Method for performing hybrid multihypothesis prediction during video coding of a coding unit, and associated apparatus
A method for performing hybrid multihypothesis prediction during video coding of a coding unit includes: processing a plurality of sub-coding units in the coding unit; and performing motion vector derivation of a portion of the sub-coding units. More particularly, the step of performing motion vector derivation of the portion of the sub-coding units further includes: deriving a plurality of motion vectors for multihypothesis motion-compensated prediction of a specific sub-coding unit of the portion of the sub-coding units from at least one other sub-coding/coding unit or by performing motion estimation. The method further includes performing multihypothesis motion-compensated prediction on the specific sub-coding unit according to the plurality of motion vectors, and more particularly, includes utilizing a linear combination of a plurality of pixel values derived from the plurality of motion vectors as a predicted pixel value of the specific sub-coding unit. An associated apparatus is also provided.
1. A method for performing hybrid multihypothesis prediction during video coding of a coding unit, the method comprising:
processing a plurality of sub-coding units in the coding unit;
performing motion vector derivation of a portion of the sub-coding units, wherein the step of performing motion vector derivation of the portion of the sub-coding units further comprises:
deriving a plurality of motion vectors for multihypothesis motion-compensated prediction of a specific sub-coding unit of the portion of the sub-coding units, at least one of motion vectors is the motion vector of one other sub-coding/coding unit, and the one other sub-coding/coding unit is coded before the corresponding motion vector is derived for multihypothesis motion-compensated prediction of the specific sub-coding unit; and
performing multihypothesis motion-compensated prediction on the specific sub-coding unit according to the plurality of motion vectors, wherein the step of performing multihypothesis motion-compensated prediction on the specific sub-coding unit according to the plurality of motion vectors further comprises:
utilizing a linear combination of a plurality of pixel values derived from the plurality of motion vectors as a predicted pixel value of the specific sub-coding unit.
2. The method of claim 1 , wherein the step of performing multihypothesis motion-compensated prediction on the specific sub-coding unit according to the plurality of motion vectors further comprises:
calculating a weighted summation of the plurality of pixel values to derive the predicted pixel value of the specific sub-coding unit.
3. The method of claim 1 , wherein the step of performing multihypothesis motion-compensated prediction on the specific sub-coding unit according to the plurality of motion vectors further comprises:
calculating an average of the plurality of pixel values to derive the predicted pixel value of the specific sub-coding unit.
4. The method of claim 1 , wherein the step of performing motion vector derivation of the portion of the sub-coding units further comprises:
performing motion vector derivation of the portion of the sub-coding units based on an explicit flag.
5. The method of claim 1 , wherein the plurality of motion vectors is derived from a remaining portion of the sub-coding units in the coding unit.
6. The method of claim 5 , wherein motion vector prediction of the remaining portion of the sub-coding units is performed before performing multihypothesis motion-compensated prediction of the portion of the sub-coding units.
7. The method of claim 1 , wherein the step of processing the plurality of sub-coding units in the coding unit further comprises:
determining a size of the specific sub-coding unit to be a transform size regarding video coding of the coding unit.
8. The method of claim 1 , wherein the step of processing the plurality of sub-coding units in the coding unit further comprises:
based on a predetermined pattern, an implicit flag, or an explicit flag, determining distribution of the portion of the sub-coding units for performing multihypothesis motion-compensated prediction.
9. The method of claim 8 , wherein the implicit flag is derived from one or a combination of a bitstream carrying the coding unit, motion vectors of coded sub-coding/coding units, a motion vector variance of the coded sub-coding/coding units, a quantization parameter (QP) value, a bit-rate, a reconstructed residual signal of the coded sub-coding/coding units, a transmitted discrete cosine transform (DCT) coefficient, a motion partition type, a block size, and statistical data.
10. The method of claim 1 , wherein the at least one other sub-coding/coding unit is a coded sub-coding/coding unit.
11. The method of claim 10 , wherein the at least one other sub-coding/coding unit comprises at least one spatially coded sub-coding/coding unit and/or at least one temporally coded sub-coding/coding unit.
12. The method of claim 1 , wherein the at least one other sub-coding/coding unit is a motion-compensated sub-coding/coding unit.
13. The method of claim 1 , wherein the at least one other sub-coding unit/coding unit is a sub-coding unit in a neighboring coding unit.
14. The method of claim 1 , wherein the plurality of motion vectors are derived from a single sub-coding unit/coding unit.
15. An apparatus for performing hybrid multihypothesis prediction during video coding of a coding unit, the apparatus comprising:
a processing circuit arranged to perform video coding on the coding unit, wherein the processing circuit comprises:
a preprocessing module arranged to process a plurality of sub-coding units in the coding unit and perform motion vector derivation of a portion of the sub-coding units, wherein the preprocessing module derives a plurality of motion vectors for multihypothesis motion-compensated prediction of a specific sub-coding unit of the portion of the sub-coding units, wherein at least one of motion vectors is the motion vector of one other sub-coding/coding unit and the one other sub-coding/coding unit is coded before the corresponding motion vector is derived for multihypothesis motion-compensated prediction of the specific sub-coding unit, and performs multihypothesis motion-compensated prediction on the specific sub-coding unit according to the plurality of motion vectors, and the preprocessing module utilizes a linear combination of a plurality of pixel values derived from the plurality of motion vectors as a predicted pixel value of the specific sub-coding unit; and
at least one coding module arranged to perform video coding on the coding unit based upon the multihypothesis motion-compensated prediction performed by the preprocessing module.
16. The apparatus of claim 15 , wherein the preprocessing module calculates a weighted summation of the plurality of pixel values to derive the predicted pixel value of the specific sub-coding unit.
17. The apparatus of claim 15 , wherein the preprocessing module calculates an average of the plurality of pixel values to derive the predicted pixel value of the specific sub-coding unit.
18. The apparatus of claim 15 , wherein the preprocessing module performs motion vector derivation of the portion of the sub-coding units based on an explicit flag.
19. The apparatus of claim 15 , wherein the preprocessing module derives the motion vectors from a remaining portion of the sub-coding units in the coding unit.
20. The apparatus of claim 19 , wherein the preprocessing module performs motion vector prediction on the remaining portion of the sub-coding units before performing multihypothesis motion-compensated prediction on the portion of the sub-coding units.
21. The apparatus of claim 15 , wherein the preprocessing module determines a size of the specific sub-coding unit to be a transform size regarding video coding of the coding unit.
22. The apparatus of claim 15 , wherein based on a predetermined pattern, an implicit flag, or an explicit flag, the preprocessing module determines distribution of the portion of the sub-coding units for performing multihypothesis motion-compensated prediction.
23. The apparatus of claim 22 , wherein the implicit flag is derived from one or a combination of a bitstream carrying the coding unit, motion vectors of coded sub-coding/coding units, a motion vector variance of the coded sub-coding/coding units, a quantization parameter (QP) value, a bit-rate, a reconstructed residual signal of the coded sub-coding/coding units, a transmitted discrete cosine transform (DCT) coefficient, a motion partition type, a block size, and statistical data.
24. The apparatus of claim 15 , wherein the at least one other sub-coding/coding unit is a coded sub-coding/coding unit.
25. The apparatus of claim 24 , wherein the at least one other sub-coding/coding unit comprises at least one spatially coded sub-coding/coding unit and/or at least one temporally coded sub-coding/coding unit.
26. The apparatus of claim 15 , wherein the at least one other sub-coding/coding unit is a motion-compensated sub-coding/coding unit.
27. The apparatus of claim 15 , wherein the at least one other sub-coding unit/coding unit is a sub-coding unit in a neighboring coding unit.
28. The apparatus of claim 15 , wherein the plurality of motion vectors are derived from a single sub-coding unit/coding unit.