Adaptive resolution change in video processing
The present disclosure provides systems and methods for performing adaptive resolution change during video encoding and decoding. The methods include: comparing resolutions of a target picture and a first reference picture; in response to the target picture and the first reference picture having different resolutions, resampling the first reference picture to generate a second reference picture; and encoding or decoding the target picture using the second reference picture.
1. A video processing method, comprising:
comparing resolutions of a target picture and a reference picture; and
in response to the target picture and the reference picture having different resolutions, encoding or decoding a block of the target picture by applying a band-pass filter to the reference picture,
wherein the band-pass filter is used to resample the reference picture and perform a motion compensated interpolation based on the resampled reference picture, and
wherein the band-pass filter has a plurality of coefficients derived from a cosine windowed-sinc filter, and the cosine windowed-sinc filter has a kernel function
f
(
n
)
=
f
c
r
Sinc
(
f
c
r
n
)
cos
(
π
n
L
-
1
)
,
wherein
n
=
-
L
-
1
2
,
…
,
L
-
1
2
,
fc being a cutoff frequency of the cosine windowed-sinc filter, L being a kernel length, and r being a down-sampling ratio.
2. The method according to claim 1 , wherein applying the band-pass filter to the reference picture comprises:
applying an 8-tap band-pass filter to luma samples of the reference picture.
3. The method according to claim 1 , wherein applying the band-pass filter to the reference picture comprises:
applying a 4-tap band-pass filter to chroma samples of the reference picture.
4. The method according to claim 1 , wherein a sum of the plurality of coefficients is equal to 64.
5. The method according to claim 1 , wherein a sum of the plurality of coefficients is equal to 128.
6. The method according to claim 1 , wherein the reference picture has a higher resolution than the target picture.
7. The method according to claim 1 , wherein the fc is equal to 0.9 and the L is equal to 13.
8. The method according to claim 1 , wherein the cosine windowed-sinc filter is a 32-phase filter.
9. The method according to claim 1 , wherein applying the band-pass filter to the reference picture comprises:
obtaining a luma sample or a chroma sample at a fractional sample position.
10. A device, comprising:
one or more memories storing computer instructions; and
one or more processors configured to execute the computer instructions to cause the device to:
compare resolutions of a target picture and a reference picture; and
in response to the target picture and the reference picture having different resolutions, encode or decode a block of the target picture by applying a band-pass filter to the reference picture,
wherein the band-pass filter is used to resample the reference picture and perform a motion compensated interpolation based on the resampled reference picture, and
wherein the band-pass filter has a plurality of coefficients derived from a cosine windowed-sinc filter, and the cosine windowed-sinc filter has a kernel function
f
(
n
)
=
f
c
r
Sinc
(
f
c
r
n
)
cos
(
π
n
L
-
1
)
,
wherein
n
=
-
L
-
1
2
,
…
,
L
-
1
2
,
fc being a cutoff frequency of the cosine windowed-sinc filter, L being a kernel length, and r being a down-sampling ratio.
11. The device according to claim 10 , wherein the one or more processors configured to execute the computer instructions to cause the device to:
apply an 8-tap band-pass filter to luma samples of the reference picture.
12. The device according to claim 10 , wherein the one or more processors configured to execute the computer instructions to cause the device to:
apply a 4-tap band-pass filter to chroma samples of the reference picture.
13. The device according to claim 10 , wherein a sum of the plurality of coefficients is equal to 64.
14. The device according to claim 10 , wherein a sum of the plurality of coefficients is equal to 128.
15. The device according to claim 10 , wherein the reference picture has a higher resolution than the target picture.
16. A non-transitory computer readable medium storing a bitstream of a video for processing according to a method comprising:
comparing resolutions of a target picture and a reference picture; and
in response to the target picture and the reference picture having different resolutions, encoding or decoding a block of the target picture by applying a band-pass filter to the reference picture,
wherein the band-pass filter is used to resample the reference picture and perform a motion compensated interpolation based on the resampled reference picture, and
wherein the band-pass filter has a plurality of coefficients derived from a cosine windowed-sinc filter, and the cosine windowed-sinc filter has a kernel function ƒ(n)=fc/r Sinc(fc/r n)cos(πn/L−1), wherein n=−L−1/2, . . . , L−1/2, fc being a cutoff frequency of the cosine windowed-sinc filter, L being a kernel length, and r being a down-sampling ratio.