JPH09233468A - Video signal decoder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decode a bit stream, for which a video signal in a system different from the system decided for a display device for displaying images is encoded, as well and to display it on the display device. SOLUTION: A system detection control means 20 detects the video signal system of a video elementary stream and corresponding to whether that detected system is equal with the system shown by a system select signal inputted from an input terminal 19, the system switching signals of different logical values are supplied to a system converting means 21 and a delay quantity switching means 22. Assuming that the video system of the display device or the like connected to a decoder is an NTSC system, when this video signal system detected result shows a PAL system, the system converting means 21 generates a video signal converted to the PAL system and outputs it to an output terminal 23. Besides, when the video signal system detected result shows the NTSC system, the video signal inputted from a video coder 12 is not converted but passed through the system converting means 21 as it is and outputted to the output terminal 23.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal decoding device, and more particularly to a video signal decoding device for decoding a coded digital video signal to restore a video signal.

[0002]

2. Description of the Related Art Conventionally, an analog video signal of a standard system such as an NTSC system or a PAL system is, if necessary, for example, MPEG or MP which is a color moving image coding system.
After being encoded by the EG2 system and converted into a digital signal, it is transmitted through a transmission path such as a recording medium, and decoded by a decoding device provided on the receiving side or the reproducing side to restore the original analog video signal. To be done.

FIG. 3 shows a block diagram of an example of a conventional video signal decoding apparatus. In the figure, a bit stream, which is a digital signal encoded by, for example, the MPEG2 system, is input to an input terminal 10 to receive a demultiplexer 11
Is supplied to. The bit stream input to the demultiplexer 11 is a digital signal in which video packets in which video signals relating to a plurality of programs are encoded, audio packets in which audio signals are encoded, and system information are time-division multiplexed. The multiplexer 11 separates the video packet and the audio packet of the selected program and the system control information based on the program selection signal from the system decoder 14 described later.

The video elementary stream composed of video packets output from the demultiplexer 11 is supplied to the video decoder 12, where it is decoded and restored to a video signal. Further, the audio elementary stream composed of audio packets output from the demultiplexer 11 is supplied to the audio decoder 13, where it is decoded and restored to the original audio signal.

Further, the system information output from the demultiplexer 11 is supplied to the system decoder 14,
Here, it is decoded and restored to a program selection signal, a reproduction timing signal and the like. The program selection signal is supplied to the demultiplexer 11 and
Is controlled. Further, the reproduction timing signal is supplied to the video decoder 12 and the audio decoder 13 to determine the reproduction output timing of the video signal from the video decoder 12 to the output terminal 15, and the reproduction output of the audio signal from the audio decoder 13 to the output terminal 16. Determine the timing.

[0006]

[Problems to be Solved by the Invention] MPEG and MPEG2
According to the encoding standard such as the system, it is possible to encode / decode an analog video signal of any standard system such as the NTSC system and the PAL system, but these are the same as the encoded video signal. It is decrypted by the method. Therefore,
For example, in a country or region where NTSC system video signals are transmitted and received, the above decoding device is used by being connected to an NTSC system display device, VTR, or the like, but a standard system video signal other than NTSC system such as PAL system is encoded. Since the converted bit stream has a different video signal system, it could not be displayed or recorded although it could be decoded.

[0007] The present invention has been made in view of the above points,
It is an object of the present invention to provide a video signal decoding device which also decodes a bit stream obtained by encoding a video signal of a system different from a system determined by a display device for displaying an image so that the bit stream can be displayed on the display device.

[0008]

In order to achieve the above-mentioned object, the present invention is a video signal decoding apparatus for decoding a coded video signal to restore the video signal. A system detecting means for detecting the video signal system based on information indicating the video signal system added to the signal, a desired video signal system selected and instructed by a system selection signal input from the outside, and system detection The video signal system detected by the means is compared, and when they are different, the video signal encoded so as to have a desired video signal system is decoded and converted, and when they are the same, they are encoded. And a means for outputting the video signal obtained by decoding the video signal as it is.

Further, the present invention is based on a video decoder for decoding a video elementary stream which is an encoded video signal to restore a video signal, and information indicating a video signal system added to the video elementary stream. And a method detection control means for comparing the obtained video signal method with a method selection signal indicating a desired video signal method input from the outside and outputting a method switching signal indicating whether or not they are different. Receiving the output video signal of the video decoder and the format switching signal as input signals, and converting the output video signal of the video decoder to the desired video signal format when the detected video signal format and the desired video signal format differ. And a system converting means for directly outputting the output video signal of the video decoder when both are the same. Therefore, in the present invention, the video signal system of the input coded video signal (video elementary stream) is detected, and when the video signal system does not match the desired video signal system input from the outside, the desired video signal input from the outside is detected. The decoded video signal is automatically converted and output so that the video signal system of FIG.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a block diagram of an embodiment of a video signal decoding apparatus according to the present invention. In the figure,
The same components as those in FIG. 3 are designated by the same reference numerals, and the description thereof will be omitted. In the embodiment shown in FIG. 1, the system detection control means 20, the system conversion means 21, and the delay amount switching means 2 are added to the conventional device.
2 is added. The system detection means 20 receives the system selection signal and the output video elementary stream of the demultiplexer 11 as an input signal, and generates a system switching signal for switching the system of the video packet of the input bit stream to the system according to the system selection signal. To the system conversion means 21 and the delay amount switching means 22 respectively.

The system conversion means 21 converts the decoded video signal into a system according to the system switching signal or outputs it as it is. The delay amount switching means 22 is the method converting means 2
In accordance with the system switching signal from 1, the delay amount corresponding to the time alignment with the output video signal of the system converting means 21 is added to the decoded audio signal and output.

As shown in FIG. 2, the system detection control means 20 includes a header detection / analysis circuit 201 that receives a video stream as an input signal, and a system switching determination circuit 202 to which the output signal of the header detection / analysis circuit 201 is input. It consists of As shown in FIG.
The scanning line conversion circuit 211 that receives the video signal from the video decoder 12 and the output signal of the system switching determination circuit 202 as input signals, and the output signal of the scanning line conversion circuit 211 and the output signal of the system switching determination circuit 202 are input. Field frequency conversion circuit 212.

Next, the operation of this embodiment will be described. Display device or V connected to this decryption device
A system selection signal indicating a video system such as TR is selected by a user, and a system detection control means 20 is input from a central processing unit (CPU) or a switch circuit via an input terminal 19.
Is supplied to. Here, the above-mentioned system selection signal is a display device or VTR, field frequency is 60 Hz, scanning line number is 525, and color subcarrier frequency of carrier color signal is 3.58 M.
Hz, 720 horizontal pixels, 480 effective scanning lines NTSC system, field frequency 50 Hz, 625 scanning lines, color subcarrier frequency of carrier color signal 4.433M
It is assumed that any one of the PAL system of Hz, 720 horizontal pixels, and 576 effective scanning lines is specified.

On the other hand, the video elementary stream separated by the demultiplexer 11 is branched into two, one is inputted to the video decoder 12 and the other is inputted to the system detection control means 20. This video elementary stream is, for example, H.264 of the International Telecommunication Union Telecommunication Standardization Sector (ITU-T). Since the information indicating the video signal system is stored in the sequence header at the specific position of the digital signal conforming to the H.262 standard, the system detection control means 20 detects this.

The information indicating the video signal system is specifically the frame frequency and both horizontal and vertical resolutions. Therefore, as shown in FIG. 2, the system detection control means 20 checks the frame frequency, horizontal resolution, and vertical resolution by the header detection / analysis circuit 201 and supplies the analysis result to the system switching determination circuit 202. The system switching determination circuit 202 detects the video signal system of the video elementary stream based on the input analysis result, and the detected system is the input terminal 1
A system switching signal (conversion instruction control signal) having a different logical value is supplied to the system converting unit 21 and the delay amount switching unit 22 depending on whether or not it is the same as the system indicated by the system selection signal input from the device 9.

When the video system of the display device or VTR connected to the decoding device is the NTSC system and the detection result of the video signal system is the PAL system, the system conversion means 21 is shown in FIG. As shown in the figure, the scanning line number conversion circuit 211 performs scanning line number conversion for converting the video signal from the video decoder 12 into five lines per six scanning lines, and then the field frequency conversion circuit 2
12 converts the field frequency to 60Hz, NT
A video signal conforming to the SC system is generated and output to the output terminal 23.

When the video signal system detection result is the NTSC system, the scanning line number conversion circuit 211 and the field frequency conversion circuit 212 of the system conversion means 21 convert the video signal input from the video decoder 12. Instead, it is directly passed through and output to the output terminal 23.

Even when the video system of the display device or the VTR connected to the decoding device is the PAL system, if the system detection result of the input video signal is the NTSC system as described above, the system is The conversion means 21 performs conversion of the frame frequency, conversion of the number of scanning lines into 6 for every 5 scanning lines, and the like to generate a video signal converted into the PAL system and output it to the output terminal 23. When the detection result of the video signal system is the PAL system, the system conversion means 21 directly passes through the output terminal 2 without converting the video signal input from the video decoder 12.
Output to 3. The above operation by the method conversion means 21 is summarized in the following table.

[0019]

[Table 1] When the system detection result and the system selection signal are different, that is, when the system conversion unit 21 performs the system conversion operation, the delay amount switching unit 22 outputs the delay amount corresponding to the system conversion processing time of the system conversion unit 21 to the audio decoder. It is added to the output audio signal of 13 and output to the output terminal 24. Also,
When the system conversion unit 21 does not perform the system conversion operation described above, the delay amount switching unit 22 directly outputs the output terminal 24 without delaying the output audio signal of the audio decoder 13.
Output to

As described above, according to the embodiment of the present invention, it is possible to automatically convert into a video signal system suitable for a display device to which the decoding device is connected and to decode the video signal system. The output terminals 23 and 24 can output video signals and audio signals not only in the form of analog signals but also in the form of digital signals.

The present invention is not limited to the above-mentioned embodiment, and for example, the method of system conversion is NTSC.
The system is not limited to the PAL system and the PAL system, and other systems such as SECAM system are possible, and the encoding system is DSS (Digital Satellite Syst) which is practically used in the United States.
An encoding method by em) is also possible.

Further, in the above description, the means (21, 22) for system conversion is added and realized after the video decoder and the audio decoder. However, the system conversion means is incorporated in the video decoder and the audio decoder itself. Of course, it is possible to reduce the number of circuits.

[0023]

As described above, according to the present invention,
The video signal system is detected from the encoded bit stream, the video signal system is automatically converted to the same as the specified video signal system, and the decoded video signal is output. The software resources that could not be used because the video signal system is different from the conventional one can be effectively used, and the versatility of the device can be improved compared with the conventional one.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is a block diagram of an example of a main part of FIG.

FIG. 3 is a block diagram of an example of the related art.

[Explanation of symbols]

 11 Demultiplexer 12 Video Decoder 13 Audio Decoder 14 System Decoder 19 System Selection Signal Input Terminal 20 System Detection Control Means 21 System Conversion Means 22 Delay Amount Switching Means 201 Header Detection / Analysis Circuit 202 Method Switching Judgment Circuits 211 Scan Line Conversion Circuits 212 Fields Frequency conversion circuit

Claims (2)

[Claims] 1. A video signal decoding device for decoding a coded video signal to restore a video signal, based on information indicating a video signal system added to the input coded video signal. Then, a method detecting means for detecting the video signal method, a desired video signal method selected and instructed by a method selecting signal input from the outside, and a video signal method detected by the method detecting means are compared, When the two are different, the encoded video signal is decoded and converted so that the desired video signal system is obtained, and when the two are the same, the video obtained by decoding the encoded video signal A video signal decoding device, comprising: an output unit that outputs a signal as it is. 2. A video decoder for decoding a video elementary stream which is an encoded video signal to restore the video signal, and detection based on information indicating a video signal system added to the video elementary stream. A method detection control means for comparing the obtained video signal method with a method selection signal indicating a desired video signal method input from the outside, and outputting a method switching signal indicating whether or not they are different, When an output video signal of the video decoder and the system switching signal are received as input signals and the detected video signal system and the desired video signal system are different, the output video of the video decoder is set to the desired video signal system. And a system converting means for converting the signal and outputting the output video signal of the video decoder as it is when both are the same. Video signal decoding apparatus according to symptoms.