JP2003199110A - Video signal encoding apparatus and video signal encoding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a video signal encoding apparatus for outputting an encoded video signal suitable for recording. <P>SOLUTION: The video signal encoding apparatus includes: a first encoding means (13) for encoding a video signal by a first encoding parameter; a second encoding means (27) for encoding the video signal by the second encoding parameter by which an encoding amount can be reduced more than the encoding by using the first encoding parameter; and a selection output means (26) for selectively outputting either the video signal encoded by the first encoding means or the video signal encoded by the second encoding means. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal coding apparatus and a video signal coding method for coding an input video signal. For example, the present invention relates to a video signal coding apparatus and a video signal coding method of the MPEG2 system.

[0002]

2. Description of the Related Art In recent years, a video data recording / reproducing apparatus for compressing a moving image by using a compression method called MPEG2 and recording it on an optical disk typified by a DVD has been developed, replacing a conventional VTR (magnetic recording / reproducing apparatus). I'm trying.

[0003]

In the conventional video data recording apparatus, even if the compressed information amount is too large and the decompression buffer overflows to generate a bit stream that cannot be decompressed as an image, the large capacity recording medium is still used. There was a problem that it would be recorded in.

An object of the present invention is to avoid this inconvenience, and it is an object of the present invention to provide a video signal coding apparatus and a video signal coding method for outputting a coded video signal suitable for recording.

[0005]

In order to solve the above problems and achieve the object, a video signal coding apparatus and a video signal coding method of the present invention are configured as follows.

(1) The video signal encoding device of the present invention is
A first coding means for coding a video signal with a first coding parameter and a video signal with a second coding parameter capable of having a smaller code amount than the coding of the first coding parameter. Second encoding means for encoding the video signal, and the video signal encoded by the first encoding means and the second video signal according to the result of encoding the video signal by the first encoding means. Selection output means for selectively outputting either one of the video signals encoded by the encoding means.

(2) The video signal encoding method of the present invention is
The video signal is coded by the first coding parameter, and the video signal is coded by the second coding parameter capable of making the code amount smaller than the coding of the first coding parameter. One of the video signal encoded by the first encoding parameter and the video signal encoded by the second encoding parameter according to the result of encoding the video signal by the first encoding parameter. Is selectively output.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing a schematic configuration of a video data recording / reproducing apparatus according to an example of the present invention.

As shown in FIG. 1, the video data recording / reproducing apparatus includes an addition processing unit 11, a discrete cosine transform (DCT) processing unit 12, a first quantization processing unit 13, and an inverse quantization processing unit 1.
4, inverse discrete cosine transform processing (DCT) unit 15, motion compensation unit 16, first variable length coding (VLC) unit 17, buffer 20, overflow detection unit 20a, variable length decoding (VLD) unit 21, reverse Quantization processing unit 22, inverse discrete cosine transform processing unit 23, first delay buffer 25, selection processing unit 26, second quantization processing unit 27, second variable length coding (VLC) unit 28, second The delay buffer 30 and the recording processing unit 31 are provided.

The operation of the above video data recording / reproducing apparatus will be described.

The image data (video signal) is added by the addition processing unit 11.
The image data for each macroblock input to the input processing unit 11 and provided by the addition processing unit 11 is subjected to the discrete cosine transform processing in the discrete cosine transform processing unit 12 and becomes image data composed of DCT transform coefficients. The image data composed of the DCT transform coefficient provided from the discrete cosine transform processing unit 12 is quantized by the first quantization processing unit 13 and the second quantization processing unit 27, respectively. The first quantization processing unit 13 quantizes the image data with the first coding parameter. The second quantization processing unit 27 quantizes the image data with the second coding parameter. The second coding parameter is a parameter that can reduce the code amount as compared with the coding of the first coding parameter.

The image data in units of macroblocks, which is composed of the quantized coefficients provided from the first quantization processing unit 13, is inversely quantized in the inverse quantization processing unit 14 to become image data composed of DCT transform coefficients. The image data composed of the DCT transform coefficient provided from the inverse quantization processing unit 14 is subjected to the inverse discrete cosine transform in the inverse discrete cosine transform processing unit 15 and restored to the image data. The restored image data is input to the motion compensation unit 16, and the output of the motion compensation unit 16 is the addition processing unit 1.
Added in the direction of being subtracted to 1.

Further, the image data in units of macroblocks, which is composed of the quantized coefficients provided from the first quantization processing unit 13, is subjected to variable length compression by the first variable length encoding unit 17,
The bit stream 18 is stored in the buffer 20, and is output to the variable length decoding unit 21. The variable-length decoding unit 21 converts the first bit stream 18 into image data in units of macroblocks including quantized coefficients, and the inverse quantization processing unit 22 dequantizes the image data to include image data including DCT transform coefficients. The discrete cosine transform processing unit 23 performs inverse discrete cosine transform to restore the image data. At the same time, the first bit stream 18 is temporarily stored in the first delay buffer 25 and waits for being read by the selection processing unit 26.

On the other hand, the image data in units of macro blocks consisting of the quantized coefficients provided from the second quantization processing unit 27 is variably length-compressed by the second variable length coder 28 and
Of the second delay buffer 3
It is temporarily stored in 0 and waits for being read by the selection processing unit 26.

The buffer 20 has an overflow detector 2
0a is provided, and when the overflow detection unit 20a detects the overflow, the selection processing unit 26 is notified of the overflow by the signal S1 that notifies the detection of the overflow. The selection processing unit 26 selects the bit stream stored in either the first delay buffer 25 or the second delay buffer 30 depending on the presence or absence of the signal S1. The bitstream selected by the selection processing unit is provided to the recording processing unit 31, and the recording processing unit 31 records the provided bitstream on the magneto-optical disk 19.

Next, the operation of the selection processing unit 26 will be described with reference to FIG.

As shown in FIG. 2, the first delay buffer 2
5, the first bit stream is stored, and the second
The second bit stream is stored in the delay buffer 25 of the. Signal S1 notifying the detection of overflow
Is temporarily turned on when, for example, an overflow occurs. It is assumed that an overflow occurs at the time of P1. The position of the first bitstream corresponding to P1 is P3. Selection processing unit 2 before overflow occurs
6 selectively outputs the first bit stream. After the overflow occurs, the selection processing unit 26 finds P2 as the delimiter position of the first bitstream, ends the selective output of the first bitstream at the delimiter position P2, and starts the selective output of the second bitstream. This delimiter position is a position convenient for switching from the first bit stream to the second bit stream. The selection processing unit 26 selects and outputs the second bit stream, and after P3, which is the position where the first bit stream overflows, finds P4 again as a delimiter position, and then the second bit at the delimiter position P4. The selective output of the stream is ended and the selective output of the first bit stream is started. This separation position is the second
This is a convenient position for switching from the bit stream of 1 to the first bit stream. That is, the first bit stream is from the occurrence of overflow of the output bit stream output from the selection processing unit 26 to the break position P2, and the second bit stream is from the break position P2 to the break position P4 of the output bit stream. It becomes a bit stream. That is, when the code amount of the first bitstream exceeds the predetermined value, the bitstream corresponding to the first bitstream exceeding the specified value is replaced with the second bitstream.

Next, referring to FIG. 3, the video signal encoding process according to an example of the present invention will be summarized.

First, image data (video signal) is input to the addition processing section 11 (ST1). The input image data is coded by the first coding parameter and also by the second coding parameter through the steps described above (ST2). The image data encoded with the first encoding parameter is accumulated in the buffer 20, for example, in frame units. At this time, if the overflow detection unit 20a does not detect an overflow (specified size over) (ST3, NO), the image data encoded by the first encoding parameter is selectively output (ST).
4) It is recorded (ST6). However, when the overflow is detected by the overflow detection unit 20a (ST3, YES), the image data encoded by the second encoding parameter is selected instead of the image data encoded by the first encoding parameter. It is output (ST5) and recorded (ST6). Until there is no input image data (S
(T7, YES), the above processing continues. That is, if the specified size over of the code amount of the video signal of the predetermined unit coded by the first coding parameter is not detected,
The video signal coded by the first coding parameter is selected and output. However, when the specified size over is detected, at least a signal corresponding to the video signal of a predetermined unit corresponding to the specified size over is selected from the video signals encoded by the second encoding parameter and output.

Here, the effects of the present invention will be summarized. The size of the information amount of the bitstream depends on the coding parameter. The amount of information increases as the restored image is encoded so as to be closer to the original image. If the input video moves rapidly and the data required to restore the one-frame image is too large, the data may not fit in the buffer and may overflow. In the conventional video data recording apparatus, even if a bit stream that cannot be restored as an image is generated due to the amount of compressed information being too large and the decompression buffer overflowing, it is still recorded.

According to the video data recording / reproducing apparatus of the present invention, the information in which the image data is coded by the first coding parameter and the second code which can make the code amount smaller than the coding by the first coding parameter are used. By selectively using the information obtained by encoding the image data with the encoding parameter of 1, the reproducibility of the original image can be kept high and the restoration trouble can be reduced. For example, information that is coded with the second coding parameter is recorded for a video that moves rapidly, and information that is coded with the first coding parameter is recorded for a normal video.

Next, a concrete example of a position convenient for switching bit streams will be described. GOP (group of pic) is a convenient location for switching bitstreams.
(ture) breaks apply. That is, the bit stream is switched in GOP units. Accordingly, even if the unified bitstream is selectively output from the first and second bitstreams and restored, the image does not become unnatural at the switching point.

The GOP will be briefly described with reference to FIG. FIG. 4 is a diagram showing a data structure of the MPEG2 video standard. As shown in FIG. 4, in the upper layer of the MPEG2 video data, SH (Sequence heade)
r), GOP (Group Of Picture), SE (Sequence En)
d Code) is placed. This GOP contains GH (Gr
oup Of Picture Header) and multiple pictures (I-
Picture, P-picture, B-picture). Specifically, 1 GOP contains 15 pictures (1
5 frames) are included. PH (Pi
Cture Header) and a plurality of MBs (Macro Brock) are included.

FIG. 5 is a diagram showing a prediction method of the MPEG2 video standard. There are three types of I-pictures, P-pictures, and B-pictures depending on the prediction method.
The I-picture is an intra-frame coded image that does not perform prediction and is a starting point of prediction. The P-picture performs prediction using a temporally past I-picture or P-picture as a reference image. The B-picture performs prediction using an I-picture or P-picture that is temporally past or future as a reference image.

The invention of the present application is not limited to the above-described embodiment, and can be variously modified at the stage of implementation without departing from the spirit of the invention. In addition, the respective embodiments may be combined as appropriate as much as possible, in which case the combined effects can be obtained. Further, the embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. For example, even if some constituent elements are deleted from all the constituent elements shown in the embodiment, the problem described in the section of the problem to be solved by the invention can be solved, and the effect described in the section of the effect of the invention If you get
A configuration in which this component is deleted can be extracted as an invention.

[0027]

According to the present invention, it is possible to provide a video signal coding apparatus and a video signal coding method for outputting a coded video signal suitable for recording.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of a video data recording / reproducing apparatus according to an example of the present invention.

FIG. 2 is a diagram for explaining an operation of a selection processing unit in the video data recording / reproducing device.

FIG. 3 is a flowchart showing a video signal encoding process.

FIG. 4 is a diagram showing a data structure of the MPEG2 video standard.

FIG. 5 is a diagram showing a prediction method of the MPEG2 video standard.

[Explanation of symbols]

11 ... Addition processing unit 12 ... Discrete Cosine Transform (DCT) Processing Unit 13 ... First quantization processing unit 14 ... Inverse quantization processing unit 15 ... Inverse Discrete Cosine Transform Processing (DCT) Unit 16 ... Motion compensation unit 17 ... First Variable Length Coding (VLC) Unit 19 ... Magneto-optical disk 20 ... buffer 20a ... Overflow detection unit 21 ... Variable Length Decoding (VLD) Unit 22 ... Inverse quantization processing unit 23 ... Inverse Discrete Cosine Transform Processing Unit 25 ... First delay buffer 26 ... Selection processing unit 27 ... Second quantization processing unit 28 ... Second variable length coding (VLC) unit 30 ... Second delay buffer

Continued front page    F-term (reference) 5C053 FA24 GA11 GB22 GB26 GB28                       GB29 GB32 GB38 KA03                 5C059 KK35 MA00 MA01 MA23 MC11                       MC38 ME01 PP05 PP06 PP07                       SS13 TA46 TB03 TC15 TC18                       TD06 TD11 UA02 UA05 UA33                 5D044 AB07 BC04 CC04 EF03 GK07                       HH02

Claims (8)

[Claims] 1. A first encoding means for encoding a video signal according to a first encoding parameter, and a second code capable of having a smaller code amount than the encoding of the first encoding parameter. Second coding means for coding a video signal according to a coding parameter; and a video signal coded by the first coding means according to a result of coding the video signal by the first coding means. And a selection output means for selectively outputting either one of the video signals encoded by the second encoding means, and a video signal encoding device. 2. A first coding means for coding a video signal with a first coding parameter, and a second code capable of having a smaller code amount than the coding with the first coding parameter. Second encoding means for encoding a video signal according to an encoding parameter; detection means for detecting a specified size over of the code amount of a predetermined unit of the video signal encoded by the first encoding means; If the prescribed size over is not detected by the means, the video signal encoded by the first encoding means is selected and output, and when the prescribed size over is detected by the detecting means, at least a predetermined corresponding to the prescribed size over is detected. Selection output means for selecting and outputting a signal corresponding to a unit video signal from the video signal encoded by the second encoding means, Video signal encoding device. 3. A first encoding means for encoding a video signal with a first encoding parameter, and a second code capable of having a smaller code amount than the encoding with the first encoding parameter. Second encoding means for encoding a video signal according to an encoding parameter; detection means for detecting a specified size over of the code amount of a predetermined unit of the video signal encoded by the first encoding means; If the prescribed size over is not detected by the means, the video signal encoded by the first encoding means is selected and output, and when the prescribed size over is detected by the detecting means, at least a predetermined corresponding to the prescribed size over is detected. A selection output unit that selects and outputs a signal corresponding to a unit video signal from the video signal encoded by the second encoding unit, and outputs by the selection output unit. A video signal encoding apparatus comprising: a recording unit that records a video signal that is input. 4. The video signal encoding apparatus according to claim 3, wherein the selection output means selects and outputs a video signal in GOP units. 5. A video signal is coded by a first coding parameter, and a video signal is coded by a second coding parameter capable of making the code amount smaller than the coding of the first coding parameter. A video signal encoded by the first encoding parameter and an image encoded by the second encoding parameter according to a result of encoding the video signal by the first encoding parameter. A video signal encoding method, characterized in that either one of the signals is selectively output. 6. A video signal is coded by a first coding parameter, and a video signal is coded by a second coding parameter capable of making the code amount smaller than the coding of the first coding parameter. If the video signal is encoded and the specified size of the code amount of the video signal of the predetermined unit coded by the first coding parameter is not detected, the video signal coded by the first coding parameter is selected and output. Then, when the specified size over is detected, at least a signal corresponding to a video signal of a predetermined unit corresponding to the specified size over is selected from the video signals encoded by the second encoding parameter and output. Video signal coding method. 7. A video signal is coded by a first coding parameter, and a video signal is coded by a second coding parameter capable of making the code amount smaller than the coding of the first coding parameter. If the video signal is encoded and the specified size of the code amount of the video signal of the predetermined unit coded by the first coding parameter is not detected, the video signal coded by the first coding parameter is selected and output. Then, when the specified size over is detected, at least a signal corresponding to the video signal of a predetermined unit corresponding to the specified size over is selected from the video signals coded by the second coding parameter, is output, and is selectively output. A video signal coding method, characterized in that the video signal is recorded. 8. The video signal encoding method according to claim 6, wherein the video signal is selected and output in GOP units.