Memory reduction implementation for weighted angular prediction
A method and apparatus for decoding JVET video, including receiving a bitstream and generating predictor pixels for angular prediction using pixels at projected positions along both a top reference row (main reference line) and a left reference column (side reference line). By combining projected pixel values on the main reference line with projected pixel values on the side reference, a predictor pixel at coordinate (x,y) can be determined. Further weighting the values according to a distance between predictor pixels and projected pixel positions on the main and side references may be included in the combination of pixel values. The weight parameter may be determined from a weighting table. Further, the weights for horizontal and vertical predictors may be computed based on that of a horizontal and vertical predictor, whichever is more accurate.
1. An apparatus for coding video data by generating predictor pixels for angular prediction using pixels at projected positions on both top reference row and left reference column positions, the apparatus comprising one or more processors configured to:
receive a bitstream comprising video data;
select an intra direction mode for coding at least a portion of the video data, wherein the intra direction mode is a first intra direction mode in a plurality of intra direction modes that includes at least one weighted intra direction mode; and
predict a pixel at coordinate (x,y) in accordance with P(x,y)=((((x+1)*Recon[x+y+2,−1]))+((y+1)*Recon[−1,x+y+2])*S[x+y+2]+(y+x+2)/2)/(y+x+2))>>ShiftDenom),
wherein Recon[0,0] is a reconstructed pixel at top left coordinate (0,0) of a current coding node, S[n] is a weight parameter determined from a weighting table, and ShiftDenom is a factor for a shifted down operation,
wherein the prediction includes weighting values according to a distance between predictor pixels and projected pixels in the row and column.
2. The apparatus of claim 1 , wherein the weight parameter S[n] is determined from a weighting table S[n] having a sum of width and height of 256 and ShiftDenom equal to 10 as:
S
[
n
]
=
{
0
,
0
,
512
,
341
,
256
,
205
,
171
,
146
,
128
,
114
,
103
,
93
,
85
,
79
,
73
,
68
,
64
,
60
,
57
,
54
,
51
,
49
,
47
,
45
,
43
,
41
,
39
,
38
,
37
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35
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34
,
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32
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11
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11
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11
,
10
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10
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10
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10
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10
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10
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10
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10
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10
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10
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10
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9
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5
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5
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5
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4
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4
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4
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4
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4
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4
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4
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4
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5
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4
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4
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4
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4
,
4
,
4
,
4
,
4
}
.
3. The apparatus of claim 1 , wherein the weight parameter is determined from a weighting table S[n] with a sum of width and height of 512 and the factor for shift conversion is 10:
S
[
n
]
=
{
0
,
0
,
512
,
341
,
256
,
205
,
171
,
146
,
128
,
114
,
103
,
93
,
85
,
79
,
73
,
68
,
64
,
60
,
57
,
54
,
51
,
49
,
47
,
45
,
43
,
41
,
39
,
38
,
37
,
35
,
34
,
33
,
32
,
31
,
30
,
29
,
28
,
28
,
27
,
26
,
26
,
25
,
24
,
24
,
23
,
23
,
22
,
22
,
21
,
21
,
20
,
20
,
20
,
19
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18
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12
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11
,
11
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11
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11
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11
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11
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11
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11
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11
,
10
,
10
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10
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10
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10
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10
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10
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10
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10
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10
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9
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8
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7
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4
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,
5
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3
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3
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3
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2
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2
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2
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2
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2
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2
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2
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2
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2
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2
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2
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2
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2
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2
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2
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2
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2
,
2
,
2
,
2
,
2
}
.
4. The apparatus of claim 1 , wherein the weight parameter is determined from a weighting table S[n] with a sum of width and height of 128 and ShiftDenonm=10:
S
[
n
]
=
{
341
,
256
,
205
,
171
,
146
,
128
,
114
,
103
,
93
,
85
,
79
,
73
,
68
,
64
,
60
,
57
,
54
,
51
,
49
,
47
,
45
,
43
,
41
,
39
,
38
,
37
,
35
,
34
,
33
,
32
,
31
,
30
,
29
,
28
,
28
,
27
,
26
,
26
,
25
,
24
,
24
,
23
,
23
,
22
,
22
,
21
,
21
,
20
,
20
,
20
,
19
,
19
,
19
,
18
,
18
,
18
,
17
,
17
,
17
,
16
,
16
,
16
,
16
,
16
,
15
,
15
,
15
,
15
,
14
,
14
,
14
,
14
,
14
,
14
,
13
,
13
,
13
,
13
,
13
,
12
,
12
,
12
,
12
,
12
,
12
,
11
,
11
,
11
,
11
,
11
,
11
,
11
,
11
,
11
,
10
,
10
,
10
,
10
,
10
,
10
,
10
,
10
,
10
,
10
,
10
,
9
,
9
,
9
,
9
,
9
,
9
,
9
,
9
,
9
,
9
,
9
,
9
,
8
,
8
,
8
,
8
,
8
,
8
,
8
,
}
.
5. The apparatus of claim 1 , wherein the weight parameter is determined from a weighting table S[n] with a sum of width and height of 128 and ShiftDenonm=9:
S
[
n
]
=
{
171
,
128
,
102
,
85
,
73
,
64
,
57
,
51
,
47
,
43
,
39
,
37
,
34
,
32
,
30
,
28
,
27
,
26
,
24
,
23
,
22
,
21
,
20
,
20
,
19
,
18
,
18
,
17
,
17
,
16
,
16
,
15
,
15
,
14
,
14
,
13
,
13
,
13
,
12
,
12
,
12
,
12
,
11
,
11
,
11
,
11
,
10
,
10
,
10
,
10
,
10
,
9
,
9
,
9
,
9
,
9
,
9
,
9
,
8
,
8
,
8
,
8
,
8
,
8
,
8
,
8
,
7
,
7
,
7
,
7
,
7
,
7
,
7
,
7
,
7
,
7
,
6
,
6
,
6
,
6
,
6
,
6
,
6
,
6
,
6
,
6
,
6
,
6
,
6
,
6
,
6
,
5
,
5
,
5
,
5
,
5
,
5
,
5
,
5
,
5
,
5
,
5
,
5
,
5
,
5
,
5
,
5
,
5
,
5
,
5
,
5
,
4
,
4
,
4
,
4
,
4
,
4
,
4
,
4
,
4
,
4
,
4
,
4
,
4
,
4
,
4
}
.
6. The apparatus of claim 1 , wherein P[x,y] weights parameters based on at least one of a horizontal or vertical predictor.
7. The apparatus of claim 6 , wherein the calculation to determine P[x,y] is further weighted with at least one of horWeight or verWeight by computing:
P
[
x
,
y
]
=
(
(
(
(
x
+
1
)
*
Recon
[
x
+
y
+
2
,
-
1
]
)
)
+
(
(
y
+
1
)
*
Recon
[
-
1
,
x
+
y
+
2
]
)
)
*
S
[
y
+
x
+
2
]
+
(
y
+
x
+
2
)
/
2
)
/
(
y
+
x
+
2
)
)
≫
ShiftDenom
)
,
wherein
horWeight
=
{
(
1
≪
ShiftDenom
)
-
verWeight
when
x
<
y
(
y
+
1
)
*
S
[
x
+
y
+
2
]
otherwise
,
and
wherein
verWeight
=
{
(
x
+
1
)
*
S
[
x
+
y
+
2
]
when
x
<
y
(
1
≪
ShiftDenom
)
-
horWeight
otherwise
.
8. The apparatus of claim 6 , wherein the calculation to determine P[x,y] is further weighted with at least one of horWeight or verWeight by computing:
P
[
x
,
y
]
=
(
(
(
(
x
+
1
)
*
Recon
[
x
+
y
+
2
,
-
1
]
)
)
+
(
(
y
+
1
)
*
Recon
[
-
1
,
x
+
y
+
2
]
)
)
*
S
[
y
+
x
+
2
]
+
(
y
+
x
+
2
)
/
2
)
/
(
y
+
x
+
2
)
)
≫
ShiftDenom
)
,
wherein
horWeight
=
{
(
1
≪
ShiftDenom
)
-
verWeight
when
x
<
y
(
y
+
1
)
*
S
[
x
+
y
-
1
]
otherwise
,
and
wherein
verWeight
=
{
(
x
+
1
)
*
S
[
x
+
y
-
1
]
when
x
<
y
(
1
≪
ShiftDenom
)
-
horWeight
otherwise
.
9. The apparatus of claim 1 , wherein said apparatus decodes a Joint Video Exploration Team said video data.
10. The apparatus of claim 1 , wherein said coding unit is rectangular.
11. The apparatus of claim 1 , wherein said coding unit is coded without further partitioning into prediction units.
12. The apparatus of claim 1 , wherein said coding unit is coded without further partitioning into transform units.