Unique command generating means 42: Unique command identifying means 44: Freeze control means

Claims (6)

[Claims] 1. CCITT Recommendation H.264. 261 and Recommendation H.264.
221, which is an image communication terminal device conforming to 221
Recommendation H.T. An image communication terminal device, wherein an original command is set using an escape table value defined by a bit rate allocation signal value of the frame structure 221. 2. The image communication terminal device according to claim 1, wherein the unique commands are a freeze request command and a freeze release request command from the image receiving side to the image transmitting side. 3. The image communication terminal device according to claim 1, wherein the unique command is a transmission condition control command from the image receiving side to the image transmitting side. 4. A freeze control method comprising: transmitting a moving image for a predetermined number of frames and then stopping the moving image transmission in response to a freeze request. 5. In response to a freeze request, moving images are transmitted until the difference value between frames becomes less than a predetermined value δ, and when the difference value between frames becomes less than a predetermined value, transmission of images is stopped. A characteristic freeze control method. 6. A freeze control method, wherein one frame is intra-coded and transmitted in response to a freeze request.