Method and apparatus for intra mode coding
A method of and an apparatus for controlling intra prediction for decoding of a video sequence are provided. The method includes determining a ratio of a width to a height of a coding unit, and based on the determined ratio being different than one, adding, to a table including intra prediction modes corresponding to intra prediction angles, first wide angles toward a bottom-left edge of the coding unit, second wide angles toward a top-right edge of the coding unit, and additional intra prediction modes respectively corresponding to the first wide angles and the second wide angles. The method further includes selecting, for decoding the video sequence, one of the intra prediction modes and the additional intra prediction modes added to the table.
1. A method of controlling intra prediction for decoding of a video sequence, the method being performed by at least one processor, and the method comprising:
determining a ratio of a width to a height of a coding unit;
based on the determined ratio being different than one, adding, to a table including a plurality of intra prediction modes corresponding to intra prediction angles, first wide angles toward a bottom-left edge of the coding unit, second wide angles toward a top-right edge of the coding unit, and additional intra prediction modes respectively corresponding to the first wide angles and the second wide angles; and
selecting, for decoding the video sequence, one of the plurality of intra prediction modes and the additional intra prediction modes added to the table,
wherein each of the intra prediction angles included in the table has an angular direction α with tan(α) equal to {0/32, 1/32, 2/32, 3/32, 4/32, 6/32, 8/32, 10/32, 12/32, 14/32, 16/32, 18/32, 20/32, 23/32, 26/32, 29/32, 32/32}, and
each of the first wide angles added to the table has the angular direction α with tan(α) equal to {35/32, 39/32, 45/32, 51/32, 57/32, 64/32, 73/32, 86/32, 102/32, 128/32, 171/32, 256/32, 341/32, 512/32}.
2. The method of claim 1 , wherein a number of the second wide angles added to the table is 14.
3. The method of claim 2 , wherein each of the second wide angles added to the table has the angular direction α with tan(α) equal to {35/32, 39/32, 45/32, 51/32, 57/32, 64/32, 73/32, 86/32, 102/32, 128/32, 171/32, 256/32, 341/32, 512/32}.
4. The method of claim 1 , wherein a number of the first wide angles added to the table is 15.
5. The method of claim 4 , wherein each of the first wide angles added to the table has the angular direction α with tan(α) equal to {35/32, 39/32, 45/32, 51/32, 57/32, 64/32, 73/32, 86/32, 102/32, 128/32, 171/32, 256/32, 341/32, 512/32, 1024/32}.
6. The method of claim 1 , wherein a number of the second wide angles added to the table is 15.
7. The method of claim 6 , wherein each of the second wide angles added to the table has the angular direction α with tan(α) equal to {35/32, 39/32, 45/32, 51/32, 57/32, 64/32, 73/32, 86/32, 102/32, 128/32, 171/32, 256/32, 341/32, 512/32, 1024/32}.
8. The method of claim 1 , wherein a first number of the plurality of intra prediction modes included in the table is 67,
a second number of the additional intra prediction modes added to the table is 28, and
the table includes:
predModeIntra
−14
−13
−12
−11
intraPredAngle
512
341
256
171
predModeIntra
−10
−9
−8
−7
−6
−5
−4
−3
−2
−1
2
3
4
5
6
7
8
intraPredAngle
128
102
86
73
64
57
51
45
39
35
32
29
26
23
20
18
16
predModeIntra
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
intraPredAngle
14
12
10
8
6
4
3
2
1
0
−1
−2
−3
−4
−6
−8
−10
predModeIntra
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
intraPredAngle
−12
−14
−16
−18
−20
−23
−26
−29
−32
−29
−26
−23
−20
−18
−16
−14
−12
predModeIntra
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
intraPredAngle
−10
−8
−6
−4
−3
−2
−1
0
1
2
3
4
6
8
10
12
14
predModeIntra
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
intraPredAngle
16
18
20
23
26
29
32
35
39
45
51
57
64
73
86
102
128
predModeIntra
77
78
79
80
intraPredAngle
171
256
341
512
where predModeIntra denotes the plurality of intra prediction modes, and intraPredAngle denotes the intra prediction angles.
9. An apparatus for controlling intra prediction for decoding of a video sequence, the apparatus comprising:
at least one memory configured to store computer program code; and
at least one processor configured to access the at least one memory and operate according to the computer program code, the computer program code comprising:
determining code configured to cause the at least one processor to determine a ratio of a width to a height of a coding unit;
adding code configured to cause the at least one processor to, based on the determined ratio being different than one, add, to a table including a plurality of intra prediction modes corresponding to intra prediction angles, first wide angles toward a bottom-left edge of the coding unit, second wide angles toward a top-right edge of the coding unit, and additional intra prediction modes respectively corresponding to the first wide angles and the second wide angles; and
selecting code configured to cause the at least one processor to select, for decoding the video sequence, one of the plurality of intra prediction modes and the additional intra prediction modes added to the table,
wherein each of the intra prediction angles included in the table has an angular direction α with tan(α) equal to {0/32, 1/32, 2/32, 3/32, 4/32, 6/32, 8/32, 10/32, 12/32, 14/32, 16/32, 18/32, 20/32, 23/32, 26/32, 29/32, 32/32}, and
each of the first wide angles added to the table has the angular direction α with tan(α) equal to {35/32, 39/32, 45/32, 51/32, 57/32, 64/32, 73/32, 86/32, 102/32, 128/32, 171/32, 256/32, 341/32, 512/32}.
10. The apparatus of claim 9 , wherein a number of the second wide angles added to the table is 14.
11. The apparatus of claim 10 , wherein each of the second wide angles added to the table has the angular direction α with tan(α) equal to {35/32, 39/32, 45/32, 51/32, 57/32, 64/32, 73/32, 86/32, 102/32, 128/32, 171/32, 256/32, 341/32, 512/32}.
12. The apparatus of claim 9 , wherein a number of the first wide angles added to the table is 15.
13. The apparatus of claim 12 , wherein each of the first wide angles added to the table has the angular direction α with tan(α) equal to {35/32, 39/32, 45/32, 51/32, 57/32, 64/32, 73/32, 86/32, 102/32, 128/32, 171/32, 256/32, 341/32, 512/32, 1024/32}.
14. The apparatus of claim 9 , wherein a number of the second wide angles added to the table is 15.
15. The apparatus of claim 14 , wherein each of the second wide angles added to the table has the angular direction α with tan(α) equal to {35/32, 39/32, 45/32, 51/32, 57/32, 64/32, 73/32, 86/32, 102/32, 128/32, 171/32, 256/32, 341/32, 512/32, 1024/32}.
16. A non-transitory computer-readable storage medium storing instructions that cause a processor to:
determine a ratio of a width to a height of a coding unit;
based on the determined ratio being different than one, add, to a table including a plurality of intra prediction modes corresponding to intra prediction angles, first wide angles toward a bottom-left edge of the coding unit, second wide angles toward a top-right edge of the coding unit, and additional intra prediction modes respectively corresponding to the first wide angles and the second wide angles; and
select, for decoding a video sequence, one of the plurality of intra prediction modes and the additional intra prediction modes added to the table,
wherein each of the intra prediction angles included in the table has an angular direction α with tan(α) equal to {0/32, 1/32, 2/32, 3/32, 4/32, 6/32, 8/32, 10/32, 12/32, 14/32, 16/32, 18/32, 20/32, 23/32, 26/32, 29/32, 32/32}, and
each of the first wide angles added to the table has the angular direction α with tan(α) equal to {35/32, 39/32, 45/32, 51/32, 57/32, 64/32, 73/32, 86/32, 102/32, 128/32, 171/32, 256/32, 341/32, 512/32}.