JP3514785B2 - Image communication terminal - Google Patents

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 such as a video conference / telephone terminal capable of performing picture-in-picture processing of a partner image and a self image.

[0002]

2. Description of the Related Art In recent years, the market expansion of image communication terminals such as video conferences / telephone terminals is expected due to the spread of ISDN and the recommendation of image encoding algorithms in CCITT. As a function required of such an image communication terminal, there is a picture-in-picture function for simultaneously displaying a partner image and a self image.

Here, a conventional method of realizing the picture-in-picture function in the image communication terminal is shown in FIG.
To explain. For simplification of description, the television signal system will be described as the NTSC system (the number of scanning lines = 525, vertical frequency = 60 kHz).

First, an NTSC analog video signal from a local camera or the like is input to CCITT H.264. The operation up to the output of the image coded data on the self side in accordance with the H.261 recommendation (video coding standard for moving image communication at a low bit rate of 64 kb / s to 2 Mb / s) will be described. First, the local NTSC analog video signal from the local camera 1 is input to the Y / C decoder circuit 2, separated into a digital luminance (Y) signal and a digital color (C) signal, and output. Next, the digital luminance signal and the digital color signal (N
The effective scanning lines of 480 TSC) are held in the first frame memory 3, and then the digital luminance signal and the digital color signal held in the first frame memory 3 are stored in the common intermediate format (CIF) by the CIF conversion circuit 4. ), And the CIF-converted digital luminance signal and digital chrominance signal output from the CIF conversion circuit 4 are held in the second frame memory 5. Next, the second frame memory 5
The digital luminance signal and digital chrominance signal held in
261 encoder circuit 6 to input CCITT H.264. Two
The image coding process based on the 61st recommendation is performed, and the coded data of the own-side moving image is output.

Next, a description will be given of the process of inputting the encoded data of the moving image of the other party and outputting the NTSC analog video signal of the other party. First, the encoded data of the moving image of the other party is converted into H.264. 261 decoder circuit 7 to input CCITT
H. Decoding processing according to the H.261 recommendation is performed, and CIF
It outputs the digital luminance signal and digital color signal of the format. Next, H. The digital luminance signal and the digital color signal output from the H.261 decoder 7 are held in the third frame memory 8, and the digital luminance signal and the digital color signal held in the third frame memory 8 are inverse CIF conversion circuit 9 It converts to the NTSC television signal format and outputs a digital luminance signal and a digital color signal. Next, the output signal of the inverse CIF conversion circuit 9 is converted into a fourth signal.
In the frame memory 10, and the digital luminance signal and the digital color signal held in the fourth frame memory 10 are converted into NTSC analog video signals by the Y / C encoder circuit 11 and the other side moving image NTSC analog Output video signal.

Next, the picture-in-picture processing for creating a small screen of the moving image of the own side and realizing simultaneous display with the moving image of the other side will be described. First of all, a small screen creation circuit 1 is provided for the local NTSC analog video signal from the local camera 1.
5 and down-sampling each in the horizontal and vertical directions (usually 48 NTSC effective lines).
About 1/3 of 0, 160 lines are sampled. ) Is performed to output a digital luminance signal and a digital color signal. Next, the output from the small screen creation circuit 15 is temporarily held in the small screen frame memory 16, and the small screen Y / C encoder circuit 17 generates an NTSC analog video signal from the held small screen data. , Outputs the NTSC analog video signal of its own small screen. Partner NT
Input the SC analog video signal and this small screen NTSC analog video signal to the parent screen / small screen compositing analog switch 18 and monitor the NTSC analog video signal with the moving image of the other party as the parent screen. 12 to realize the picture-in-picture function.

[0007]

However, in the above-mentioned prior art, the circuit section (15 to 18) for creating a small screen must be changed for each television signal system, and all television signal systems are required. There was a problem that the amount of hardware would be large in order to deal with it. Further, since two analog video signals of the own side and the other side are input and processed, there is a problem that the number of analog circuit parts increases, peripheral components increase, and they are easily affected by noise and the like. . Further, there is a problem in that the picture-in-picture display on the other party cannot be realized when the other party image communication terminal does not have the picture-in-picture function.

The present invention solves the above-mentioned conventional problems, and does not store in each television signal system,
Another object of the present invention is to provide an image communication terminal capable of realizing a picture-in-picture function with a simple hardware configuration.

[0009]

The present invention SUMMARY OF], in order to achieve the above object, the image communication terminal, conversion for converting an image signal of the television system of the own side camera or found in the data of the CIF format A circuit and a frame memory for temporarily holding the converted CIF format data,
An encoder circuit that performs image encoding by inputting the CIF format data, and a small screen creation circuit that creates a small screen for a picture-in-picture own-side image as CIF format data from the data held in the frame memory A decoder circuit for converting the image coded data from the other side into the CIF format, a frame memory for temporarily holding the CIF format data output from the decoder circuit, and the other side CIF format data of the television system. An inverse conversion circuit for converting to a frame format and an encoder circuit for converting the output of the inverse conversion circuit into an analog video signal are provided, and the small screen data output from the small screen creation circuit is stored in the latter frame memory. Write and picture in pic It is characterized in that to produce the tea screen data. The present invention also relates to achieve the above object, an image signal of the television system of the own side camera or al a circuit for CIF conversion, a frame memory for temporarily holding the CIF format image data after conversion, This CIF format image data is read out from the frame memory and the H. H.264 that performs image coding conforming to the H.261 recommendation. H.261 encoder circuit and H.264 that converts image coded data from the other side into CIF format. Two
61 decoder circuit, a frame memory for temporarily holding the CIF format data of the other party, and a C side of the other party
An inverse CIF conversion circuit 9 for converting the IF format data into a television image signal, and a small screen creation circuit for creating a small screen of a desired size from the CIF format data on the own side are provided.

[0010]

According to the present invention, since the small screen is created by using the data after the CIF format according to the above configuration, the picture-in-picture process can be performed only by the digital processing similar to the processing for performing the CIF format. Can be easily realized. Also, by performing the same processing on the image sent from the other party and sending the picture-in-picture processed data to the other party, the picture-in-picture processed image is also sent to the other party's terminal. Can be displayed.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. In order to make the description easy to understand, the reference numerals used in the description of the conventional example are used for the same elements, and the television signal system is the NTSC system. In FIG. 1, reference numeral 1 denotes a self-side camera, and 2 denotes a self-side NTSC analog video signal from the self-side camera 1 which separates and outputs a digital luminance (Y) signal and a digital color (C) signal. A / C decoder circuit, 3 is a first frame memory for holding a digital luminance signal and a digital color signal (all image data within an effective scanning line), and 4 is a digital frame memory held by the first frame memory 3. A CIF conversion circuit for converting the luminance signal and the digital color signal into a common intermediate format (CIF), and a second reference 5 for holding the CIF-converted digital luminance signal and digital color signal output from the CIF conversion circuit 4. A frame memory 6 of the CCITT H.264 inputting the digital luminance signal and the digital color signal held in the second frame memory 5. H.264 for performing image coding processing in accordance with the H.261 recommendation (algorithm for low-speed moving image coding) and outputting image coded data on the local side. 261 encoder circuit. 7 is the CCI of the coded image coded data sent from the other side
TT H. H.264 for performing image decoding processing compliant with the H.261 recommendation and outputting CIF-formatted data. 261 decoder circuit 8 is a digital luminance signal and a digital chrominance signal output from the small screen creating circuit 13, and H.264. A third frame memory for holding the CIF-formatted digital luminance signal and digital chrominance signal output from the H.261 decoder circuit 7, 9 is a third
Inverse CIF conversion circuit for converting the digital luminance signal and digital chrominance signal held in the frame memory 8 into the format of the NTSC television signal system, and 10 is a fourth for holding the output of the inverse CIF conversion circuit 9. Is a Y / C encoder circuit for converting the digital luminance signal and the digital color signal held in the fourth frame memory 10 into an NTSC analog video signal, and 12 is a monitor. Reference numeral 13 denotes a small screen creation circuit for creating a small screen of a picture-in-picture own-side image from the CIF data from the second frame memory 5 and outputting it to the third frame memory 8.

The operation of the image communication terminal configured as above will be described below. The first frame memory 3 holds at least 480 lines of data per field, and the CIF conversion circuit 4 reads the luminance and color signals from the first frame memory 3 and
Convert to format. For the luminance signal, horizontal conversion is performed by sampling 360 times per line, and vertical conversion is performed by thinning out 480 to 288 lines (thinning from 5 lines to 3 lines). The CIF formatted data created in this way is temporarily held in the second frame memory 5. H. The H.261 encoder circuit 6 reads the CIF-formatted data held in the second frame memory 5, and H.264. Encoding according to the H.261 recommendation is performed, and the encoded image data on the local side for transmission to the terminal on the partner side is output.

CCITTH.TM. For communicating image data such as moving images and still images through a communication line. In an image communication terminal such as a video conference / telephone terminal conforming to the H.261 recommendation, input image data of a moving image is defined by a common intermediate format (CIF), and is encoded based on this CIF data. In the case of the NTSC television signal system, it is necessary to thin the lines from 480 effective lines to 288 lines in CIF format, that is, 3/5. When a small screen for picture-in-picture, usually a small screen of 1/9 size, is created, 160 lines are cut out from 480 effective lines of the NTSC television signal system, that is, lines are thinned to 1/3. Perform processing. It is necessary to perform similar line thinning-out processing for both the CIF format processing and the small screen creation processing, and the present invention utilizes this fact to make the CI
The image data after being F-formatted is further down-sampled to create a small screen.

The CIF-formatted image data of 288 lines × 360 dots is input to the small screen creating circuit 13, and this image data is down-sampled to 1/9 (1/3 in the horizontal direction, that is, 120 dots, vertical). Direction to 1/3 or 96 lines). Here 1 /
Although the case of creating a small screen of 9 sizes is described, regarding the size of the small screen and whether the effective screen of the small screen is the whole of CIF format data (288 lines x 360 dots) or smaller than the whole, It is not an essential matter of the present invention and can be changed as necessary.

The image coded data of the other party sent from the other party terminal is H.264. The H.261 decoder circuit 7 converts the image CIF data of the other party into the third frame memory 8
Held in. The small screen creation circuit 13 reads the CIF conversion data on its own side from the second frame memory 5 and creates a small screen of a desired size. This processing is similar to the processing in the CIF conversion circuit 4. The CIF conversion data for the small screen is written in the third frame memory 8 so that the CIF
Achieve picture-in-picture in the format. Then, the inverse CIF conversion circuit 9 reads the CIF conversion data written in the third frame memory 8 and
C digital luminance and color signals are converted and once written in the fourth frame memory 10. Further, the Y / C encoder circuit 11 reads the data from the fourth frame memory 10, converts the data into an NTSC analog video signal, and causes the monitor 12 to display the picture-in-picture processed image.

Next, a second embodiment of the present invention will be described with reference to FIG. The configuration is such that a second small screen creating circuit 14 is added to the first embodiment. The second small screen creation circuit 14 inputs the other party image CIF conversion data from the third frame memory 8 and performs the same processing as the first small screen creation circuit 13 to create the other side small screen. Then
Write to the second frame memory 5. By this,
The image data which has been picture-in-picture processed with the image of the other party as a small screen is CCITT H.264. H.261 based on the H.261 recommendation. It can be encoded by the H.261 encoder circuit 6, transmitted to the other party, and displayed on the other party's monitor.

[0017]

As described above, according to the present invention, the CIF
Since the picture-in-picture function is realized by the formatted or CIF-formatted image data, only digital processing can be performed and the amount of data to be handled can be small. This eliminates the need to have a picture-in-picture circuit for each television signal system, simplifies the hardware, eliminates the need for an analog circuit, and is not affected by noise or the like. Further, by performing the processing reverse to the above processing, by transmitting the picture-in-picture processed data of the self-side image coded data and the partner side small screen data as the image coded data to be transmitted to the partner side, The picture-in-picture processed video can be displayed even on the other-side image communication terminal that does not have the picture-in-picture function.

[Brief description of drawings]

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

FIG. 2 is a functional block diagram of an image communication terminal according to a second embodiment of the present invention.

FIG. 3 is a functional block diagram of an image communication terminal in a conventional example.

[Explanation of symbols]

1 camera 2 Y / C decoder circuit 3 First frame memory 4 CIF conversion circuit 5 Second frame memory 6 H. 261 encoder circuit 7 H. 261 decoder circuit 8 Third frame memory 9 Inverse CIF conversion circuit 10 Fourth frame memory 11 Y / C encoder circuit 12 monitors 13 Small screen creation circuit 14 Second small screen creation circuit

Claims (3)

(57) [Claims] 1. A video communication terminal for communicating image data through a communication line, a decoder circuit for converting the own side camera or these self side digital signal inputted analog video signal, holds the digital signal And a conversion circuit for converting a digital signal held in the first frame memory into CIF format data, and a CIF format data output from the conversion circuit. A second frame memory, an encoder circuit that performs image encoding processing by using the data held in the second frame memory as an input, and outputs image encoded data on its own side; and the second frame memory The small screen for the picture-in-picture own-side image from the data stored in And the small screen creation circuit for creating a chromatography data, that holds a decoder circuit for outputting image coded data encoded transmitted from the other party to CIF formatted, the image data output from the decoder circuit
A third frame memory; an inverse conversion circuit for converting the data held in the third frame memory into a television signal frame format; and an output of the inverse conversion circuit into an analog video signal An image communication terminal, comprising: an encoder circuit for performing the operation, and writing the small screen data output from the small screen creating circuit into the third frame memory to generate picture-in-picture screen data. Wherein communicating image <br/> image data of a moving image or a still image picture through a communication line CCITT H. In the image communication terminal conforming to 261 recommendation, a Y / C decoder circuit configured to separate the own side camera or these self side receives an analog video signal digital luminance signal and digital color signal, said digital luminance A first frame memory for holding a signal and the digital color signal; a CIF conversion circuit for converting the digital luminance signal and the digital color signal held in the first frame memory into CIF format data; A second frame memory for holding the CIF-converted digital luminance signal and digital color signal output from the CIF conversion circuit, and inputting the digital luminance signal and digital color signal held in the second frame memory As CCITT H. 26
H.264 for performing image encoding processing in accordance with the Recommendation 1 and outputting the image encoded data on the local side. 261 encoder circuit, a small screen creating circuit for creating a small screen for a picture-in-picture own side image from the CIF-converted data from the second frame memory, and an encoded image from the other side CCITT the data
H. The image is decoded according to the H.261 recommendation, and the CI
H.264 for outputting F-converted data. H.261 decoder circuit, the digital luminance signal and the digital color signal output from the small screen creating circuit, and the H.264. A third frame memory for holding the CIF-converted digital luminance signal and digital color signal output from the H.261 decoder circuit, and the digital luminance signal and digital color signal held in the third frame memory Inverse CIF conversion circuit for converting the signal to a television signal format, a fourth frame memory for holding the output of the inverse CIF conversion circuit, and a digital luminance signal held in the fourth frame memory And an Y / C encoder circuit for converting a digital color signal into an analog video signal. 3. A small screen for the image of the other party is created by inputting the image data from the other party held in the third frame memory, and the small screen data is written in the second frame memory and transmitted to the other party. 3. The image communication terminal according to claim 1, further comprising a second small screen creating circuit for creating picture-in-picture screen data to be reproduced.