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, the base layer signal to generate a reconstructed 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, the 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, and
predictively reconstructing the enhancement layer signal using the inter-layer prediction signal,
wherein the first decoding unit is configured to decode, using the processor, first side information from the coded data stream, the first side information indicating application of none, one, or both of sample adaptive offset filtering and deblocking filtering of the base layer signal to reconstruct the base layer signal, and
the second decoding unit is configured to decode, using the processor, second side information from the coded data stream, the second side information indicating application of none, one, or both of sample adaptive offset filtering and deblocking filtering of the enhancement layer signal to reconstruct the enhancement layer signal,
wherein the scalability refinement includes a bit depth refinement, a quality refinement or a resolution refinement, and the second decoding unit is configured to perform, using the processor, the scalability refinement by up-sampling the base layer signal to perform the resolution refinement.
2. The video decoder of claim 1 , wherein the first decoding unit is configured to reconstruct, using the processor, 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, using the processor, the scalability refinement by tone-mapping from n bits to m bits with m>n so as to achieve the bit depth refinement.
4. The video decoder of claim 1 , wherein the second decoding unit is configured to perform, using the processor, a predictive reconstruction by spatially or temporally predicting a portion of the 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 signal.
5. The video decoder of claim 4 , wherein the second decoding unit is configured to perform, using the processor, 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 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 signal vary over different spatial frequency components.
7. The video decoder of claim 1 , wherein deblocking and/or sample adaptive offset filtering varies in transfer function according to the first side information and the second 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:
decoding first side information from the data stream, the first side information indicating application of none, one, or both of sample adaptive offset filtering and deblocking filtering of the base layer signal;
reconstructing, using a processor, the base layer signal to generate a reconstructed base layer signal based on transform decoding of a base layer residual signal from the data stream and the first side information;
decoding second side information from the data stream, the second side information indicating application of none, one, or both of sample adaptive offset filtering and deblocking filtering of the enhancement layer signal; 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, and
predictively reconstructing the enhancement layer signal using the inter-layer prediction signal and based on the second side information,
wherein the scalability refinement includes a bit depth refinement, a quality refinement or a resolution refinement, and the base layer signal is upsampled to perform the resolution refinement.
9. The non-transitory computer-readable medium of claim 8 , the base layer signal is reconstructed based on block-based prediction coding.
10. A video encoder for encoding a video, comprising:
a first encoding unit including a base layer coder configured to, using a processor, determine a base layer residual signal for a base layer of the video, and encode into an coded 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 coder 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, and
predictively encoding the enhancement layer signal using the inter-layer prediction signal,
wherein the first encoding unit is configured to encode, using the processor, first side information into the coded data stream, the first side information indicating application of none, one, or both of sample adaptive offset filtering and deblocking filtering of the base layer signal to encode the base layer signal, and
the second encoding unit is configured to encode, using the processor, second side information into the coded data stream, the second side information indicating application of none, one, or both of sample adaptive offset filtering and deblocking filtering of the enhancement layer signal to encode the enhancement layer signal,
wherein the scalability refinement includes a bit depth refinement, a quality refinement or a resolution refinement, and the second encoding unit is configured to perform, using the processor, the scalability refinement by up-sampling the base layer signal to perform the resolution refinement.
11. The video encoder of claim 10 , wherein the first encoding unit is configured to encode, using the processor, the base layer signal based on block-based prediction coding.
12. The video encoder of claim 10 , wherein the second encoding unit is configured to perform, using the processor, the scalability refinement by tone-mapping from n bits to m bits with m>n so as to achieve the bit depth refinement.
13. The video encoder of claim 10 , wherein the second encoding unit is configured to perform, using the processor, the predictive encoding by spatially or temporally predicting a portion of the 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 signal.
14. The video encoder of claim 13 , wherein the second encoding unit is configured to perform, using the processor, 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 signal.