Adaptive weighting of reference pictures in video encoding

Abstract

A video decoder, encoder, and corresponding methods for processing video data for an image block and a particular reference picture index to predict the image block are disclosed that utilize adaptive weighting of reference pictures to enhance video compression, where a decoder includes a reference picture weighting factor unit for determining a weighting factor corresponding to the particular reference picture index; an encoder includes a reference picture weighting factor assignor for assigning a weighting factor corresponding to the particular reference picture index; and a method for decoding includes receiving a reference picture index with the data that corresponds to the image block, determining a weighting factor for each received reference picture index, retrieving a reference picture for each index, motion compensating the retrieved reference picture, and multiplying the motion compensated reference picture by the corresponding weighting factor to form a weighted motion compensated reference picture.

1 . A video encoder for encoding video data for an image block and a particular reference picture index, the reference picture index used for encoding the image block, the encoder assigning an offset corresponding to the particular reference picture index,
 wherein the particular reference picture index independently indicates, without use of another index, (1) a particular reference picture corresponding to the particular reference picture index and (2) the offset corresponding to the particular reference picture index.   
     
     
         2 . A video encoder as defined in  claim 1 , further comprising a reference picture store for providing a reference picture corresponding to the particular reference picture index. 
     
     
         3 . A video encoder as defined in  claim 1 , further comprising:
 a reference picture weighting factor assignor for assigning a weighting factor corresponding to the particular reference picture index; and   a variable length coder in communication with the reference picture weighting factor assignor.   
     
     
         4 . A video encoder as defined in  claim 3 , further comprising a motion compensation unit in communication with the reference picture weighting factor assignor for providing motion compensated reference pictures responsive to the reference picture weighting factor assignor. 
     
     
         5 . A video encoder as defined in  claim 4 , further comprising a multiplier in communication with the motion compensation unit and the reference picture weighting factor assignor for applying a weighting factor to a motion compensated reference picture predictor. 
     
     
         6 . A video encoder as defined in  claim 5  usable with bi-predictive picture predictors, the encoder further comprising prediction means for forming first and second predictors from two different reference pictures. 
     
     
         7 . A video encoder as defined in  claim 6  wherein the two different reference pictures are both from the same direction relative to the image block picture.