JPH0646415A - Image/voice communication equipment - Google Patents

Abstract

PURPOSE:To provide an image/voice communication equipment which contains a means to correct the transmission errors of the data on the still pictures, etc., with use of a multiplex frame of the moving images, the voices and the data prescribed by the CCITT recommendation H.221. CONSTITUTION:A function which controls a multiplex frame of H.221 is provided together with a block control part 8 which turns the data into the blocks and detects the block errors, and a BAS control part 10 which sends a fact that a wrong block is received and the number of the block via an extended BAS. In such a constitution, the display of errors is not carried out even if an error is caused in the received data by the transmission error caused in a communication mode. Furthermore it is not required to transmit again all data by the instruction of a user. Then only the wrong block is automatically retransmitted. Thus the transmission efficiency is improved for an image/voice communication equipment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video / audio communication device having a multiplex transmission function for moving images, voice, data and the like.

[0002]

2. Description of the Related Art In recent years, CCITT (International Telegraph and Telephone Advisory Committee) has officially made a recommendation of a video encoding system, a multiplexing system, and a communication procedure for audiovisual services. Video / audio communication devices such as conference systems and video-phones have been put on the market.

A conventional video / audio communication apparatus will be described below with reference to the drawings. As shown in FIG. 5, a conventional image / voice communication device includes a handset 1, a camera 2 for taking a self-portrait, a monitor 3 for displaying an image or a self-portrait from a partner device, and a scanner 4 for reading a still image. An audio control unit 5 that is provided as an external device and that encodes and decodes audio data, a moving image control unit 6 that encodes and decodes moving image data, and that controls the display of images on the monitor 3, and read from the scanner 4. The still image control unit 7 that encodes and decodes the captured still image data and controls the display of the image on the monitor 3 receives data such as moving images, voices, and still images from CCITT Recommendation H.264. H. 221 transmitted from the other device is multiplexed in a frame format of H. 221 (frame structure of 64 kbit / s to 1920 kbit / s channel in audiovisual teleservice). 221 frame demultiplexing unit 9 that separates a moving image, audio, and data from CCITT Recommendation H.264. 242 (1
Method for setting communication between audiovisual terminals using digital channels up to 920 kbit / s)
It is composed of a BAS (bit rate allocation signal) control unit 10 for executing a communication procedure based on the above, a line interface unit 11 for connecting to an ISDN, etc., and is connected to an ISDN 12. Further, FIG. 4 shows CCITT Recommendation H.264. 221 shows a multiplexing frame structure defined by H.221.

Hereinafter, each component and its operation will be described. First, the line interface unit 11 uses the ISDN 12
The connection control of the B channel (not shown) is performed with the partner terminal via the. After the connection is completed, the BAS control unit 10 sends H.264 via the B channel. A mode initialization procedure based on 242 is activated. In the mode initialization procedure, first, FAS in the multiplexed frame as shown in FIG.
The synchronization is established under the control of (frame synchronization signal), and after the establishment of the synchronization, CCITT is set at the BAS position shown in FIG.
Recommendation H. Among the BAS codes shown in the numerical table of BAS codes defined in H.221 (hereinafter abbreviated as the BAS code numerical table of H.221), the audio / transfer rate capability (10
0) and the data / video capability (101) are set to exchange the capability with the other device, and the command BAS code is used in consideration of the capabilities of the own device and the other device. Switch to a different operation mode.

An example of transmitting still image data with the conventional configuration shown in FIG. 5 will be described below. When the still image data is transmitted in response to a user's instruction or when the scanner 4 reads the still image data, the still image control unit 7 issues a still image transmission command to the BAS control unit 10, and then multiplexes. By transferring the still image data to the separating unit 9, the still image data is multiplexed with the moving image and audio data and sent to the ISDN 12. Here, the BAS control unit 1 that has received the still image transmission command from the still image control unit 7
In the case of 0, there is a method of using a BAS code as an example to convey to the receiving side device that the still image data is transmitted. Regarding the BAS code, H.264 is used. Although it is defined in the BAS code numerical table of 221, there is an unallocated portion, for example, "[1 of" Video, other command (010) ".
By assigning “still image on, still image off” to “0], [11]” and transmitting as a BAS code, it is possible to convey to the receiving side device that still image data will be transmitted.

In the receiving side device, the BAS of "still image ON"
When the code is detected by the BAS control unit 10, the demultiplexing unit 9 separates the still image data from the received frame, transfers the still image data to the still image control unit 7, and the still image control unit 7 stores the still image data. Processing and display processing on the monitor 3 are performed.

[0007]

However, in the above conventional configuration, when an error occurs in the received data due to a transmission error during communication, for example, when the received data is still image data, the received still image data is displayed. If this is done, the original image read from the scanner by the transmission side device will be completely different, and still image data may not be decoded if it is encoded data. In such cases,
Since the error recovery procedure is not specified, there is a problem that all data has to be retransmitted according to the user's instruction even in the case of a large amount of data such as still images.

The present invention solves the above-mentioned conventional problems, and CCITT Recommendation H.264. It is an object of the present invention to provide an image / sound communication device having means for recovering a transmission error such as a still image in a multiplexed frame of a moving image, sound and data defined by 221.

[0009]

In order to achieve the above object, the video / audio communication apparatus of the present invention is provided with a block controller in addition to the conventional structure. When transmitting data such as a still image, the block control unit divides the data such as a still image into a certain length and blocks the divided data and a header including a block number and an error control code. , Means for framing a plurality of blocks and a start flag and an end flag,
When receiving data such as still images, an error in the received block data is detected from the block data in the frame and the error control code, and if there is an error, the fact that the wrong block was received and its block number are expanded. Means for transmitting to the transmitting side device by the BAS code, and when the transmitting side device detects the extended BAS code, only the block data such as the still image corresponding to the incorrect block number is reframed and transmitted. have.

[0010]

According to the present invention, in the above-mentioned structure, by providing the block control unit, data such as a still image is framed by a plurality of blocks, and an error occurs in the received data due to a transmission error during communication. Even in the case, it can be detected by the error control code in the block, and when an error is detected, it can be transmitted to the transmitting side device that the wrong block is received and the wrong block number by the extended BAS code.
Further, when the extended BAS code is received, it is not necessary to retransmit all data, and only the erroneous block is automatically framed and retransmitted, so that the video / audio communication device with high transmission efficiency can be obtained.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, the video / audio communication apparatus of this embodiment has a handset 1, a camera 2 for taking a self-portrait, a monitor 3 for displaying an image or self-portrait from a partner device, and still image data reading. An audio controller 5 for encoding and decoding audio data, and a moving image controller for encoding and decoding moving image data and controlling the display of images on the monitor 3 are provided with a scanner 4 as an external device for bending. 6, a still image control unit 7 that encodes and decodes still image data read from the scanner 4 and controls the display of the image on the monitor 3. In the case of data transmission, data such as a still image is transmitted for a certain length. Into blocks, and each of the divided data and a header including a block number and an error control code are divided into blocks, and a plurality of blocks, a start flag, and Performs frame by Ryo flag,
In the case of data reception, the block control unit 8 which detects an error in the reception block from the block data in the frame and the error control code, and the data such as the moving image, the voice, and the still image are CCI.
TT Recommendation H. H. 221 that is multiplexed in the frame format of H. 221 and sent from the other device. Demultiplexing unit 9 for demultiplexing 221 frames into video, audio and data, CCI
TT Recommendation H. BAS control based on 242, and if there is an error in the received block, the fact that an erroneous block has been received and the BAS with the expanded block number are transmitted to the transmitting side device to detect the expanded BAS.
It is composed of an AS control unit 10 and a line interface unit 11 for connecting to an ISDN, and is connected to an ISDN 12.

The relationship and operation of each component will be described below.
First, the case of transmitting still image data will be described with reference to FIG. When the still image data is transmitted in response to a user's instruction or the scanner 4 reading the still image data, the still image control unit 7 issues a still image transmission command to the BAS control unit 10. Here, the BAS code table expanded as shown in FIG. 221 BA
For the attribute “(110)” that is not used in the S code numeric table,
It is assumed that the contents shown in FIG. 3 are assigned to "[0] to [31]". Upon receiving the still image transmission command, the BAS control unit 10 multiplexes the BAS code transmission command corresponding to "40k", for example, when the still image transmission rate is 40 kbps, following the extended BAS code of "still image ON". The demultiplexing unit 9 is performed, and the expanded BAS code is transmitted from the demultiplexing unit 9 to the partner device via the line interface unit 11.

The still picture control unit 7 issues a still picture transmission command to the BAS control unit 10 and then issues a still picture data transmission command to the block control unit 8. The block control unit 8 sends a plurality of demultiplexing units 9 a plurality of data. By transferring the still image data framed by the block and the start flag and the end flag, the still image data is transmitted to the partner device. When the still image data is framed as shown in FIG. 2, the header b provided between the start flag a and the end flag e has a block number when the still image data is divided into blocks and the data c has a constant length. The divided still image data and the error control code d are determined in advance from the data (for example, horizontal parity check method, group count check method,
A frame is composed of values calculated using a CRC method or the like).

In addition to the block number, various control information can be set in the header b, and each block is composed of N blocks from block I to block N and ends with an end flag e. . Next, a case of receiving still image data will be described. BAS control unit 1
0 indicates “still image on” and “40k” as shown in FIG.
When the extended BAS code is detected, the still image control unit 7 is notified of the still image reception. The still image control unit 7 issues a still image data reception command to the block control unit 8, and the block control unit 8 receives the framed still image data transferred from the demultiplexing unit 9. Will be described below. When the block control unit 8 detects a start flag a peculiar to the still image data shown in FIG. 2, the block number currently being received is recognized from the header b, and the data c in the block is sent to the still image control unit 7. The error control code d is calculated while transferring, and it is judged whether or not the error control code d in the block is correct by the error control code d calculated when the end flag e is received. Block notification is sent to the BAS controller 10.
In the BAS control unit 10, the block number is BAS after the extended BAS code of “block error” shown in FIG.
A BAS code transmission command is issued to the demultiplexing unit 9 so as to set the code position, and the demultiplexing unit 9 transmits the demultiplexing unit 9 to the transmission side device via the line interface unit 11.

When the BAS control unit 10 of the transmission side device detects an extended BAS code of "block error", an incorrect block number is subsequently detected from the received BAS code and the still image data is retransmitted to the block control unit 8. Give a command. After the transmission of all the still image data is completed, the block control unit 8 frames the still image data corresponding to the wrong block number and transfers the still image data to the demultiplexing unit 9 again, so that the other device Wrong block is retransmitted.

[0017]

As is apparent from the above embodiments, according to the present invention, even if an error occurs in the received data due to a transmission error during communication or the like, an erroneous display is not made and a user instruction is given. Since it is unnecessary to retransmit all data and automatically retransmit only erroneous blocks, it is possible to realize an excellent video / audio communication device with good transmission efficiency.

[Brief description of drawings]

FIG. 1 is a block diagram of an audiovisual communication apparatus according to an embodiment of the present invention.

FIG. 2 is a data frame structure diagram of a still image or the like in the embodiment.

FIG. 3 is a diagram showing an extended BAS code in the same embodiment.

FIG. 4 CCITT Recommendation H. 221 Multiplexing frame structure diagram defined in 221

FIG. 5 is a block diagram of a conventional image and voice communication device.

[Explanation of symbols]

 8 block control unit 10 BAS control unit a start flag b header c data d error control code e end flag

Claims (2)

[Claims] 1. A transmission side device for transmitting data such as a still image divides the data into fixed lengths, and the divided data, a header including a block number, and an error control code are divided into blocks, and a plurality of pieces are further formed. Framed with blocks and start and end flags,
In the receiving side device, a block control unit for detecting an error in the received block data from the block data in the frame and the error control code, and if the received block data has an error, the fact that an erroneous block has been received and its block number are indicated. ,
An audiovisual communication apparatus comprising: a BAS control unit that transmits the expanded BAS code to a transmission side apparatus and detects the expanded BAS code. 2. A block control unit for re-framing the block data corresponding to the block number when the BAS control unit detects that the wrong block is received by the extended BAS code and its block number. Item 1
The image and voice communication device described.