Method and apparatus for video coding
Method and decoder for reconstructing at least a sample of a block using an intra prediction angle determined from an intra prediction mode. The method includes decoding at least one syntax element from a coded video sequence. The at least one symax element is indicative of an intra prediction mode. An intra prediction angle is determined that corresponds to the indicated intra prediction mode based on a stored relationship between a plurality of intra prediction modes and a plurality of intra prediction angles. At least one sample of a block is reconstructed using the infra prediction angle that is determined to correspond to the indicated intra prediction mode. The plurality of intra prediction modes in the stored relationship can include at least one of a first plurality of wide angle prediction modes and a second plurality of wide angle prediction modes. The first plurality of wide angle prediction modes is beyond a bottom left direction diagonal mode and the second plurality of wide angle prediction modes is beyond a top right direction diagonal mode.
1. A method for video decoding in a video decoder, the method comprising:
decoding a coded video sequence to obtain an intra prediction mode that is a directional intra prediction mode and not a planar intra prediction mode;
determining an intra prediction angle, based on a predetermined plurality of intra prediction modes and a corresponding predetermined plurality of intra prediction angles, the determined intra prediction angle corresponding to the obtained intra prediction mode, the intra prediction angle being (i) beyond a bottom left direction 45 degrees from horizontal diagonal mode; or (ii) beyond a top right direction 45 degrees from horizontal diagonal mode; and
reconstructing at least one sample of a block based on the intra prediction angle that is determined to correspond to the obtained intra prediction mode.
2. The method recited in claim 1 , wherein
the intra prediction angle corresponds to intraPredAngle and the intra prediction mode corresponds to predModeIntra, and
a relationship between the predetermined plurality of intra prediction modes and the corresponding predetermined plurality of intra prediction angles is as follows:
predModeIntra
−10
−9
−8
−7
−6
−5
−4
−3
−2
−1
2
3
4
5
6
7
8
intraPredAngle
114
93
79
68
60
54
49
45
39
35
32
29
26
23
21
19
17
predModeIntra
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
intraPredAngle
15
13
11
9
7
5
3
2
1
0
−1
−2
−3
−5
−7
−9
−11
predModeIntra
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
intraPredAngle
−13
−25
−17
−19
−21
−23
−26
−29
−32
−29
−26
−23
−21
−19
−17
15
−13
predModeIntra
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
intraPredAngle
−11
−9
−7
−5
−3
−2
−1
0
1
2
3
5
7
9
11
13
15
predModeIntra
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
intraPredAngle
17
19
21
23
26
29
32
35
39
45
49
54
60
68
79
93
114.
3. The method recited in claim 2 , wherein the reconstructing comprises:
reconstructing the at least one sample of a non-square block based on the relationship between predModeIntra and intraPredAngle.
4. The method recited in claim 1 , wherein the reconstructing comprises:
reconstructing the at least one sample of a non-square block based on a relationship between the plurality of intra prediction modes and the plurality of intra prediction angles.
5. The method recited in claim 1 , wherein
a number of the intra prediction modes that are beyond the bottom left direction 45 degrees from horizontal diagonal mode is ten; and
a number of the intra prediction modes that are beyond the top right direction 45 degrees from horizontal diagonal mode is ten.
6. The method recited in claim 1 , wherein
a first plurality of the intra prediction modes that are beyond the bottom left direction 45 degrees from horizontal diagonal mode have integer values in a range of −1 to −10; and
a second plurality of the intra prediction modes that are beyond the top right direction 45 degrees from horizontal diagonal mode have integer values in a range of 67 to 76.
7. The method recited in claim 6 , wherein
the plurality of intra prediction angles corresponding to each of the first and second plurality of prediction modes are in a range of 35 to 114.
8. The method recited in claim 1 , wherein:
the intra prediction modes go beyond mode 2 of the HEVC (High Efficiency Video Coding) standard; and
the intra prediction modes go beyond mode 34 of the HEVC standard.
9. The method recited in claim 1 , comprising:
when a width W of the block is greater than a height H of the block,
the intra prediction angle is greater than ((32*H/W)+1), and
the intra prediction mode is less 34,
modifying the intra prediction mode by adding 65 when the intra prediction angle is less than 9, and
setting the intra prediction mode to 66 when the intra prediction angle is at least 9.
10. The method recited in claim 1 , comprising:
when a width W of the block is less than a height H of the block,
the intra prediction angle is greater than ((32*W/H)+1), and
the intra prediction mode greater than 34,
modifying the intra prediction mode by subtracting 67 when the intra prediction angle is greater than 9, and
setting the intra prediction mode to 2 when the intra prediction angle is 9 or less.
11. The method recited in claim 1 , comprising:
when a width W of the block is greater than a height H of the block,
the intra prediction angle is greater than ((32*H/W)+1), and
the intra prediction mode is less than 34,
modifying the intra prediction mode by adding 65 when the intra prediction angle is less than 9, and
modifying the intra prediction mode by subtracting the intra prediction mode from 68 when the intra prediction angle is at least 9.
12. The method recited in claim 1 , comprising:
when a width W of the block is less than a height H of the block,
the intra prediction angle is greater than ((32*W/H)+1), and
the intra prediction mode is greater than 34,
modifying the intra prediction mode by subtracting 67 when the intra prediction angle is greater than 9, and
modifying the intra prediction mode by subtracting the intra prediction mode from 68 when the intra prediction angle is 9 or less.
13. The method recited in claim 1 , comprising:
when a width W of the block is greater than a height H of the block,
the intra prediction angle is greater than ((32*H/W)+1), and
the intra prediction mode is less than 34,
modifying the intra prediction mode by adding 65 when the intra prediction angle is less than 9, and
setting the intra prediction mode to 76 when the intra prediction angle is at least 9.
14. The method recited in claim 1 , comprising:
when a width W of the block is less than a height H of the block,
the intra prediction angle is greater than ((32*W/H)+1), and
the intra prediction mode is greater than 34,
modifying the intra prediction mode by subtracting 67 when the intra prediction angle is greater than 9, and
setting the intra prediction mode to −10 when the intra prediction angle is 9 or less.
15. The method of claim 1 , wherein the plurality of intra prediction modes go beyond mode 34 of the HEVC standard.
16. A video decoder for video decoding, comprising:
processing circuitry configured to:
decode a coded video sequence to obtain an intra prediction mode that is a directional intra prediction mode and not a planar intra prediction mode;
determine an intra prediction angle, based on a predetermined plurality of intra prediction modes and a corresponding predetermined plurality of intra prediction angles the determined intra prediction angle corresponding to the obtained intra prediction mode , the intra prediction angle being (i) beyond a bottom left direction 45 degrees from horizontal diagonal mode, or (ii) beyond a top right direction 45 degrees from horizontal diagonal mode; and
reconstruct at least one sample of a block based on the intra prediction angle that is determined to correspond to the obtained intra prediction mode.
17. The video decoder recited in claim 16 , wherein
the intra prediction angle corresponds to intraPredAngle and the intra prediction mode corresponds to predModeIntra, and
a relationship between the predetermined plurality of intra prediction modes and the corresponding predetermined plurality of intra prediction angles is as follows:
preModeIntra
−10
−9
−8
−7
−6
−5
−4
−3
−2
−1
2
3
4
5
6
7
8
intraPredAngle
114
93
79
68
60
54
49
45
39
35
32
29
26
23
21
19
17
predModeIntra
9
19
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
intraPredAngle
15
13
11
9
7
5
3
2
1
0
−1
−2
−3
−5
−7
−9
−11
preModeIntra
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
intraPredAngle
−13
−25
−17
−19
−21
−23
−26
−29
−32
−29
−26
−23
−21
−19
−17
−15
−13
preModeIntra
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
intraPredAngle
−11
−9
−7
−5
−3
−2
−1
0
1
2
3
5
7
9
11
13
15
preModeIntra
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
intraPredAngle
17
19
21
23
26
29
32
35
39
45
49
54
60
68
79
93
114.
18. The video decoder recited in claim 17 , wherein the processing circuitry is configured to reconstruct the at least one sample of a non-square block based on the relationship between predModeIntra and intraPredAngle.
19. The video decoder recited in claim 16 , wherein the processing circuitry is configured to reconstruct the at least one sample of a non-square block based on a relationship between the plurality of intra prediction modes and the plurality of intra prediction angles.
20. The video decoder recited in claim 16 , wherein
a number of the intra angle prediction modes that are beyond the bottom left direction 45 degrees from horizontal diagonal mode is ten; and
a number of the intra angle prediction modes that are beyond the top right direction 45 degrees from horizontal diagonal mode is ten.
21. The video decoder recited in claim 16 , wherein
a first plurality of the intra prediction modes have integer values in a range of −1 to −10; and
a second plurality of the intra prediction modes have integer values in a range of 67 to 76.
22. The video decoder recited in claim 21 , wherein
the plurality of intra prediction angles corresponding to each of the first and second plurality of prediction modes are in a range of 35 to 114.
23. The video decoder recited in claim 16 , wherein:
the intra prediction modes go beyond mode 2 of the HEVC (High Efficiency Video Coding) standard; and
the intra prediction modes go beyond mode 34 of the HEVC standard.
24. A non-transitory computer-readable medium storing instructions which when executed by a computer for video decoding cause the computer to perform:
decoding a coded video sequence to obtain an intra prediction mode that is a directional intra prediction mode and not a planar intra prediction mode;
determining an intra prediction angle, based on a predetermined plurality of intra prediction modes and a corresponding predetermined plurality of intra prediction angles, the determined intra prediction angle corresponding to the obtained intra prediction mode, the intra prediction angle being (i) beyond a bottom left direction 45 degrees from horizontal diagonal mode, or (ii) beyond a top right direction 45 degrees from horizontal diagonal mode; and
reconstructing at least one sample of a block based on the intra prediction angle that is determined to correspond to the obtained intra prediction mode.
25. The medium recited in claim 24 , wherein
the intra prediction angle corresponds to intraPredAngle and the intra prediction mode corresponds to predModeIntra, and
a relationship between the predetermined plurality of intra prediction modes and the corresponding predetermined plurality of intra prediction angles is as follows:
preModeIntra
−10
−9
−8
−7
−6
−5
−4
−3
−2
−1
2
3
4
5
6
7
8
intraPredAngle
114
93
79
68
60
54
49
45
39
35
32
29
26
23
21
19
17
predModeIntra
9
19
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
intraPredAngle
15
13
11
9
7
5
3
2
1
0
−1
−2
−3
−5
−7
−9
−11
preModeIntra
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
intraPredAngle
−13
−25
−17
−19
−21
−23
−26
−29
−32
−29
−26
−23
−21
−19
−17
−15
−13
preModeIntra
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
intraPredAngle
−11
−9
−7
−5
−3
−2
−1
0
1
2
3
5
7
9
11
13
15
preModeIntra
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
intraPredAngle
17
19
21
23
26
29
32
35
39
45
49
54
60
68
79
93
114.