Intra-prediction apparatus for removing a directional intra-prediction mode from a set of predetermined directional intra-prediction modes
An intra-prediction apparatus removes a directional intra-prediction mode from a set of predetermined directional intra-prediction modes. The intra-prediction apparatus comprises: a reference sample determining unit configured to select the directional intra-prediction mode from the set of predetermined directional intra-prediction modes, and to determine a plurality of available reference samples; a directional intra-prediction mode removing unit configured to remove the directional intra-prediction mode from the set of predetermined directional intra-prediction modes if a length (L RSlonger ) associated with the plurality of available reference samples is smaller than a multiple of a length (L longer ) of a first side of the video coding block for obtaining a reduced set; and an intra-prediction unit configured to intra-predict pixel values of pixels of the rectangular video coding block on the basis of the reduced set. The intra-prediction apparatus can further comprise an area determining unit.
1. An intra-prediction apparatus, comprising a processor and a non-transitory memory having instructions stored thereon, wherein the instructions, when executed by the processor, facilitate:
selecting a directional intra-prediction mode for a rectangular video coding block from an extended set of predetermined directional intra-prediction modes to determine a plurality of available reference samples based on a predetermined direction of the directional intra-prediction mode, wherein each predetermined directional intra-prediction mode of the extended set of predetermined directional intra-prediction modes is associated with a predetermined direction, wherein the rectangular video coding block has a first side and a second side, wherein a length of the first side is greater than a length of the second side, wherein a number of extended directional intra-prediction modes of the extended set of predetermined directional intra-prediction modes is based on an aspect ratio of the rectangular video coding block, and wherein the aspect ratio of the rectangular video coding block is
R
asp
=
L
shorter
L
longer
,
where L shorter and L longer are the lengths of the second and first sides of the rectangular video coding block, respectively;
and
intra-predicting pixel values of pixels of the rectangular video coding block based on the plurality of available reference samples.
2. The intra-prediction apparatus of claim 1 , wherein the instructions, when executed by the processor, further facilitate:
removing a directional intra-prediction mode from a set of predetermined directional intra-prediction modes in response to a length associated with the plurality of available reference samples being smaller than a multiple of the length of the first side.
3. The intra-prediction apparatus of claim 1 , wherein the instructions, when executed by the processor, further facilitate:
determining a non-prediction area within the rectangular video coding block based on the length of the second side and the predetermined direction of the directional intra-prediction mode.
4. The intra-prediction apparatus of claim 3 , wherein determining the non-prediction area within the rectangular video coding block is based on the following equation:
S
uncov
=
L
shorter
2
·
tan
γ
2
,
wherein S uncov denotes the non-prediction area, and γ denotes an angle associated with the predetermined direction of the directional intra-prediction mode.
5. The intra-prediction apparatus of claim 3 , wherein determining the non-prediction area within the rectangular video coding block further comprises:
determining a fractional non-prediction area within the rectangular video coding block based on the length of the first side, the length of the second side, and the predetermined direction of the directional intra-prediction mode.
6. The intra-prediction apparatus of claim 5 , wherein determining the fractional non-prediction area within the rectangular video coding block is based on the following equation:
P
area
=
L
shorter
L
longer
·
tan
γ
2
,
wherein P area denotes the fractional non-prediction area, and γ denotes the angle associated with the predetermined direction of the directional intra-prediction mode.
7. The intra-prediction apparatus of claim 1 , wherein the rectangular video coding block is a coding unit, a prediction unit, or a transform unit.
8. The intra-prediction apparatus of claim 1 , wherein the intra-prediction apparatus is part of an encoding apparatus configured to encode the rectangular video coding block based on a predicted rectangular video coding block.
9. The intra-prediction apparatus of claim 1 , wherein the intra-prediction apparatus is part of a decoding apparatus configured to restore a rectangular video coding block based on an encoded rectangular video coding block and a predicted rectangular video coding block.
10. The intra-prediction apparatus of claim 1 , wherein the number of extended directional intra-prediction modes is based on an angle α, wherein:
α
=
π
4
-
arctan
(
L
shorter
L
longer
)
.
11. The intra-prediction apparatus of claim 10 , wherein the number of extended directional intra-prediction modes (N) is based on:
N
=
⌊
α
s
⌋
,
wherein └·┘ is a floor operation, and s is an average angle step between neighbor directional modes.
12. An intra-prediction method, comprising:
selecting, by an intra-prediction apparatus, a directional intra-prediction mode for a rectangular video coding block from an extended set of predetermined directional intra-prediction modes, wherein each predetermined directional intra-prediction mode of the extended set of predetermined directional intra-prediction modes is associated with a predetermined direction, wherein the rectangular video coding block has a first side and a second side, wherein a length of the first side is greater than a length of the second side, wherein a number of extended directional intra-prediction modes of the extended set of predetermined directional intra-prediction modes is based on an aspect ratio of the rectangular video coding block, and wherein the aspect ratio of the rectangular video coding block is
R
asp
=
L
shorter
L
longer
,
where L shorter and L longer are the lengths of the second and first sides of the rectangular video coding block, respectively;
determining, by the intra-prediction apparatus, a plurality of available reference samples based on a predetermined direction of the selected directional intra-prediction mode;
and
intra-predicting, by the intra-prediction apparatus, pixel values of pixels of the rectangular video coding block based on the plurality of available reference samples.
13. The intra-prediction method of claim 12 , wherein the number of extended directional intra-prediction modes is based on an angle α, wherein:
α
=
π
4
-
arctan
(
L
shorter
L
longer
)
.
14. The intra-prediction method of claim 13 , wherein the number of extended directional intra-prediction modes (N) is based on:
N
=
⌊
α
s
⌋
,
wherein └·┘ is a floor operation, and s is an average angle step between neighbor directional modes.
15. The intra-prediction method of claim 12 , wherein the method further comprises:
determining a non-prediction area within the rectangular video coding block based on the length of the second side and the predetermined direction of the directional intra-prediction mode.
16. The intra-prediction method of claim 12 , wherein the rectangular video coding block is a coding unit, a prediction unit, or a transform unit.
17. A non-transitory computer readable medium having processor-executable instructions stored thereon for intra-prediction, wherein the processor-executable instructions, when executed, facilitate:
selecting a directional intra-prediction mode for a rectangular video coding block from an extended set of predetermined directional intra-prediction modes, wherein each predetermined directional intra-prediction mode of the extended set of predetermined directional intra-prediction modes is associated with a predetermined direction, wherein the rectangular video coding block has a first side and a second side, wherein a length of the first side is greater than a length of the second side, wherein a number of extended directional intra-prediction modes of the extended set of predetermined directional intra-prediction modes is based on an aspect ratio of the rectangular video coding block, and wherein the aspect ratio of the rectangular video coding block is
R
asp
=
L
shorter
L
longer
,
where L shorter and L longer are the lengths of the second and first sides of the rectangular video coding block, respectively;
determining a plurality of available reference samples based on a predetermined direction of the selected directional intra-prediction mode;
and
intra-predicting pixel values of pixels of the rectangular video coding block based on the plurality of available reference samples.
18. The non-transitory computer readable medium of claim 17 , wherein the number of extended directional intra-prediction modes is based on an angle α, wherein:
α
=
π
4
-
arctan
(
L
shorter
L
longer
)
.
19. The non-transitory computer readable medium of claim 18 , wherein the number of extended directional intra-prediction modes (N) is based on:
N
=
⌊
α
s
⌋
,
wherein └·┘ is a floor operation, and s is an average angle step between neighbor directional modes.
20. The non-transitory computer readable medium of claim 17 , wherein the processor-executable instructions, when executed, further facilitate:
determining a non-prediction area within the rectangular video coding block based on the length of the second side and the predetermined direction of the directional intra-prediction mode.