Scalable video coding system with parameter signaling

Abstract

A method is provided for encoding a digital video to provide for improved color mapping. The digital video has values in a first color space, and the method includes performing a color mapping operation on values in each sub-picture to convert the values in the first color space to values in a second, narrower, color space, wherein the color mapping operation is adapted based on the content of each sub-picture, encoding the values in the second color space into a base layer, performing a reverse color mapping operation on decoded values from the base layer in the second color space in each sub-picture to generate a reconstructed reference frame having values in the first color space, encoding values in the first color space into an enhancement layer based at least in part on the reconstructed reference frame, combining the base layer and the enhancement layer into a bitstream, sending the bitstream to a decoder, and sending one or more parameters to the decoder that describe the adaption of the reverse color mapping operation for at least some sub-pictures.

1 . A method of encoding a digital video, comprising:
 receiving a digital video at a video encoder, said digital video comprising values in a first color space;   performing a color mapping operation on values in each sub-picture at said video encoder to convert said values in said first color space to values in a second color space, wherein said video encoder adapts said color mapping operation based on the content of each sub-picture using a procedure that is independent of color mapping operations of other sub-pictures;   encoding said values in said second color space into a base layer;   decoding and performing a reverse color mapping operation on said values in said second color space in each sub-picture as decoded from said base layer to generate a reconstructed reference frame having values in said first color space;   encoding said values in said first color space into an enhancement layer based at least in part on said reconstructed reference frame;   combining said base layer and said enhancement layer into a bitstream;   sending said bitstream to a decoder;   sending one or more parameters to said decoder that describe the adaptation of said reverse color mapping operation for at least some sub-pictures.   
     
     
         2 . A method of decoding a digital video, comprising:
 receiving a bitstream comprising a base layer and an enhancement layer at a video decoder;   receiving one or more parameters associated with at least some sub-pictures;   decoding base layer values in a first color space from said base layer;   performing a reverse color mapping operation on said base layer values within each subpicture,   to generate a reconstructed reference picture having values in a second color space that is wider than said first color space, wherein said video decoder adapts said reverse color mapping operation for each sub-picture based on received parameters associated with that sub-picture using a procedure that is independent of color mapping operations of other sub-pictures; and   decoding enhancement layer values in said second color space from said enhancement layer using prediction based on said reconstructed reference picture.   
     
     
         3 . The method of  claim 2 , further comprising predicting parameters for sub-pictures for which parameters were not received, based on received parameters associated with neighboring sub-pictures. 
     
     
         4 . The method of  claim 2 , further comprising:
 reversing a previously performed color mapping operation performed on sub-pictures of a reference frame using a first set of parameters associated with the sub-pictures of the reference frame;   re-mapping the sub-pictures of a reference frame with a color mapping operation using a second set of parameters associated with a current sub-picture; and   decoding the current sub-picture with reference to the re-mapped sub-pictures of the reference frame.   
     
     
         5 . A video encoder, comprising:
 a data transmission interface configured to receive a digital video comprising full resolution values; and   a processor configured to:
 perform a downsampling operation to convert said full resolution values into downsampled values; 
 encode said downsampled values into a base layer; 
 decode said base layer into reconstructed downsampled values; 
 perform an upsampling operation on said reconstructed downsampled values to generate a reconstructed full resolution reference frame for a particular coding level; 
 encode said full resolution values into an enhancement layer based at least in part on said reconstructed full resolution reference frame; and 
 combine said base layer and said enhancement layer into a bitstream, wherein said data transmission interface is further configured to: 
 send said bitstream to a decoder; and 
 send one or more parameters to said decoder that describe said upsampling operation for said particular coding level. 
   
     
     
         6 . The video encoder of  claim 5 , wherein said upsampling operation is a color mapping operation that converts a triplet of values from a first color space to a corresponding spatial location in a second color space. 
     
     
         7 . The video encoder of  claim 5 , wherein said particular coding level is a sub-picture level for encoding one or more sub-pictures within said digital video. 
     
     
         8 . The video encoder of  claim 5 , wherein said particular coding level is a picture level for encoding a picture within said digital video. 
     
     
         9 . The video encoder of  claim 8 , wherein said parameters are sent in a picture parameter set associated with said picture. 
     
     
         10 . The video encoder of  claim 5 , wherein said particular coding level is a supra-picture level for encoding a sequence of pictures within said digital video. 
     
     
         11 . The video encoder of  claim 10 , wherein said parameters are sent in a supplemental enhancement information (SEI) message associated with said sequence of pictures. 
     
     
         12 . A video decoder, comprising:
 a data transmission interface configured to receive a bitstream comprising a base layer and an enhancement layer, and one or more parameters associated with an upsampling operation for a particular coding level; and   a processor configured to:
 derive said upsampling operation for said particular coding level from said one or more parameters; 
 decode said base layer into values at a downsampled resolution; 
 perform said upsampling operation to generate a reconstructed reference picture at a full resolution; and 
 decode a picture in said enhancement layer using said reconstructed reference picture. 
   
     
     
         13 . The video decoder of  claim 12 , wherein said upsampling operation is a color mapping operation that converts a triplet of values from a first color space to a corresponding spatial location in a second color space. 
     
     
         14 . The video decoder of  claim 12 , wherein said upsampling operation is a two-dimensional filter selected from a set of two-dimensional filters. 
     
     
         15 . The video decoder of  claim 12 , wherein said upsampling operation is a transfer function. 
     
     
         16 . The video decoder of  claim 12 , wherein said particular coding level is a sub-picture level for encoding one or more sub-pictures within said digital video. 
     
     
         17 . The video decoder of  claim 12 , wherein said particular coding level is a picture level for encoding a picture within said digital video. 
     
     
         18 . The video decoder of  claim 17 , wherein said parameters are sent in a picture parameter set associated with said picture. 
     
     
         19 . The video decoder of  claim 18 , wherein said particular coding level is a supra-picture level for encoding a sequence of pictures within said digital video. 
     
     
         20 . The video decoder of  claim 19 , wherein said parameters are sent in a supplemental enhancement information (SEI) message associated with said sequence of pictures. 
     
     
         21 . A method of decoding a digital video signal, comprising:
 receiving in a video decoder a bitstream containing the digital video signal, the bitstream comprising a base layer and an enhancement layer, where said digital video signal includes a plurality of sequential frames;   receiving one or more sets of parameters, each associated with a respective one or more of said plurality of sequential frames in the bitstream, each of the frames having a different temporal position within said digital video signal;   decoding base layer values in a first color space in said base layer;   within each of the frames, performing a reverse color mapping operation on said base layer values within each respective frame using the set of parameters respectively associated with the respective frame, to generate a reconstructed reference frame having values in a second color space wider than said first color space, wherein said reverse color mapping operation for each respective frames maps a color in the first color space of the base layer to a color in the second color space of the base layer, wherein the mapping of a color in the first color space to a color in the second color space differs between at least two of the plurality of frames; and   decoding enhancement layer values in said second color space in said enhancement layer using prediction based on said reconstructed reference picture and providing the decoder output to a video player; wherein   the decoding of the enhancement layer comprises decoding a current frame with reference to the re-mapped frame output.