Intra Prediction For Multi-Hypothesis

Abstract

A video decoder that decodes a current block of pixels by using multi-hypothesis combined prediction mode is provided. The video decoder generates a first prediction of the current block based on an inter prediction mode. The video decoder enables the combined prediction mode for the current block based on a block size of the current block determined according to a width and a height of the current block. The combined prediction mode is disabled when the width of or the height of the current block is greater than a threshold length. When the combined prediction mode is enabled, the video decoder generates a second prediction and a combined prediction for the current block based on the first prediction and the second prediction. The video decoder reconstructs the current block by using the combined prediction.

What is claimed is: 
     
         1 . A video decoding method comprising:
 receiving to-be-decoded data from a bitstream for a block of pixels to be decoded as a current block of a current picture of a video;   generating a first prediction of the current block based on an inter prediction mode;   determining a block size of the current block according to a width or a height of the current block;   enabling a combined prediction mode for the current block based on the block size of the current block, wherein the combined prediction mode is disabled when the width or the height of the current block is greater than a threshold length; and   when the combined prediction mode is enabled:
 generating a second prediction; 
 generating a combined prediction for the current block based on the first prediction and the second prediction; and 
 reconstructing the current block by using the combined prediction. 
   
     
     
         2 . The method of  claim 1 , wherein the second prediction is generated based on an intra prediction mode. 
     
     
         3 . The method of  claim 2 , wherein the inter prediction mode is selected from a first candidate list that comprises one or more candidate inter prediction modes and the intra prediction mode is selected from a second candidate list that comprises one or more candidate intra prediction modes. 
     
     
         4 . The method of  claim 3 , wherein the one or more inter prediction candidates of the first candidate list are identical to one or more candidates of a merge candidate list of the current block. 
     
     
         5 . The method of  claim 3 , wherein the second candidate list comprises no more than one candidate intra-prediction mode. 
     
     
         6 . The method of  claim 2 , wherein the intra prediction mode is planar mode. 
     
     
         7 . The method of  claim 2 , wherein the intra prediction mode is computed without at least one of (i) reference availability check and substitution, (ii) reference sample filtering, (iii) horizontal planar predictor generation and averaging, and (iv) position dependent intra prediction combination (PDPC). 
     
     
         8 . The method of  claim 2 , wherein generating the second prediction based on the intra prediction mode comprises (i) using the intra prediction mode to identify a set of neighboring pixels and (ii) applying an interpolation filter to the identified set of neighboring pixels to produce a set of interpolated pixels, wherein the set of interpolated pixels is used as the second prediction without further improvement. 
     
     
         9 . The method of  claim 8 , wherein the interpolation filter has three or less taps. 
     
     
         10 . The method of  claim 2 , wherein the second prediction is computed without using position dependent intra prediction combination (PDPC) or angular intra prediction. 
     
     
         11 . The method of  claim 1 , wherein the threshold length is 64. 
     
     
         12 . The method of  claim 1 , wherein the combined prediction mode is enabled when the block size of the current block is greater than or equal to 64. 
     
     
         13 . A video encoding method comprising:
 receiving raw pixel data for a block of pixels to be encoded as a current block of a current picture of a video into a bitstream;   generating a first prediction of the current block based on an inter prediction mode;   determining a block size of the current block according to a width or a height of the current block;   enabling a combined prediction mode for the current block based on the block size of the current block, wherein the combined prediction mode is disabled when the width or the height of the current block is greater than a threshold length; and   when the combined prediction mode is enabled:
 generating a second prediction; 
 generating a combined prediction for the current block based on the first prediction and the second prediction; and 
 encoding the current block into the bitstream by using the combined prediction. 
   
     
     
         14 . An electronic apparatus comprising:
 a video decoder circuit capable of:
 receiving to-be-decoded data from a bitstream for a block of pixels to be decoded as a current block of a current picture of a video; 
 generating a first prediction of the current block based on an inter prediction mode; 
 determining a block size of the current block according to a width or a height of the current block; 
 enabling a combined prediction mode for the current block based on the block size of the current block, wherein the combined prediction mode is disabled when the width or the height of the current block is greater than a threshold length; and 
 when the combined prediction mode is enabled:
 generating a second prediction; 
 generating a combined prediction for the current block based on the first prediction and the second prediction; and 
 reconstructing the current block by using the combined prediction. 
 
   
     
     
         15 . A video coding method comprising:
 receiving data to be encoded or decoded as a current block of a current picture of a video;   generating a first prediction of the current block based on an inter prediction mode;   determining a block size of the current block according to a width or a height of the current block;   enabling a combined prediction mode for the current block based on the block size of the current block, wherein the combined prediction mode is disabled when the width or the height of the current block is greater than a threshold length; and   when the combined prediction mode is enabled:
 generating a second prediction; 
 generating a combined prediction for the current block based on the first prediction and the second prediction; and 
 using the combined prediction to reconstruct the current block or to encode the current block into a bitstream.