Video encoding and video decoding
Decoding of a merge-predicted block is carried out, for triangular partitions of the block, using a combination of inter-prediction and intra-prediction. The combination of inter-prediction and intra-prediction to be used is signalled on a received bitstream. Combination may be algorithmic, for example arithmetic.
1. A decoder for decoding a block on a bitstream, the decoder being operable to extract triangular prediction configuration information from the bitstream, on the basis of which the decoder is operable to generate a prediction comprising two parts corresponding to a triangular partition of the block, at least one of the parts being predicted using information obtained by intra-prediction, and wherein the decoder is operable to extract, from the bitstream, triangular prediction information comprising an index to one of a plurality of sets of prediction configuration attributes, each set of prediction configuration attributes being capable of being used to configure the decoder to generate a prediction in accordance with a particular triangular partition-based prediction mode, wherein each set of prediction configuration attributes comprises at least one of:
an inter-prediction mode indicator on the basis of which the decoder is to form an inter-prediction for the samples in a triangular partition;
an intra-prediction mode indicator on the basis of which the decoder is to form an intra-prediction for the samples in the triangular partition.
2. A decoder in accordance with claim 1 , wherein the decoder is operable to generate said prediction in which at least one of the parts is predicted using merge prediction.
3. A decoder in accordance with claim 1 , wherein the decoder is operable to generate said prediction in which at least one of the parts is predicted on the basis of a combination of inter-prediction and intra-prediction.
4. A decoder in accordance with claim 1 , wherein the decoder is operable to extract, from the bitstream, prediction configuration attributes capable of being used to configure the decoder to generate a prediction in accordance with a particular triangular partition-based prediction mode.
5. A decoder in accordance with claim 1 , wherein the triangular partition comprises a first triangular partition and each set of prediction configuration attributes comprises a split attribute indicative of the direction in which samples of a block are triangularly partitioned into the first triangular partition and a second triangular partitions.
6. A decoder in accordance with claim 1 , wherein each set of prediction configuration attributes comprises weightings on the basis of which the samples in each of the intra-prediction and inter-prediction are to be combined to form a combined prediction of a corresponding sample in the first triangular partition.
7. A decoder in accordance with claim 5 , wherein each set of prediction configuration attributes comprises at least one of:
an inter-prediction mode indicator on the basis of which the decoder is to form an inter-prediction for the samples in the second triangular partition;
an intra-prediction mode indicator on the basis of which the decoder is to form an intra-prediction for the samples in the second triangular partition; and
weightings on the basis of which the samples in each of the intra-prediction and inter-prediction are to be combined to form a combined prediction of a corresponding sample in the second triangular partition.
8. A decoder in accordance with claim 1 , wherein the prediction configuration attributes are at least in part computed on the basis of a list of merge candidates used for inter-prediction.
9. A decoder in accordance with claim 1 , wherein the prediction configuration attributes are at least in part computed on the basis of a list of most probable modes used for intra-prediction.
10. A decoder in accordance with claim 1 , wherein the decoder is operable to extract, from the bitstream, information comprising a flag for each triangular prediction partition, each flag determining whether the triangular partition should be predicted by means of intra-prediction in accordance with a particular triangular partition-based prediction mode.
11. A storage medium storing information defining an encoded block, the information comprising triangular prediction configuration information suitable for use by a decoder in accordance with claim 1 .
12. A method of decoding a block on a bitstream, comprising extracting triangular prediction configuration information from the bitstream, and generating a prediction comprising two parts corresponding to a triangular partition of the block, at least one of the parts being predicted using information obtained by intra-prediction, and wherein the method further comprises extracting, from the bitstream, triangular prediction information comprising an index to one of a plurality of sets of prediction configuration attributes, each set of prediction configuration attributes being capable of being used to generate a prediction in accordance with a particular triangular partition-based prediction mode, wherein each set of prediction configuration attributes comprises at least one of:
an inter-prediction mode indicator on the basis of which an inter-prediction for the samples in a triangular partition is formed;
an intra-prediction mode indicator on the basis of which an intra-prediction for the samples in the triangular partition is formed.
13. An encoder operable to encode a block for dispatch on a bitstream, the encoder being operable to generate a prediction comprising two parts corresponding to a triangular partition of the block, at least one of the parts being predicted using information obtained by intra-prediction, the encoder being operable to place on the bitstream triangular prediction configuration information for use by a decoder in producing a corresponding prediction of the block, the encoder further being operable to place on the bitstream triangular prediction information comprising an index to one of a plurality of sets of prediction configuration attributes, each set of prediction configuration attributes being capable of being used to configure said decoder to generate a prediction in accordance with a particular triangular partition-based prediction mode, wherein each set of prediction configuration attributes comprises at least one of:
an inter-prediction mode indicator on the basis of which the decoder is to form an inter-prediction for the samples in a triangular partition;
an intra-prediction mode indicator on the basis of which the decoder is to form an intra-prediction for the samples in the triangular partition.
14. A method of encoding a block for dispatch on a bitstream, comprising generating a prediction comprising two parts corresponding to a triangular partition of the block, at least one of the parts being predicted using information obtained by intra-prediction, and placing on the bitstream triangular prediction configuration information for used by a decoder in producing a corresponding prediction of the block, and placing on the bitstream triangular prediction information comprising an index to one of a plurality of sets of prediction configuration attributes, each set of prediction configuration attributes being capable of being used to configure said decoder to generate a prediction in accordance with a particular triangular partition-based prediction mode, wherein each set of prediction configuration attributes comprises at least one of:
an inter-prediction mode indicator on the basis of which an inter-prediction for the samples in a triangular partition is formed;
an intra-prediction mode indicator on the basis of which an intra-prediction for the samples in the triangular partition is formed.