JPH08130722A - Picture communication terminal equipment - Google Patents

Abstract

PURPOSE: To provide a picture communication terminal equipment capable of automatically switching moving picture display and still picture display corresponding to the transmission amount of picture data. CONSTITUTION: A frame memory 18 stores the picture data transmitted from the picture communication terminal equipment on a transmission side and a data amount detection part 15 detects the transmission amount of the picture data transmitted from the picture communication terminal equipment on the transmission side. A data amount comparison part 16 compares the transmission amount of the picture data detected by the data amount detection part 15 with a predetermined threshold value, decides that initialized moving picture communication is to be continued when the transmission amount is equal to or less than the threshold value and decides that the picture data stored in the frame memory 18 are to be outputted when the transmission amount exceeds the threshold value. A picture switching part 17 controls a BAS code control part 13 and switches the moving picture communication and still picture communication corresponding to the decided result of the data amount comparison part 16.

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 voice data, moving image data and still image data.

[0002]

2. Description of the Related Art In recent years, CCITT (now ITU-TS: International Telegraph and Telephone Advisory Committee) recommendation officially recommends a video coding method, a still image coding method, a multiplexing method and a communication procedure for audiovisual services. Was converted into
Along with this, image communication terminal devices such as a video conference system and a video phone, which comply with the recommendations, have been developed by various companies.

FIG. 2 is a functional block diagram of a conventional image communication terminal device. The image communication terminal device 100 of FIG. 2 includes a voice control unit 8, a moving image control unit 9, a still image control unit 10, a multiplexing / demultiplexing unit 11, a line interface unit 12, a BAS (Bit-rate Allocation Signal). ) A code control unit 13 and a call control processing unit 14 are included.

The voice control unit 8 has a microphone 1 for inputting voice.
And a speaker 2 for outputting sound are connected. The moving image control unit 9 includes a photographing camera 3 and a document camera 4.
Is connected. Further, the moving image control unit 9 and the still image control unit 10 are connected to a monitor 5 that displays an image sent from the partner device or an image captured by the image capturing camera 3 or the document camera 4. Further, a scanner 6 for capturing a still image is connected to the still image control unit 10. A key operation unit 7 for inputting a telephone number and selecting a function is connected to the call control processing unit 14.

The voice control unit 8 compression-codes and decompresses voice data. The moving image control unit 9 compression-codes and decompresses moving image data. The still image control unit 10 compression-codes and decompresses still image data.

The multiplexer / separator 11 converts the audio data, the moving image data and the still image data into CCITT (current ITU-
TS) Recommendation H. In addition to multiplexing with the frame format according to 221, the frame transmitted from the partner device is separated into audio data, moving image data, and still image data. Here, CCITT (currently ITU-TS) Recommendation H.264. 221 defines the frame structure of 64 kbps to 1920 kbps channels in audiovisual teleservices.

[0007] The BAS code control unit 13 is a CCITT (current ITU-TS) recommendation H.264 standard. The communication procedure based on 242 is executed. Here, CCITT (currently ITU-TS) Recommendation H.264. 242 defines a method for setting communication between audiovisual terminals using digital channels up to 1920 kbps.

The call control processor 14 manages calls such as incoming and outgoing calls and disconnections. The multiplexer / demultiplexer 11 is connected to an ISDN (Integrated Service Digital Network) 20 via a line interface 12.

FIG. 3 shows CCITT (current ITU-TS) Recommendation H.264. 22 shows a multiplexing frame structure defined by H.221. As shown in FIG. 3, sub-channels 1 to 7 are allocated to bit numbers 1 to 7, respectively, and a frame synchronization signal (FAS) and a bit rate allocation signal (B
AS) and sub-channel 8 are assigned.

In FIGS. 4 and 5, CCITT (current ITU-
TS) Recommendation H. 221 shows a numerical table of BAS codes defined by H.221.

This numerical table shows the BAS code in 8 bits, and the column header shows the attribute in the form of bits (b0, b1, b2). Bit (000) in FIG. 4 indicates an audio command, and bit (001) indicates a transfer rate command. Bit (010) indicates video or other command, and bit (011) indicates LSD (low speed data) /
3 shows an MLP (Multi Layer Protocol) command. Bit (100) in FIG. 5 indicates audio / transfer rate capability, bit (101) indicates data / video capability, and bit (111) indicates escape. The leftmost column of the numerical table shows the values in decimal notation of bits [b3, b4, b5, b6, b7]. For example, "chan. # 6" is (001)
It has a value of [10110].

Next, the image communication terminal device 10 shown in FIG.
The operation of 0 will be described. When the operator sets the telephone number of the partner device using the key operation unit 7 and presses the call key, the call control processing unit 14 connects the partner device with the B channel via the line interface unit 12. .

After the connection is completed, the BAS code control unit 13 uses the B channel and CCITT (current ITU-TS) recommendation H.264.
Based on 242, frame synchronization is established. After the synchronization is established, the reception capability notified from the other device using the values of the audio / transfer rate capability and the data / video capability of the BAS code numerical table shown in FIG. 5 is referred to as the transmission capability of the image communication terminal device 100. By comparison, the operation mode is determined so as to perform the communication with the common maximum function. Then, the BAS code control unit 13 transmits a command (audio command, transfer rate command, and other command) indicating the determined operation mode to the partner device by using the BAS code shown in FIG. Command mode switching.

After that, when transmitting the moving image data to the other party's device, the moving image control unit 9 sends the moving image data fetched from the photographing camera 3 and the document camera 4 to the NTS.
C system (National Television System Committee; Japanese and US television systems) and PAL system (Ph
ASE Alternation by Line color television; CIF (luminance signal Y: 352 x 288, color difference signal CB, CR: 176 x 144) or QCIF, which is an intermediate video signal format common to European television systems.
(Luminance signal Y: 176 × 144, color difference signals CB, C
R: 88 × 72) and then compressed.

When the transmission request key is pressed by the key operation unit 7, the moving image control unit 9 outputs the processed moving image data to the multiplexing / demultiplexing unit 11. The multiplexing / separating unit 11 multiplexes the moving image data with other data to form a frame having the structure shown in FIG. 3, and transmits the frame from the line interface unit 12 to the partner device via the ISDN 20.

The transmission capacity provided by a single channel of the ISDN 20 is 64 kbps, 384 kbps or 1536/1920 kbps, but if the transfer capability of both terminal devices permits, a plurality of these channels should be used. It is also possible to set a transmission capacity line having an intermediate value and perform data transmission by the set line. For example, if two 64 kbps channels are used, 1
A line with a transmission capacity of 28 kbps can be set. In this case, additional call setup is performed after it has been confirmed that the terminal devices on both the transmitting side and the receiving side have the transfer capability of using multiple channels in the capability exchange by the B channel connected first. , Channels are added.

[0017]

However, in the image communication terminal device 100 described above, communication is performed in the mode set in the first capacity exchange regardless of the amount of image data transmitted (compressed code amount). Therefore, even if the transmitted image moves sharply and the transmission amount (compression code amount) of the image data increases, the communication is performed in the default mode. As a result, block distortion occurs in the received image, or the image movement deteriorates, resulting in image quality deterioration.
Such image quality deterioration is very noticeable in a video conference using the image communication terminal device 100.

It is an object of the present invention to provide an image communication terminal device capable of automatically switching between moving image display and still image display according to the amount of image data transmitted.

[0019]

[Means for Solving the Problems]

(1) First Invention An image communication terminal device according to the first invention comprises a communication unit, a moving image control unit, a frame storage unit, a still image control unit, a transmission amount detection unit, and an image switching unit.

The communication means receives the image data. The moving image control means outputs the image data received by the communication means as moving image data. The frame storage means stores the image data received by the communication means in frame units. The still image control means outputs the image data stored in the frame storage means as still image data. The transmission amount detection means detects the transmission amount of the image data received by the communication means. The image switching unit switches output of moving image data by the moving image control unit and output of still image data by the still image control unit based on the detection result of the transmission amount detection unit.

(2) Second Aspect of the Invention An image communication terminal device according to a second aspect of the present invention is the image communication terminal device according to the first aspect of the invention, in which the transmission amount detected by the transmission amount detecting means is predetermined. It further comprises a transmission amount comparing means for comparing with a threshold value. The image switching means keeps the moving image data output by the moving image control means when the transmission amount is less than or equal to the threshold value, and outputs the moving image data by the moving image control means when the transmission amount exceeds the threshold value. To output still image data by the still image control means.

(3) Third Invention An image communication terminal device according to a third invention is the image communication terminal device according to the first invention, wherein the image switching means comprises:
The output of moving image data by the moving image control means and the output of still image data by the still image control means are switched by the BAS code.

(4) Fourth Invention An image communication terminal device according to a fourth invention is the image communication terminal device according to the first invention, wherein a still image is output when still image data is output by the still image control means. It further comprises display means for displaying that the data is being output.

[0024]

In the image communication terminal device according to the first to fourth aspects of the invention, the received image data is output as moving image data by the moving image control means and is also stored in the frame storage means in frame units. The image data stored in the frame storage means can be output as still image data by the still image control means. On the other hand, the transmission amount of the received image data is detected by the transmission amount detecting means, and based on the detection result, the moving image control means outputs the moving image data and the still image control means outputs the still image data. Can be switched by.

Therefore, when the transmission amount (compression code amount) of the image data is large, the image data accumulated in the frame accumulating means is output as still image data and a still image is displayed. In this case, it is not necessary to worry about deterioration of image quality such as occurrence of block distortion and clutter of image movement. vice versa,
If the image data transmission amount (compression code amount) is small,
Normal moving image display is performed by the moving image control means.

Particularly, in the image communication terminal device according to the fourth aspect of the present invention, when the still image control means outputs the still image data, it is displayed that the still image data is in the output state, so that the moving image data is output. It is possible to prevent the user from determining that the communication is disconnected when switching from the output to the output of the still image data.

[0027]

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

FIG. 1 is a functional block diagram of an image communication terminal device according to an embodiment of the present invention. This image communication terminal device is used, for example, in a video conference. 1 and 2
In FIG. 6, the same or corresponding parts are designated by the same reference numerals, and the description thereof will be omitted.

The image communication terminal device 100a shown in FIG. 1 differs from the image communication terminal device 100 shown in FIG. 2 in that a data amount detection unit 15, a data amount comparison unit 16, an image switching unit 17, and a frame memory 18 are further provided. Is.

The frame memory 18 stores the image data transmitted from the image communication terminal device 100a on the transmission side in frame units. The data amount detection unit 15 detects the amount of image data transmitted from the image communication terminal device 100a on the transmission side. The data amount comparison unit 16 performs normal moving image communication based on the transmission amount of the image data detected by the data amount detection unit 15, or the frame memory 1
8 determines whether to output the image data stored. The image switching unit 17 determines the CCITT (current ITU-TS) recommendation H.264 according to the determination result of the data amount comparison unit 16. The BAS code defined in 221 is switched to either moving image communication or still image communication.

In this embodiment, the multiplexing / demultiplexing unit 11 and the line interface unit 12 form a communication means. Also,
The frame memory 18 constitutes a frame accumulating unit, the data amount detecting unit 15 constitutes a transmission amount detecting unit, and the image switching unit 17 and the BAS code control unit 13 constitute an image switching unit.

Next, the operation of the image communication terminal device 100a shown in FIG. 1 will be described. When the operator sets the telephone number of the other device (the image communication terminal device 100a on the receiving side) using the key operation unit 7 and presses the call key, the call control processing unit 14 causes the other device via the line interface unit 12. The B channel is connected to and from.

After the connection is completed, the BAS code control unit 13
CCITT (currently ITU-TS) Recommendation H.264 Based on 242, frame synchronization is established. After the synchronization is established, the audio data of the BAS code numerical table shown in FIG.
The reception capability notified from the partner device using the numerical values of the transfer rate capability and the data / video capability is compared with the transmission capability of the image communication terminal device (image communication terminal device on the transmission side) 100a, and the maximum common function is used. The operation mode is determined so that the communication is performed. Then, the BAS code control unit 13 transmits a command (audio command, transfer rate command and other command) indicating the determined operation mode to the partner device by using the BAS code shown in FIG. Command mode switching.

After that, when the moving image data is transmitted to the other party's device, the moving image control unit 9 sends the moving image data fetched from the photographing camera 3 and the document camera 4 to the NTS.
It is converted to CIF or QCIF which is an intermediate video signal format common to the C system and the PAL system and compressed.

When the transmission request key is pressed by the key operation unit 7, the moving image control unit 9 outputs the processed moving image data to the multiplexing / separating unit 11. The multiplexing / demultiplexing unit 11 multiplexes the moving image data with other data to form a frame having the structure shown in FIG. 3, and transmits the frame from the line interface unit 12 to the partner device via the ISDN 20.

As described in the description of the image communication terminal apparatus 100 of FIG. 2, the transmission capacity provided by the single channel of the ISDN 20 is 64 kbps, 384 kbps or 1536/1920 kbps, but both terminals have the same transmission capacity. If the transfer capability permits, a plurality of these channels can be used to set a line having a transmission capacity having an intermediate value, and data can be transmitted by the set line.

In the present embodiment, the frame memory 18 stores the image data sent from the image communication terminal device 100a on the sending side in frame units. Data amount detection unit 15
Detects the transmission amount of image data sent from the image communication terminal device 100a on the transmission side, and gives the detection result to the data amount comparison unit 16. The data amount comparison unit 16 compares the detected transmission amount of the image data with a predetermined threshold value, and if the transmission amount of the image data is less than or equal to the threshold value, continues the initially set moving image communication. If the transmission amount exceeds the threshold value, the image data stored in the frame memory 18 is output. The image switching unit 17 follows the B determination result of the data amount comparison unit 16
The AS code control unit 13 is controlled to switch between moving image communication and still image communication.

As a result, when the amount of image data transmitted is small, the moving image data is output from the moving image control means 9 and displayed on the monitor 5 as a moving image. On the other hand, when the transmission amount of image data is small, the frame memory 18
The image data stored in is output to the still image control unit 10, the still image control unit 10 outputs the still image data, and the still image is displayed on the monitor 5. In this case, the display of "freeze" is superimposed on the monitor 5 to notify the user that the still image data is being output. This prevents the user from deciding that the switching from the moving image display to the still image display is the disconnection of communication. In this way, a comfortable video conference is realized.

[0039]

As described above, according to the present invention, there is provided an image communication terminal device capable of automatically switching between moving image display and still image display according to the amount of image data transmitted. Therefore, when the transmission amount of the image data sent from the transmitting side is large, the image data accumulated in advance in the frame accumulating means is automatically output as still image data to display the still image, and the image data When the transmission amount is small, the initially set moving image display is performed. Therefore, the user does not have to worry about the image quality deterioration such as the block distortion and the awkwardness of the motion, and the comfortable image communication can be realized.

[Brief description of drawings]

FIG. 1 is a functional block diagram of an image communication terminal device according to an embodiment of the present invention.

FIG. 2 is a functional block diagram of a conventional image communication terminal device.

FIG. 3 CCITT (current ITU-TS) Recommendation H.264. 221
Of the multiplex frame structure specified in

FIG. 4 CCITT (current ITU-TS) Recommendation H.264. 221
Showing a numerical table of BAS codes defined in

FIG. 5: CCITT (current ITU-TS) Recommendation H.264. 221
Showing a numerical table of BAS codes defined in

[Explanation of symbols]

 1 Microphone 2 Speaker 3 Shooting Camera 4 Document Camera 5 Monitor 6 Scanner 7 Key Operation Section 8 Voice Control Section 9 Moving Image Control Section 10 Still Image Control Section 11 Multiplex / Demultiplex Section 12 Line Interface Section 13 BAS Code Control Section 14 Calls Control processing unit 15 Data amount detecting unit 16 Data amount comparing unit 17 Image switching unit 18 Frame memory 20 ISDN 100a Image communication terminal device

Claims (4)

[Claims] 1. A communication unit for receiving image data, a moving image control unit for outputting the image data received by the communication unit as moving image data, and image data received by the communication unit for each frame. Frame accumulating means, a still image control means for outputting the image data accumulated in the frame accumulating means as still image data, a transmission amount detecting means for detecting a transmission amount of the image data received by the communication means, An image communication terminal device comprising: an image switching unit that switches between output of moving image data by the moving image control unit and output of still image data by the still image control unit based on a detection result of the transmission amount detection unit. 2. A transmission amount comparing means for comparing the transmission amount detected by the transmission amount detecting means with a predetermined threshold value, wherein the image switching means has a transmission amount less than or equal to the threshold value. In this case, the output of the moving image data by the moving image control means is continued, and the output of the moving image data by the moving image control means is output by the still image control means when the transmission amount exceeds the threshold value. The image communication terminal device according to claim 1, wherein the image communication terminal device is switched to output of data. 3. The image according to claim 1, wherein the image switching means switches between output of moving image data by the moving image control means and output of still image data by the still image control means by a BAS code. Communication terminal equipment. 4. The image communication terminal device according to claim 1, further comprising display means for displaying that the still image data is being output when the still image control means outputs the still image data. .