Method and system for intra mode coding

A video coding system, comprising:

• a memory storing computer program instructions;
• and
• a processor coupled to the memory and, when executing the computer program instructions, configured to perform:
• obtaining a current frame of a video input;
• partitioning the current video frame into a plurality of coding blocks;
• predicting a symbol level for each coding block in intra prediction modes included in an allowed intra prediction mode (AIPM) set, wherein the intra prediction modes included in the AIPM set are a subset of all available intra prediction modes in video coding formats of different video coding schemes and are determined based on coding efficiency and compression performance, and each of the intra prediction modes included in the AIPM set is identified by an index number;
• transforming and quantizing a residual symbol level;
• entropy coding the transformed and quantized residual symbol level;
• and
• outputting a bitstream;
• wherein the intra prediction modes included in the AIPM set are determined by:
• determining whether a current video coding format for the current frame is of a video coding scheme based on a Versatile Video Coding (VVC) standard or a video coding scheme based on an AOMedia Video 1 (AV1) standard;
• when the current video coding format is of the video coding scheme based on the VVC standard, including 6 most probable modes (MPM) and 32 remaining modes in the AIPM set;
• and
• when the current video coding format is of the video coding scheme based on the AV1 standard, including directional modes of 8 nominal angles and non-directional smooth modes in the AIPM set, regardless of a size of the current coding block or the intra prediction modes of neighboring coding blocks.