Scalable video coding system with parameter signaling
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 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;
receiving one or more sets of parameters, each associated with a respective one of a plurality of sub-pictures in the bitstream, each of the subpictures having a different spatial position within a picture relative to other said subpictures;
decoding base layer values in a first color space in said base layer;
within each of the sub-pictures, performing a reverse color mapping operation on said base layer values within each respective subpicture using the set of parameters respectively associated with the respective sub-picture, to generate a reconstructed reference picture having values in a second color space wider than said first color space, wherein said reverse color mapping operation for each respective subpicture 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 sub-pictures; 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 sub-picture with reference to the re-mapped sub-pictures output.
2. The method of claim 1 , further comprising predicting parameters for sub-pictures for which parameters were not received, based on received parameters associated with neighboring sub-pictures.