ADAPTIVE TRANSFORM OPTIONS FOR SCALABLE EXTENSION
In one embodiment, a method determines a first size of a first unit of video used for a prediction process in an enhancement layer. The enhancement layer is useable to enhance a base layer. The method then determines a second size of a second unit of video used for a transform process in the enhancement layer and determines whether adaptive transform is to be used in the transform process based on the first size of the first unit and the second size of the second unit where the adaptive transform provides at least three transform options. When adaptive transform is used, a transform option is selected from the at least three transform options for the transform process.
1 . A method comprising:
determining, by a computing device, a first size of a first unit of video used for a prediction process in an enhancement layer, wherein the enhancement layer is useable to enhance a base layer;
determining, by the computing device, a second size of a second unit of video used for a transform process in the enhancement layer;
determining, by the computing device, whether adaptive transform is to be used in the transform process based on the first size of the first unit and the second size of the second unit, wherein the adaptive transform provides at least three transform options; and
when adaptive transform is used, selecting, by the computing device, a transform option from the at least three transform options for the transform process.
2 . The method of claim 1 further comprising signaling the selected transform option from an encoder to a decoder when adaptive transform is used.
3 . The method of claim 1 further comprising signaling the selected transform option from an encoder to a decoder for all sizes of the second unit of video.
4 . The method of claim 1 further comprising when adaptive transform is not used, selecting from only two transform options that are available.
5 . The method of claim 4 wherein the selected one of the only two transform options is signaled from an encoder to a decoder.
6 . The method of claim 1 further comprising when adaptive transform is not used, determining a single transform option that is available.
7 . The method of claim 6 wherein the single transform option is not signaled from an encoder to a decoder.
8 . The method of claim 1 wherein determining whether adaptive transform is to be used in the transform process comprises allowing the adaptive transform for a largest size of the second size of the second unit of video that fits within the first size of the first unit of video.
9 . The method of claim 1 wherein determining whether adaptive transform is to be used in the transform process comprises:
determining the first size is a 2 N×2 N prediction unit;
determining the second size is a 2 N×2 N transform unit; and
determining adaptive transform is to be used in the transform process when the second size is 2 N×2 N and the first size is 2 N×2 N.
10 . The method of claim 1 wherein determining whether adaptive transform is to be used in the transform process comprises:
determining the first size is a N×2 N prediction unit;
determining the second size is a N×N transform unit; and
determining adaptive transform is to be used in the transform process when the second size is N×N and the first size is N×2 N.
11 . The method of claim 1 wherein determining whether adaptive transform is to be used in the transform process comprises:
determining the first size is a 2 N×N prediction unit;
determining the second size is a N×N transform unit; and
determining adaptive transform is to be used in the transform process when the second size is 2 N×N and the first size is N×N.
12 . The method of claim 1 wherein determining whether adaptive transform is to be used in the transform process comprises:
determining the first size is a 0.5 N×2 N prediction unit;
determining the second size is a 0.5 N×0.5 N transform unit; and
determining adaptive transform is to be used in the transform process for a 0.5 N×0.5 N portion of the 0.5 N×2 N prediction unit when the second size is 0.5 N×0.5 N.
13 . The method of claim 1 wherein determining whether adaptive transform is to be used in the transform process comprises:
determining the first size is a 2 N×0.5 N prediction unit;
determining the second size is a 0.5 N×0.5 N transform unit; and
determining adaptive transform is to be used in the transform process for a 0.5 N×0.5 N portion of the 2 N×0.5 N prediction unit when the second size is 0.5 N×0.5 N.
14 . The method of claim 1 wherein adaptive transform is to be used in the transform process for all sizes of the first size of the first unit of video and the second size of the second unit of video.
15 . The method of claim 1 wherein adaptive transform is to be used in the transform process for a first portion of sizes for the second unit of video and not to be used for a second portion of sizes for the second unit of video.
16 . The method of claim 1 wherein the first unit of video is a prediction unit and the second unit of video is a transform unit.
17 . A decoder comprising:
one or more computer processors; and
a non-transitory computer-readable storage medium comprising instructions that, when executed, control the one or more computer processors to be configured for:
receiving an encoded bitstream;
determining if information is included in the encoded bitstream for a selected transform option, wherein an encoder selected the transform option based on a first size of a first unit of video used for a prediction process in an enhancement layer that is useable to enhance a base layer and a second size of a second unit of video used for a transform process in the enhancement layer, wherein the transform option is selected from at least three transform options; and
when information is included in the encoded bitstream for the selected transform option, using the selected transform option from the at least three transform options for the transform process.
18 . The decoder of claim 17 wherein when the information is not included in the encoded bitstream for the selected transform option, the decoder is configured for:
determining the first size of the first unit of video;
determining the second size of the second unit of video;
determining whether adaptive transform is to be used in the transform process based on the first size of the first unit and the second size of the second unit, wherein the adaptive transform provides the at least three transform options; and
when adaptive transform is used, selecting a transform option from the at least three transform options for the transform process.
19 . An encoder comprising:
one or more computer processors; and
a non-transitory computer-readable storage medium comprising instructions that, when executed, control the one or more computer processors to be configured for:
determining a first size of a first unit of video used for a prediction process in an enhancement layer, wherein the enhancement layer is useable to enhance a base layer;
determining a second size of a second unit of video used for a transform process in the enhancement layer;
determining whether adaptive transform is to be used in the transform process based on the first size of the first unit and the second size of the second unit, wherein the adaptive transform provides at least three transform options; and
when adaptive transform is used, selecting a transform option from the at least three transform options for the transform process.
20 . The encoder of claim 19 further configured for signaling the selected transform option from an encoder to a decoder when adaptive transform is used.