# US 10,123,025 B2 · Coding of significance maps and transform coefficient blocks > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,123,025 B2 - Document ID: US10123025B2 - Status: Granted - Kind: B2 - Application number: 15/940,820 - Filed: 2018-03-29 - Published: 2018-08-02 - Granted: 2018-11-06 - Earliest claimed: 2010-04-13 - Assignees: Ge Video Compression, LLC - Applicants: GE Video Compression, LLC - Inventors: Heiner Kirchhoffer; Heiko Schwarz; Tung Nguyen; Detlev Marpe; Thomas Wiegand - Web page: https://patentgrep.com/patent/US10123025B2 ## CPC - H04N 19/18: the unit being a set of transform coefficients - H04N 19/124: Quantisation - H04N 19/129: Scanning of coding units, e.g. zig-zag scan of transform coefficients or flexible macroblock ordering [FMO] - H04N 19/13: Adaptive entropy coding, e.g. adaptive variable length coding [AVLC] or context adaptive binary arithmetic coding [CABAC] - H04N 19/136: Incoming video signal characteristics or properties - H04N 19/139: Analysis of motion vectors, e.g. their magnitude, direction, variance or reliability - H04N 19/176: the region being a block, e.g. a macroblock - H04N 19/46: Embedding additional information in the video signal during the compression process (H04N19/517, H04N19/68, H04N19/70 take precedence) - H04N 19/50: using predictive coding (H04N19/61 takes precedence) - H04N 19/51: Motion estimation or motion compensation - H04N 19/59: involving spatial sub-sampling or interpolation, e.g. alteration of picture size or resolution - H04N 19/61: in combination with predictive coding - H04N 19/70: characterised by syntax aspects related to video coding, e.g. related to compression standards - H04N 19/91: Entropy coding, e.g. variable length coding [VLC] or arithmetic coding - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract A higher coding efficiency for coding a significance map indicating positions of significant transform coefficients within a transform coefficient block is achieved by the scan order by which the sequentially extracted syntax elements indicating, for associated positions within the transform coefficient block, as to whether at the respective position a significant or insignificant transform coefficient is situated, are sequentially associated to the positions of the transform coefficient block, among the positions of the transform coefficient block depends on the positions of the significant transform coefficients indicated by previously associated syntax elements. Alternatively, the first-type elements may be context-adaptively entropy decoded using contexts which are individually selected for each of the syntax elements dependent on a number of significant transform coefficients in a neighborhood of the respective syntax element, indicated as being significant by any of the preceding syntax elements. ## Claims ### Claim 1 An apparatus for decoding a significance map encoded in a data stream, wherein the significance map indicates positions of significant transform coefficients within a transform coefficient block, the apparatus comprising: a decoder configured to extract first-type syntax elements from the data stream, wherein each of the first-type syntax elements at least indicates, for an associated position within the transform coefficient block, whether a significant transform coefficient is present; and an associator configured to associate each of the extracted first-type syntax elements with a respective associated position within the transform coefficient block in a scan order, wherein the scan order is determined with respect to the transform coefficient block and based on prior positions of significant transform coefficients indicated by prior first-type syntax elements previously extracted. ### Claim 2 (depends on 1) The apparatus according to claim 1, wherein the decoder is further configured to determine, based on information extracted from the data stream and independent of a statistic associated with insignificant transform coefficients, whether at a current position having a significant transform coefficient is where a last significant transform coefficient is in the transform coefficient block. ### Claim 3 (depends on 1) The apparatus according to claim 1, wherein the decoder is further configured to extract, from the data stream with respect to a current position of the transform coefficient block, a second-type syntax element indicating whether the current position is where the last significant transform coefficient is in the transform coefficient block. ### Claim 4 (depends on 1) The apparatus according to claim 1, wherein the decoder is further configured to extract from the data stream, subsequent to extraction of at least one of the first-type syntax elements, information related to the significant transform coefficients within the transform coefficient block, wherein the associator is configured to associate the extracted significant transform coefficients with their respective positions in the transform coefficient block in a coefficient scan order, by which the transform coefficient block is scanned in sub-blocks of the transform coefficient block in accordance with a sub-block scan order, and the transform coefficients within the sub-blocks are scanned in a position sub-scan order. ### Claim 5 (depends on 1) The apparatus according to claim 1, wherein the decoder is configured to extract the first-type syntax elements based on context-adaptive entropy decoding using contexts selected for the first-type syntax elements, wherein a context for a current first-type syntax element being decoded is determined based on a number of positions, in a neighborhood with respect to the position of the current first-type syntax element, that are associated with significant transform coefficients indicated by prior first-type syntax elements previously extracted. ### Claim 6 (depends on 5) The apparatus according to claim 5, wherein the neighborhood comprises at least one position horizontally and/or vertically adjacent to the current first-type syntax element. ### Claim 7 (depends on 5) The apparatus according to claim 5, wherein the decoder is further configured to map the number of positions to a context index pointing to a set of possible context indices. ### Claim 8 (depends on 1) The apparatus according to claim 1, wherein the associator is further configured to associate the extracted first-type syntax elements with positions of the transform coefficient block along a sequence of sub-paths wherein the sub-paths are located at positions having increasing distances from a position of the lowest frequency in both the vertical and horizontal directions, and wherein the associator is configured to determine a direction of each of the sub-paths, along which the extracted first-type syntax elements are associated with the positions of the transform coefficient block, based on a number of positions of the significant transform coefficients along a previous sub-path. ### Claim 9 (depends on 1) The apparatus according to claim 1, wherein the data stream comprises at least a portion associated with color samples. ### Claim 10 (depends on 1) The apparatus according to claim 1, wherein the data stream comprises at least a portion associated with depth values related to a depth map. ### Claim 11 A method for decoding a significance map encoded in a data stream, wherein the significance map indicates positions of significant transform coefficients within a transform coefficient block, the method comprising: extracting first-type syntax elements from the data stream, wherein each of the first-type syntax elements at least indicates, for an associated position within the transform coefficient block, whether a significant transform coefficient is present; and associating each of the extracted first-type syntax elements with a respective associated position within the transform coefficient block in a scan order, wherein the scan order is determined with respect to the transform coefficient block and based on prior positions of significant transform coefficients indicated by prior first-type syntax elements previously extracted. ### Claim 12 (depends on 11) The method according to claim 11, further comprising determining, based on information extracted from the data stream and independent of a statistic associated with insignificant transform coefficients, whether at a current position having a significant transform coefficient is where a last significant transform coefficient is in the transform coefficient block. ### Claim 13 (depends on 11) The method according to claim 11, further comprising extracting, from the data stream, with respect to a current position of the transform coefficient block, a second-type syntax element indicating whether the current position is where the last significant transform coefficient is in the transform coefficient block. ### Claim 14 (depends on 11) The method according to claim 11, wherein the data stream comprises at least a portion associated with color samples. ### Claim 15 (depends on 11) The method according to claim 11, wherein the data stream comprises at least a portion associated with depth values related to a depth map. ### Claim 16 (depends on 11) The method according to claim 11, further comprising extracting from the data stream, subsequent to extraction of at least one of the first-type syntax elements, information related to the significant transform coefficients within the transform coefficient block; and associating the extracted significant transform coefficients with their respective positions in the transform coefficient block in a coefficient scan order, by which the transform coefficient block is scanned in sub-blocks of the transform coefficient block in accordance with a sub-block scan order, and the transform coefficients within the sub-blocks are scanned in a position sub-scan order. ### Claim 17 (depends on 11) The method according to claim 11, further comprising extracting the first-type syntax elements based on context-adaptive entropy decoding using contexts selected for the first-type syntax elements, wherein a context for a current first-type syntax element being decoded is determined based on a number of positions, in a neighborhood with respect to the position of the current first-type syntax element, that are associated with significant transform coefficients indicated by prior first-type syntax elements previously extracted. ### Claim 18 (depends on 17) The method according to claim 17, wherein the neighborhood comprises at least one position horizontally and/or vertically adjacent to the current first-type syntax element. ### Claim 19 (depends on 17) The method according to claim 17, further comprising mapping the number of positions to a context index pointing to a set of possible context indices. ### Claim 20 (depends on 11) The method according to claim 11, further comprising associating the extracted first-type syntax elements with positions of the transform coefficient block along a sequence of sub-paths wherein the sub-paths are located at positions having increasing distances from a position of the lowest frequency in both the vertical and horizontal directions; and Determining a direction of each of the sub-paths, along which the extracted first-type syntax elements are associated with the positions of the transform coefficient block, based on a number of positions of the significant transform coefficients along a previous sub-path. ### Claim 21 An apparatus for encoding a significance map indicating positions of significant transform coefficients within a transform coefficient block into a data stream, wherein the apparatus is configured to code first-type syntax elements into the data stream by entropy encoding, wherein each of the first-type syntax elements at least indicates, for an associated position within the transform coefficient block, whether a significant transform coefficient is present, the apparatus being configured to code each of the first-type syntax elements with a respective associated position within the transform coefficient block in a scan order, wherein the scan order is determined with respect to the transform coefficient block and based on prior positions of significant transform coefficients indicated by prior first-type syntax elements previously encoded. ### Claim 22 (depends on 21) The apparatus according to claim 21, wherein the apparatus is further configured to code, independent of a statistic of insignificant transform coefficients, whether at a current position associated with a significant transform coefficient a last significant transform coefficient in the transform coefficient block is situated. ### Claim 23 (depends on 21) The apparatus according to claim 21, wherein the apparatus is further configured to code, with respect to a current position of the transform coefficient block, a second-type syntax element indicating whether the current position is where the last significant transform coefficient is in the transform coefficient block. ### Claim 24 (depends on 21) The apparatus according to claim 21, wherein the data stream comprises at least a portion associated with color samples. ### Claim 25 (depends on 21) The apparatus according to claim 21, wherein the data stream comprises at least a portion associated with depth values related to a depth map. ### Claim 26 A non-transitory computer-readable medium for storing data associated with a video, comprising: a data stream stored in the non-transitory computer-readable medium, the data stream comprising therein an encoded significance map indicating positions of significant transform coefficients within a transform coefficient block, wherein first-type syntax elements are coded into the data stream by entropy encoding, the first-type syntax elements at least indicating, for an associated position within the transform coefficient block, whether a significant transform coefficient is present, wherein each of the first-type syntax elements with a respective associated position within the transform coefficient block is coded in a scan order, the scan order being determined with respect to the transform coefficient block and based on prior positions of significant transform coefficients indicated by prior first-type syntax elements previously encoded. ### Claim 27 (depends on 26) The computer-readable medium according to claim 26, further comprising encoded information indicating, independent of a statistic of insignificant transform coefficients, whether at a current position associated with a significant transform coefficient a last significant transform coefficient in the transform coefficient block is situated. ### Claim 28 (depends on 26) The computer-readable medium according to claim 26, further comprising an encoded a second-type syntax element indicating information about a last significant transform coefficient in the transform coefficient block. ### Claim 29 (depends on 26) The computer-readable medium according to claim 26, wherein the data stream comprises at least a portion associated with color samples. ### Claim 30 (depends on 26) The computer-readable medium according to claim 26, wherein the data stream comprises at least a portion associated with depth values related to a depth map.