WO2006093306A1 - Dispositif et méthode de conversion de méthode de codage d’image - Google Patents

Dispositif et méthode de conversion de méthode de codage d’image Download PDF

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Publication number
WO2006093306A1
WO2006093306A1 PCT/JP2006/304210 JP2006304210W WO2006093306A1 WO 2006093306 A1 WO2006093306 A1 WO 2006093306A1 JP 2006304210 W JP2006304210 W JP 2006304210W WO 2006093306 A1 WO2006093306 A1 WO 2006093306A1
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WO
WIPO (PCT)
Prior art keywords
encoding
coefficient
image data
coding
encoding method
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Application number
PCT/JP2006/304210
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English (en)
Japanese (ja)
Inventor
Toru Taima
Original Assignee
Pioneer Corporation
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Publication date
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Publication of WO2006093306A1 publication Critical patent/WO2006093306A1/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/169—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding
    • H04N19/17—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being an image region, e.g. an object
    • H04N19/176—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being an image region, e.g. an object the region being a block, e.g. a macroblock
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/169—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding
    • H04N19/18—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being a set of transform coefficients
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/40—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using video transcoding, i.e. partial or full decoding of a coded input stream followed by re-encoding of the decoded output stream

Definitions

  • the present invention relates to an image encoding method conversion apparatus and method for converting encoded image data into encoded image data of another encoding method.
  • image encoding methods for compressing image data such as MPEG, MPEG 2, H. 26 61, etc.
  • An image coding system conversion apparatus is used.
  • an input frame rate ⁇ measuring means for measuring the frame rate of the decoded image data after decoding the encoded image data corresponding to the encoding method, and its decoding
  • a target code amount calculating means for calculating a target code amount for each picture based on the transmission capacity of the line for transmitting the converted image data and the input frame rate measured by the input frame rate measuring means, and dividing the picture picture Calculating a ratio of a predetermined unit code amount obtained in a predetermined unit for each predetermined unit, and determining a target code amount for each predetermined unit based on the calculation result and a target code amount for each picture; Based on the determination, there is an apparatus provided with an encoding means for encoding the decoded image data by another encoding method (see Japanese Patent Laid-Open No. 2 0 0 3- 1 8 9 3 1 1). See)
  • the re-encoding method is used without using the information of the original coding method except for the motion vector of the macro block. Since the target code amount of each picture is determined and re-encoding is simply performed, the encoded image data obtained by re-encoding the decoded image data has the disadvantage of causing image quality degradation. 7
  • the problems to be solved by the present invention include the above-mentioned drawbacks as an example.
  • An image coding method conversion apparatus and method capable of preventing image quality deterioration due to re-encoding by different coding methods, and a method thereof are provided. It is an object of the present invention to provide a computer to be executed and a readable program.
  • the image coding method conversion apparatus of the present invention converts an image data encoded by the first encoding method into image data encoded by a second encoding method different from the first encoding method.
  • An encoding method conversion device comprising: decoding means for decoding image data encoded by the first encoding method to generate decoded image data and detecting an encoding coefficient for each macroblock; Coding coefficient conversion means for converting the coding coefficient of the first coding method detected by the decoding means into the coding coefficient of the second coding method for each macroblock; and the decoded image A code for generating image data encoded by the second encoding method by encoding data using the encoding coefficient of the second encoding method converted by the encoding coefficient conversion means for each macroblock. And means It is characterized in that was.
  • the image encoding method conversion method of the present invention is an image for converting image data encoded by the first encoding method into image data encoded by a second encoding method different from the first encoding method.
  • An encoding method conversion method wherein the image data encoded by the first encoding method is decoded to generate decoded image data, and for each macro block A decoding step for detecting a coding coefficient, and a code for converting the coding coefficient of the first coding method for each macro block detected in the decoding step into a coding coefficient of the second coding method.
  • a program according to the present invention is a computer-readable program for executing an image coding method conversion method, wherein image data encoded by the first coding method is a second code different from the first coding method.
  • An image encoding method conversion method for converting into image data encoded by an encoding method, wherein the image data encoded by the first encoding method is decoded to generate decoded image data and a macroblock Decoding process for detecting each coding coefficient and converting the coding coefficient of the first coding method for each macroblock detected in the decoding process to the coding coefficient of the second coding method And encoding the decoded image data using the encoding coefficient of the second encoding method obtained by converting the decoded image data in the encoding coefficient conversion process for each macroblock. Coding It is characterized by comprising: a coding step of generating the image data encoded by the expression, a.
  • FIG. 1 is a block diagram showing the configuration of an image coding method conversion apparatus according to the present invention.
  • FIG. 2 is a diagram showing a quantization coefficient conversion table used in the apparatus of FIG.
  • FIG. 3 is a diagram showing an example of image data used for creating a quantization coefficient conversion table.
  • FIG. 4 is a block diagram showing the configuration of the encoding apparatus in the apparatus of FIG.
  • FIG. 5 is a flowchart showing the encoding method conversion operation of the apparatus of FIG.
  • FIG. 6 is a flowchart showing the encoding process by the encoding device.
  • FIG. 1 is a block diagram showing a configuration of an image coding method conversion apparatus according to the present invention.
  • the image encoding method conversion apparatus shown in FIG. 1 converts image data encoded by the MPEG 2 method as the first encoding method into H.264-based encoded image data of the second encoding method.
  • the device includes an input buffer 1, a decoding device 2, a frame memory 3, a rate controller 4, an encoding device 5, and a transmission buffer 6.
  • the input buffer 1 is a memory for storing a stream of input image data encoded by the MPEG 2 method before decoding.
  • the decoding device 2 decodes the image data stored in the input buffer 1 and supplies the decoded image data to the frame memory 3.
  • a motion vector and a quantization coefficient are extracted for each macroblock and a picture code amount is detected.
  • the motion vector information is supplied to the encoding device 5, and the quantization coefficient and picture code amount information is supplied to the rate controller 4.
  • the frame memory 3 holds at least one frame of image data decoded by the decoding device 2.
  • the rate controller 4 controls the quantization coefficient at the time of quantization in the encoding device 5 based on the quantization coefficient and the information of the picture code amount supplied from the decoding device 2.
  • the encoding device 5 converts the decoded image data held in the frame memory 3 into H.264-type encoded image data.
  • a quantization coefficient conversion table is used for conversion.
  • the quantization coefficient conversion table is for MPEG 2 quantization coefficient G.
  • An example of the quantization coefficient conversion table is shown in FIG.
  • the range of quantization coefficients in MPEG 2 (first predetermined range) is 1 to 32, and the quantization scale determined for each quantization coefficient differs between linear scale mode and nonlinear scale mode.
  • the S / N ratio of decoded coefficients and decoded images is not related.
  • the quantization coefficient range (second predetermined range) of H.264 is 0 to 51, and the quantization scale is set so that the quantization coefficient and the SZN ratio of the decoded image are proportional. It has been established.
  • specific image data as shown in Fig. 3 is encoded using the MP EG 2 method while changing the quantization coefficient.
  • the difference d between the reconstructed image A obtained by decoding the decoded image A and the reconstructed image B obtained by encoding the same image data in the same way using the H.264 method and decoding it is as follows. Calculated by the formula. Incidentally, a xy elements of the reproduced image A obtained by decrypt, b xy are elements of the reproduced image B obtained by decoding.
  • a quantization coefficient conversion table is created by associating quantization coefficients with a small difference d.
  • the transmission buffer 6 holds the encoded image data output from the encoding device 5 and outputs it to a predetermined transmission path.
  • the encoding device 5 includes an arithmetic unit 11, a DCT converter 12, a quantizer 13, a variable length encoder 14, a buffer 15, an inverse quantizer 16, and an inverse DCT transform vessel 1 7, Computation unit 1 8, Frame memory 1 9, Motion compensator 2 0 and Motion vector holder 2 1
  • the arithmetic unit 11 subtracts the predicted image data motion-compensated by the motion compensator 20 for each macroblock from the input image data, and outputs the difference data to the DCT converter 12.
  • Macroblock is each block obtained by dividing image data into 16 pixels x 16 pixels. Note that the processing block for converting the input image data into macroblocks is not shown in FIG.
  • the 00 converter 1 2 performs two-dimensional discrete cosine transform on the output data of the arithmetic unit 1 1.
  • the quantizer 13 quantizes the image data after DCT conversion and outputs the quantized image data to the variable length encoder 14 and the inverse quantizer 16.
  • the variable length encoder 1 4 performs variable length encoding on the quantized data supplied from the quantizer 1 3 and the motion vector supplied from the decoding device 2 and outputs the result to the no-offer 15. .
  • the buffer 15 holds and outputs the variable length data supplied from the variable length encoder 14.
  • the inverse quantizer 16 inversely quantizes the quantized data input from the quantizer 13 and outputs it to the inverse DCT converter 17.
  • the inverse D C T converter 17 performs inverse D C T conversion on the dequantized data and supplies it to the computing unit 18.
  • the arithmetic unit 18 adds the predicted image data motion-compensated by the motion compensator 20 and the error data input from the inverse DCT converter 17 to convert to the original image data. Supply the image data to the frame memory 19 and store it.
  • the motion compensator 20 generates predicted image data by performing motion compensation on the image data read from the frame memory 19 corresponding to the motion vector.
  • the motion vector holder 2 1 holds and outputs the motion vector information supplied from the decoding device 2.
  • the operation of each unit 1 1 to 2 1 of the encoding device 5 is a controller (not shown). Controlled by.
  • FIG. 5 shows an outline of the system conversion operation by the image encoding system conversion apparatus
  • FIG. 6 shows an outline of the encoding process operation by the encoding apparatus 5.
  • thick arrow lines indicate the flow of data
  • thin arrow lines indicate the flow of processing and requests.
  • the encoded image data of the MPEGG2 system of frame k is supplied to the buffer 1.
  • the inputted MPE G 2 encoded image data of frame k is supplied from the buffer 1 to the decoding device 2 for each macroblock.
  • the decryption device 2 performs decryption processing on the MPEG 2 system and outputs decoded image data (step S .1).
  • the output decoded image data is held in the frame memory 3 (step S 2).
  • a motion vector and a quantization coefficient are extracted for each macroblock and a picture code amount is detected.
  • the motion vector information is supplied to the encoder 5 and held in the motion vector holder 21.
  • Information on the quantization coefficient and the picture code amount is supplied to the rate controller 4 and held in an internal memory (not shown) (step S 3).
  • the encoding device 5 executes an encoding process for converting the decoded image data output from the decoding device 2 into H.264-type encoded image data (step S 4).
  • the image indicated by the decoded image data of the supplied frame k is a macro block composed of 16 pixels ⁇ 16 pixels. Is divided into n blocks (step SI 01), and the counter value i is set to 0 (step S 102). Then, the quantization coefficient for macroblock i is set (step S 1 03). In step S 1 03, the quantization coefficient of macroblock i is required for rate controller 4.
  • the rate controller 4 reads the quantization coefficient of the macroblock i from the internal memory as G (step S5), and calculates the quantization coefficient Q corresponding to the quantization coefficient G as the quantization coefficient. Quantization coefficient conversion is performed by searching and reading from the conversion table (step S6). The quantization coefficient Q is designated as the quantization coefficient of the macroblock i (step S7).
  • step S 104 it is determined whether or not the frame k is an intra-coded picture.
  • Information about whether or not the frame is an intra-coded picture is supplied from the decoding apparatus 2 together with the motion vector information. If the picture is not an intra-coded picture, that is, if it is an inter-coded picture, the motion vector of macroblock i is read from the motion vector holder 21 (step S 105), and the frame memory 1 The image data stored in 9 is read out, motion compensation is performed, and predicted image data is output (step S 106).
  • the MP EG 2 motion vector predicts with 1Z2 pixel accuracy, and the H.264 motion vector has 1Z4 pixel accuracy, so the MP EG 2 motion vector must be doubled.
  • the scaling is performed by Predicted image data is supplied to computing units 1 1 and 1 8, and computing unit 1 1 supplies differential data (prediction error) between image data of macroblock i and predicted image data to DCT converter 1 2.
  • DCT converter 1 2 DCT converts the difference data
  • the data is supplied to the quantizer 1 3 (step S 107), and the quantizer 1 3 quantizes the supplied data in accordance with the set quantization coefficient, and the quantized data is converted into the variable length encoder 14 and This is supplied to the inverse quantizer 16 (step S 1 08).
  • step S 104 If it is determined in step S 104 that the picture is an intra-encoded picture, the image data of the macroblock i is transferred to the DCT converter 1 via the arithmetic unit 1 without executing steps S 1 05 and S 106. Supplied to 2. Therefore, in step S107, not the difference data but the image data of the macro block i is DCT transformed, and in step S108, the image data after the DCT transformation is quantized.
  • the inverse quantizer 16 dequantizes the quantized data supplied from the quantizer 13 according to the set quantization coefficient (step S 109), and the inverse DC T converter 17 is inversely quantized. The obtained data is further subjected to inverse DCT conversion and supplied to the arithmetic unit 18 (step S 1 1 0).
  • the arithmetic imager 18 is supplied with the predicted image data from the motion compensator 20 together with the inverse DCT conversion result data.
  • the arithmetic unit 18 adds the data and decodes the image data for each macro block. This decoded image data is stored in the frame memory 19 in units of frames in step S 114 described later, and is used as a reference image for encoding the image data of the next frame.
  • the variable length encoder 14 performs variable length encoding on the quantized data supplied from the quantizer 1 3 and the motion vector supplied from the motion vector holder 2 1, Output (Step S 1 1 1).
  • the buffer 1'5 holds the variable length data supplied from the variable length encoder 14 as H.264 encoded image data.
  • the counter value i is incremented by 1 (step S112).
  • the counter value i is 1 frame It is determined whether the number of blocks is smaller than n (step S 1 1 3). If i ⁇ n, the process returns to step S 1 03 and the encoding process for the next macroblock i is performed.
  • step S 114 the decoded image data for frame k is stored in frame memory 19 (step S 114).
  • the H.264 method quantization coefficient Q corresponding to the MPEG-2 method quantization coefficient G obtained by the decoding process is used. Is read and set for each macroblock from the quantization coefficient conversion table, and quantization is performed in the re-encoding process according to the quantization coefficient Q. Therefore, the quantization coefficient setting in the re-encoding process can be simplified. In addition, since the quantization coefficient Q of the H.264 system corresponding to the quantization coefficient G of the MP EG 2 system is set using the quantization coefficient conversion table, image quality degradation due to re-encoding of the H.264 system is reduced. Can be prevented.
  • the quantization coefficient is shown as the encoding coefficient used for encoding by the encoding means.
  • the present invention is not limited to this, and other coefficients used for encoding may be used. . .
  • image data encoded by the first encoding method is recovered.
  • Decoding means for generating decoded image data and detecting coding coefficients for each macroblock, and coding coefficients for the first coding method for each macroblock detected by the decoding means Coding coefficient conversion means for converting the image data into coding coefficients of the second coding method, and coding coefficients of the second coding method obtained by converting the decoded image data for each macroblock by the coding coefficient conversion means.

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Compression Or Coding Systems Of Tv Signals (AREA)

Abstract

L’invention concerne un dispositif et une méthode de conversion de méthode de codage d’image comprenant : un moyen de décodage pour générer des données image décodées en décodant des données image codées par une première méthode de codage et en détectant un coefficient de codage pour chaque macro bloc ; un moyen de conversion de coefficient de codage pour convertir le coefficient de codage de la première méthode de codage pour chaque macro bloc détecté par le moyen de décodage en un coefficient de codage d’une deuxième méthode de codage ; et un moyen de codage pour coder les données image décodées en utilisant le coefficient de codage de la deuxième méthode de codage converti par le moyen de conversion de coefficient de codage pour chaque macro bloc et générer des données image codées par la deuxième méthode de codage.
PCT/JP2006/304210 2005-03-03 2006-02-28 Dispositif et méthode de conversion de méthode de codage d’image WO2006093306A1 (fr)

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Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH07312756A (ja) * 1994-03-25 1995-11-28 Sanyo Electric Co Ltd 圧縮動画像符号信号の情報量変換回路、装置、及び方法
JPH0865663A (ja) * 1994-08-19 1996-03-08 Canon Inc ディジタル画像情報処理装置
JP2000508855A (ja) * 1996-04-12 2000-07-11 イメディア コーポレイション ビデオ・トランスコーダ
JP2000312362A (ja) * 1999-02-23 2000-11-07 Matsushita Electric Ind Co Ltd 画像符号化方式変換装置、画像符号化方式変換方法および記録媒体
JP2000312363A (ja) * 1999-02-25 2000-11-07 Matsushita Electric Ind Co Ltd 動画像符号化方式の変換方法及びその装置
JP2001268514A (ja) * 2000-03-17 2001-09-28 Matsushita Electric Ind Co Ltd 信号記録装置、信号記録方法、信号再生装置、信号再生方法、媒体、および情報集合体
JP2003006984A (ja) * 2001-06-26 2003-01-10 Sony Corp 信号処理装置および方法
WO2004054158A2 (fr) * 2002-12-10 2004-06-24 Tut Systems, Inc. Regulation de debit avec fenetre d'anticipation basee sur l'image

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH07312756A (ja) * 1994-03-25 1995-11-28 Sanyo Electric Co Ltd 圧縮動画像符号信号の情報量変換回路、装置、及び方法
JPH0865663A (ja) * 1994-08-19 1996-03-08 Canon Inc ディジタル画像情報処理装置
JP2000508855A (ja) * 1996-04-12 2000-07-11 イメディア コーポレイション ビデオ・トランスコーダ
JP2000312362A (ja) * 1999-02-23 2000-11-07 Matsushita Electric Ind Co Ltd 画像符号化方式変換装置、画像符号化方式変換方法および記録媒体
JP2000312363A (ja) * 1999-02-25 2000-11-07 Matsushita Electric Ind Co Ltd 動画像符号化方式の変換方法及びその装置
JP2001268514A (ja) * 2000-03-17 2001-09-28 Matsushita Electric Ind Co Ltd 信号記録装置、信号記録方法、信号再生装置、信号再生方法、媒体、および情報集合体
JP2003006984A (ja) * 2001-06-26 2003-01-10 Sony Corp 信号処理装置および方法
WO2004054158A2 (fr) * 2002-12-10 2004-06-24 Tut Systems, Inc. Regulation de debit avec fenetre d'anticipation basee sur l'image

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