Ultra light models and decision fusion for increasing the speed of intra-prediction are described. Using a machine-learning (ML) model, an ML intra-prediction mode is obtained. A most-probable intra-prediction mode is obtained from amongst available intra-prediction modes for encoding the current block. As an encoding intra-prediction mode, one of the ML intra-prediction mode or the most-probable intra-prediction mode is selected, and the encoding intra-prediction mode is encoded in a compressed bitstream. A current block is encoded using the encoding intra-prediction mode. Selection of the encoding intra-prediction mode is based on relative reliabilities of the ML intra-prediction mode and the most-probable intra-prediction mode.

Ultra light models and decision fusion for increasing the speed of intra-prediction are described. Using a machine-learning (ML) model, an ML intra-prediction mode is obtained. A most-probable intra-prediction mode is obtained from amongst available intra-prediction modes for encoding the current block. As an encoding intra-prediction mode, one of the ML intra-prediction mode or the most-probable intra-prediction mode is selected, and the encoding intra-prediction mode is encoded in a compressed bitstream. A current block is encoded using the encoding intra-prediction mode. Selection of the encoding intra-prediction mode is based on relative reliabilities of the ML intra-prediction mode and the most-probable intra-prediction mode.

An intra prediction method includes obtaining respective intra prediction modes or texture distributions of P reconstructed picture blocks in a surrounding region of a current block; obtaining, based on the respective intra prediction modes or texture distributions of the P reconstructed picture blocks, Q priori candidate intra prediction modes of the current block and Q probability values; obtaining, based on M probability values corresponding to M priori candidate intra prediction modes, M weighting factors corresponding to the M priori candidate intra prediction modes; separately performing intra prediction based on the M priori candidate intra prediction modes to obtain M predicted values; and obtaining a predicted value of the current block based on a weighted summation of the M predicted values and the corresponding M weighting factors.

An intra prediction method includes obtaining respective intra prediction modes or texture distributions of P reconstructed picture blocks in a surrounding region of a current block; obtaining, based on the respective intra prediction modes or texture distributions of the P reconstructed picture blocks, Q priori candidate intra prediction modes of the current block and Q probability values; obtaining, based on M probability values corresponding to M priori candidate intra prediction modes, M weighting factors corresponding to the M priori candidate intra prediction modes; separately performing intra prediction based on the M priori candidate intra prediction modes to obtain M predicted values; and obtaining a predicted value of the current block based on a weighted summation of the M predicted values and the corresponding M weighting factors.

A video processing method includes performing a conversion between a video having one or more video layers including one or more video pictures and a bitstream of the video according to a rule. The rule specifies a condition under which no picture that has been generated by a decoding process for generating an unavailable reference picture is referred to by an active entry in a reference picture list of a current slice of a current picture.

Devices, systems and methods for palette mode coding are described. An exemplary method for video processing includes determining, for a conversion between a block of a video region in a video and a bitstream representation of the video, a prediction mode based on one or more allowed prediction modes that include at least a palette mode of the block. An indication of usage of the palette mode is determined according to the prediction mode. The method also includes performing the conversion based on the one or more allowed prediction modes.

There is includes a method and apparatus comprising computer code configured to cause a hardware processor or processors to perform obtaining a block of video data, splitting the block into an L-shaped partition and a second partition, the second partition being one of a rectangular shaped partition and another L-shaped partition, and performing intra prediction of the L-shaped partition by using a reference sample chain, comprising a chain of neighboring reconstructed samples, as reference samples.

There is provided a method and apparatus of encoding/decoding an intra prediction mode. The method comprises deriving an intra prediction mode with respect to a current block, constructing a reference sample for the current block on the basis of the derived intra prediction mode, and performing the intra prediction with respect to the current block using the derived intra prediction mode and the constructed reference sample, wherein the intra prediction mode is derived on the basis of a most probable mode (MPM).

A method of signaling an intra prediction mode used to encode a current block in an encoded video bitstream using at least one processor includes generating a first most probable mode (MPM) list corresponding to a zero reference line of the current block, wherein the first MPM list includes a plurality of angular intra prediction modes; generating a second MPM list corresponding to one or more non-zero reference lines of the current block, wherein the second MPM list includes the plurality of angular intra prediction modes; signaling a reference line index indicating a reference line used to encode the current block from among the zero reference line and the one or more non-zero reference lines; and signaling an intra mode index indicating the intra prediction mode within the first MPM list or the second MPM list.

A method of signaling an intra prediction mode used to encode a current block in an encoded video bitstream using at least one processor includes generating a first most probable mode (MPM) list corresponding to a zero reference line of the current block, wherein the first MPM list includes a plurality of angular intra prediction modes; generating a second MPM list corresponding to one or more non-zero reference lines of the current block, wherein the second MPM list includes the plurality of angular intra prediction modes; signaling a reference line index indicating a reference line used to encode the current block from among the zero reference line and the one or more non-zero reference lines; and signaling an intra mode index indicating the intra prediction mode within the first MPM list or the second MPM list.