Implementation design for hybrid transform coding scheme
A method and system may identify a video data block using a video codec and apply a transform kernel of a butterfly asymmetric discrete sine transform (ADST) to the video data block in a pipeline.
1. A non-transitory computer-readable storage medium storing instructions that when executed by a processor of a video encoder cause the processor to perform a process, the instructions comprising instructions to:
identify a video data block using a video codec; and
transform the video data block by generating a single instruction to apply a transform kernel of a butterfly asymmetric discrete sine transform (ADST) to process a plurality of data in the video data block using a butterfly structure in a parallel pipeline, wherein the transform kernel is
sin
(
2
n
-
1
)
(
2
k
-
1
)
π
4
N
,
where N is a block dimension, and where n and k, respectively, denote a time index and a frequency index, where both n and k range from 1 to N.
2. The non-transitory computer-readable storage medium of claim 1 , the transform kernel including a combination of a discrete cosine transform (DCT) and the butterfly ADST transform having a basis that is asymmetric.
3. The non-transitory computer-readable storage medium of claim 1 , wherein the butterfly ADST is performed in integer format.
4. The non-transitory computer-readable storage medium of claim 1 , wherein the processor communicates with a single instruction memory and control processor.
5. The non-transitory computer-readable storage medium of claim 1 , the instructions further comprising instructions to:
select a set of one-dimensional transforms depending on a prediction direction.
6. The non-transitory computer-readable storage medium of claim 5 , the instructions further comprising instructions to:
form a two-dimensional transform using the set of one-dimensional transforms.
7. The non-transitory computer-readable storage medium of claim 1 , wherein the butterfly ADST is applied to a residual pixel block generated from the video data block.
8. The non-transitory computer-readable storage medium of claim 1 , wherein the transform kernel provides for parallel computing via single instruction multiple data operations.
9. An apparatus, comprising:
a processor executing a video codec configured to identify a video data block;
a hybrid transform encoder configured to:
provide an intra-frame coding scheme for the video data block using a transform kernel based on a combination of a discrete cosine transform (DCT) and a butterfly asymmetric discrete sine transform (ADST) transform having an asymmetric basis;
produce a butterfly structured implementation of the intra-frame coding scheme, using the butterfly ADST, wherein the transform kernel is
sin
(
2
n
-
1
)
(
2
k
-
1
)
π
4
N
,
where N is a block dimension, and where n and k, respectively, denote a time index and a frequency index, where both n and k range from 1 to N, and
transform the video data block by generating a single instruction to apply the transform kernel to process a plurality of data in the video data block using a butterfly structure in a parallel pipeline.
10. The apparatus of claim 9 , wherein the butterfly structured implementation is performed in integer format.
11. The apparatus of claim 9 , wherein the processor communicates with a single instruction memory and control processor.
12. The apparatus of claim 9 , further comprising:
a selector configured to select a set of one-dimensional transforms depending on a prediction direction.
13. The apparatus of claim 12 , the selector further configured to:
form a two-dimensional transform using the set of one-dimensional transforms.
14. The apparatus of claim 9 , wherein the butterfly ADST is applied to a residual pixel block generated from the video data block.
15. The apparatus of claim 9 , wherein the butterfly structured implementation provides for parallel computing via single instruction multiple data operations.
16. A non-transitory computer-readable storage medium storing instructions that when executed by a processor of a video encoder cause the processor to perform a process, the instructions comprising instructions to:
provide an intra-frame coding scheme for a video data block using a combination of a discrete cosine transform (DCT) and a butterfly asymmetric discrete sine transform (ADST) transform having a transform kernel approximating an original ADST having an asymmetric basis;
produce a butterfly structured implementation of the intra-frame coding, using the butterfly ADST, wherein the transform kernel is
sin
(
2
n
-
1
)
(
2
k
-
1
)
π
4
N
,
where N is a block dimension, and where n and k, respectively, denote a time index and a frequency index, where both n and k range from 1 to N; and
transform the video data block by generating a single instruction to apply the transform kernel to process a plurality of data in the video data block using a butterfly structure in a parallel pipeline.
17. The non-transitory computer-readable storage medium of claim 16 , the instructions further comprising instructions to:
select a set of one-dimensional transforms depending on a prediction direction.
18. The non-transitory computer-readable storage medium of claim 16 , the instructions further comprising instructions to:
form a two-dimensional transform using the set of one-dimensional transforms.