Simplified signaling method for affine linear weighted intra prediction mode
Prediction information for a current block in a current picture is decoded, the prediction information indicating whether the current block is coded in matrix based intra prediction (MIP). When the current block is coded in the MIP, an MIP mode index indicating one of a plurality of MIP modes is determined. When the current block is not coded in the MIP and one of a plurality of neighboring blocks is coded in the MIP, an intra prediction candidate mode for the current block is determined to be a Planar intra prediction mode. The current block is reconstructed according to (i) the one of the plurality of MIP modes when the current block is coded in the MIP and (ii) the Planar intra prediction mode when the current block is not coded in the MIP and the one of the plurality of neighboring blocks is coded in the MIP.
1 . A method for video decoding in a decoder, comprising:
decoding prediction information for a current block in a current picture that is a part of a coded video sequence, the prediction information indicating whether the current block is coded in matrix based intra prediction (MIP);
when the prediction information indicates that the current block is coded in the MIP,
determining an MIP mode index, the MIP mode index indicating one of a plurality of MIP modes;
when the current block is not coded in the MIP and one of a plurality of neighboring blocks is coded in the MIP,
determining an intra prediction candidate mode for the current block to be a Planar intra prediction mode; and
reconstructing the current block according to (i) the one of the plurality of MIP modes when the prediction information indicates that the current block is coded in the MIP and (ii) the Planar intra prediction mode when the prediction information indicates the current block is not coded in the MIP and the one of the plurality of neighboring blocks is coded in the MIP.
2 . The method of claim 1 , wherein the MIP mode index is one of a truncated binary codeword, a fixed length codeword, and a truncated unary codeword.
3 . The method of claim 1 , further comprising:
when the prediction information indicates that the current block is coded in the MIP,
constructing a mode candidate list including at least one fixed mode candidate, the at least one fixed mode candidate being a predetermined subset of the plurality of MIP modes.
4 . The method of claim 1 , wherein a total number of the plurality of MIP modes is a power of 2.
5 . The method of claim 1 , further comprising:
when the prediction information indicates that the current block is not coded in the MIP and the one of the plurality of neighboring blocks is coded in the MIP,
constructing a mode candidate list based on one of (i) a preset intra prediction mode and (ii) an intra prediction mode of another neighboring block of the neighboring blocks, the mode candidate list including the Planar intra prediction mode.
6 . The method of claim 5 , wherein the preset intra prediction mode is one of a Planar intra prediction mode, a DC intra prediction mode, a Horizontal intra prediction mode, and a Vertical intra prediction mode.
7 . The method of claim 5 , wherein the constructing further comprises:
setting the one of the plurality of neighboring blocks as unavailable.
8 . The method of claim 1 , further comprising:
when the prediction information indicates that the current block is coded in the MIP and a derived mode is used for an associated chroma block of the current block,
setting a prediction mode of the associated chroma block to be a preset intra prediction mode.
9 . A method for video decoding in a decoder, comprising:
decoding prediction information for a current block in a current picture that is a part of a coded video sequence, the prediction information indicating that the current block is coded in matrix based intra prediction (MIP);
determining whether a neighboring block adjacent to the current block is coded in the MIP;
when the neighboring block is not coded in the MIP,
constructing a mode candidate list based on one of (i) a preset MIP mode and (ii) an MIP mode of another neighboring block; and
reconstructing the current block based on the mode candidate list.
10 . The method of claim 9 , wherein the constructing further comprises:
when the neighboring block is not coded in the MIP, setting the neighboring block as unavailable.
11 . The method of claim 9 , wherein the neighboring block is adjacent to a top-right corner or a bottom-left corner of the current block.
12 . The method of claim 9 , wherein a size of the mode candidate list is based on coded information of the neighboring block included in the coded video sequence.
13 . The method of claim 9 , wherein the prediction information indicates that a chroma block of the current block is associated with multiple luma blocks, the method further comprises:
determining whether a luma block of the multiple luma blocks is coded in a non-MIP intra prediction mode; and
when the luma block is coded in the non-MIP intra prediction mode, determining a prediction mode of the chroma block of the current block to be a non-ALWIP intra prediction mode of the luma block.
14 . The method of claim 13 , further comprising:
when each of the multiple luma blocks is coded in the MIP, determining the prediction mode of the chroma block of the current block to be a preset intra prediction mode.
15 . A method for video encoding in an encoder, comprising:
when a current block in a current picture is coded in matrix based intra prediction (MIP),
determining an MIP mode index for the current block, the MIP mode index indicating one of a plurality of MIP modes;
when the current block is not coded in the MIP and a first neighboring block of the current block is coded in the MIP,
determining an intra prediction candidate mode for the current block to be a Planar intra prediction mode; and
encoding the current block according to (i) the one of the plurality of MIP modes when the current block is coded in the MIP and (ii) the Planar intra prediction mode when the current block is not coded in the MIP and the first neighboring block of the current block is coded in the MIP.
16 . The method of claim 15 , wherein the MIP mode index is one of a truncated binary codeword, a fixed length codeword, and a truncated unary codeword.
17 . The method of claim 15 , further comprising:
when the current block is coded in the MIP,
constructing a mode candidate list including at least one fixed mode candidate, the at least one fixed mode candidate being a predetermined subset of the plurality of MIP modes.
18 . A method for video encoding in an encoder, comprising:
determining that a current block in a current picture is coded in matrix based intra prediction (MIP);
determining whether a first neighboring block of the current block is coded in the MIP;
when the first neighboring block is not coded in the MIP,
constructing a mode candidate list for the current block based on one of (i) a preset MIP mode and (ii) an MIP mode of a second neighboring block of the current block; and
encoding the current block based on the mode candidate list.
19 . A non-transitory computer-readable storage medium storing instructions which when executed by a processor cause the processor to perform a method of encoding a bitstream, the method comprising:
when a current block in a current picture is coded in matrix based intra prediction (MIP),
determining an MIP mode index for the current block, the MIP mode index indicating one of a plurality of MIP modes;
when the current block is not coded in the MIP and a first neighboring block of the current block is coded in the MIP,
determining an intra prediction candidate mode for the current block to be a Planar intra prediction mode;
encoding, in the bitstream, the current block according to (i) the one of the plurality of MIP modes when the current block is coded in the MIP and (ii) the Planar intra prediction mode when the current block is not coded in the MIP and the first neighboring block of the current block is coded in the MIP; and
transmitting the bitstream.
20 . A non-transitory computer-readable storage medium storing instructions which when executed by a processor cause the processor to perform a method of encoding a bitstream, the method comprising:
determining that a current block in a current picture is coded in matrix based intra prediction (MIP);
determining whether a first neighboring block of the current block is coded in the MIP;
when the first neighboring block is not coded in the MIP,
constructing a mode candidate list for the current block based on one of (i) a preset MIP mode and (ii) an MIP mode of a second neighboring block of the current block;
encoding, in the bitstream, the current block based on the mode candidate list; and
transmitting the bitstream.