# US 12,003,751 B2 · High level syntax control of loop filter > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,003,751 B2 - Document ID: US12003751B2 - Status: Granted - Kind: B2 - Application number: 18/046,423 - Filed: 2022-10-13 - Published: 2023-02-23 - Granted: 2024-06-04 - Earliest claimed: 2020-03-29 - Assignees: Alibaba Group Holding Limited - Applicants: Alibaba Group Holding Limited - Inventors: Jie Chen; Jiancong Luo; Yan Ye; Mohammed Golam Sarwer - Web page: https://patentgrep.com/patent/US12003751B2 ## CPC - 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 19/117: Filters, e.g. for pre-processing or post-processing (sub-band filter banks H04N19/635) - H04N 19/174: the region being a slice, e.g. a line of blocks or a group of blocks - H04N 19/186: the unit being a colour or a chrominance component - H04N 19/1883: {the unit relating to sub-band structure, e.g. hierarchical level, directional tree, e.g. low-high [LH], high-low [HL], high-high [HH]} - H04N 19/70: characterised by syntax aspects related to video coding, e.g. related to compression standards - H04N 19/82: involving filtering within a prediction loop - H04N 19/98: Adaptive-dynamic-range coding [ADRC] - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract Methods and apparatuses for video encoding, comprising: receiving a video sequence; encoding the video sequence by using control flags for luma mapping with chroma scaling (LMCS) at a sequence level, a picture level, or a slice level, wherein the sequence level, the picture level, and the slice level are levels ranking from high to low; signaling a first control flag indicating whether the LMCS is enabled at a first level; and in response to the first control flag indicating the LMCS is enabled at the first level, signaling a second control flag indicating whether LMCS is enabled at a second level, wherein: the LMCS is enabled at the second level when a value of the second control flag equals to 1; the LMCS is disabled at the second level when the value of the second control flag equals to 0; and the second level is a lower level than the first level. ## Claims ### Claim 1 A video encoder, comprising: a memory storing a set of instructions; and at least one processor configured to execute the set of instructions to: receive a video sequence; encode the video sequence by using control flags for adaptive loop filter (ALF) at a sequence level, a picture level, or a slice level, wherein the sequence level, the picture level, and the slice level are levels ranking from high to low; signal a first control flag indicating whether the ALF is enabled at a first level; and in response to the first control flag indicating the ALF at the first level is enabled, signal a second control flag indicating whether ALF is enabled at a second level, wherein: the ALF is enabled at the second level when a value of the second control flag equals to 1; the ALF is disabled at the second level when the value of the second control flag equals to 0; the second level is a lower level than the first level; and the first control flag is a control flag for ALF at the sequence level, and the second control flag is a control flag for ALF at one of the picture level or the slice level depending on a third control flag signaled at a Picture Parameter Set (PPS). ### Claim 2 (depends on 1) The video encoder of claim 1, wherein when the second control flag is a control flag for ALF at the picture level and the value of the second control flag equals to 1, the ALF information is signaled in picture header, the ALF is enabled for at least one slice associated with the picture. ### Claim 3 (depends on 1) The video encoder of claim 1, wherein when the second control flag is a control flag for ALF at the slice level and the value of the second control flag equals to 1, the ALF information is signaled in slice header, and the ALF is applied to Y, Cb, or Cr color component in the slice. ### Claim 4 (depends on 1) The video encoder of claim 1, wherein the at least one processor is further configured to: in response to the second flag indicating the ALF is enabled at the second level, signal a fourth control flag indicating whether Cross Component Adaptive loop filter (CCALF) is enabled for Cb color component at the second level, wherein: the CCALF is enabled at the second level for Cb color component when a value of the fourth control flag equals to 1; and the CCALF is disabled at the second level for Cb color component when the value of the fourth control flag equal to 0; and in response to the second flag indicating the ALF is enabled at the second level, signal a fifth control flag indicating whether CCALF is enabled for Cr color component at the second level, wherein: the CCALF is enabled at the second level for Cr color component when a value of the fifth control flag equals to 1; and CCALF is disabled at the second level for Cr color component when the value of the fifth control flag equals to 0. ### Claim 5 (depends on 1) The video encoder of claim 1, wherein when a parameter of the ALF is signaled in a picture header of a picture, all slices of the picture share the parameter of the ALF. ### Claim 6 (depends on 4) The video encoder of claim 4, wherein the second level is the picture level and when the fourth control flag or the fifth control flag is not signaled, CCALF is not enabled for the Cb or Cr component of the picture associated with the second control flag. ### Claim 7 A video decoder, comprising: a memory storing a set of instructions; and at least one processor configured to execute the set of instructions to cause the decoder to perform: receive a bitstream; decode the bitstream by using control flags for adaptive loop filter (ALF) at a sequence level, a picture level, or a slice level, wherein the sequence level, the picture level, and the slice level are levels ranking from high to low; decode a first control flag indicating whether the ALF is enabled at a first level; and in response to the first control flag indicating the ALF at the first level is enabled, decode a second control flag indicating whether ALF is enabled at a second level, wherein: the ALF is enabled at the second level when a value of the second control flag equals to 1; the ALF is disabled at the second level when the value of the second control flag equals to 0; the second level is a lower level than the first level; and the first control flag is a control flag for ALF at the sequence level, and the second control flag is a control flag for ALF at one of the picture level or the slice level depending on a third control flag signaled at a Picture Parameter Set (PPS). ### Claim 8 (depends on 7) The video decoder of claim 7, wherein when the second control flag is a control flag for ALF at the picture level and the value of the second control flag equals to 1, the ALF information is signaled in picture header, the ALF is enabled for at least one slice associated with the picture. ### Claim 9 (depends on 7) The video decoder of claim 7, wherein when the second control flag is a control flag for ALF at the slice level and the value of the second control flag equals to 1, the ALF information is signaled in slice header, and the ALF is applied to Y, Cb, or Cr color component in the slice. ### Claim 10 (depends on 7) The video decoder of claim 7, wherein the at least one processor is configured to execute the set of instructions to cause the decoder to further: in response to the second flag indicating the ALF is enabled at the second level, decode a fourth control flag indicating whether Cross Component Adaptive loop filter (CCALF) is enabled for Cb color component at the second level, wherein: the CCALF is enabled at the second level for Cb color component when a value of the fourth control flag equals to 1; and the CCALF is disabled at the second level for Cb color component when the value of the fourth control flag equal to 0; and in response to the second flag indicating the ALF is enabled at the second level, decode a fifth control flag indicating whether CCALF is enabled for Cr color component at the second level, wherein: the CCALF is enabled at the second level for Cr color component when a value of the fifth control flag equals to 1; and CCALF is disabled at the second level for Cr color component when the value of the fifth control flag equals to 0. ### Claim 11 (depends on 7) The video decoder of claim 7, wherein when a parameter of the ALF is signaled in a picture header of a picture, all slices of the picture share the parameter of the ALF. ### Claim 12 (depends on 10) The video decoder of claim 10, wherein the second level is the picture level and when the fourth control flag or the fifth control flag is not signaled, CCALF is not enabled for the Cb or Cr component of the picture associated with the second control flag. ### Claim 13 A non-transitory computer readable medium storing a bitstream that is processed according to a method comprising: receiving a video sequence corresponding to the bitstream; encoding the video sequence by using control flags for adaptive loop filter (ALF) at a sequence level, a picture level, or a slice level, wherein the sequence level, the picture level, and the slice level are levels ranking from high to low; signaling a first control flag indicating whether the ALF is enabled at a first level; and in response to the first control flag indicating the ALF at the first level is enabled, signaling a second control flag indicating whether ALF is enabled at a second level, wherein: the ALF is enabled at the second level when a value of the second control flag equals to 1; the ALF is disabled at the second level when the value of the second control flag equals to 0; the second level is a lower level than the first level; and wherein the first control flag is a control flag for ALF at the sequence level, and the second control flag is a control flag for ALF at one of the picture level or the slice level depending on a third control flag signaled at a Picture Parameter Set (PPS). ### Claim 14 (depends on 13) The non-transitory computer readable medium of claim 13, wherein when the second control flag is a control flag for ALF at the picture level and the value of the second control flag equals to 1, the ALF information is signaled in picture header, the ALF is enabled for at least one slice associated with the picture. ### Claim 15 (depends on 13) The non-transitory computer readable medium of claim 13, wherein when the second control flag is a control flag for ALF at the slice level and the value of the second control flag equals to 1, the ALF information is signaled in slice header, and the ALF is applied to Y, Cb, or Cr color component in the slice. ### Claim 16 (depends on 13) The non-transitory computer readable medium of claim 13, wherein the method further comprising: in response to the second flag indicating the ALF is enabled at the second level, signaling a fourth control flag indicating whether Cross Component Adaptive loop filter (CCALF) is enabled for Cb color component at the second level, wherein: the CCALF is enabled at the second level for Cb color component when a value of the fourth control flag equals to 1; and the CCALF is disabled at the second level for Cb color component when the value of the fourth control flag equal to 0; and in response to the second flag indicating the ALF is enabled at the second level, signaling a fifth control flag indicating whether CCALF is enabled for Cr color component at the second level, wherein: the CCALF is enabled at the second level for Cr color component when a value of the fifth control flag equals to 1; and CCALF is disabled at the second level for Cr color component when the value of the fifth control flag equals to 0. ### Claim 17 (depends on 13) The non-transitory computer readable medium of claim 13, wherein when a parameter of the ALF is signaled in a picture header of a picture, all slices of the picture share the parameter of the ALF. ### Claim 18 (depends on 16) The non-transitory computer readable medium of claim 16, wherein the second level is the picture level and when the fourth control flag or the fifth control flag is not signaled, CCALF is not enabled for the Cb or Cr component of the picture associated with the second control flag.