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 method of decoding a bitstream to output one or more pictures for a video stream, the method comprising:
receiving a bitstream; and
decoding, using coded information of the bitstream, one or more pictures,
wherein the decoding comprises:
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 comprising a first set of coefficients {0, 1, −5, 62, 8, −3, 1, 0} associated with integer reference sample positions.
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.
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.
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.
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 first interpolation filter is an N-tap filter, and the plurality of integer interpolation coefficients are derived based on:
∑
k
=
0
5
(
W
k
(
α
)
·
D
l
,
k
)
,
wherein l denotes integer reference sample positions and
l
=
-
(
N
2
)
+
1
,
…
,
N
2
)
,
wherein α 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
)
wherein
D
l
,
k
=
1
3
·
cos
(
2
·
l
+
5
12
·
k
·
π
)
.
12. A method of encoding a video sequence into a bitstream, the method comprising:
receiving a video sequence;
encoding one or more pictures of the video sequence; and
generating a bitstream,
wherein the encoding comprises:
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 comprising a first set of coefficients {0, 1,−5, 62, 8,−3, 1, 0} associated with integer reference sample positions.
13. The method according to claim 12 , 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.
14. The method according to claim 12 , 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.
15. The method according to claim 12 , 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.
16. A method of storing a bitstream of a video, the method comprising:
generating a bitstream comprising coded information, wherein the coded information is generated by applying a first interpolation filter to a reference picture to perform motion compensated interpolation based on the reference picture; and
storing the bitstream in a non-transitory computer readable medium,
wherein the first interpolation filter has a 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.
17. The method according to claim 16 , 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.
18. The method according to claim 16 , 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.
19. The method according to claim 16 , 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.
20. The method according to claim 16 , wherein the first interpolation filter is a 6-tap filter.