Motion compensation methods for video coding
The present disclosure provides methods and systems for motion compensation. The method can include: determining a plurality of intermediate interpolation coefficients of an interpolation filter, the determining of the plurality of intermediate interpolation coefficients being: based on positions of a plurality of integer samples respectively, and based on fractional reference positions of a plurality of fractional samples respectively; determining a plurality of integer interpolation coefficients of the interpolation filter by rounding the plurality of intermediate interpolation coefficients to a plurality of integers respectively; and applying the plurality of integer interpolation coefficients on a picture to perform motion compensation prediction.
1. A computer-implemented method for processing video content, comprising:
encoding or decoding a picture block by applying a first interpolation filter to a reference picture to perform motion compensated interpolation based on the reference picture,
wherein the first interpolation filter has a plurality of integer interpolation coefficients derived based on a discrete cosine transform (DCT) interpolation filter, the plurality of integer interpolation coefficients comprising a first set of coefficients {0, 1, −5, 62, 8, −3, 1, 0} associated with integer reference sample positions {−3, −2, −1, 0, 1, 2, 3, 4}, respectively.
2. The method according to claim 1 , wherein the first set of coefficients is used for estimating luma values at a ⅛ fractional sample position.
3. The method according to claim 1 , wherein the plurality of integer interpolation coefficients comprises a second set of coefficients {0, 2, −8, 60, 13, −4, 1, 0} associated with integer reference sample positions {−3, −2, −1, 0, 1, 2, 3, 4}, respectively.
4. The method according to claim 3 , wherein the second set of coefficients is used for estimating luma values at a 3/16 fractional sample position.
5. The method according to claim 1 , wherein the plurality of integer interpolation coefficients comprises a second set of coefficients {0, 3, −11, 45, 34, −10, 3, 0} associated with integer reference sample positions {−3, −2, −1, 0, 1, 2, 3, 4}, respectively.
6. The method according to claim 5 , wherein the second set of coefficients is used for estimating luma values at a 7/16 fractional sample position.
7. The method according to claim 1 , wherein the plurality of integer interpolation coefficients comprises a second set of coefficients {0, 3, −11, 40, 40, −11, 3, 0} associated with integer reference sample positions {−3, −2, −1, 0, 1, 2, 3, 4}, respectively.
8. The method according to claim 7 , wherein the second set of coefficients is used for estimating luma values at a ½ fractional sample position.
9. The method according to claim 1 , wherein the plurality of integer interpolation coefficients comprises 15 sets of coefficients, each set of the coefficients being used for estimating luma values at a 1/16 fractional sample position.
10. The method according to claim 1 , wherein the first interpolation filter is a 6-tap filter.
11. The method according to claim 1 , wherein the DCT interpolation filter is used in a High Efficiency Video Coding (HEVC) standard.
12. The method according to claim 1 , wherein the first interpolation filter is an N-tap filter, and the plurality of integer interpolation coefficients are derived based on:
Σ k=0 5 ( W k (α)· D l,k ),
wherein l denotes integer reference sample positions and l=−(N/2)+1, . . . , N/2),
wherein a denotes fractional sample positions associated with the first interpolation filter,
wherein:
W
k
(
α
)
=
{
1
2
(
k
=
0
)
cos
(
2
·
α
+
5
12
·
k
·
π
)
(
k
=
1
…
N
-
1
)
,
and
wherein
D
l
,
k
=
1
3
·
cos
(
2
·
l
+
5
12
·
k
·
π
)
.
13. A system for processing video content, comprising:
a memory for storing a set of instructions; and
at least one processor configured to execute the set of instructions to cause the system to perform:
encoding or decoding a picture block by applying a first interpolation filter to a reference picture to perform motion compensated interpolation based on the reference picture,
wherein the first interpolation filter has a plurality of integer interpolation coefficients derived based on a discrete cosine transform (DCT) interpolation filter, the plurality of integer interpolation coefficients comprising a first set of coefficients {0, 1, −5, 62, 8, −3, 1, 0} associated with integer reference sample positions {−3, −2, −1, 0, 1, 2, 3, 4}, respectively.
14. The system according to claim 13 , wherein the plurality of integer interpolation coefficients comprises a second set of coefficients {0, 2, −8, 60, 13, −4, 1, 0} associated with integer reference sample positions {−3, −2, −1, 0, 1, 2, 3, 4}, respectively.
15. The system according to claim 13 , wherein the plurality of integer interpolation coefficients comprises a second set of coefficients {0, 3, −11, 45, 34, −10, 3, 0} associated with integer reference sample positions {−3, −2, −1, 0, 1, 2, 3, 4}, respectively.
16. The system according to claim 13 , wherein the plurality of integer interpolation coefficients comprises a second set of coefficients {0, 3, −11, 40, 40, −11, 3, 0} associated with integer reference sample positions {−3, −2, −1, 0, 1, 2, 3, 4}, respectively.
17. A non-transitory computer readable medium storing a bitstream of a video for processing according to a method comprising:
encoding or decoding a picture block by applying a first interpolation filter to a reference picture to perform motion compensated interpolation based on the reference picture,
wherein the first interpolation filter has a plurality of integer interpolation coefficients derived based on a discrete cosine transform (DCT) interpolation filter, the plurality of integer interpolation coefficients comprising a first set of coefficients {0, 1, −5, 62, 8, −3, 1, 0} associated with integer reference sample positions {−3, −2, −1, 0, 1, 2, 3, 4}, respectively.
18. The non-transitory computer readable medium according to claim 17 , wherein the plurality of integer interpolation coefficients comprises a second set of coefficients {0, 2, −8, 60, 13, −4, 1, 0} associated with integer reference sample positions {−3, −2, −1, 0, 1, 2, 3, 4}, respectively.
19. The non-transitory computer readable medium according to claim 17 , wherein the plurality of integer interpolation coefficients comprises a second set of coefficients {0, 3, −11, 45, 34, −10, 3, 0} associated with integer reference sample positions {−3, −2, −1, 0, 1, 2, 3, 4}, respectively.
20. The non-transitory computer readable medium according to claim 17 , wherein the plurality of integer interpolation coefficients comprises a second set of coefficients {0, 3, −11, 40, 40, −11, 3, 0} associated with integer reference sample positions {−3, −2, −1, 0, 1, 2, 3, 4}, respectively.