Region specific encoding and sao-sensitive-slice-width-adaptation for improved-quality hevc encoding

Abstract

A method provides for encoding a frame of video using an edge map made up of one or more edge-blocks detected in the frame. When the edge-blocks are contiguous, at least one slice partition is formed using the edge-blocks and the slice partition is encoded using a sample adaptive offset (SAO) filter, wherein the slice partition is formed with an adaptive slice width, and the sample adaptive offset (SAO) filter is turned on or off during the encoding based on whether the edge-blocks are being encoded. When the edge-blocks are not contiguous, edge-block processing is performed around edges in the frame during encoding of the edge-blocks. The edge-block processing involves configuring one or more of: an intra block size, a transform block size, an inter prediction block size, a quantization parameter, candidate modes for intra prediction, pyramid level for motion estimation, and fractional pixel motion estimation search.

What is claimed is: 
     
         1 . A method of encoding frames of video, comprising:
 (a) processing blocks in the frames to classify the blocks as having a first degree of edges and a second degree of edges, where said first degree of edges is greater than said second degree of edges, constructing maps for respective said blocks having said first degree of edges or said second degree of edges of said frames, based upon the respective maps (i) forming at least one first slice partitioning having a size so as to enclose said first degree of edges of said blocks, and (ii) forming at least one second slice partitioning having a size so as to enclose said second degree of edges of said blocks;   (b) encoding blocks in the at least one first slice partition using a sample adaptive offset (SAO) filter;   (c) encoding blocks in the at least one second slice partition by performing edge-block processing in the second slice partition, without applying a SAO filter to edge blocks in the second partition.   
     
     
         2 . The method of  claim 1  further comprising wherein the SAO filter is disabled while encoding the at least one second slice partition. 
     
     
         3 . The method of  claim 1 , wherein the slice partition is formed with an adaptive slice width. 
     
     
         4 . The method of  claim 1 , wherein the at least one slice partition comprises a plurality of slice partitions and the plurality of slice partitions are processed in parallel. 
     
     
         5 . The method of  claim 1 , wherein the map is detected by an edge operator. 
     
     
         6 . The method of  claim 1 , wherein the map is detected by classification of samples in the frame as edges or non-edges, and by classification of blocks as edge-blocks or non-edge-blocks based on the classification of the samples. 
     
     
         7 . The method of  claim 6 , wherein the map is detected by a gradient or differences computation in a sample domain of the frame. 
     
     
         8 . The method of  claim 7 , wherein a lower threshold and a higher threshold are used on the gradient or differences computation in order to generate the map. 
     
     
         9 . The method of  claim 8 , wherein the lower threshold and the higher threshold are used on a number of edge samples per individual block to classify the individual block as one of edge-blocks or one of non-edge-blocks. 
     
     
         10 . The method of  claim 9 , wherein the lower and higher threshold are scaled based on the individual block's size used during the encoding for decisions within the individual block.