JPH0722384B2 - Heterogeneous video system compatible encoder - Google Patents

Description

The present invention relates to an image coding / decoding device.

[Conventional technology]

FIG. 4 is a block diagram showing a configuration of a transmitting side and a receiving side in a conventional image coding and transmitting apparatus for the same video system.
In the figure, 2 is an A / D converter that converts the input video signal 1 into a digital image signal 3, and 4 is a Y / C separator that separates a luminance signal Y component and a color difference signal C component. Signal 5
Is sent. Reference numeral 6 denotes a transmission side encoding / decoding circuit which performs an encoding transmission process on the image signal, and outputs the encoding information 7. Reference numeral 8 is a digital transmission line, 9 is a receiving side encoding / decoding circuit for reproducing an image signal from the encoded information 7, and outputs an image reproduction signal 10. 11 is a luminance signal Y component and a color difference signal C
A Y / C synthesizer for synthesizing the components, and outputs a Y / C synthesized signal 12. A D / A converter 13 converts the Y / C combined signal 12 into an analog output signal 14.

Next, the operation of the conventional image coding and transmitting apparatus shown in FIG. 4 will be described. Now, in the input video signal 1 on the transmission side, 30 frames per second in the case of the NTSC system, 525 horizontal scanning lines per frame, and 2 per second in the case of the PAL or SECAM system.
5 frames, 625 horizontal scanning lines per frame. The same applies to the analog output signal 14 on the receiving side.

First, on the transmitting side, the input video signal 1 is converted by the A / D converter 2 into the digital image signal 3 excluding the horizontal sync and vertical sync parts, and then the Y / C separator 4 performs the luminance signal Y component and the color difference signal. It is separated into C components. Next, in the transmission side encoding / decoding circuit 6, as the target range for encoding the Y / C separated signal 5 by the Y / C separator 4, there are M (M is a positive integer) pixels in the horizontal direction and L (in the vertical direction). L is a positive integer) Image coding and frame drop processing are performed on the pixels, and the coded information 7 is sent to the digital transmission line 8. At this time, for L pixels in the vertical direction, only one field in one frame is to be encoded, and the number of pixels to be encoded is limited by sampling lines at equal intervals. Horizontal M
The same applies to pixels.

On the other hand, on the receiving side, from the encoded information 7 received from the digital transmission line 8, the receiving side encoding / decoding circuit 9 generates an image reproduction signal 10 having M pixels in the horizontal direction and L pixels in the vertical direction, and Y / The C synthesizer 11 synthesizes the luminance signal Y component and the color difference signal C component while performing linear interpolation in the horizontal and vertical directions, and the Y / C synthesized signal 12 is converted by the D / A converter 13 to produce an analog output signal. Output 14 It should be noted that, for a frame that has been dropped due to dropped frames, the immediately preceding image reproduction signal is repeatedly output.

[Problems to be solved by the invention]

Since the above-mentioned conventional image coding and transmitting apparatus is configured as described above, when the transmitting side and the receiving side have different video systems, an image for the entire screen in the vertical direction between the transmitting side image and the receiving side image is displayed. Since the ratio of the parts is different and the reproduced image is distorted, there is a problem that a new video format conversion device is required on the transmission side or the reception side.

The present invention has been made to solve the above problems, and an object of the present invention is to obtain a heterogeneous video system compatible encoding device capable of performing video communication between different video systems without externally adding the video system conversion device. To aim.

[Means for solving problems]

The heterogeneous video system compatible encoding apparatus according to the present invention is provided with a format converter on the transmitting side in front of the encoding / decoding circuit for switching the sampling system according to the video signal on the input side, and on the receiving side for encoding / decoding. A format converter that switches the interpolation method according to the video signal on the output side is provided in the subsequent stage of the digitizing circuit.

[Action]

In the heterogeneous video system compatible encoding device of the present invention, the video system on the transmitting side is used as the format converter.
In the case of PAL or SECAM method, the sampling for the vertical line is made coarser than in the case of NTSC method, and in the receiving side, the number of line interpolation in the vertical direction is larger than that of NTSC method in the case of PAL or SECAM method. By doing so, the ratio of the image to the entire screen in the vertical direction on the transmitting side and the receiving side is made to match.

〔Example〕

FIG. 1 is a block diagram showing a configuration of a transmitting side and a receiving side in a heterogeneous video system compatible encoding apparatus according to an embodiment of the present invention. Reference numerals 1 to 14 are those of the conventional example shown in FIG. Is the same as In the figure, reference numeral 15 is a transmission side format converter, which sends out a format converted signal 16.
Reference numeral 17 denotes a transmission side frame memory, which outputs a frame signal 18 to be encoded. Reference numeral 19 denotes a receiving side frame memory that stores the image reproduction signal 10, and sends out the image reproduction signal 20.
Reference numeral 21 denotes a receiving side format converter, which outputs a format converted signal 22.

FIG. 2 is an explanatory diagram showing an example of the format conversion on the transmission side when the transmission side video system is the PAL or SECAM system in the heterogeneous video system compatible encoding apparatus of FIG. 1, and FIG. 3 is the heterogeneous video of FIG. The receiving side video system in the system compatible encoding device
It is an explanatory view showing an example of receiving side format conversion in the case of PAL or SECAM system.

Next, the operation of the heterogeneous video system compatible encoding apparatus according to the embodiment of the present invention shown in FIG. 1 will be described. With respect to the Y / C separated signal 5 on the transmitting side, the transmitting side format converter 15 simply starts from a predetermined line and n × L (n and L are positive) in the case where the input video signal 1 is the NTSC system. Is an integer of n, and n × L is less than 525)
1 line out of 6 input lines while using the weighted average between lines because the number of horizontal scanning lines in one frame is 625 lines, which is more than that in NTSC system, in the case of PAL or SECAM system. The above L lines are generated at a rate of thinning out. FIG. 2 shows an embodiment of the format conversion on the transmitting side when the input video signal 1 is the PAL or SECAM system. The format-converted signal 16 is temporarily stored in the transmission side frame memory 17, and then read out as the encoding target frame signal 18 in accordance with the encoding processing timing of the transmission side encoding / decoding circuit 6. The coding information 7 sent from the coding / decoding circuit 6 on the transmission side is the digital transmission line 8
Be transmitted to.

On the other hand, the image reproduction signal 10 reproduced by the reception side encoding / decoding circuit 9 is stored in the reception side frame memory 19 and then read out as the image reproduction signal 20 at every frame cycle of the reception side video system. At this time, for the frame dropped due to the encoding process on the transmission side, or the frame missing when the transmission side is the PAL or SECAM system and the reception side is the NTSC system, the immediately preceding image reproduction signal 20 is repeatedly read. .
Next, in the receiving side format converter 21, when the receiving side video system is the NTSC system, linear interpolation is performed on the L lines of the image reproduction signal 20 to generate the n × L lines, In the case of the PAL or SECAM method, in addition to the above linear interpolation, interpolation is performed at a ratio of 1 in 5 to n × L × 1.2.
(N × L × 1.2 is a positive integer) lines are generated. FIG. 3 shows an embodiment of the format conversion on the receiving side when the receiving side video system is the PAL or SECAM system. The format-converted signal 22 that has been format-converted by the reception-side format converter 21 is output to the Y / C combiner 11, and the D / A converter 11 performs D / A conversion after combining the luminance signal Y component and the color difference signal C component. Then, the analog output signal 14 is output by the receiving side video system.

In the above embodiment, the number of pixels to be encoded in the encoding / decoding circuit is fixed, but the number and range of pixels to be encoded can be switched in the format converter.

〔The invention's effect〕

As described above, according to the present invention, in the heterogeneous video system compatible encoding device, the transmitting side and the receiving side use the common encoding / decoding circuit for performing the encoding / decoding process, and the preceding stage of the encoding / decoding circuit on the transmitting side is used. Since the configuration is provided in the format converter at the subsequent stage of the encoding / decoding circuit on the receiving side,
The present invention has an excellent effect that the apparatus can be configured at a low cost, and an extremely versatile heterogeneous video system compatible encoding device capable of performing video communication between different video systems can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a transmitting side and a receiving side in a heterogeneous video system compatible encoding device according to an embodiment of the present invention, and FIG. 2 is a transmitting side in the heterogeneous video system compatible encoding device of FIG. Explanatory drawing showing an example of transmission side format conversion when the video system is PAL or SECAM system, FIG.
FIG. 4 is an explanatory diagram showing an example of the format conversion on the receiving side when the receiving side video system in the heterogeneous video system compatible encoding device is the PAL or SECAM system, and FIG. 4 is a conventional image encoding and transmitting device between the same video systems. FIG. 3 is a block diagram showing a configuration of a transmission side and a reception side in FIG. In the figure, 1 ... input video signal, 2 ... A / D converter,
3 ... Digital image signal, 4 ... Y / C separator, 5 ... Y
/ C separated signal, 6 ... Transmitting side encoding / decoding circuit, 7 ...
Coding information, 8 ... Digital transmission line, 9 ... Receiving side coding / decoding circuit, 10, 20 ... Image reproduction signal, 11 ... Y / C synthesizer, 12 ... Y / C synthesized signal, 13 …… D / A converter, 14 ……
Analog output signal, 15 ... Transmitter format converter,
16, 22 ... format converted signal, 17 ... transmission side frame memory, 18 ... encoding target frame signal, 19 ... reception side frame memory, 21 ... reception side format converter. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (3)

[Claims] 1. On both the transmitting side and the receiving side, M (M is a positive integer) pixels in the horizontal direction and L in the vertical direction per frame.
(L is a positive integer) pixels, and a common encoding / decoding circuit for performing an encoding / decoding process on a digital signal sequence having a predetermined format of N (N is a positive integer) frames per second is provided. On the transmission side, the digitally converted input signal of the transmission side video system is converted to the above predetermined format,
The first format converter for outputting to the first encoding / decoding circuit on the transmitting side is provided, and the receiving side reproduces the reproduction signal having the predetermined format reproduced by the second encoding / decoding circuit on the receiving side. A heterogeneous video system compatible encoding device, comprising a second format converter for converting to a format of a receiving side video system, and performing image encoding transmission between different video systems. 2. The first format converter, wherein:
If the image system on the transmitting side is NTSC, the horizontal scanning line 52
PAL or SEC is performed by sampling every n (n is a positive integer) line from the image part of 5 lines and extracting L lines.
In the case of the AM method, the data for the L lines is generated by using the weighted average between lines from the image portion in the 625 horizontal scanning lines, and the receiving side image is generated by the second format converter. When the system is the NTSC system, linear interpolation is performed on the L lines of the reproduction signal to generate n × L lines,
In the case of the PAL or SECAM method, the above n × L lines obtained by the above linear interpolation are interpolated at a ratio of one to five, and n × L × 1.2 (n × L × 1.2 is The heterogeneous video system compatible encoding apparatus according to claim 1, wherein the (positive integer) lines are generated. 3. The image on the transmitting side by setting the number of frames per second N of the predetermined format to a maximum of 25 and periodically dropping frames in the input signal sequence in the first format converter. If the system is the NTSC system, the N frames are output from 30 frames per second, and if the system is the PAL or SECAM system, the N frames are output from the 25 frames per second, and the second format conversion is performed. In the receiver, the second frame on the receiving side is set to the second frame on the receiving side with respect to the reproduced signal sequence having N frames per second or less than N frames per second by the frame dropping process by the first encoding / decoding circuit on the transmitting side. The preceding reproduction signal shall be repeatedly output during the period until the next reproduction signal is generated by the encoding / decoding circuit of, and if the receiving side video system is the NTSC system, 30 frames per second are displayed. Outputs beam, PAL or of the SECAM system, heterologous video system compatible encoding apparatus of Claims paragraph 1, wherein the outputs 25 frames per second.