Method for apparatus for deriving maximum sub-block transform size
The present disclosure provides apparatus and methods for signaling sub-block transform (SBT) information. The SBT information is used for coding video data. According to certain disclosed embodiments, an exemplary method includes: signaling a first flag in a Sequence Parameter Set (SPS) of a video sequence indicating whether a sub-block transform (SBT) is enabled; and signaling a second flag indicating a maximum transform block (TB) size that allows the SBT. A maximum coding unit (CU) size that allows the SBT is determined directly based on the maximum TB size in response to the first flag indicating that the SBT is enabled.
1. A video encoding method, comprising:
signaling a first flag in a Sequence Parameter Set (SPS) of a bitstream associated with a video sequence, the first flag indicating whether a sub-block transform (SBT) is enabled; and
signaling, in the SPS, a second flag indicating a maximum transform size in luma samples,
wherein a maximum coding unit (CU) size that allows the SBT is determined based on a value of the second flag, wherein the CU size that allows the SBT is determined to be:
64 if the value of the second flag is 1, and
32 if the value of the second flag is 0.
2. The method according to claim 1 , wherein the maximum CU size that allows the SBT is a maximum CU width or a maximum CU height.
3. The method according to claim 1 , wherein the maximum CU size that allows the SBT is determined to be equal to the maximum transform size.
4. The method according to claim 1 , further comprising:
in response to the value of the second flag being 0, setting the maximum transform size to be 32.
5. The method according to claim 1 , further comprising:
in response to the value of the second flag being 1, setting the maximum transform size to be 64.
6. The method according to claim 1 , wherein the second flag is sps_max_luma_transform_size_64_flag.
7. The method according to claim 1 , wherein the first flag is sps_sbt_enabled_flag.
8. A video decoding method, comprising:
receiving a bitstream associated with a video sequence, a Sequence Parameter Set (SPS) of the bitstream comprising:
a first flag indicating whether a sub-block transform (SBT) is enabled, and
a second flag indicating a maximum transform size in luma samples; and
in response to a value of the second flag being 1, determining a maximum coding unit (CU) size that allows the SBT to be 64, or
in response to the value of the second flag being 0, determining the maximum CU size that allows the SBT to be 32.
9. The method according to claim 8 , wherein the maximum CU size that allows the SBT is a maximum CU width or a maximum CU height.
10. The method according to claim 8 , further comprising:
determining the maximum CU size that allows the SBT to be equal to the maximum transform size.
11. The method according to claim 8 , further comprising:
in response to the value of the second flag being 0, determining the maximum transform size to be 32.
12. The method according to claim 8 , further comprising:
in response to the value of the second flag being 1, determining the maximum transform size to be 64.
13. The method according to claim 8 , wherein the second flag is sps_max_luma_transform_size_64_flag.
14. The method according to claim 8 , wherein the first flag is sps_sbt_enabled_flag.
15. A non-transitory computer readable storage medium storing a bitstream associated with a video sequence, the bitstream comprising:
a Sequence Parameter Set (SPS), the SPS comprising:
a first flag indicating whether a sub-block transform (SBT) is enabled, and
a second flag indicating a maximum transform size in luma samples; and
wherein the second flag causes a decoder to determine a maximum coding unit (CU) size that allows the SBT to be:
64 if the value of the second flag is 1, and
32 if the value of the second flag is 0.
16. The non-transitory computer readable storage medium according to claim 15 , wherein the maximum CU size that allows the SBT is a maximum CU width or a maximum CU height.
17. The non-transitory computer readable storage medium according to claim 15 , wherein the second flag causes the decoder to determine the maximum transform size to be 32 if the value of the second flag is 0.
18. The non-transitory computer readable storage medium according to claim 15 , wherein the second flag causes the decoder to determine the maximum transform size to be 64 if the value of the second flag is 1.
19. The non-transitory computer readable storage medium according to claim 15 , wherein the second flag is sps_max_luma_transform_size_64_flag.
20. The non-transitory computer readable storage medium according to claim 15 , wherein the first flag is sps_sbt_enabled_flag.