JPH07111642A - Image communication terminal equipment - Google Patents

Abstract

PURPOSE:To obtain an image communication terminal equipment which is capable of transmitting an image having high picture quality and smooth motions when a line with large transmission capacity is used and selecting a picture quality priority screen or a motion priority screen according to the degree of motions of an object. CONSTITUTION:In an image communication terminal equipment provided with the multiple transmission function of plural kinds of data including video data, the equipment is provided with a detection means 10 detecting a line rate to be set between an opposite party terminal and the equipment, and a quantization table switching means 11 switching the quantization table in an image processing based on the detection result of the detection means. The equipment is provided with a selection means 12 selecting a motion priority mode or a picture quality priority mode. When an ISDN line with large line capacity is selected between the opposite party terminal and the equipment and line capacity is increased by setting plural ISDN lines, the picture quality of an image to be transmitted to the opposite party terminal is improved.

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 having a multiplex transmission function for video, audio and data, and in particular,
It is configured so that an image with better image quality can be transmitted under the set line.

[0002]

2. Description of the Related Art In recent years, CCITT (International Telegraph and Telephone Advisory Committee) has officially recommended video coding systems, still image coding systems, multiplexing systems, communication procedures, etc. for audiovisual services, and companies have accompanied them. To CCI
Image communication terminal devices such as a video conference system and a video phone that comply with the TT recommendation have been put on the market.

As shown in FIG. 4, a conventional image communication terminal device includes a microphone 1 for inputting voice, a speaker 2 for outputting voice, a camera 3 for photographing, and a partner, as shown in FIG. Connected are a monitor 4 for displaying the images sent from the camera and images taken by the camera 3, a scanner 5 for capturing still images, and a key operation unit 6 for inputting telephone numbers and selecting functions. ing.

Further, the image communication terminal device main body 18 compresses / encodes (or expands / decodes) audio data, and the video control unit 7 compresses / encodes (or expands / decodes) moving image data. The moving picture control means 8, the still picture control means 9 for compressing / encoding (or decompressing / decoding) still picture data, and the moving picture, still picture, and audio data according to CCITT Recommendation H.264. 221 (frame structure of 64 Kbps to 1920 Kbps channel in audiovisual teleservice) is multiplexed in a frame format, and a moving image is transmitted from a frame sent from the other party.
Multiplexing / separating means 13 for separating still image and audio data,
CCITT Recommendation H. BAS (Bit-rate Allocation Signal: Bit-rate Allocation Signal) that executes communication means based on 242 (a method for setting communication between audiovisual terminals using digital channels up to 1920 Kbps)
Signal) control means 14, call control processing means 15 for managing calls such as incoming and outgoing calls and disconnection, and a line interface section 16 for connecting a terminal to an integrated service digital network (ISDN) 17.

Further, FIG. 2 shows CCITT Recommendation H.264. 22
1 shows a multiplex frame structure defined in 1.
Further, in FIG. 3, BA defined in CCITT recommendation
The numerical table of S code is shown.

This image communication terminal device operates as follows.

When the operator inputs the telephone number of the other terminal from the key operation unit 6 and presses the call key, the call control processing means 15 causes the B channel between the other terminal and the other terminal via the line interface unit 16. Connect.

After the connection is completed, the BAS control means 14 uses the B channel to send the H.264 signal. Frame synchronization is established based on 242. After synchronization is established, the partner terminal notifies the sender terminal of the receiver terminal capacity by using the audio / transfer rate capabilities and data / video capabilities of the BAS table (Fig. 3). The transmission capability of the terminal is compared with the reception capability of the partner terminal, and the operation mode is determined so that the communication is performed by the common maximum function. And BAS control means
Reference numeral 14 sends a command BAS code (audio command, transfer rate command, other command) representing the decided operation mode to the receiving side to instruct mode switching on the receiving side.

After that, when transmitting the moving image data to the partner terminal, the moving image control means 8 uses the moving image data captured by the camera 3 to the NTSC system (Japanese / American television system) and the PAL system (European system). Television system)
CIF (luminance signal Y: 352 × 288, color difference signals CB, CR: 176), which is a common intermediate video signal format of
× 144) or QCIF (luminance signal Y: 176 × 14)
4. Convert to color difference signals CB, CR: 88 × 72) and compress.

This processed moving image data is output from the moving image control means 8 to the multiplexing / separating means 13 when the transmission request key is pressed by the key operation unit 6, and the multiplexing / separating means is provided.
The data 13 is multiplexed with other data to form the frame shown in FIG. 2, and is transmitted from the line interface unit 16 to the partner terminal via the ISDN.

The transmission capacity provided by a single channel of ISDN is 64, 384 or 1536/1920.
Although it is Kbps, if the transfer capability of both terminals permits, a plurality of these channels can be used and data can be transmitted by a line having a transmission capacity having an intermediate value. For example, when two 64 Kbps channels are used, a line having a transmission capacity of 128 kbps can be set.

In this case, after confirming that both the transmitting side and the receiving side have the transfer capability of using multiple channels in the capability exchange using the first connected B channel, additional call setup is performed. Done and channels are added.

[0013]

However, in the conventional image communication terminal device, since the moving image control means quantizes the image data with a constant characteristic regardless of the transmission capacity of the line, the line having a large transmission capacity is used. Even when is used, the roughness of the quantization does not change, and the poor image quality and the awkward motion of the subject are not improved.

The present invention solves the above-mentioned conventional problems, and when a line having a large transmission capacity is used, it is possible to transmit a high-quality and smooth-moving image, and the movement of the object It is an object of the present invention to provide an image communication terminal device capable of selecting a screen of image quality priority or a screen of motion priority in accordance with the frequency.

[0015]

Therefore, in the present invention, in the image communication terminal device having the multiplex transmission function of a plurality of types of data including video data, the line rate set with the partner terminal is detected. A detection unit and a quantization table switching unit that switches the quantization table in the image processing based on the detection result of the detection unit are provided.

Further, there is provided a mode selecting means for selecting a motion priority mode or an image quality priority mode by a user,
The quantization table switching means is configured to switch the quantization table in consideration of the selection made by the mode selecting means.

[0017]

Therefore, when the ISDN line having a large line capacity is selected with the partner terminal or the line capacity is increased by setting a plurality of ISDN lines, the image quality of the image transmitted to the partner terminal is improved. To be done.

Further, when the user selects the motion priority mode by the mode selecting means when the motion of the subject is intense, the table switching means switches to the quantization table having a coarse quantization interval, and the reproducibility of the motion. It is possible to improve the image quality in the direction of increasing.

On the contrary, when the user selects the image quality priority mode, the table switching means switches to the quantization table having a narrow quantization interval to improve the image quality in the direction of making the image quality fine. To be

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, an image communication terminal device according to an embodiment of the present invention detects a BAS code relating to a transfer rate and knows a line rate (the number of channels) set between terminals. The BAS code detecting means 10 stores a quantizing table 10 for holding a plurality of quantizing tables and providing the moving picture controlling means 8 with a mode selecting means 10 for allowing a user to freely select a mode of image quality priority or motion priority.
And a table switching means 11 for switching according to the output of the mode selection means 12. Other configurations are the same as those of the conventional device (FIG. 4).

In this image communication terminal device, the B channel is connected to the other terminal by the same procedure as the conventional device, and then the H.264 / AVC communication device is connected. Frame synchronization is established based on 242. After the synchronization is established, the partner terminal notifies the sender of the terminal capacity of the receiver by using the values of the audio / transfer rate capacity and the data / video capacity of the BAS numerical table (Fig. 3), and the sender receives its own terminal. And the receiving capability of the other terminal are compared, and the operation mode is determined so that the communication is performed by the common maximum function. The BAS control means 14 sends a command BAS code (audio command, transfer rate command, other command) representing the determined operation mode to the receiving side to instruct mode switching of the receiving side.

At this time, the BAS code detecting means 10 uses the BAS
The code relating to the transfer rate among the codes is detected, the line rate set is identified, and the line rate information is output to the table switching means 11. Then, the table switching means 11 selects the quantization table corresponding to the line rate based on the information output from the BAS code detecting means 11.

After that, the moving picture control means 8 quantizes the moving picture data captured by the camera 3 in accordance with the quantization table selected by the table switching means 11. The quantized moving image data is composed into video coded data including quantization characteristic information, is output to the multiplexing / separating means 13, and is multiplexed with the audio data output from the audio control means 7 here. After that, it is transmitted to the partner terminal via the line interface unit 16.

Further, when the subject is moving a lot, the user selects the motion priority mode by the mode selecting means 12.
If the movement of the subject is small, the image quality priority mode can be selected.

When the motion priority mode is selected, the table switching means 11 switches the quantization table to a table in which coarse quantization is performed. As a result, the moving image control means 8 outputs the image data in which the number of screens is prioritized, and the reproducibility of the motion in the video is improved. On the other hand, when the image quality priority mode is selected, the quantization table is switched to a table in which fine quantization is performed. As a result, the moving image control means 8 finely samples one screen and outputs it as image data, so that the image quality is improved.

As described above, in the image communication terminal device of the embodiment, when an ISDN line having a large transmission capacity is selected and used, or when a plurality of ISDN lines are used to increase the transmission capacity, an image to be transmitted according to the ISDN line is transmitted. It is possible to improve the image quality of. Further, at that time, when the movement of the subject is small, it is possible to improve the image quality exclusively, and when the movement of the subject is large, it is possible to improve the reproducibility of the movement.

[0027]

As is apparent from the above description of the embodiments, the image communication terminal device of the present invention can be adapted to the line rate by simply adding simple hardware and control means to the conventional device. It is possible to obtain an image with high image quality and excellent motion reproducibility, and it is possible to output an image that meets the needs of the user.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of an image communication terminal device of the present invention,

FIG. 2 CCITT Recommendation H.264. 221 is a diagram showing a multiplexing frame structure defined by 221;

FIG. 3 CCITT Recommendation H.264. A numerical table of BAS codes defined by 221

FIG. 4 is a block diagram showing a structure of a conventional image communication terminal device.

[Explanation of symbols]

 1 Microphone 2 Speaker 3 Camera 4 Monitor 5 Scanner 6 Key Operation Unit 7 Voice Control Means 8 Moving Image Control Means 9 Still Image Control Means 10 BAS Code Detection Means 11 Table Switching Means 12 Mode Selection Means 13 Multiplex / Separation Means 14 BAS Control Means 15 Call control means 16 Line interface section 17 ISDN 18 Image communication terminal unit body

Claims (2)

[Claims] 1. In an image communication terminal device having a multiplex transmission function for a plurality of types of data including video data, a detection means for detecting a line rate set with a partner terminal, and a detection result of the detection means. An image communication terminal device, comprising: a quantization table switching means for switching a quantization table in image processing based on the above. 2. A mode selection means for selecting a motion priority mode or an image quality priority mode by a user is provided, and the quantization table switching means switches the quantization table in consideration of the selection of the mode selection means. The image communication terminal device according to claim 1, wherein: