Mode decision simplification for intra prediction

A video coding device configured to perform an intra-prediction process to code video data, the video coding device comprising:

• a memory configured to store a current block of video data;
• and
• a processor configured to:
• obtain a plurality of intra-prediction modes available for coding the current block of the video data;
• compute an approximate cost for each intra-prediction mode identified in a current set of intra-prediction modes of the plurality of intra-prediction modes that includes a pre-defined set of intra-prediction modes having at least one intra-prediction mode, wherein the current set of intra-prediction modes includes fewer intra-prediction modes than the plurality of intra-prediction modes available for coding the current block of the video data;
• compute an approximate cost for one or more most probable intra-prediction modes for the current block determined based on intra-prediction modes used to encode one or more neighboring blocks of video data adjacent to the current block;
• compare each of the approximate costs computed for the one or more most probable intra-prediction modes to a threshold;
• replace one or more of the intra-prediction modes identified in the current set of intra-prediction modes with the one or more most probable intra-prediction modes based on the comparisons;
• perform a rate distortion analysis with respect to each intra-prediction mode identified in the current set of intra-prediction modes to determine a rate distortion cost for each intra-prediction mode identified in the current set of intra-prediction modes;
• and
• perform intra-prediction coding with respect to the current block in accordance with one of the intra-prediction modes identified in the current set of intra-prediction modes based on the determined rate distortion costs to encode the current block.

A video coding device configured to perform an intra-prediction process to code video data, the video coding device comprising:

• means for obtaining a plurality of intra-prediction modes available for coding a current block of the video data;
• means for computing an approximate cost for each intra-prediction mode identified in a current set of intra-prediction modes of the plurality of intra-prediction modes that includes a pre-defined set of intra-prediction modes having at least one intra-prediction mode, wherein the current set of intra-prediction modes includes fewer intra-prediction modes than the plurality of intra-prediction modes available for coding the current block of the video data;
• means for computing an approximate cost for one or more most probable intra-prediction modes for the current block determined based on intra-prediction modes used to encode one or more neighboring blocks of video data adjacent to the current block;
• means for comparing each of the approximate costs computed for the one or more most probable intra-prediction modes to a threshold;
• means for replacing one or more of the intra-prediction modes identified in the current set of intra-prediction modes with the one or more most probable intra-prediction modes based on the comparisons;
• means for performing a rate distortion analysis with respect to each intra-prediction mode identified in the current set of intra-prediction modes to determine a rate distortion cost for each intra-prediction mode identified in the current set of intra-prediction modes;
• and
• means for performing intra-prediction coding with respect to the current block in accordance with one of the intra-prediction modes identified in the current set of intra-prediction modes based on the determined rate distortion costs to encode the current block.

A non-transitory computer-readable storage medium having instruction stored thereon that, when executed, cause one or more processors to:

• obtain a plurality of intra-prediction modes available for coding a current block of the video data;
• compute an approximate cost for each intra-prediction mode identified in a current set of intra-prediction modes of the plurality of intra-prediction modes that includes a pre-defined set of intra-prediction modes having at least one intra-prediction mode, wherein the current set of intra-prediction modes includes fewer intra-prediction modes than the plurality of intra-prediction modes available for coding the current block of the video data;
• compute an approximate cost for one or more most probable intra-prediction modes for the current block determined based on intra-prediction modes used to encode one or more neighboring blocks of video data adjacent to the current block;
• compare each of the approximate costs computed for the one or more most probable intra-prediction modes to a threshold;
• replace one or more of the intra-prediction modes identified in the current set of intra-prediction modes with the one or more most probable intra-prediction modes based on the comparisons;
• perform a rate distortion analysis with respect to each intra-prediction mode identified in the current set of intra-prediction modes to determine a rate distortion cost for each intra-prediction mode identified in the current set of intra-prediction modes;
• and
• perform intra-prediction coding with respect to the current block in accordance with one of the intra-prediction modes identified in the current set of intra-prediction modes based on the determined rate distortion costs to encode the current block.