Encoding method and apparatus, decoding method and apparatus, and devices therefor

An encoding method, comprising:

• in response to determining that an adaptive loop filter (ALF) sequence control enabling flag of a sequence parameter set (SPS) syntax indicates allowing a current sequence to enable an ALF, encoding a cross-component adaptive loop filter (CCALF) sequence control enabling flag in the SPS syntax;
• wherein in response to determining that decoded information of the CCALF control enabling flag represents that CCALF is enabled for the current sequence, the method further comprises:
• in response to determining that CCALF is enabled for a current processing unit obtaining a luma component reconstruction value and a chroma component reconstruction value of each pixel position of the current processing unit;
• for a current pixel position of the current processing unit, determining a target pixel position in the current processing unit associated with the current pixel position;
• based on the luma component reconstruction value of the target pixel position, a CCALF filtering coefficient of the target pixel position, the luma component reconstruction values of neighboring pixel positions for the target pixel position and CCALF filtering coefficients of the neighboring pixel positions, performing CCALF-based filtering to obtain a chroma component offset value of the current pixel position;
• based on the chroma component reconstruction value of the current pixel position and the chroma component offset value of the current pixel position, obtaining a target chroma component reconstruction value of the current pixel position;
• wherein, the neighboring pixel positions for the target pixel position comprises:
• an exactly-upper pixel position of the target pixel position, a left pixel position of the target pixel position, a right pixel position of the target pixel position, an exactly-lower pixel position of the target pixel position, a left lower pixel position of the target pixel position, a right lower pixel position of the target pixel position, an exactly-lower second row of pixel position of the target pixel position;
• wherein the CCALF filtering coefficients of the neighboring pixel positions comprise:
• a CCALF filtering coefficient of the exactly-upper pixel position of the target pixel position;
• a CCALF filtering coefficient of the left pixel position of the target pixel position;
• a CCALF filtering coefficient of the right pixel position of the target pixel position;
• a CCALF filtering coefficient of the exactly-lower pixel position of the target pixel position;
• a CCALF filtering coefficient of the left lower pixel position of the target pixel position;
• a CCALF filtering coefficient of the right lower pixel position of the target pixel position;
• a CCALF filtering coefficient of the exactly-lower second row of pixel position of the target pixel position;
• wherein, the method further comprises:
• encoding the CCALF filtering coefficients of the neighboring pixel positions in a bit stream;
• wherein, for each of the CCALF filtering coefficients, a range of the CCALF filtering coefficient is {−64, −32, −16, −8, −4, −2, −1, 0, 1, 2, 4, 8, 16, 32, 64};
• wherein, the CCALF filtering coefficient of the target pixel position is not included in the bit stream, the CCALF filtering coefficient of the target pixel position is obtained by a decoder;
• wherein, encoding the CCALF filtering coefficients of the neighboring pixel positions in the bit stream comprises:
• for each of the CCALF filtering coefficients, encoding an index value of the amplitude of the CCALF filtering coefficient by fixed-length code decoding;
• and encoding a sign bit of the CCALF filtering coefficient.

A decoder device, comprising:

• a processor and a machine-readable storage medium, wherein the machine-readable storage medium stores machine executable instructions executable by the processor;
• the processor is configured to execute the machine executable instructions to perform operations comprising:
• in response to determining that an adaptive loop filter (ALF) sequence control enabling flag of a sequence parameter set (SPS) syntax indicates allowing a current sequence to enable ALF, decoding a cross-component adaptive loop filter (CCALF) sequence control enabling flag from the SPS syntax;
• wherein in response to determining, according decoded information of the CCALF control enabling flag, that CCALF is enabled for the current sequence, the method further comprises:
• in response to determining that CCALF is enabled for a current processing unit, obtaining a luma component reconstruction value and a chroma component reconstruction value of each pixel position of the current processing unit;
• for a current pixel position of the current processing unit, determining a target pixel position in the current processing unit associated with the current pixel position;
• based on the luma component reconstruction value of the target pixel position, a CCALF filtering coefficient of the target pixel position, the luma component reconstruction values of neighboring pixel positions for the target pixel position and CCALF filtering coefficients of the neighboring pixel positions, performing CCALF-based filtering to obtain a chroma component offset value of the current pixel position;
• based on the chroma component reconstruction value of the current pixel position and the chroma component offset value of the current pixel position, obtaining a target chroma component reconstruction value of the current pixel position;
• wherein, the neighboring pixel positions for the target pixel position comprises:
• an exactly-upper pixel position of the target pixel position, a left pixel position of the target pixel position, a right pixel position of the target pixel position, an exactly-lower pixel position of the target pixel position, a left lower pixel position of the target pixel position, a right lower pixel position of the target pixel position, an exactly-lower second row of pixel position of the target pixel position;
• wherein the CCALF filtering coefficients of the neighboring pixel positions comprise:
• a CCALF filtering coefficient of the exactly-upper pixel position of the target pixel position;
• a CCALF filtering coefficient of the left pixel position of the target pixel position;
• a CCALF filtering coefficient of the right pixel position of the target pixel position;
• a CCALF filtering coefficient of the exactly-lower pixel position of the target pixel position;
• a CCALF filtering coefficient of the left lower pixel position of the target pixel position;
• a CCALF filtering coefficient of the right lower pixel position of the target pixel position;
• a CCALF filtering coefficient of the exactly-lower second row of pixel position of the target pixel position;
• wherein, a process of obtaining the CCALF filtering coefficients of the neighboring pixel positions comprises:
• decoding the CCALF filtering coefficients of the neighboring pixel positions from a bit stream;
• wherein, for each of the CCALF filtering coefficients, a range of the CCALF filtering coefficient is {−64, −32, −16, −8, −4, −2, −1, 0, 1, 2, 4, 8, 16, 32, 64};
• wherein, the CCALF filtering coefficient of the target pixel position is not included in the bit stream, the CCALF filtering coefficient of the target pixel position is obtained by a decoder;
• wherein, decoding the CCALF filtering coefficients of the neighboring pixel positions from the bit stream comprises:
• for each of the CCALF filtering coefficients, decoding an index value of an amplitude of the CCALF filtering coefficient by fixed-length code decoding to obtain the amplitude of the CCALF filtering coefficient decoding a sign bit of the CCALF filtering coefficient to obtain the sign bit of the CCALF filtering coefficient and based on the amplitude and the sign bit of the CCALF filtering coefficient, determining the CCALF filtering coefficient.