Intra prediction method and decoder

An intra prediction method, applied to an encoder and comprising:

• determining a first intra prediction mode and a second intra prediction mode of a current block when an intra weighted combined prediction mode is used for determining an intra prediction value of the current block, the first intra prediction mode and the second intra prediction mode being two different intra angular prediction modes;
• constructing a most probable mode (MPM) list for the current block;
• determining a first mode index and a second mode index of the current block according to the first intra prediction mode, the second intra prediction mode, and the MPM list;
• and
• signalling the first mode index and the second mode index into a bitstream.

A decoder, comprising:

• a processor and a memory storing instructions which, when executed by the processor, cause the processor to:
• decode a bitstream to determine an intra prediction mode parameter of a current block;
• determine a first mode index and a second mode index of the current block when the intra prediction mode parameter indicates that an intra weighted combined prediction mode is used for determining an intra prediction value of the current block;
• construct a most probable mode (MPM) list for the current block;
• determine a first intra prediction mode and a second intra prediction mode of the current block according to the first mode index, the second mode index, and the MPM list, wherein the first intra prediction mode and the second intra prediction mode are two different intra angular prediction modes;
• and
• determine a weight matrix for the current block and determining a prediction value of the current block based on the first intra prediction mode, the second intra prediction mode, and the weight matrix.