Scalable video coding using derivation of subblock subdivision for prediction from base layer
Scalable video coding is rendered more efficient by deriving/selecting a subblock subdivision to be used for enhancement layer prediction, among a set of possible subblock subdivisions of an enhancement layer block by evaluating the spatial variation of the base layer coding parameters over the base layer signal. By this measure, less of the signalization overhead has to be spent on signaling this subblock subdivision within the enhancement layer data stream, if any. The subblock subdivision thus selected may be used in predictively coding/decoding the enhancement layer signal.
1. A video decoder for decoding a video represented by a base layer signal and an enhancement layer signal, the video decoder comprising:
a first decoding unit including a base layer decoder configured to reconstruct, using a processor, a base layer signal based on transform decoding of a base layer residual signal from a coded data stream; and
a second decoding unit including an enhancement layer decoder configured to reconstruct, using the processor, an enhancement layer signal from the coded data stream at least by:
determining an inter-layer prediction signal based on a scalability refinement of the reconstructed base layer signal, the scalability refinement including bit-depth refinement, the bit-depth refinement being based on tone-mapping from n bits to m bits with m>n, and
predictively reconstructing the enhancement layer signal using the inter-layer prediction signal, wherein the first and second decoding units are configured to reconstruct the base layer and enhancement layer signals, respectively, based on one of the following:
bypassing both deblocking filtering and in-loop filtering,
bypassing one, and using the other, of the deblocking filtering and the in-loop filtering, and using both of the deblocking and the in-loop filtering;
wherein the first and second decoding units are configured to bypass or use one or both of the deblocking filtering and the in-loop filtering based on: (i) first side information in the coded data stream signaling a combination of the deblocking filtering and the in-loop filtering used to obtain the base layer signal, and (ii) second side information in the coded data stream signaling a combination of the deblocking filtering and the in-loop filtering used to obtain a base layer signal which is used in the predictive reconstruction of the enhancement layer signal.
2. The video decoder of claim 1 , wherein the first decoding unit is configured to reconstruct the base layer signal from the coded data stream based on block-based prediction coding.
3. The video decoder of claim 1 wherein the second decoding unit is configured to perform the sociability refinement by up-sampling the reconstructed base layer signal so as to achieve the resolution refinement.
4. The video decoder of claim 1 , wherein the second decoding unit is configured to perform the predictive reconstruction by
spatially or temporally predicting a portion of an enhancement layer signal, currently to be reconstructed, from an already reconstructed portion of the enhancement layer signal to acquire an enhancement layer internal prediction signal, and
combining the inter-layer prediction signal and the enhancement layer internal prediction signal to acquire the enhancement layer prediction signal.
5. The video decoder of claim 4 , wherein the second decoding unit is configured to perform the combining by forming, at a portion currently to be reconstructed, a weighted average of the inter-layer prediction signal and the enhancement layer internal prediction signal to acquire the enhancement layer prediction signal.
6. The video decoder of claim 5 , wherein weights at which the inter-layer prediction signal and the enhancement layer internal prediction signal contribute to the enhancement layer prediction signal vary over different spatial frequency components.
7. The video decoder of claim 1 , wherein the deblocking and/or in-loop filtering varies in transfer function according to side information in the coded data stream.
8. A non-transitory computer-readable medium for storing data associated with a video, comprising a data stream stored in the non-transitory computer-readable medium, the data stream comprising information related to an encoded video represented by a base layer signal and an enhancement layer signal, wherein the data stream is decoded using a plurality of operations including:
reconstructing, using a processor, the base layer signal based on transform decoding of a base layer residual signal from the data stream; and
reconstructing, using the processor, the enhancement layer signal from the data stream at least by:
determining an inter-layer prediction signal based on a scalability refinement of the reconstructed base layer signal, the scalability refinement including bit-depth refinement, the bit-depth refinement being based on tone-mapping from n bits to m bits with m>n, and
predictively reconstructing the enhancement layer signal using the inter-layer prediction signal, wherein the reconstructing of the base layer and enhancement layer signals, respectively, is based on one of the following:
bypassing both deblocking filtering and in-loop filtering,
bypassing one, and using the other, of the deblocking filtering and the in-loop filtering, and using both of the deblocking and the in-loop filtering;
wherein the bypassing or using of one or both of the deblocking filtering and the in-loop filtering are based on: (i) first side information in the data stream signaling a combination of the deblocking filtering and the in-loop filtering used to obtain the base layer signal, and (ii) second side information in the data stream signaling a combination of the deblocking filtering and the in-loop filtering used to obtain a base layer signal which is used in the predictive reconstruction of the enhancement layer signal.
9. A video encoder for encoding a video, comprising:
a first encoding unit including a base layer encoder configured to, using a processor, determine a base layer residual signal for a base layer of the video, and encode into a data stream a base layer signal based on transform decoding of the base layer residual signal; and
a second encoding unit including an enhancement layer encoder configured to encode, using the processor, an enhancement layer signal into the coded data stream at least by:
determining an inter-layer prediction signal based on a scalability refinement of the base layer signal, the scalability refinement including bit-depth refinement, the bit-depth refinement being based on tone-mapping from n bits to m bits with m>n, and predictively encoding the enhancement layer signal using the inter-layer prediction signal, wherein the first and second encoding units are configured to encode the base layer and enhancement layer signals, respectively, based on one of the following:
bypassing both deblocking filtering and in-loop filtering,
bypassing one, and using the other, of the deblocking filtering and the in-loop filtering, and using both of the deblocking and the in-loop filtering;
wherein the first and second decoding units are configured to bypass or use one or both of the deblocking filtering and the in-loop filtering based on: (i) first side information in the coded data stream signaling a combination of the deblocking filtering and the in-loop filtering used to obtain the base layer signal, and (ii) second side information in the coded data stream signaling a combination of the deblocking filtering and the in-loop filtering used to obtain a base layer signal which is used in the predictive reconstruction of the enhancement layer signal.
10. The video encoder of claim 9 , wherein the first encoding unit is configured to encode the base layer signal based on block-based prediction coding.
11. The video encoder of claim 9 , wherein the second encoding unit is configured to perform the sea/ability refinement by up-sampling the reconstructed base layer signal so as to achieve the resolution refinement.
12. The video encoder of claim 9 , wherein the second encoding unit is configured to perform the predictive encoding by
spatially or temporally predicting a portion of an enhancement layer signal, currently to be encoded, from an already encoded portion of the enhancement layer signal to acquire an enhancement layer internal prediction signal, and
combining the inter-layer prediction signal and the enhancement layer internal prediction signal to acquire the enhancement layer prediction signal.
13. The video encoder of claim 12 , wherein the second encoding unit is configured to perform the combining by forming, at a portion currently to be encoded, a weighted average of the inter-layer prediction signal and the enhancement layer internal prediction signal to acquire the enhancement layer prediction signal.