Method and apparatus for compressing coding unit in high efficiency video coding
In HEVC (High Efficiency Video Coding), a 2N×2N coding unit can be partitioned into various partition types hierarchically. The coding system uses a criterion to determine the best partition, where RD-rate is often used as the criterion. N×N partition at level k becomes redundant if 2N×2N at level k+1 will be evaluated. In order to eliminate the above redundancy, the allowable partition sizes are constrained according to a method previously disclosed. In the current invention, the complexity is further reduced. According to one embodiment, N×N partition is not allowed for any INTER mode regardless of the coding unit size. Furthermore, flexibility is provided so that either the method and apparatus with further complexity reduction can be selected or an alternative method and apparatus can be selected. Syntaxes to support embodiments according to the present invention are also disclosed.
1. A method for decoding of a video bitstream in a video decoder, the method comprising:
receiving a first indication signal from the video bitstream;
selecting a decoding process from a group consisting of a first decoding process and a second decoding process according to the first indication signal;
determining CU structure for a current coding unit (CU) associated with the video bitstream using the decoding process selected; and
reconstructing the current CU according to the CU structure determined; and
wherein when the first decoding process is selected, said determining CU structure uses a first CU structure without INTER N×N with N=4 for a 2N×2N CU.
2. The method of claim 1 , wherein the decoding process selected is used to determine the CU structure for the CU equal to a smallest CU (SCU).
3. The method of claim 1 , wherein when the second decoding process is selected, said determining CU structure uses a second CU structure comprising 2N×2N partition, 2N×N partition, and N×2N partition without N×N partition for the CU larger than a smallest CU, and the CU structure includes the N×N partition for the CU equal to the smallest CU.
4. The method of claim 1 , wherein the first decoding process is associated with a first codeword table, the second decoding process is associated with a second codeword table, and the decoding process selected is associated with the first codeword table or the second codeword table according to the first indication signal.
5. The method of claim 4 , wherein the first codeword table comprises code entries corresponding to 2N×2N partition, 2N×N partition, and N×2N partition, and the second codeword table comprises code entries corresponding to the 2N×2N partition, the 2N×N partition, the N×2N partition and N×N partition.
6. The method of claim 1 , when the first indication signal is in a sequence level of the video bitstream and the first indication signal indicates that N×N partition is allowed for the CU equal to a smallest CU, the method further comprising receiving a second indication signal from a picture level of the video bitstream, wherein whether to allow the N×N partition for a corresponding picture is according to the second indication signal.
7. The method of claim 1 , wherein the first decoding process and the second decoding process are selected from a coding type group consisting of binary arithmetic decoding and variable length decoding.
8. The method of claim 1 , wherein the first indication signal is in a sequence level of the video bitstream.
9. The method of claim 8 , wherein the decoding process selected is applied to coding units of a sequence associated with the sequence level.
10. The method of claim 8 , the method further comprising:
receiving a second indication signal from a picture level of the video bitstream; and
wherein if the second indication signal exists in the picture level, the decoding process selected is applied to the coding units in the picture associated with the picture level according to the second indication signal.
11. The method of claim 10 , wherein decision regarding whether to parse the second indication signal is dependent on the first indication signal.
12. The method of claim 1 , wherein the first indication signal is in a picture level of the video bitstream.
13. The method of claim 12 , wherein the decoding process selected is applied to coding units of a picture associated with the picture level.
14. A method for processing coding units of video data in a video encoder, the method comprising:
selecting a coding process from a group consisting of a first coding process and a second coding process to process the coding units;
incorporating a first indication signal corresponding to the coding process selected in a video bitstream associated with the video data;
receiving a current coding unit (CU); and
determining CU structure for the current CU according to the coding process selected; and
encoding the current CU according to the CU structure to generate compressed data to include in a bitstream; and
wherein when the first coding process is selected, said processing the current CU partitions a 2N×2N CU according to a first CU structure without INTER N×N with N=4.
15. The method of claim 14 , wherein the coding process selected determines CU structure of the CU when the CU equals to a smallest CU (SCU).
16. The method of claim 14 , wherein when the second coding process is selected, said processing the CU partitions the coding unit according to second CU structure comprising 2N×2N partition, 2N×N partition, and N×2N partition without N×N partition for the CU larger than a smallest CU, and the second CU structure includes the N×N partition for the CU equal to the smallest CU.
17. The method of claim 15 , wherein the first coding process is associated with a first codeword table, the second coding process is associated with a second codeword table, and the coding process selected is associated with the first codeword table or the second codeword table according to the first indication signal.
18. The method of claim 15 , when the first indication signal is in a sequence level of the video bitstream and the first indication signal indicates that N×N partition is allowed for the CU equal to a smallest CU, the method further comprising incorporating a second indication signal in a picture level of the video bitstream, wherein the coding process is applied to the coding units of the picture associated with the picture level according to the second indication signal.
19. The method of claim 14 , wherein the first coding process and the second coding process are selected from a coding type group consisting of binary arithmetic coding and variable length coding.
20. An apparatus for decoding of a video bitstream in a video decoder, the apparatus comprising one or more electronic circuits configured to:
receive a first indication signal from the video bitstream;
select a decoding process from a group consisting of a first decoding process and a second decoding process according to the first indication signal;
determine CU structure for a current coding unit (CU) associated with the video bitstream using the decoding process selected; and
reconstruct the current CU according to the CU structure determined; and
wherein when the first decoding process is selected, the CU structure corresponds to a first CU structure without INTER N×N with N=4 for a 2N×2N CU.
21. The apparatus of claim 20 , wherein when the second decoding process is selected, the CU structure corresponds to a second CU structure comprising 2N×2N partition, 2N×N partition, and N×2N partition without N×N partition for the CU larger than a smallest CU, and the second CU structure includes the N×N partition for the CU equal to the smallest CU.
22. The apparatus of claim 21 , wherein the first decoding process is associated with a first codeword table, the second decoding process is associated with a second codeword table, and the decoding process selected is associated with the first codeword table or the second codeword table according to the first indication signal.
23. The apparatus of claim 21 , when the first indication signal is in a sequence level of the video bitstream and the first indication signal indicates that the N×N partition is allowed for the CU equal to the smallest CU, said one or more electronic circuits are further configured to receive a second indication signal from a picture level of the video bitstream, wherein the decoding process selected is applied to the coding units in the picture associated with the picture level according to the second indication signal.
24. An apparatus for processing coding units of video data in a video encode, the apparatus comprising one or more electronic circuits configured to:
select a coding process from a group consisting of a first coding process and a second coding process to process the coding units;
incorporate a first indication signal corresponding to the coding process selected in a video bitstream associated with the video data;
receiving a current coding unit (CU) of the coding units; and
determine CU structure for the current CU according to the coding process selected; and
encode the current CU according to the CU structure to generate compressed data to include in a bitstream; and
wherein when the first coding process is selected, said processing the current CU partitions a 2N×2N CU according to a first CU structure without INTER N×N with N=4.
25. The apparatus of claim 24 , wherein when the second coding process is selected, the coding unit is processed according to second CU structure comprising 2N×2N partition, 2N×N partition, and N×2N partition without N×N partition for the CU larger than a smallest CU, and the second CU structure includes the N×N partition for the CU equal to the smallest CU.