Video coding using mapped transforms and scanning modes

Patent metadata

Field	Value
Publication number	US-10992958-B2
Application number	US-201113336682-A
Country	US
Kind code	B2
Filing date	Dec 23, 2011
Priority date	Dec 29, 2010
Publication date	Apr 27, 2021
Grant date	Apr 27, 2021

Abstract

A video encoder may transform residual data by using a transform selected from a group of transforms. The transform is applied to the residual data to create a two-dimensional array of transform coefficients. A scanning mode is selected to scan the transform coefficients in the two-dimensional array into a one-dimensional array of transform coefficients. The combination of transform and scanning mode may be selected from a subset of combinations that is based on an intra-prediction mode. The scanning mode may also be selected based on the transform used to create the two-dimensional array. The transforms and/or scanning modes used may be signaled to a video decoder.

First claim

What is claimed is:

1. A method of encoding video data, the method comprising:
determining a prediction block of the video data, the prediction block having a prediction block size;
determining a transform block of the prediction block, wherein the transform block has a transform block size;
determining, with a video encoder, a subset of transform and scanning mode combinations based on an intra-prediction mode and the transform block size, the subset of transform and scanning mode combinations consisting of scanning modes having predefined scanning orders;
selecting, with the video encoder, a transform and a scanning mode from the subset of transform and scanning mode combinations for the determined transform block, the selected scanning mode having one of the predefined scanning orders;
applying, with the video encoder, the selected transform to residual data associated with predicting the prediction block based on the intra-prediction mode so as to generate a two-dimensional array of transform coefficients; and
applying, with the video encoder, the selected scanning mode to the transform block containing at least part of the two-dimensional array of transform coefficients to generate a one-dimensional array of transform coefficients according to the predefined scanning order of the selected scanning mode.

2. The method of claim 1 , further comprising:
quantizing, with the video encoder, the transform coefficients in at least one of the one-dimensional array of transform coefficients and the two-dimensional array of transform coefficients; and
entropy coding, with the video encoder, the one-dimensional array of transform coefficients.

3. The method of claim 1 , further comprising:
signaling, with the video encoder, an index in an encoded video bitstream, wherein the index indicates the selected transform and scanning mode.

4. The method of claim 1 , further comprising:
signaling, with the video encoder, an index in an encoded video bitstream, wherein the index indicates the selected transform, and wherein the subset of transform and scanning mode combinations are determined such that a transform is mapped to a specific scanning mode.

5. The method of claim 1 , further comprising:
signaling, with the video encoder, an index in an encoded video bitstream, wherein the index indicates the selected transform, and wherein each of the scanning modes in the subset of transform and scanning mode combinations is based on the intra-prediction mode.

6. The method of claim 1 , the prediction block comprising a first prediction, the transform block comprising a first transform block, the two-dimensional array of transform coefficients comprising a first two-dimensional array of transform coefficients, and the one-dimensional array of transform coefficients comprising a first one-dimensional array of transform coefficients, the method further comprising:
determining, with the video encoder, a second prediction block of the video data, the second prediction block being predicted using the intra-prediction mode for the first prediction block;
determining, with the video encoder, a second transform block of the second prediction block with the transform block size of the first transform block;
determining, with the video encoder, the subset of transform and scanning mode combinations based on the intra-prediction mode and the transform block size, the subset of transform and scanning mode combinations comprising the scanning modes having predefined scanning orders;
selecting, with the video encoder, the transform and the scanning mode for the second transform block from the subset of transform and scanning mode combinations for the determined second transform block, the selected scanning mode having the predefined scanning order, and the selected transform and scanning mode being the same as the selected transform and scanning mode as selected for the first transform block;
applying, with the video encoder, the selected transform to second residual data associated with predicting the second prediction block based on the intra-prediction mode so as to generate a second two-dimensional array of transform coefficients; and
applying, with the video encoder, the selected scanning mode to the second transform block containing at least part of the second two-dimensional array of transform coefficients to generate a second one-dimensional array of transform coefficients according to the predefined scanning order of the selected scanning mode.

7. The method of claim 1 , wherein the transform block size is different that the prediction block size.

8. The method of claim 1 , wherein the subset of transform and scanning mode combinations is determined from a total of 12 different combinations of transforms and scanning modes based on the intra-prediction mode and the transform block size.

9. The method of claim 1 , wherein the subset of transform and scanning mode combinations comprises four combinations or fewer.

10. A method of decoding video data, the method comprising:
receiving, with a video decoder, encoded video data encoded according to an intra-prediction mode;
determining a prediction block of the encoded video data, the prediction block having a prediction block size;
determining a transform block of the prediction block, wherein the transform block has a transform block size;
entropy decoding, with the video decoder, the encoded video data, thereby creating a one-dimensional array of transform coefficients;
determining, with the video decoder, a transform from a subset of transform and scanning mode combinations, wherein the subset is based on the intra-prediction mode and the transform block size, the subset of transform and scanning mode combinations consisting of scanning modes having predefined scanning orders;
determining, with the video decoder, a scanning mode from the subset of transform and scanning mode combinations for the determined transform block, the determined scanning mode having one of the predefined scanning orders;
scanning, with the video decoder, the one-dimensional array of transform coefficients associated with the determined transform block with the determined scanning mode to produce a two-dimensional array of transform coefficients according to the predefined scanning order of the determined scanning mode; and
inverse transforming, with the video decoder, the two-dimensional array of transform coefficients with the determined transform to produce residual video data associated with predicting the prediction block based on the intra-prediction mode.

11. The method of claim 10 , further comprising:
performing, with the video decoder, an intra-predictive video coding process on the residual video data according to the intra-prediction mode to produce decoded video data.

12. The method of claim 10 , further comprising:
receiving, with the video decoder, an index indicating the determined transform and the determined scanning mode; and
entropy decoding the index using CABAC or CAVLC.

13. The method of claim 12 , wherein the index is a 2-bit index.

14. The method of claim 10 , further comprising:
receiving, with the video decoder, an index indicating the determined transform, wherein the scanning mode is determined based on the determined transform.

15. The method of claim 10 , further comprising:
receiving, with the video decoder, an index indicating the determined transform, wherein the scanning mode is determined based on the intra-prediction mode.

16. The method of claim 10 , the method being executable on a wireless communication device, wherein t

Assignees

• Chen Peisong
• Zheng Yunfei
• Joshi Rajan Laxman
• Coban Muhammed Zeyd
• Karczewicz Marta
• Qualcomm Inc

Inventors

• Chen Peisong
• Zheng Yunfei
• Joshi Rajan Laxman
• Coban Muhammed Zeyd
• Karczewicz Marta

Classifications

• H04N19/147

  according to rate distortion criteria (rate-distortion as a criterion for motion estimation H04N19/567) · CPC title

• H04N19/159

  Prediction type, e.g. intra-frame, inter-frame or bidirectional frame prediction · CPC title

• H04N19/176

  the region being a block, e.g. a macroblock · CPC title

• H04N19/46

  Embedding additional information in the video signal during the compression process (H04N19/517, H04N19/68, H04N19/70 take precedence) · CPC title

• H04N19/60 Primary

  using transform coding · CPC title