A video processing method includes determining, for a conversion between a current block of a video and a bitstream representation of the video, whether to enable a level mapping operation or a level remapping operation based on a rule, wherein the level mapping operation or the level remapping operation includes changing between a first representation of a residual coefficient of the current block and a second representation of the residual coefficient of the current block based on neighboring residual coefficients of the residual coefficient; and performing the conversion by selectively using the level mapping operation or the level remapping operation based on the determining.

A video processing method includes determining, for a conversion between a current block of a video and a bitstream representation of the video, whether to enable a level mapping operation or a level remapping operation based on a rule, wherein the level mapping operation or the level remapping operation includes changing between a first representation of a residual coefficient of the current block and a second representation of the residual coefficient of the current block based on neighboring residual coefficients of the residual coefficient; and performing the conversion by selectively using the level mapping operation or the level remapping operation based on the determining.

Aspects of the disclosure provide methods and apparatuses for video encoding and/or decoding. In some examples, an apparatus for video decoding includes processing circuitry that can decode coded information of a transform block (TB) from a coded video bitstream. The coded information indicates a region of the TB on which a secondary transform is applied. The region includes a first sub-region having transform coefficients calculated by the secondary transform and a second sub-region that is a zero-out region. In response to a determination that a neighboring transform coefficient is in the second sub-region and a current transform coefficient in the TB is not in the second sub-region, the processing circuitry determines the current transform coefficient according to a default value for the neighboring transform coefficient. The processing circuitry reconstructs a sample in the TB based on the transform coefficient for the sample.

Aspects of the disclosure provide methods and apparatuses for video encoding and/or decoding. In some examples, an apparatus for video decoding includes processing circuitry that can decode coded information of a transform block (TB) from a coded video bitstream. The coded information indicates a region of the TB on which a secondary transform is applied. The region includes a first sub-region having transform coefficients calculated by the secondary transform and a second sub-region that is a zero-out region. In response to a determination that a neighboring transform coefficient is in the second sub-region and a current transform coefficient in the TB is not in the second sub-region, the processing circuitry determines the current transform coefficient according to a default value for the neighboring transform coefficient. The processing circuitry reconstructs a sample in the TB based on the transform coefficient for the sample.

A media data coding mechanism is disclosed. The mechanism includes partitioning media data into a plurality of blocks. A transform is applied to the blocks to obtain a plurality of quantization coefficients. The quantization coefficients are sorted into quality layers of decreasing priority based on frequency, wherein each subsequent layer includes data to incrementally increase quality of a reconstructed media data. Quantization coefficients for all blocks are positioned in a media data packet according to quality layer in order of decreasing priority. The media data packet is stored.

When dependent scalar quantization is used, the choice of the quantizer depends on the decoding of the preceding transform coefficient, and the entropy decoding of a transform coefficient depends on quantizer choice. To maintain high throughput in hardware implementations for transform coefficient entropy coding, several decision schemes of the scaler quantizer are proposed. In one implementation, the state transition and the context model selection are based on only regular coded bins. For example, the state transition can be based on the sum of the SIG, gt1 and gt2 flags, the exclusive-or function of the SIG, gt1 and gt2 flags, or based on only the gt1 or gt2 flag. When a block of transform coefficients is coded, the regular mode bins can be coded first in one or more scan passes, and the remaining bypass coded bins are grouped together in another one or more scan passes.

When dependent scalar quantization is used, the choice of the quantizer depends on the decoding of the preceding transform coefficient, and the entropy decoding of a transform coefficient depends on quantizer choice. To maintain high throughput in hardware implementations for transform coefficient entropy coding, several decision schemes of the scaler quantizer are proposed. In one implementation, the state transition and the context model selection are based on only regular coded bins. For example, the state transition can be based on the sum of the SIG, gt1 and gt2 flags, the exclusive-or function of the SIG, gt1 and gt2 flags, or based on only the gt1 or gt2 flag. When a block of transform coefficients is coded, the regular mode bins can be coded first in one or more scan passes, and the remaining bypass coded bins are grouped together in another one or more scan passes.

Aspects of the disclosure provide methods and apparatuses for video encoding and/or decoding. In some examples, an apparatus for video decoding includes processing circuitry that can decode coded information of a transform block (TB) from a coded video bitstream. The coded information indicates a region of the TB on which a secondary transform is applied. The region includes a first sub-region having transform coefficients calculated by the secondary transform and a second sub-region that is a zero-out region. In response to a determination that a neighboring transform coefficient is in the second sub-region and a current transform coefficient in the TB is not in the second sub-region, the processing circuitry determines the current transform coefficient according to a default value for the neighboring transform coefficient. The processing circuitry reconstructs a sample in the TB based on the transform coefficient for the sample.

Aspects of the disclosure provide methods and apparatuses for video encoding and/or decoding. In some examples, an apparatus for video decoding includes processing circuitry that can decode coded information of a transform block (TB) from a coded video bitstream. The coded information indicates a region of the TB on which a secondary transform is applied. The region includes a first sub-region having transform coefficients calculated by the secondary transform and a second sub-region that is a zero-out region. In response to a determination that a neighboring transform coefficient is in the second sub-region and a current transform coefficient in the TB is not in the second sub-region, the processing circuitry determines the current transform coefficient according to a default value for the neighboring transform coefficient. The processing circuitry reconstructs a sample in the TB based on the transform coefficient for the sample.

A subblock-based coding of transform coefficient blocks of the enhancement layer is rendered more efficient. To this end, the subblock subdivision of the respective transform coefficient block is controlled on the basis of the base layer residual signal or the base layer signal. In particular, by exploiting the respective base layer hint, the subblocks may be made longer along a spatial frequency axis transverse to edge extensions observable from the base layer residual signal or the base layer signal.