US 8,619,853 B2 · Separable directional transforms

Abstract

This disclosure describes techniques for transforming residual blocks of video data. In particular, a plurality of different transforms selectively applied to the residual blocks based on the prediction mode of the video blocks. At least a portion of the plurality of transforms are separable directional transform specifically trained for a corresponding prediction mode to provide better energy compaction for the residual blocks of the given prediction mode. Using separable directional transforms offers the benefits of lower computation complexity and storage requirement than use of non-separable directional transforms. Additionally, a scan order used to scan the coefficients of the residual block may be adjusted when applying separable directional transforms. In particular, the scan order may be adjusted based on statistics associated with one or more previously coded blocks to better ensure that non-zero coefficients are grouped near the front of the one-dimensional coefficient vector to improve the effectiveness of entropy coding.

Claims46

Dependent claims

A method of coding video data, the method comprising:

selecting at least one transform of a plurality of transforms for a video block based on a directional prediction mode for predicting the video block, the directional prediction mode for the video block being one of a plurality of directional prediction modes, the plurality of transforms being used for transforming between residual pixel values of the video block and residual transform coefficients of the video block, wherein each of the plurality of transforms is associated with at least one directional prediction mode of the plurality of directional prediction modes and at least a portion of the plurality of transforms are separable directional transforms;
applying the selected at least one transform to the video block to transform between the residual pixel values of the video block and the residual transform coefficients of the video block;
and
entropy coding the residual transform coefficients of the video block.

1 more element

A device for coding video data, the device comprising:

a memory configured to:
store a plurality of transforms for use in transforming between residual pixel values of a video block and residual transform coefficients of the video block, wherein each of the plurality of transforms is associated with at least one directional prediction mode of a plurality of directional prediction modes and at least a portion of the plurality of transforms are separable directional transforms;
and
a processor configured to:
select at least one transform of the plurality of transforms for the video block based on a directional prediction mode for predicting the video block, the directional prediction mode for the video block being one of the plurality of directional prediction modes;
apply the selected at least one transform to the video block to transform between the residual pixel values of the video block and the residual transform coefficients of the video block;
and
entropy code the residual transform coefficients of the video block.

5 more elements

A non-transitory computer-readable medium upon which is stored instructions that upon execution in a device cause the device to code video blocks, wherein the instructions cause the device to:

store a plurality of transforms for use in transforming between residual pixel values of a video block and residual transform coefficients of the video block, wherein each of the plurality of transforms is associated with at least one directional prediction mode of a plurality of directional prediction modes and at least a portion of the plurality of transforms are separable directional transforms;
select at least one transform of the plurality of transforms for the video block based on a directional prediction mode for predicting the video block, the directional prediction mode for the video block being one of the plurality of directional prediction modes;
apply the selected at least one transform to the video block to transform between the residual pixel values of the video block and the residual transform coefficients of the video block;
and
entropy code the residual transform coefficients of the video block.

2 more elements

A device for coding video data, the device comprising:

means for storing a plurality of transforms for use in transforming between residual pixel values of a video block and residual transform coefficients of the video block, wherein each of the plurality of transforms is associated with at least one directional prediction mode of a plurality of directional prediction modes and at least a portion of the plurality of transforms are separable directional transforms;
means for selecting at least one transform of the plurality of transforms for the video block based on a directional prediction mode for predicting the video block, the directional prediction mode for the video block being one of the plurality of directional prediction modes;
means for applying the selected at least one transform to the video block to transform between the residual pixel values of the video block and the residual transform coefficients of the video block;
and
means for entropy coding the residual transform coefficients of the video block.

2 more elements

Dependencies are inferred from the claim text.

Separable directional transforms

Life of this patent

Separable directional transforms

Life of this patent

Abstract

Claims46