Techniques For Resource Conservation During Performance Of Intra Block Copy Prediction Searches

Abstract

Methods are described for encoding and decoding blocks of image data using intra block copying (IBC). A source block for intra block copying is selected from a source region of a current image that is closer to the current block than a threshold, wherein the source region does not include a portion of the current image that is further from the current block than the threshold.

We claim: 
     
         1 . A method for image block coding, comprising:
 coding blocks of an input image on a block-by-block basis;   decoding the coded blocks; and   storing decoded blocks of the input image in a buffer;   wherein the coding, for a given block, comprises searching for a prediction reference for the given block from within a source region of the buffer and comprises outputting an indication of the prediction reference; wherein the source region is constrained to a first portion of the input image within a predetermined distance of the given block.   
     
     
         2 . The method of  claim 1 , further comprising evicting decoded blocks from storage when they are separated from a given block by more than the predetermined distance. 
     
     
         3 . The method of  claim 1 , further comprising:
 filtering decoded blocks of the input image,   storing filtered blocks of the input image in the buffer, wherein the searching for a prediction reference includes searching among the filtered blocks and is constrained to the first portion of the input image within a predetermined distance of the given block.   
     
     
         4 . The method of  claim 1 , wherein the threshold is determined by a height measured from the current block. 
     
     
         5 . The method of  claim 1 , wherein the threshold is determined by a block count threshold measured from the current block. 
     
     
         6 . The method of  claim 5 , wherein the block count threshold is a count of coding unit (CU) or largest coding unit (LCU) sized blocks. 
     
     
         7 . A method for video decoding, comprising:
 decoding coded video data received from a channel on a pixel block-by-pixel block basis, wherein the coded video data includes, for a given pixel block, an indication of a reference pixel block, wherein the decoding comprises predicting the given pixel block from within a source region of a buffer;   storing the decoded pixel blocks in the buffer;   following the decoding of the given pixel block, adjusting the source region to include a first portion of the current image that is closer to the given pixel block than a threshold and to not include a second portion of the current image that is further from the current block than the threshold; and   relinquishing the second portion.   
     
     
         8 . The method of  claim 7 , wherein the decoded region is relinquished by freeing it from memory. 
     
     
         9 . The method of  claim 7 , further comprising:
 filtering the decoded blocks in the second portion; and   storing the filtered blocks in the buffer.   
     
     
         10 . The method of  claim 7 , wherein the threshold distance includes a height measured from the current block within the current image. 
     
     
         11 . The method of  claim 7 , wherein the threshold distance includes a block count measured from the current block within the current image. 
     
     
         12 . A system for image block coding, comprising a processor and memory, the memory containing instructions that, when executed on the processor, cause the system to at least:
 code blocks of an input image on a block-by-block basis;   decode the coded blocks; and   store decoded blocks of the input image in a buffer;   wherein the coding, for a given block, comprises searching for a prediction reference for the given block from within a source region of the buffer and comprises outputting an indication of the prediction reference; wherein the source region is constrained to a first portion of the input image within a predetermined distance of the given block.   
     
     
         13 . The system of  claim 12 , further comprising instructions to evict decoded blocks from storage when they are separated from a given block by more than the predetermined distance. 
     
     
         14 . The system of  claim 12 , further comprising instructions to:
 filter decoded blocks of the input image,   store filtered blocks of the input image in the buffer, wherein the searching for a prediction reference includes searching among the filtered blocks and is constrained to the first portion of the input image within a predetermined distance of the given block.   
     
     
         15 . The system of  claim 12 , wherein the threshold is determined by a height measured from the current block. 
     
     
         16 . The system of  claim 12 , wherein the threshold is determined by a block count threshold measured from the current block. 
     
     
         17 . The system of  claim 16 , wherein the block count threshold is a count of CU or LCU sized blocks. 
     
     
         18 . A system for video decoding, comprising a processor and memory, the memory containing instructions that, when executed on the processor, cause the system to at least:
 decode coded video data received from a channel on a pixel block-by-pixel block basis, wherein the coded video data includes, for a given pixel block, an indication of a reference pixel block; wherein the decoding comprises predicting the given pixel block from within a source region of a buffer;   store the decoded pixel blocks in the buffer;   following the decoding of the given pixel block, adjust the source region to include a first portion of the current image that is closer to the given pixel block than a threshold and to not include a second portion of the current image that is further from the current block than the threshold, and   relinquish the second portion.   
     
     
         19 . The system of  claim 18 , wherein the decoded region is relinquished by freeing it from memory. 
     
     
         20 . The system of  claim 18 , further comprising instructions to:
 filter the decoded blocks in the second portion; and   store the filtered blocks in the buffer.   
     
     
         21 . The system of  claim 18 , wherein the threshold distance includes a height measured from the current block within the current image. 
     
     
         22 . The system of  claim 18 , wherein the threshold distance includes a block count measured from the current block within the current image.