Methods and apparatus of motion vector rounding, clipping and storage for
View Patent ↗A method for video coding is provided, including: providing a motion vector (MV) rounding process that is configured to perform a MV rounding operation; applying the MV rounding process to at least a first MV used in a first prediction tool selected from a first set of tools including: pair-wise merge candidate, triangle prediction mode, and affine mode; and applying the MV rounding process to at least a second MV used in a second prediction tool selected from a second set of tools including: temporal motion vector prediction (TMVP), alternative temporal motion vector prediction (ATMVP), and merge mode with motion vector differences (MMVD).
1. A method for video decoding, comprising:
determining an inter prediction process; and
in response to determining the inter prediction process is one of derivation processes for advance motion vector prediction (AMVP) mode, alternative temporal motion vector prediction (ATMVP) mode, merge mode with motion vector differences (MMVD) mode, decoder-side motion vector derivation (DMVR) mode, affine inheritance mode or explicit affine mode, performing a motion vector (MV) clipping operation to at least one MV in the inter prediction process according to a first MV clipping mode,
wherein an upper limit of the first MV clipping mode is 2 17 −1 and the lower limit of the first MV clipping mode is −2 17 .
2. The method of claim 1 , wherein the MV clipping operation is defined by an equation of:
L
clip
=
{
2
1
7
-
1
,
L
≥
2
1
7
-
2
1
7
,
L
<
-
2
1
7
L
,
otherwise
where
L is an MV value before rounding; and
L clip is a value of a clipped MV.
3. The method of claim 1 , further comprising applying the MV clipping process to all MVs and CPMVs derived in merge mode with motion vector differences (MMVD) mode, decoder-side motion vector derivation (DMVR) mode, and affine inheritance mode.
4. An apparatus for video coding, comprising:
a processor; and
a memory configured to store instructions executable by the processor;
wherein the processor, upon execution of the instructions, is configured to:
determine an inter prediction process; and
in response to determining the inter prediction process is one of derivation processes for advance motion vector prediction (AMVP) mode, alternative temporal motion vector prediction (ATMVP) mode, merge mode with motion vector differences (MMVD) mode, decoder-side motion vector derivation (DMVR) mode, affine inheritance mode or explicit affine mode, perform a motion vector (MV) clipping operation to at least one MV in the inter prediction process according to a first MV clipping mode,
wherein an upper limit of the first MV clipping mode is 2 17 −1 and the lower limit of the first MV clipping mode is −2 17 .
5. The apparatus of claim 4 , wherein the first MV clipping mode is defined by an equation of:
L
clip
=
{
2
1
7
-
1
,
L
≥
2
1
7
-
2
1
7
,
L
<
-
2
1
7
L
,
otherwise
where
L is an MV value before rounding; and
L clip is a value of a clipped MV.
6. The apparatus of claim 4 , the processor is further configured to: apply the MV clipping process to all MVs and CPMVs derived in merge mode with motion vector differences (MMVD) mode, decoder-side motion vector derivation (DMVR) mode, and affine inheritance mode.
7. A non-transitory computer readable storage medium having instructions stored therein, when the instructions are executed by a processor, the instructions causing the processor to determine an inter prediction process;
in response to determining the inter prediction process is one of derivation processes for advance motion vector prediction (AMVP) mode, alternative temporal motion vector prediction (ATMVP) mode, merge mode with motion vector differences (MMVD) mode, decoder-side motion vector derivation (DMVR) mode, affine inheritance mode or explicit affine mode, perform a motion vector (MV) clipping operation to at least one MV in the inter prediction process according to a first MV clipping mode,
wherein an upper limit of the first MV clipping mode is 2 17 −1 and the lower limit of the first MV clipping mode is −2 17 .
8. The non-transitory computer readable storage medium of claim 7 , wherein the first MV clipping mode is defined by an equation of:
L
clip
=
{
2
1
7
-
1
,
L
≥
2
1
7
-
2
1
7
,
L
<
-
2
1
7
L
,
otherwise
where
L is an MV value before rounding; and
L clip is a value of a clipped MV.
9. The non-transitory computer readable storage medium of claim 7 , wherein the instructions further cause the processor to: apply the MV clipping process to all MVs and CPMVs derived in merge mode with motion vector differences (MMVD) mode, decoder-side motion vector derivation (DMVR) mode, and affine inheritance mode.