# US 2019/0174137 A1 · Embedding information about eob positions > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0174137 A1 - Document ID: US20190174137A1 - Status: Published application - Kind: A1 - Application number: 16/269,882 - Filed: 2019-02-07 - Published: 2019-06-06 - Earliest claimed: 2017-08-21 - Assignees: Google Inc. - Applicants: Google LLC - Inventors: Dake He - Web page: https://patentgrep.com/patent/US20190174137A1 ## CPC - H04N 19/18: the unit being a set of transform coefficients - H04N 19/129: Scanning of coding units, e.g. zig-zag scan of transform coefficients or flexible macroblock ordering [FMO] - H04N 19/46: Embedding additional information in the video signal during the compression process (H04N19/517, H04N19/68, H04N19/70 take precedence) - H04N 19/467: characterised by the embedded information being invisible, e.g. watermarking - 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 19/48: using compressed domain processing techniques other than decoding, e.g. modification of transform coefficients, variable length coding [VLC] data or run-length data (motion estimation in a transform domain H04N19/547; processing of decoded motion vectors H04N19/513) - H04N 19/513: Processing of motion vectors - H04N 19/547: Motion estimation performed in a transform domain - H04N 19/96: Tree coding, e.g. quad-tree coding - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract A method for decoding a transform block of quantized transform coefficients. The method includes decoding, from an encoded bitstream, a predetermined number of coefficients of the quantized transform coefficients, the transform block includes the predetermined number of coefficients and subsequent quantized transform coefficients; determining a value for the predetermined number of coefficients; decoding, from the encoded bitstream, a subsequent quantized transform coefficient of the subsequent quantized transform coefficients; and determining whether to decode an end-of-block (EOB) indicator based on the value that is determined for the predetermined number of coefficients. ## Claims ### Claim 1 A method for decoding a transform block of quantized transform coefficients, comprising: decoding, from an encoded bitstream, a predetermined number of coefficients of the quantized transform coefficients, wherein the transform block comprises the predetermined number of coefficients and subsequent quantized transform coefficients; determining a value for the predetermined number of coefficients; decoding, from the encoded bitstream, a subsequent quantized transform coefficient of the subsequent quantized transform coefficients; and determining whether to decode an end-of-block (EOB) indicator based on the value that is determined for the predetermined number of coefficients. ### Claim 2 (depends on 1) The method of claim 1, wherein the value comprises a parity of the predetermined number of coefficients, the parity indicating whether a sum of the predetermined number of coefficients is even or odd. ### Claim 3 (depends on 1) The method of claim 1, wherein determining whether to decode the EOB indicator based on the value that is determined for the predetermined number of coefficients comprising: on condition that the subsequent quantized transform coefficient is a non-zero coefficient, decoding a coefficient immediately following the subsequent quantized transform coefficient, wherein the decoding uses a position of the subsequent quantized transform coefficient and the value of the predetermined number of coefficients to determine whether to decode the EOB indicator. ### Claim 4 (depends on 3) The method of claim 3, wherein the position of the subsequent quantized transform coefficient is the position in a list of non-zero coefficients following the predetermined number of coefficients. ### Claim 5 (depends on 1) The method of claim 1, wherein determining whether to decode the EOB indicator based on the value that is determined for the predetermined number of coefficients comprising: on condition that the subsequent quantized transform coefficient is a non-zero coefficient, decoding a coefficient immediately following the subsequent quantized transform coefficient, wherein the decoding uses a position of the subsequent quantized transform coefficient and the value of the predetermined number of coefficients to determine whether to traverse a coefficient token tree starting at a root node or starting at another node in the coefficient token tree. ### Claim 6 (depends on 5) The method of claim 5, wherein, to determine whether to traverse the coefficient token tree starting at the root node or starting at another node in the coefficient token tree, the decoding the subsequent quantized transform coefficient further uses whether a sum of the predetermined number of coefficients exceeds a threshold. ### Claim 7 (depends on 5) The method of claim 5, wherein, to determine whether to traverse the coefficient token tree starting at the root node or starting at another node in the coefficient token tree, the decoding the subsequent quantized transform coefficient further uses whether a distance between a first non-zero coefficient of the predetermined number of coefficients and a last non-zero coefficient of the predetermined number of coefficients exceeds a distance threshold. ### Claim 8 (depends on 1) The method of claim 1, wherein the predetermined number of coefficients does not include a DC coefficient. ### Claim 9 An method for decoding a transform block of quantized transform coefficients, the quantized transform coefficients including zero coefficients and non-zero coefficients, comprising: decoding, from an encoded bitstream, a predetermined number of coefficients of the quantized transform coefficients; determining a value for the predetermined number of coefficients, the value indicating which subsequent non-zero quantized transform coefficients can be a last non-zero quantized transform coefficient of the transform block; and determining, based on the value, whether to decode from the encoded bitstream an end-of-block (EOB) indicator subsequent to decoding a non-zero coefficient. ### Claim 10 (depends on 9) The method of claim 9, wherein determining, based on the value, whether to decode from the encoded bitstream the EOB indicator is further based on whether a distance between a first and a last non-zero coefficient of the predetermined number of coefficients exceeds a distance threshold. ### Claim 11 (depends on 10) The method of claim 10, wherein the value for the predetermined number of coefficients is a parity of the predetermined number of coefficients, and wherein determining, based on the value, whether to decode from the encoded bitstream the EOB indicator comprises: decoding the subsequent quantized transform coefficient by reading bits from the encoded bitstream and traversing a coefficient token tree having a root node, the root node indicating an EOB token, wherein the decoding uses the parity to determine whether to traverse the coefficient token tree starting at the root node or starting at another node in the coefficient token tree. ### Claim 12 (depends on 9) The method of claim 9, wherein determining, based on the value, whether to decode from the encoded bitstream the EOB indicator is further based on whether a number of non-zero coefficients in the predetermined number of coefficients exceeds a number threshold. ### Claim 13 (depends on 12) The method of claim 12, wherein determining, based on the value, whether to decode from the encoded bitstream the EOB indicator comprises: on condition that the number of non-zero coefficients not exceeding the number threshold, decoding the EOB indicator. ### Claim 14 (depends on 9) The method of claim 9, wherein the value is a sum of the predetermined number of coefficients. ### Claim 15 An apparatus for encoding a transform block of quantized transform coefficients, the quantized transform coefficients including zero coefficients and non-zero coefficients, the apparatus comprising: a memory; and a processor, the processor configured to execute instructions stored in the memory to: partition the quantized transform coefficients into at least a first coefficients group and a second coefficients group; determine a value for the first coefficients group, the value indicating whether a number of non-zero coefficients in the second coefficients group is even or odd; encode a transform coefficient of the second coefficients group, wherein the transform coefficient is a non-zero transform coefficient; and determine, based on the value, whether to encode an end-of-block (EOB) indicator subsequent to the encoding of the transform coefficient of the second coefficients group. ### Claim 16 (depends on 15) The apparatus of claim 15, wherein the second coefficients group comprising a first non-zero coefficient and a second non-zero coefficient, the second non-zero coefficient being a next immediate non-zero coefficient after the first non-zero coefficient, and wherein to determine, based on the value, whether to encode the EOB indicator subsequent to the encoding of the transform coefficient comprises to: encode the EOB indicator, based on the value, after only one of the first non-zero coefficient or the second non-zero coefficient. ### Claim 17 (depends on 15) The apparatus of claim 15, wherein the value is a parity of the first coefficients group, and wherein the instructions further comprise instructions to: conform the parity of the first coefficients group and a number of the non-zero coefficients of the second coefficients group. ### Claim 18 (depends on 17) The apparatus of claim 17, wherein to conform the parity of the first coefficients group and the number of the non-zero coefficients of the second coefficients group comprises to: on condition that the parity is even and a number of non-zero coefficients is odd or on condition that the parity is odd and the number of non-zero coefficients is even, adjust at least one of the quantized transform coefficients of the first coefficients group so that the parity and the number of the non-zero coefficients match. ### Claim 19 (depends on 17) The apparatus of claim 17, wherein to conform the parity of the first coefficients group and the number of the non-zero coefficients of the second coefficients group comprises to: on condition that the parity is even and a number of non-zero coefficients is odd or on condition that the parity is odd and the number of non-zero coefficients is even, set at least one of the non-zero coefficients of the second coefficients group to zero so that the parity and the number of the non-zero coefficients match. ### Claim 20 (depends on 17) The apparatus of claim 17, to encode the EOB indicator for the transform coefficient of the second coefficients group based on the value comprises to: on condition that a position of the transform coefficient in the second coefficients group matching the parity, encode the transform coefficient including the EOB indicator; and on condition that the position of the transform coefficient in the second coefficients group not matching the parity, encode the transform coefficient excluding the EOB indicator.