Motion vector obtaining method and apparatus
This application provides a motion vector obtaining method and apparatus. The method includes: determining a target offset vector of a block and identifier information of a target picture, wherein the block comprises at least one sub-block; determining a location of the sub-block; determining, as a target location coordinate value of a collocated sub-block, a location coordinate value obtained by performing a clipping operation on an initial location coordinate value in a range, wherein the initial location coordinate value is based on the location of the sub-block and the target offset vector; and obtaining a motion vector of the sub-block based on a motion vector corresponding to the target location coordinate value. Thus, a range of the target offset vector is limited, so that a quantity of memory read times can be reduced in a process of obtaining the motion vector of the collocated sub-block.
1. A motion vector obtaining method for use in image encoding or image decoding implemented by a coding device, comprising:
determining a target offset motion vector of a to-be-processed block in a current picture and identifier information of a target picture, wherein the to-be-processed block comprises at least one to-be-processed sub-block;
determining, based on a location of the to-be-processed sub-block and the target offset motion vector, an initial location of a collocated sub-block that is of the to-be-processed sub-block and that is in the target picture;
determining the initial location as a target location when the initial location is inside a preset area of the target picture;
determining a location that is in the preset area and that is closest to the initial location as a target location when the initial location is outside the preset area; and
obtaining a motion vector of the to-be-processed sub-block based on a motion vector corresponding to the target location,
wherein
the preset area is represented by a horizontal coordinate value range and a vertical coordinate value range,
wherein the horizontal coordinate value range comprises a minimum horizontal coordinate value and a maximum horizontal coordinate value, and the vertical coordinate value range comprises a minimum vertical coordinate value and a maximum vertical coordinate value, and
wherein the target location is determined according to following formulas:
x (i,j) =Clip3(HorMin,HorMax, x (i,j) ); and
y (i,j) =Clip3(VerMin,VerMax, y (i,j) ), wherein
HorMin is the minimum horizontal coordinate value, HorMax is the maximum horizontal coordinate value, VerMin is the minimum vertical coordinate value, VerMax is the maximum vertical coordinate value, a Clip3 function is a clipping function, and the Clip3 function is defined as follows:
Clip
3
(
x
,
y
,
z
)
=
{
x
;
z
<
x
y
;
z
>
y
z
;
otherwise
;
and
wherein one or more of HorMin, HorMax, VerMin or VerMax of the preset area is determined based on a location and a size of a coding tree unit (CTU) in which the to-be-processed block is included, a size of the target picture, and an extension range of a temporal motion vector field of the CTU.
2. The method according to claim 1 , wherein the determining, based on the location of the to-be-processed sub-block and the target offset motion vector, the initial location of the collocated sub-block that is of the to-be-processed sub-block and that is in the target picture comprises:
offsetting location coordinates of the to-be-processed sub-block according to the following formulas, to obtain location coordinates of the initial location of the collocated sub-block that is of the to-be-processed sub-block and that is in the target picture:
{
x
(
i
,
j
)
=
x
+
M
×
i
+
M
2
+
x
off
y
(
i
,
j
)
=
y
+
N
×
j
+
N
2
+
y
off
,
wherein
(x, y) represents location coordinates of a top-left vertex of the to-be-processed block, i represents the i th sub-block in the to-be-processed block in a horizontal direction, j represents the j th sub-block in the to-be-processed block in a vertical direction, (x off , y off ) represents values of components of the target offset motion vector in the horizontal direction and the vertical direction, M and N are respectively a width and a height of the to-be-processed sub-block, and (x (i,j) , y (i,j) ) represents the location coordinates of the (i, j) th collocated sub-block.
3. The method according to claim 1 , wherein the extension range of the temporal motion vector field of the current CTU comprises: an extension range of the temporal motion vector field of the current CTU in a horizontal direction and an extension range of the temporal motion vector field of the current CTU in a vertical direction.
4. The method according to claim 1 , wherein information about the extension range of the temporal motion vector field of the current CTU is carried in at least one of a sequence parameter set SPS, a picture parameter set PPS, or a header field.
5. The method according to claim 1 , wherein a value of the extension range of the temporal motion vector field of the CTU is a predetermined value.
6. The method according to claim 1 , wherein the preset area is obtained through calculation according to following formulas:
HorMin=Max(CTUX−Range L, 0);
HorMax=Min(CTUX+CTUW+Range R −1,Pic W −1);
VerMin=Max(CTUY−Range U, 0); and
VerMax=Min(CTUY+CTUH+Range B −1,Pic H −1), wherein
HorMin and HorMax are respectively a minimum value and a maximum value of the preset area in the horizontal direction, VerMin and VerMax are respectively a minimum value and a maximum value of the preset area in the vertical direction, CTUX and CTUY represent location coordinates of the CTU in which the to-be-processed block is included, CTUW and CTUH represent a width and a height of the CTU in which the to-be-processed block is included, RangeU, RangeB, RangeL, and RangeR respectively represent extension values that are in an up direction, a bottom direction, a left direction, and a right direction and that are of the temporal motion vector field of the CTU in which the to-be-processed block is included, and PicW and PicH are respectively a width and a height of the target picture.
7. The method according to claim 6 , wherein RangeU, RangeB, RangeL, or RangeR is a predetermined value.
8. The method according to claim 1 , wherein the determining the target offset motion vector of a to-be-processed block comprises:
determining a motion vector of a spatially neighboring block of the to-be-processed block as the target offset motion vector.
9. The method according to claim 1 , wherein the target location indicates a target location of the collocated sub-block of the to-be-processed sub-block.
10. The method according to claim 1 , wherein the target offset vector is a temporal vector.
11. A coding apparatus, comprising:
at least one processor; and
one or more memories coupled to the at least one processor and storing programming instructions for execution by the at least one processor to cause the coding apparatus to:
determine a target offset motion vector of a to-be-processed block in a current picture and identifier information of a target picture, wherein the to-be-processed block comprises at least one to-be-processed sub-block;
determine, based on a location of the to-be-processed sub-block and the target offset motion vector, an initial location of a collocated sub-block that is of the to-be-processed sub-block and that is in the target picture;
determine the initial location as a target location when the initial location is inside a preset area of the target picture;
determine a location that is in the preset area and that is closest to the initial location as a target location when the initial location is outside the preset area; and
obtain a motion vector of the to-be-processed sub-block based on a motion vector corresponding to the target location,
wherein
the preset area is represented by a horizontal coordinate value range and a vertical coordinate value range,
the horizontal coordinate value range comprises a minimum horizontal coordinate value and a maximum horizontal coordinate value, and the vertical coordinate value range comprises a minimum vertical coordinate value and a maximum vertical coordinate value, and
wherein the target location is determined according to following formulas:
x (i,j) =Clip3(HorMin,HorMax, x (i,j) ); and
y (i,j) =Clip3(VerMin,VerMax, y (i,j) ), wherein
HorMin is the minimum horizontal coordinate value, HorMax is the maximum horizontal coordinate value, VerMin is the minimum vertical coordinate value, VerMax is the maximum vertical coordinate value, a Clip3 function is a clipping function, and the Clip3 function is defined as follows:
Clip
3
(
x
,
y
,
z
)
=
{
x
;
z
<
x
y
;
z
>
y
z
;
otherwise
;
and
wherein one or more of HorMin, HorMax, VerMin or VerMax of the preset area is determined based on a location and a size of a coding tree unit (CTU) in which the to-be-processed block is included, a size of the target picture, and an extension range of a temporal motion vector field of the CTU.
12. The apparatus according to claim 11 , wherein the at least one processor further executes the instructions to:
offsetting location coordinates of the to-be-processed sub-block according to the following formulas, to obtain location coordinates of the initial location of the collocated sub-block that is of the to-be-processed sub-block and that is in the target picture:
{
x
(
i
,
j
)
=
x
+
M
×
i
+
M
2
+
x
off
y
(
i
,
j
)
=
y
+
N
×
j
+
N
2
+
y
off
,
wherein
(x, y) represents location coordinates of a top-left vertex of the to-be-processed block, i represents the i th sub-block in the to-be-processed block in a horizontal direction, j represents the j th sub-block in the to-be-processed block in a vertical direction, (x off , y off ) represents values of components of the target offset motion vector in the horizontal direction and the vertical direction, M and N are respectively a width and a height of the to-be-processed sub-block, and (x (i,j) , y (i,j) ) represents the location coordinates of the (i, j) th collocated sub-block.
13. The apparatus according to claim 11 , wherein the extension range of the temporal motion vector field of the current CTU comprises: an extension range of the temporal motion vector field of the current CTU in a horizontal direction and an extension range of the temporal motion vector field of the current CTU in a vertical direction.
14. The apparatus according to claim 11 , wherein information about the extension range of the temporal motion vector field of the current CTU is carried in at least one of a sequence parameter set SPS, a picture parameter set PPS, or a header field.
15. The apparatus according to claim 11 , wherein a value of the extension range of the temporal motion vector field of the CTU is a predetermined value.
16. The apparatus according to claim 11 , wherein the preset area is obtained through calculation according to following formulas:
HorMin=Max(CTUX−Range L, 0);
HorMax=Min(CTUX+CTUW+Range R −1,Pic W −1);
VerMin=Max(CTUY−Range U, 0); and
VerMax=Min(CTUY+CTUH+Range B −1,Pic H −1), wherein
HorMin and HorMax are respectively a minimum value and a maximum value of the preset area in the horizontal direction, VerMin and VerMax are respectively a minimum value and a maximum value of the preset area in the vertical direction, CTUX and CTUY represent location coordinates of the CTU in which the to-be-processed block is included, CTUW and CTUH represent a width and a height of the CTU in which the to-be-processed block is included, RangeU, RangeB, RangeL, and RangeR respectively represent extension values that are in an up direction, a bottom direction, a left direction, and a right direction and that are of the temporal motion vector field of the CTU in which the to-be-processed block is included, and PicW and PicH are respectively a width and a height of the target picture.
17. The apparatus according to claim 16 , wherein RangeU, RangeB, RangeL, or RangeR is a predetermined value.
18. A non-transitory computer-readable medium storing computer instructions that, when executed by one or more processors, cause the one or more processors to perform operations of obtaining a motion vector in image encoding or image decoding, the operations comprising:
determining a target offset motion vector of a to-be-processed block in a current picture and identifier information of a target picture, wherein the to-be-processed block comprises at least one to-be-processed sub-block;
determining, based on a location of the to-be-processed sub-block and the target offset motion vector, an initial location of a collocated sub-block that is of the to-be-processed sub-block and that is in the target picture;
determining the initial location as a target location when the initial location is inside a preset area of the target picture;
determining a location that is in the preset area and that is closest to the initial location as a target location when the initial location is outside the preset area; and
obtaining a motion vector of the to-be-processed sub-block based on a motion vector corresponding to the target location,
wherein
the preset area is represented by a horizontal coordinate value range and a vertical coordinate value range,
the horizontal coordinate value range comprises a minimum horizontal coordinate value and a maximum horizontal coordinate value, and the vertical coordinate value range comprises a minimum vertical coordinate value and a maximum vertical coordinate value, and
wherein the target location is determined according to following formulas:
x (i,j) =Clip3(HorMin,HorMax, x (i,j) ); and
y (i,j) =Clip3(VerMin,VerMax, y (i,j) ), wherein
HorMin is the minimum horizontal coordinate value, HorMax is the maximum horizontal coordinate value, VerMin is the minimum vertical coordinate value, VerMax is the maximum vertical coordinate value, a Clip3 function is a clipping function, and the Clip3 function is defined as follows:
Clip
3
(
x
,
y
,
z
)
=
{
x
;
z
<
x
y
;
z
>
y
z
;
otherwise
and
wherein one or more of HorMin, HorMax, VerMin or VerMax of the preset area is determined based on a location and a size of a coding tree unit (CTU) in which the to-be-processed block is included, a size of the target picture, and an extension range of a temporal motion vector field of the CTU.