Decoding method, encoding method, and storage medium

An encoding method, applicable to an encoder and comprising:

• determining, based on distortion costs corresponding to a plurality of matrix based intra prediction (MIP) modes, an optimal MIP mode for predicting a current block, wherein the distortion costs corresponding to the plurality of MIP modes comprise distortion costs obtained by predicting samples in a template region adjacent to the current block in the plurality of MIP modes;
• determining a first intra prediction mode, wherein the first intra prediction mode comprises at least one of:
• a suboptimal MIP mode, determined based on the distortion costs corresponding to the plurality of MIP modes, for predicting the current block, an intra prediction mode derived from a decoder side intra mode derivation (DIMD) mode, or an intra prediction mode derived from a template based intra mode derivation (TIMD) mode;
• predicting the current block in the optimal MIP mode and in the first intra prediction mode to obtain a prediction block of the current block;
• obtaining a residual block of the current block based on the prediction block of the current block and an original block of the current block;
• and
• encoding the residual block of the current block to obtain a bitstream.

A computer-readable storage medium storing a bitstream, the bitstream being generated according to the following:

• determining, based on distortion costs corresponding to a plurality of matrix based intra prediction (MIP) modes, an optimal MIP mode for predicting a current block, wherein the distortion costs corresponding to the plurality of MIP modes comprise distortion costs obtained by predicting samples in a template region adjacent to the current block in the plurality of MIP modes;
• determining a first intra prediction mode, wherein the first intra prediction mode comprises at least one of:
• a suboptimal MIP mode, determined based on the distortion costs corresponding to the plurality of MIP modes, for predicting the current block, an intra prediction mode derived from a decoder side intra mode derivation (DIMD) mode, or an intra prediction mode derived from a template based intra mode derivation (TIMD) mode;
• predicting the current block in the optimal MIP mode and in the first intra prediction mode to obtain a prediction block of the current block;
• obtaining a residual block of the current block based on the prediction block of the current block and an original block of the current block;
• and
• encoding the residual block of the current block to obtain the bitstream.