In an encoding apparatus or a decoding apparatus, an encoding method or decoding method combines various coding tools with intra sub partitioning mode in which a coding unit is split in multiple sub partitions. At least one embodiment particularly aims at the selection of primary transforms among a set of multiple transforms for video encoding or decoding of intra sub block partitions. At least one embodiment particularly aims at intra coding using Ma-trix-Based Intra Prediction mode combined with Intra Sub Partition mode. At least one embodiment particularly aims at intra coding using Multi-Reference-Line intra prediction mode combined with Intra Sub Partition mode.

A video decoding method includes: performing entropy decoding processing on an encoding block of a video image frame to obtain a quantized coefficient block of residual data corresponding to the encoding block; calculating quantization coefficients in the quantized coefficient block to obtain an implicitly derived index value; determining a transformation mode of the encoding block according to the implicitly derived index value and a value of an index identifier included in the encoding block; and performing inverse transformation processing on an inverse quantization result of the quantized coefficient block based on the transformation mode of the encoding block.

A feature data encoding method, an encoder, a feature data decoding method, and a decoder are provided. The feature data encoding method includes following steps. A transform unit is divided into a plurality of sub-blocks and N sub-transform units. A reference origin and a LSC are determined in an i-th sub-transform unit of the sub-transform units, and an original coordinate of the last significant coefficient of the i-th sub-transform unit is modified to a specific coordinate. The i-th sub-transform unit is scanned from a specific sub-block of the i-th sub-transform unit, and significant feature coefficients in the i-th sub-transform unit are individually encoded as coded data.

A feature data encoding method, an encoder, a feature data decoding method, and a decoder are provided. The feature data encoding method includes following steps. A transform unit is divided into a plurality of sub-blocks and N sub-transform units. A reference origin and a LSC are determined in an i-th sub-transform unit of the sub-transform units, and an original coordinate of the last significant coefficient of the i-th sub-transform unit is modified to a specific coordinate. The i-th sub-transform unit is scanned from a specific sub-block of the i-th sub-transform unit, and significant feature coefficients in the i-th sub-transform unit are individually encoded as coded data.

In a video bitstream, Cb and Cr channels are demultiplexed before dequantization instead of after inverse transformation. In this way, regular Cb and Cr quantization control parameters can be used, optionally with minor adjustments when a video block is joint-chroma coded. In one embodiment, some specific quantization control parameters canbe specified. In another embodiment, separate Cb and Cr offsets can be specified for joint chroma coded blocks. In another embodiment, quantization control parameters specific to joint chroma coded blocks can be used for both Cb and Cr channels instead of nominal chroma quantization parameters.

In a video bitstream, Cb and Cr channels are demultiplexed before dequantization instead of after inverse transformation. In this way, regular Cb and Cr quantization control parameters can be used, optionally with minor adjustments when a video block is joint-chroma coded. In one embodiment, some specific quantization control parameters canbe specified. In another embodiment, separate Cb and Cr offsets can be specified for joint chroma coded blocks. In another embodiment, quantization control parameters specific to joint chroma coded blocks can be used for both Cb and Cr channels instead of nominal chroma quantization parameters.

An apparatus for decoding a sequence of pictures from a data stream is configured for decoding a picture of the sequence by: deriving a residual transform signal of the picture from the data stream; combining the residual transform signal with a buffered transform signal of a previous picture of the sequence so as to obtain a transform signal of the picture, the transform signal representing the picture in spectral components; and subjecting the transform signal to a spectral-to-spatial transformation, wherein the buffered transform signal comprises a selection out of spectral components representing the previous picture.

An apparatus for decoding a sequence of pictures from a data stream is configured for decoding a picture of the sequence by: deriving a residual transform signal of the picture from the data stream; combining the residual transform signal with a buffered transform signal of a previous picture of the sequence so as to obtain a transform signal of the picture, the transform signal representing the picture in spectral components; and subjecting the transform signal to a spectral-to-spatial transformation, wherein the buffered transform signal comprises a selection out of spectral components representing the previous picture.

An apparatus comprising: at least one processor; and at least one non-transitory memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: receive a signal, the signal comprising a sparse signal; perform residual coding on the signal; perform predictive coding on the signal; determine a residual, the residual comprising a residual of the signal and a base signal or a residual of an approximation and the base signal, the approximation being an approximation of the signal; and determine whether to transmit the residual or the signal over a communication channel.

An apparatus comprising: at least one processor; and at least one non-transitory memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: receive a signal, the signal comprising a sparse signal; perform residual coding on the signal; perform predictive coding on the signal; determine a residual, the residual comprising a residual of the signal and a base signal or a residual of an approximation and the base signal, the approximation being an approximation of the signal; and determine whether to transmit the residual or the signal over a communication channel.