# US 12,015,798 B2 · Methods and apparatus on transform and coefficient signaling > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,015,798 B2 - Document ID: US12015798B2 - Status: Granted - Kind: B2 - Application number: 17/750,169 - Filed: 2022-05-20 - Published: 2022-09-08 - Granted: 2024-06-18 - Earliest claimed: 2019-11-21 - Assignees: Beijing Dajia Internet Information Technology Co., Ltd. - Applicants: Beijing Dajia Internet Information Technology Co., Ltd. - Inventors: Xiaoyu Xiu; Tsung-Chuan Ma; Yi-Wen Chen; Xianglin Wang; Hong-Jheng Jhu; Bing Yu - Web page: https://patentgrep.com/patent/US12015798B2 ## CPC - H04N 19/12: Selection from among a plurality of transforms or standards, e.g. selection between discrete cosine transform [DCT] and sub-band transform or selection between H.263 and H.264 - H04N 19/625: using discrete cosine transform [DCT] - H04N 19/129: Scanning of coding units, e.g. zig-zag scan of transform coefficients or flexible macroblock ordering [FMO] - H04N 19/14: Coding unit complexity, e.g. amount of activity or edge presence estimation (H04N19/146 takes precedence) - H04N 19/176: the region being a block, e.g. a macroblock - H04N 19/18: the unit being a set of transform coefficients - H04N 19/186: the unit being a colour or a chrominance component - H04N 19/46: Embedding additional information in the video signal during the compression process (H04N19/517, H04N19/68, H04N19/70 take precedence) - H04N 19/70: characterised by syntax aspects related to video coding, e.g. related to compression standards - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract An electronic apparatus performs a method of encoding and decoding video data. The method comprises: receiving bitstream encoding a transform block, wherein the transform block includes a non-zero region and a zero-out region; checking whether there is any non-zero coefficient within the zero-out region; in accordance with a determination that there is no non-zero coefficient within the zero-out region of the transform block: determining a scan order index of a last non-zero coefficient of the transform block along a scanning direction; in accordance with a determination that the scan order index of the last non-zero coefficient is greater than a predefined threshold: receiving, from the bitstream, a value for multiple transform selection (MTS) index; and applying respective transforms to transform coefficients of the transform block in both horizontal and vertical directions based on the value of the MTS index. ## Claims ### Claim 1 A method for video decoding, comprising: receiving a bitstream comprising a transform block, wherein the transform block includes a non-zero region and a zero-out region; determining whether any coding group of the transform block located within the zero-out region has a non-zero coefficient; in accordance with a determination that no coding group of the transform block located within the zero-out region has a non-zero coefficient: receiving, from the bitstream, a value for a multiple transform selection (MTS) index; and applying respective inverse transforms to transform coefficients of the transform block in horizontal and vertical directions based on the value of the MTS index. ### Claim 2 (depends on 1) The method of claim 1, further comprising: in accordance with a determination that a coding group of the transform block located within the zero-out region has a non-zero coefficient: applying a predefined default inverse transform to transform the coefficients of the transform block in both the horizontal and vertical directions. ### Claim 3 (depends on 2) The method of claim 2, wherein the predefined default inverse transform is inverse DCT-2 transform and the horizontal inverse transform and the vertical inverse transform are either inverse DST-7 transform or inverse DCT-8 transform. ### Claim 4 (depends on 1) The method of claim 1, wherein applying the respective inverse transforms to the transform coefficients of the transform block comprises: in accordance with a determination that the MTS index has a first value: receiving, from the bitstream, a value for an MTS horizontal flag and a value for an MTS vertical flag; applying a horizontal inverse transform to the coefficients of the transform block in the horizontal direction based on the value for the MTS horizontal flag; and applying a vertical inverse transform to the coefficients of the transform block after the horizontal transform in the vertical direction based on the value for the MTS vertical flag; and in accordance with a determination that the MTS index has a second value that is different from the first value: transforming the coefficients of the transform block using a predefined default transform in both the horizontal and vertical directions. ### Claim 5 (depends on 1) The method of claim 1, wherein chroma residuals of the transform block are coded in joint coding of chroma residuals (JCCR) mode and a transform skip mode is enabled for a corresponding chroma transform block. ### Claim 6 (depends on 1) The method of claim 1, wherein the non-zero region is a top-left 16×16 region of the transform block. ### Claim 7 (depends on 1) The method of claim 1, wherein a scan order of the coefficients of the transform block is a diagonal scan order. ### Claim 8 An electronic apparatus comprising: one or more processing units; memory coupled to the one or more processing units; and a plurality of programs stored in the memory that, when executed by the one or more processing units, cause the electronic apparatus to perform a method for video decoding, the method including: receiving a bitstream comprising a transform block, wherein the transform block includes a non-zero region and a zero-out region; determining whether any coding group of the transform block located within the zero-out region has a non-zero coefficient; in accordance with a determination that no coding group of the transform block located within the zero-out region has a non-zero coefficient: receiving, from the bitstream, a value for a multiple transform selection (MTS) index; and applying respective inverse transforms to transform coefficients of the transform block in horizontal and vertical directions based on the value of the MTS index. ### Claim 9 (depends on 8) The electronic apparatus of claim 8, wherein the method further comprises: in accordance with a determination that a coding group of the transform block located within the zero-out region has a non-zero coefficient: applying a predefined default inverse transform to transform the coefficients of the transform block in both the horizontal and vertical directions. ### Claim 10 (depends on 9) The electronic apparatus of claim 9, wherein the predefined default inverse transform is inverse DCT-2 transform and the horizontal inverse transform and the vertical inverse transform are either inverse DST-7 transform or inverse DCT-8 transform. ### Claim 11 (depends on 8) The electronic apparatus of claim 8, wherein applying the respective inverse transforms to the transform coefficients of the transform block comprises: in accordance with a determination that the MTS index has a first value: receiving, from the bitstream, a value for an MTS horizontal flag and a value for an MTS vertical flag; applying a horizontal inverse transform to the coefficients of the transform block in the horizontal direction based on the value for the MTS horizontal flag; and applying a vertical inverse transform to the coefficients of the transform block after the horizontal transform in the vertical direction based on the value for the MTS vertical flag; and in accordance with a determination that the MTS index has a second value that is different from the first value: transforming the coefficients of the transform block using a predefined default transform in both the horizontal and vertical directions. ### Claim 12 (depends on 8) The electronic apparatus of claim 8, wherein chroma residuals of the transform block are coded in joint coding of chroma residuals (JCCR) mode and a transform skip mode is enabled for a corresponding chroma transform block. ### Claim 13 (depends on 8) The electronic apparatus of claim 8, wherein the non-zero region is a top-left 16×16 region of the transform block. ### Claim 14 (depends on 8) The electronic apparatus of claim 8, wherein a scan order of the coefficients of the transform block is a diagonal scan order. ### Claim 15 A non-transitory computer readable storage medium storing bitstream to be decoded by a method for video decoding, the method including: receiving the bitstream comprising a transform block, wherein the transform block includes a non-zero region and a zero-out region; determining whether any coding group of the transform block located within the zero-out region has a non-zero coefficient; in accordance with a determination that no coding group of the transform block located within the zero-out region has a non-zero coefficient: receiving, from the bitstream, a value for a multiple transform selection (MTS) index; and applying respective inverse transforms to transform coefficients of the transform block in horizontal and vertical directions based on the value of the MTS index. ### Claim 16 (depends on 15) The non-transitory computer readable storage medium of claim 15, wherein the method further comprises: in accordance with a determination that a coding group of the transform block located within the zero-out region has a non-zero coefficient: applying a predefined default inverse transform to transform the coefficients of the transform block in both the horizontal and vertical directions. ### Claim 17 (depends on 16) The non-transitory computer readable storage medium of claim 16, wherein the predefined default inverse transform is inverse DCT-2 transform and the horizontal inverse transform and the vertical inverse transform are either inverse DST-7 transform or inverse DCT-8 transform. ### Claim 18 (depends on 15) The non-transitory computer readable storage medium of claim 15, wherein applying the respective inverse transforms to the transform coefficients of the transform block comprises: in accordance with a determination that the MTS index has a first value: receiving, from the bitstream, a value for an MTS horizontal flag and a value for an MTS vertical flag; applying a horizontal inverse transform to the coefficients of the transform block in the horizontal direction based on the value for the MTS horizontal flag; and applying a vertical inverse transform to the coefficients of the transform block after the horizontal transform in the vertical direction based on the value for the MTS vertical flag; and in accordance with a determination that the MTS index has a second value that is different from the first value: transforming the coefficients of the transform block using a predefined default transform in both the horizontal and vertical directions. ### Claim 19 (depends on 15) The non-transitory computer readable storage medium of claim 15, wherein chroma residuals of the transform block are coded in joint coding of chroma residuals (JCCR) mode and a transform skip mode is enabled for a corresponding chroma transform block. ### Claim 20 (depends on 15) The non-transitory computer readable storage medium of claim 15, wherein the non-zero region is a top-left 16×16 region of the transform block. ### Claim 21 (depends on 15) The non-transitory computer readable storage medium of claim 15, wherein a scan order of the coefficients of the transform block is a diagonal scan order.