WO2011099789A2 - Procédé et appareil de traitement de signaux vidéo - Google Patents

Procédé et appareil de traitement de signaux vidéo Download PDF

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WO2011099789A2
WO2011099789A2 PCT/KR2011/000893 KR2011000893W WO2011099789A2 WO 2011099789 A2 WO2011099789 A2 WO 2011099789A2 KR 2011000893 W KR2011000893 W KR 2011000893W WO 2011099789 A2 WO2011099789 A2 WO 2011099789A2
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transform
value
block
values
present
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WO2011099789A3 (fr
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김정선
박승욱
임재현
박준영
최영희
성재원
전병문
전용준
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엘지전자 주식회사
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    • 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
    • H04N19/48—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using compressed domain processing techniques other than decoding, e.g. modification of transform coefficients, variable length coding [VLC] data or run-length data
    • 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
    • H04N19/102—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or selection affected or controlled by the adaptive coding
    • H04N19/129—Scanning of coding units, e.g. zig-zag scan of transform coefficients or flexible macroblock ordering [FMO]
    • 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
    • H04N19/50—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding
    • H04N19/593—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding involving spatial prediction techniques

Definitions

  • the present invention relates to a method and apparatus for processing a video signal, and more particularly, to a video signal processing method and apparatus for encoding or decoding a video signal with high efficiency.
  • Compression coding refers to a series of signal processing techniques for transmitting digitized information through a communication line or for storing in a form suitable for a storage medium.
  • the object of compression encoding includes objects such as voice, video, text, and the like.
  • a technique of performing compression encoding on an image is called video image compression.
  • Compression coding on a video signal is performed by removing redundant information in consideration of spatial correlation, temporal correlation, and stochastic correlation.
  • more efficient video signal processing methods and apparatus are required.
  • the present invention was devised to solve the above requirements, and a method of processing a video signal according to the present invention is to propose a high-efficiency video encoding and decoding method.
  • the present invention proposes various methods and apparatuses for generating pseudo DC or virtual DC in performing a DC conversion step.
  • the present invention also proposes various methods and apparatuses for generating a pseudo DC or virtual DC in performing a DC conversion step including a skip mode.
  • the present invention also proposes a method and apparatus for determining an optimal kernel index value applied to a directional transform (DT).
  • DT directional transform
  • the present invention is to propose a method and apparatus for entropy coding the determined optimal kernel index (kernel index) value.
  • a video signal processing method includes a block encoding step of performing a block encoding transformation by dividing an input signal into blocks having a predetermined size, and performing a DC transformation process on a DC value generated after the block encoding transformation.
  • the method may further include performing a DC conversion step, wherein the DC conversion step determines the size of the DC conversion block, generates the required number of virtual DC values in the determined DC conversion block, and performs a DC conversion process. do.
  • the video signal processing method is to obtain the information on the virtual DC value used in the DC conversion process from the input signal, and performing an inverse DC conversion process from the obtained information It is characterized by.
  • the virtual DC value may be determined as an average value of existing DC values, or may be used by copying any one of the existing DC values.
  • the DC conversion step is also applicable to the skip mode.
  • the video signal processing method does not set a kernel index value to a fixed value when applying a Directional Transform (DT), and an optimal kernel index ( and calculating the kernel index) value.
  • DT Directional Transform
  • the determined optimal kernel index value may be entropy encoded and included in the bitstream.
  • the video signal processing method is characterized by reconstructing the entropy coded kernel index value and performing inverse direction transformation.
  • the present invention is characterized by providing an encoder device and a decoder device supporting the various exemplary methods of the present invention.
  • efficient image encoding and decoding are possible.
  • efficient DC conversion e.g., Hadamard transform
  • high efficiency direction conversion e.g., 'MDDT'
  • FIG. 1 schematically shows an encoder device applicable to the present invention.
  • FIG. 2 schematically shows a decoder device applicable to the present invention.
  • FIG. 3 is a table illustrating an example having an adaptive block size applied to a block encoding transformation according to an embodiment of the present invention.
  • 4 to 6 illustrate an example of a DC transform applied in block transform encoding according to an embodiment of the present invention.
  • FIG. 7 to 10 illustrate an example of a DC transform applied in block transform encoding according to another embodiment of the present invention.
  • 11 to 12 illustrate an example of a DC transform applied in block transform encoding according to another embodiment of the present invention.
  • FIG. 13 to 14 illustrate flowcharts of an encoding method applicable to a DT transform applied during block transform encoding, according to another embodiment of the present invention.
  • Coding may be interpreted as encoding or decoding in some cases, and information is a term including all values, parameters, coefficients, elements, and the like. As the meaning can be interpreted differently according to the present invention is not limited thereto.
  • the unit is used to mean a basic unit of image processing or a specific position of an image, and in some cases, the unit may be used interchangeably with terms such as a block or an area.
  • the encoding apparatus 100 of the present invention is largely composed of a transformer 110, a quantizer 115, an inverse quantizer 120, an inverse transformer 125, a filter 130, and a predictor ( 150 and the entropy coding unit 160.
  • the converter 110 obtains a transform coefficient value by converting a pixel value of an input video signal or a residual signal between the video signal and a motion predicted / compensated image.
  • a transform coefficient value for converting a pixel value of an input video signal or a residual signal between the video signal and a motion predicted / compensated image.
  • a Discrete Cosine Transform or a Hadamard Transform or Directional Transform (DT) (e.g., a Mode Dependent Directional Transform (MDDT)) or Wavelet Transform. Transform
  • DT e.g., a Mode Dependent Directional Transform (MDDT)
  • Wavelet Transform. Transform e.g., Wavelet Transform. Transform
  • DCT Discrete Cosine Transform
  • DCT is widely used as a type of block encoding technique for performing frequency transformation by dividing an input image signal into blocks having a predetermined size.
  • the frequency component generated after the discrete cosine transform (DCT) (also referred to as a 'DCT coefficient') is mainly distributed in the low frequency region (eg, the upper left of the block), and the component having the largest DCT coefficient value This is called a direct current component (hereinafter referred to as a 'DC value').
  • a direct current component hereinafter referred to as a 'DC value'.
  • a method of increasing coding efficiency by performing the 'DC transformation' for example, a Hadamard transform
  • a coding method using the 'DC transform' (for example, a Hadamard transform) will be described later in detail with reference to FIGS. 4 to 12.
  • the direction transform (DT: for example, 'MDDT') will be described later in detail with reference to FIGS. 13 to 14.
  • the quantization unit 115 quantizes the transform coefficient value output from the transform unit 110.
  • the inverse quantization unit 120 inverse quantizes the transform coefficient value, and the inverse transform unit 125 restores the original pixel value by using the inverse quantized transform coefficient value.
  • the filtering unit 130 performs a filtering operation for improving the quality of the reconstructed image.
  • a deblocking filter and / or an adaptive loop filter may be included.
  • the filtered image is stored in the frame storage unit 156 for output or use as a reference image.
  • a method of predicting an image by using an already coded region and adding a residual value between the original image and the predicted image to a reconstructed image is used instead of coding the image signal as it is.
  • the intra predictor 152 performs intra prediction within the current image
  • the inter predictor 154 predicts the current image using at least one reference image stored in the frame storage 156.
  • the intra predictor 152 performs the intra prediction from the reconstructed regions in the current image and transmits the intra encoding information to the entropy coding unit 160.
  • the inter predictor 154 may further include a motion compensator 162 and a motion estimator 164.
  • the motion estimator 164 acquires a motion vector value of a region to be currently encoded by using reference images stored in the frame storage.
  • the motion estimator 164 transmits the position information (reference frame, motion vector, etc.) of the reference region to the entropy coding unit 160 so that the motion estimation unit 164 may be included in the bitstream.
  • the motion compensator 162 performs inter-screen motion compensation by using the motion vector value transmitted from the motion estimator 164.
  • the entropy coding unit 160 entropy codes the quantized transform coefficients, inter picture encoding information, intra picture encoding information, and reference region information input from the inter prediction unit 154 to generate a video signal bitstream.
  • the entropy coding unit 160 may use a variable length coding (VLC) method, arithmetic coding, or the like.
  • VLC variable length coding
  • the variable length coding (VLC) scheme converts input symbols into consecutive codewords, which may have a variable length. For example, symbols that occur frequently are represented by short codewords and symbols that do not occur frequently by long codewords.
  • a context-based adaptive variable length coding (CAVLC) method may be used as a variable length coding method.
  • Arithmetic coding converts consecutive data symbols into a single prime number, which arithmetic coding can obtain the optimal fractional bits needed to represent each symbol.
  • Context-based Adaptive Binary Arithmetic Code (CABAC) may be used as arithmetic coding.
  • the decoding apparatus 200 of the present invention largely includes an entropy decoding unit 210, an inverse quantization unit 220, an inverse transform unit 225, a filtering unit 230, and a prediction unit 250.
  • the entropy decoding unit 210 entropy decodes the video signal bitstream and extracts a coding type, transform coefficients for each region, a motion vector, and the like.
  • the inverse quantization unit 220 inverse quantizes the entropy decoded transform coefficient, and the inverse transform unit 225 restores the original pixel value by using the inverse quantized transform coefficient.
  • the inverse transform unit 225 is characterized in that the inverse process of the block transform method shown in Figures 3 to 12 to be described later.
  • the predictor 250 includes an intra predictor 252 and an inter predictor 254, and includes an encoding type decoded by the entropy decoder 210 described above, transform coefficients for each region, a motion vector, and the like. The predicted image is reconstructed using the information of.
  • the intra prediction unit 252 generates the intra prediction image from the decoded sample in the current image.
  • the inter prediction unit 254 generates a prediction image using the reference image stored in the frame storage unit 256.
  • the reconstructed video frame is generated by adding the pixel value output from the inverse transformer 225 to the predicted image output from the intra predictor 252 or the inter predictor 254.
  • the filtering unit 230 performs filtering on the restored video frame to improve the image quality. This may include a deblocking filter for reducing block distortion and an adaptive loop filter for removing distortion of the entire image.
  • the filtered image is output as the final image and stored in the frame storage unit 256 for use as a reference image for the next frame.
  • an embodiment of the present invention is to provide an efficient block coding scheme in consideration of the characteristics of the image and the characteristics of the input signal in the above-described transform unit 110 and inverse transform unit (125, 225).
  • FIG. 3 is a table illustrating an example having an adaptive block size applied to a block encoding transform according to an embodiment of the present invention.
  • 3 (a) shows an example of an intra picture encoding (or an intra mode)
  • FIG. 3 (b) shows an inter picture encoding (or an inter mode). ) Is shown as an example.
  • an embodiment of the present invention is characterized in that the coding of the color difference component corresponding to the block size of the luminance component can be more efficiently performed.
  • a block size of chroma components corresponding to a block size applied to luma components is adaptively changed in intra picture encoding.
  • the DCT block size of the chrominance component is set to '4 x 4' (302a), or the block size of the luminance component is '8 x 8'.
  • the DCT block size of the chrominance component is '8 x 8' (302b), or if the block size for the luminance component is '16 x 16 ', the DCT block size of the chrominance component is '16 x 16' (302c), If the block size of the luminance component is '32 x 32 ', the coding scheme 302d is set to make the DCT block size of the chrominance component '16 x 16'.
  • a block size of chroma components corresponding to a block size applied to luma components in inter-screen encoding is adaptively changed.
  • the DCT block size of the color difference component is set to '4 x 4' (312a), or the luminance component.
  • the DCT block size of the chrominance component is set to' 4 x 4 '(312b), or the block size for the luminance component is' 32 x 16 ',' 16 x 32 ',' 16 x 16 ', the DCT block size of the chrominance component is set to' 8 x 8 '(312c), or the block size for the luminance component is '64 x 64', '
  • a coding scheme 312d having a DCT block size of a chrominance component of '16 x 16' is proposed.
  • Tables (a) and (b) shown in FIG. 3 are merely examples of examples proposed in the embodiments of the present invention, and embodiments of the present invention are not necessarily limited to numerical values presented. That is, an embodiment of the present invention is characterized in that the block size of the color difference component can be adaptively changed corresponding to the block size of the luminance component.
  • DC transform eg, Hamadad transform
  • the DC transform according to the present invention can be applied to other transform schemes in addition to the hammad transform.
  • the Hamidard transform is a simple orthogonal transformation using only addition and subtraction, and is also called a Discrete Hamadard Transform (DHT) under another name.
  • DHT Discrete Hamadard Transform
  • FIGS. 4 to 6 illustrate an example of a DC transform applied in block transform encoding according to an embodiment of the present invention. That is, the embodiments of FIGS. 4 to 6 are characterized in that the block sizes of DC transforms are differently determined according to the sizes of the DCT transformed blocks.
  • the DCT block size of the color difference signal according to the present invention is set to '4 ⁇ 4', when the table of FIG. 3 (a) or (b) is used.
  • the block size for the DC transform can also be applied in various ways.
  • FIG. 4A illustrates a macro block 400 having pixels (pixels) and line number '16 x 16 ', and a block size having pixels (pixels) and line number' 4 x 4 '.
  • An example of dividing into 16 sub-blocks 401 to 416 having a structure is illustrated. DCT conversion is performed for each of the '4 x 4' sized sub-blocks 401 to 416, and as described above, a DC value is generated as a DC component on the upper left of each DCT block. Therefore, a total of 16 DC values are generated in the 16 ⁇ 16 macroblock 400. Subsequently, in order to increase coding efficiency, only 16 DC values are collected to perform a separate DC transform. In this case, the size of the DC transform block is a 4 ⁇ 4 block size as shown in FIG. Have.
  • FIG. 5A illustrates a macro block 500 having a pixel (pixel) and line number '16 x 16 ', and a block size having a pixel (pixel) and line number' 8 x 8 '.
  • a DCT value is provided as a DC component on the upper left of each DCT block. Therefore, a total of four DC values are generated in the 16 ⁇ 16 macroblock 500. Subsequently, in order to increase coding efficiency, only four DC values are collected and a separate DC transform is performed. In this case, the size of the DC transform block is a '2 x 2' block size as shown in FIG. Have.
  • FIG. 6 (a) shows a pixel block and a macro block 600 having a line count of '16 x 16 'as a '16 x 16' block size without dividing into additional sub blocks.
  • the case where DCT conversion is performed is shown. Accordingly, a total of one DC value (eg, DC [0] [0]) is generated in the 16 ⁇ 16 macroblock 500, and in this case, a separate DC transform is not performed (FIG. 5 (b)).
  • DC transform for example, when applying the above-described Hammad transform (hamadard transform) can be applied to the following transform equation. In this case, two orthogonal transformations are performed across rows and columns.
  • the '2 x 2' Hamidard transform and the '4 x 4' Hamard transform are presented as an example and the present invention is not limited thereto.
  • the '2 x 2' and the '4 x 4' hammad transform (example) will be equally applicable to all DC transformation methods to be described later.
  • 7 shows an example of a DC conversion scheme according to another embodiment of the present invention.
  • 7 illustrates a case in which different sized sub blocks (eg, '4 x 4', '8 x 8') exist in a macro block 700 having a size of '16 x 16 '. . That is, for example, according to FIG. 7A, a total of 12 '4 x 4' subblocks 701 to 712 in which DCT transformation is performed are performed in the macro block 700 having a size of 16 x 16. It can be seen that there is also one '8 x 8' subblock 713. Therefore, a total of 13 DC values exist.
  • different sized sub blocks eg, '4 x 4', '8 x 8'
  • FIG. 7 (b) illustrates a method of generating three '2 x 2' DC transform blocks as an embodiment of performing DC transformation on the macro block 700 encoded as shown in FIG. will be. That is, for example, a first '2 x 2' DC conversion block with each DC value generated by blocks 701, 702, 703, and 704 having a size of '4 x 4' among the subblocks of FIG. 7 (a). 721 is generated, and a second '2 x 2' DC conversion block 722 is generated using the respective DC values generated by the blocks 705, 706, 707, and 708, and further, 709, 710, 711, A third '2 ⁇ 2' DC conversion block 722 is generated with each DC value generated by the 712 block. However, a separate DC conversion is not performed on the DC value 713a generated by the subblock 713 having the size of '8 ⁇ 8' among the subblocks of FIG.
  • 8 shows an example of a DC conversion scheme according to another embodiment of the present invention.
  • 8 illustrates a case in which different sizes of sub blocks (eg, '4 x 4' and '8 x 8') exist in a macro block 800 having a size of '16 x 16 '. . That is, for example, according to FIG. 8 (a), a total of eight '4 x 4' subblocks 801 to 808 in which DCT conversion is performed in the macro block 800 having a size of '16 x 16 'are performed. It can be seen that there are two '8 ⁇ 8' subblocks 809 and 810. Therefore, 10 DC values exist in total.
  • FIG. 8 (b) illustrates a method of generating three '2 ⁇ 2' DC transform blocks as an embodiment of performing DC transformation on the macro block 800 encoded as shown in FIG. 8 (a).
  • a first '2 x 2' DC conversion block with each DC value generated by blocks 801, 802, 803, and 804 having a size of '4 x 4' among the sub blocks of FIG. 8 (a).
  • the third '2 x 2' DC by utilizing the DC values 809a and 810a generated by the sub blocks 809 and 810 having the size of '8 x 8' among the sub blocks of FIG. 8 (a).
  • the required DC values are four, whereas only two DC values exist (809a, 810a).
  • the virtual value is determined. This is called a pseudo DC coefficient (or 'virtual DC coefficients') and will be briefly referred to as 'DCp'.
  • the two DCp values may be determined as, for example, an average value of existing DC values 809a and 810a.
  • the DCp value may be determined in various ways such as an intermediate value, a minimum value, and a maximum value, not an average value. This will be described in more detail with reference to FIG. 10. It is also possible to determine the two DCp values as different values rather than the same values.
  • the third '2 x 2' The position of the existing DC values 809a and 810a in the DC conversion block 823 may be determined from the position of the DC values in the original macro block 800.
  • the positions of the '8 x 8' sub-blocks 809 and 810 are located at the upper right and lower left of the macro block 800, respectively, so that the positions of the corresponding DC values 809a and 810a are also represented.
  • 3 may be positioned at the upper right and lower left, respectively, in the '2 x 2' DC conversion block 823. Therefore, the newly generated DCp values will be located at the upper left and lower right, respectively.
  • 9 shows an example of a DC conversion scheme according to another embodiment of the present invention.
  • 9 illustrates a case in which different sized sub-blocks (eg, '4 x 4', '8 x 8') exist in the macro block 900 having a size of '16 x 16 '. . That is, for example, according to FIG. 9 (a), a total of eight '4 x 4' subblocks 901 to 908 in which DCT conversion is performed in the macro block 900 having a size of '16 x 16 'are performed. It can be seen that there are two '8 x 8' subblocks 909 and 910. Therefore, 10 DC values exist in total.
  • FIG. 9B illustrates an embodiment of performing DC conversion on the macroblock 900 encoded as shown in FIG. 9A.
  • the method of generating one '4 ⁇ 4' DC conversion block 921 is illustrated in FIG. It is shown. That is, for example, the '4 x 4' DC conversion block (for each DC value generated by blocks 901, 902, 903, and 904 having a size of '4 x 4' in the sub-blocks of FIG. 9 (a)).
  • the lower right portion 932 of the '4 x 4' DC conversion block 921 is generated.
  • the '4 x 4' DC conversion is performed by utilizing the DC values 909a and 910a generated by the sub blocks 909 and 910 having the size of '8 x 8' among the sub blocks of FIG. 9 (a).
  • the remaining portions 933 and 934 of block 921 will be generated. That is, in generating the remaining portions 933 and 934 of the '4 x 4' DC conversion block 921, the required DC values are eight, whereas only two DC values exist (909a and 910a).
  • the remaining six DC values are determined by the aforementioned 'DCp' value. In relation to the above, the six DCp values may be determined as, for example, an average value of existing DC values 909a and 910a.
  • the DCp value may be determined in various ways such as an intermediate value, a minimum value, and a maximum value, not an average value. This will be described in more detail with reference to FIG. 10. It is also possible to determine the six DCp values as different values from each other instead of the same values.
  • the existing DC in the block 921 is generated.
  • the location of the values 909a and 910a may be determined from the location of the DC value in the original macro block 900.
  • the positions of the '8 x 8' sub-blocks 909 and 910 are located at the upper right and lower left of the macro block 900, respectively, so that the position of the corresponding DC values 909a and 910a is'
  • the upper right position in the upper right portion 933 in the 4 x 4 'DC conversion block 921 and the lower left position in the lower left portion 934 may be determined, respectively.
  • the remaining positions of the portions 933 and 934 except for the DC values 909a and 910a are generated as DCp values.
  • FIG. 10 illustrates, by way of example, various schemes for determining the aforementioned DCp value.
  • FIG. 10 (a) illustrates a method of determining a DCp value as an average value of DC values of a sub block having a size of '8 ⁇ 8'. That is, it is the same as the method applied for example in Figs. 8 (b) and 9 (b) described above.
  • FIG. 10 (b) illustrates a method of determining a DCp value by duplication of a DC value of a sub block having a size of '8 ⁇ 8' as it is.
  • three DCp values applied in the upper right portion 933 in the aforementioned '4 x 4' DC conversion block 921 are Both may be determined to be the same value as the present DC value 909a in the corresponding portion 933, that is, DC [1] [0] [0].
  • all three DCp values applied in the lower left portion 934 in the aforementioned '4 x 4' DC conversion block 921 are all present DC values 910a in the portion 934, ie, DC [2] [ 0] [0]).
  • FIG. 10 (c) illustrates a method of determining a DCp value as an average value of all DC values existing in a '16 ⁇ 16 'macro block.
  • the existing DC values Fig. In 9 (b)
  • FIG. 10 (d) shows a method of determining a DCp value as an average value of all DC values existing in a '16 x 16 'macro block, but giving a weight to a' 8 x 8 'size DC value.
  • DC values generated from a DCT transform of a '4 x 4' block size eg DC values present in the areas 931 and 932 have no weight, but are generated from a DCT transform of an '8 x 8' block size.
  • DC values for example, 909a and 910a
  • the total number of dividing should be '16'.
  • FIG. 11 shows an example of a DC conversion method according to another embodiment of the present invention.
  • the embodiment of FIG. 11 relates to a case in which a skipped sub-block, which is skipped by a skip mode, exists in a macro block 1100 having a size of '16 ⁇ 16 '.
  • a total of 12 '4 x 4' subblocks 1101 to 1112 in which DCT transformation is performed are performed in the '16 x 16 'macro block 1100. It can be seen that there exists one subblock 1113 of the size '8 ⁇ 8' that is also skipped.
  • FIG. 11 (b) illustrates an embodiment of performing DC conversion on the macro block 1100 encoded as shown in FIG. 11 (a).
  • the upper left portion 1131 of 1121 is generated, and each DC value generated by blocks 1105, 1106, 1107, and 1108 having a size of '4 ⁇ 4' among the subblocks of FIG.
  • Blocks 1109, 1110, 1111, and 1112 which generate a lower left portion 1132 of the '4 x 4' DC conversion block 1121 and have a '4 x 4' size among the subblocks of FIG.
  • the lower right portion 1133 of the '4 x 4' DC conversion block 1121 is generated with each DC value generated by.
  • the upper right portion 1134 of the remaining '4 x 4' DC conversion block 1121 is generated by replacing the DCp value as described above.
  • the method of generating the DCp value it may be determined by the method 1141 to obtain the average value of all DC values existing in the current macro block 1100, as in the method of FIG. 10 (c) described above.
  • FIG. 12 illustrates a case of applying a different DCp value 1210 in determining the DCp value in the above-described embodiment of FIG. 11. That is, for example, instead of uniformly applying the same DCp value as in FIG. 11 (b), it is possible to apply differently to the characteristics of each DCp position.
  • 'DCp1' is determined as an average value of four DC values present in the upper left portion 1131 of the '4 x 4' DC conversion block 1121
  • 'DCp3' is '4 x 4'.
  • 'DCp4' is the lower right portion 1133 of the '4 x 4' DC conversion block 1121.
  • the average value of the four DC values present at is determined as, and the last 'DCp2' may be determined as the average value of the obtained DCp1, DCp3, Dcp4.
  • FIG. 13 is a flowchart illustrating a method of determining an optimal kernel index value applied to a Mode Dependent Directional Transform (MDDT) transformation method, which is a type of Directional Transform (DT).
  • MDDT Mode Dependent Directional Transform
  • DT Directional Transform
  • 14 is a flowchart illustrating a method of entropy encoding the determined kernel index.
  • the MDDT transformation scheme is particularly applicable to a method for encoding transformation of a residual generated during intra prediction.
  • the MDDT The transformation method independently defines transform matrices applied to the individual intra prediction modes, and then applies the transformations to perform encoding transformation. This has the advantage that the input image can be encoded more easily when the input image does not simply have vertical or horizontal edge characteristics, but has various edges such as diagonal lines, parabolas, and circles. .
  • a kernel index value is separately defined.
  • the kernel index value adjusts a transform matrices value applied to the MDDT to adjust a frequency of generation of non-zero high frequency domain components.
  • bit-rates bit-rates
  • degree of distortion when applying the MDDT transformation according to the kernel index value.
  • an embodiment of the present invention is characterized in that the optimum kernel index value is determined without setting the above-described kernel index value to a fixed value.
  • it is characterized in that the entropy encoding of the determined kernel index (kernel index) value.
  • the determined optimal The prediction mode k and the optimal kernel index i are entropy coded and included in the bitstream for transmission.
  • the decoder receiving the bitstream restores the optimal prediction mode (k) and the optimal kernel index (k) index value through entropy decoding, and applies the already-programmed and stored MDDT-transform matrix to perform MDDT conversion. The block can be restored.
  • a residual value is generated by a specific prediction mode k (S101 and S102).
  • an RD-cost 'rdcost' is obtained by applying the above-described step S1031 to a specific kernel index value 'i' among a plurality of kernel index values, and the obtained 'rdcost' The value is compared with the minimum RD-cost value obtained before (this is called 'min_rdcost_i') (S1032).
  • the new 'rdcost' value is smaller than the existing 'min_rdcost_i', the 'rdcost' value is set to a new 'min_rdcost_i' (S1033), and the steps S1031, S1032 and S1033. Is repeated until all kernel index values have been applied.
  • the comparison result of step S1032 when the new 'rdcost' value has a larger value than the existing 'min_rdcost_i', the index value is changed to the next index value without changing the existing 'min_rdcost_i' (S1034). The new kernel index value will be applied.
  • a new RD-cost ('rdcost') to which a new kernel index value is applied is generated by applying the above-described step S1031, and the step S1032 is repeated.
  • step S1035 it is checked whether the above process is completed for all kernel index values, and if the application is not completed for all kernel index values, the index value is changed (S1034) to generate a new kernel index value. Thereafter, the process of generating a new RD-coast ('rdcost') to which the new kernel index value is applied in step S1031 is repeated.
  • the kernel index value i having the minimum RD-cost value 'min_rdcost_i' stored in step S1033 is determined in the prediction mode k.
  • the optimal kernel index value is determined, and the minimum RD-cost value 'min_rdcost_i' corresponding to the determined kernel index value is compared with values in the next prediction mode (S104).
  • step S104 the new minimum RD-cost value 'min_rdcost_i' to which the optimal kernel index value is applied in the specific prediction mode determined in step S103 is used, and the existing minimum RD-cost value generated in another existing prediction mode (this is 'min_rdcost'). Step). If the new 'min_rdcost_i' value is smaller than the existing 'min_rdcost' as a result of the comparison in step S104, the 'min_rdcost_i' value is set as a new 'min_rdcost' (S105). Step S103 is repeated until all of the prediction modes are applied.
  • step S104 when the new 'min_rdcost_i' value has a larger value than the existing 'min_rdcost', without changing the existing 'min_rdcost', it is changed to the next prediction mode (S107) Steps S102 and S103 are repeated.
  • step S106 it is checked whether the application is completed for all prediction modes, and if the application is not completed for all prediction modes, the prediction mode is changed (S107) to the steps S101, S102, Step S103 is repeated. In addition, if the application is completed for all prediction modes in step S106, the entropy encoding of the finally determined prediction mode 'k' (prediction mode k) and the kernel index value 'i' (kernel index i) in the corresponding mode is performed. (S108)
  • FIG. 13 Each step of FIG. 13 is provided as an example for convenience of description, and it will be apparent that each of the steps may have various application processes. That is, the present invention is not limited only to the flowchart of FIG.
  • FIG. 14 is a flowchart illustrating a method of entropy coding a kernel index value, in particular in the step S108.
  • an MPI (Most Probable Index, hereinafter referred to as 'MPI') is determined (S201). For example, the intra prediction mode of the coding block may be set to the MPI. Thereafter, whether the kernel index value to be entropy coded is equal to the MPI is compared (S202). If the kernel index value to be entropy coded is equal to the MPI, the corresponding kernel index value is '1'. Entropy coding with (S203). If the kernel index value to be entropy coded differs from the MPI, the kernel index value is set to '0' (S204), and the subsequent remaining steps are performed.
  • Step S205 is a step of checking the difference between the kernel index value and the MPI value. Therefore, if the kernel index value is smaller than the MPI value, entropy coding is performed without modification of the kernel index value (S207). However, if the kernel index value is greater than the MPI value, the kernel index value is subtracted by '1' (S206), and then entropy coding is performed (S207).
  • the decoder receiving the entropy coded bitstream restores the optimal prediction mode (k) and the optimal kernel index (i) value through entropy decoding and utilizes the MDDT transformed block. Can be restored.
  • the image encoding method applied to the present invention may be produced as a program for execution on a computer and stored in a computer-readable recording medium.
  • the computer readable recording medium includes all kinds of storage devices in which data that can be read by a computer system is stored. Examples of computer-readable recording media include ROM, RAM, CD-ROM, magnetic tape, floppy disk, optical data storage, and the like, and may also be implemented in the form of a carrier wave (for example, transmission over the Internet). Include.
  • the bitstream generated by the encoding method to which the present invention is applied may be stored in a computer-readable recording medium or transmitted using a wired / wireless communication network.
  • the present invention can be applied to an encoder device and a decoder device for efficient video encoding.
  • the present invention has been described by way of limited embodiments and drawings, the present invention is not limited thereto and is intended by those skilled in the art to which the present invention pertains, and claims to be described below. Various modifications and variations may be made within the scope of equivalents of the scope.

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Abstract

La présente invention concerne un procédé et un appareil de traitement de signaux vidéo. Le procédé de traitement de signaux vidéo selon un mode de réalisation de la présente invention comporte : une étape de codage par blocs, où un signal d'entrée est d'abord fractionné en blocs d'une taille prédéterminée et soumis à un codage par blocs ; et une étape de transformée DC, où un processus de transformée DC est réalisé sur une valeur générée après le codage par blocs, l'étape de transformée DC comportant les étapes consistant à déterminer la taille d'un bloc de transformée DC et à générer un nombre donné de valeurs DC virtuelles nécessaires pour le bloc de transformée DC qui a été déterminé. Au moyen de divers modes de réalisation proposés dans la présente invention, le codage et le décodage d'images peuvent être effectués de manière efficiente. Par exemple, l'utilisation de valeurs DC virtuelles accroît le rendement de la transformée DC (par ex. une transformée de Hadamard), et un indice de noyau optimal obtenu autorise une transformée directionnelle à haut rendement (par ex. une MDDT).
PCT/KR2011/000893 2010-02-10 2011-02-10 Procédé et appareil de traitement de signaux vidéo WO2011099789A2 (fr)

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