Storage and signaling resolutions of motion vectors

Patent metadata

Field	Value
Publication number	US-2016337662-A1
Application number	US-201615151429-A
Country	US
Kind code	A1
Filing date	May 10, 2016
Priority date	May 11, 2015
Publication date	Nov 17, 2016
Grant date	—

Abstract

An example method of decoding video data includes obtaining, from a video bitstream, a representation of a difference between a motion vector (MV) predictor and a MV that identifies a predictor block for a current block of video data in a current picture; obtaining, from the video bitstream, a syntax element indicating whether adaptive motion vector resolution (AMVR) is used for the current block; determining, based on the representation of the difference between the MV predictor and the MV that identifies the predictor block, a value of the MV; storing the value of the MV at fractional-pixel resolution regardless of whether AMVR is used for the current block and regardless of whether the predictor block is included in the current picture; determining, based on the value of the stored MV, pixel values of the predictor block; and reconstructing the current block based on the pixel values of the predictor block.

First claim

What is claimed is:

1 . A method of decoding video data, the method comprising:
obtaining, from a coded video bitstream, a representation of a difference between a motion vector predictor and a motion vector that identifies a predictor block for a current block of video data in a current picture; obtaining, from the coded video bitstream, a syntax element that indicates whether adaptive motion vector resolution is used for the current block of video data; determining, based on the representation of the difference between the motion vector predictor and the motion vector that identifies the predictor block, a value of the motion vector; storing the value of the motion vector at fractional-pixel resolution regardless of whether adaptive motion vector resolution is used for the current block of video data and regardless of whether the predictor block is included in the current picture; determining, based on the value of the stored motion vector, pixel values of the predictor block; and reconstructing the current block based on the pixel values of the predictor block.

2 . The method of claim 1 , wherein determining the pixel values of the predictor block based on the value of the motion vector comprises:
identifying, without scaling the value of the stored motion vector and regardless of whether the predictor block is included in the current picture, the predictor block.

3 . The method of claim 2 , wherein, where the syntax element indicates that adaptive motion vector resolution is used for the current block of video data or the predictor block is included in the current picture, and wherein determining the value of the motion vector comprises:
right-shifting the motion vector predictor by N; and left-shifting the sum of the right-shifted motion vector predictor and the representation of the difference between the motion vector predictor and the motion vector that identifies the predictor block by N.

4 . The method of claim 3 , wherein N is two.

5 . The method of claim 3 , wherein, where the syntax element indicates that adaptive motion vector resolution is not used for the current block of video data and the predictor block is not included in the current picture, and wherein determining the value of the motion vector comprises:
adding the motion vector predictor to the representation of the difference between the motion vector predictor and the motion vector that identifies the predictor block.

6 . The method of claim 1 , wherein storing the value of the motion vector at fractional-pixel resolution comprises storing the value of the motion vector at quarter-pixel resolution regardless of whether adaptive motion vector resolution is used for the current block of video data and regardless of whether the predictor block is included in the current picture.

7 . A method of encoding video data, the method comprising:
selecting a predictor block for a current block of video data in a current picture of video data; determining a value of a motion vector that identifies the selected predictor block for the current block; encoding, in a coded video bitstream, a representation of a difference between a motion vector predictor and the value of the motion vector; encoding, in the coded video bitstream, a syntax element that indicates whether adaptive motion vector resolution is used for the current block of video data; storing the value of the motion vector at fractional-pixel resolution regardless of whether adaptive motion vector resolution is used for the current block of video data and regardless of whether the predictor block is included in the current picture; determining, based on the value of the stored motion vector, pixel values of the predictor block; and reconstructing the current block based on the pixel values of the predictor block.

8 . The method of claim 7 , wherein determining the pixel values of the predictor block based on the value of the motion vector comprises:
identifying, without scaling the value of the stored motion vector and regardless of whether the predictor block is included in the current picture, the predictor block.

9 . The method of claim 8 , wherein, where adaptive motion vector resolution is used for the current block of video data or the predictor block is included in the current picture, and wherein determining the value of the motion vector comprises:
right-shifting the motion vector predictor by N; and left-shifting the sum of the right-shifted motion vector predictor and the representation of the difference between the motion vector predictor and the motion vector that identifies the predictor block by N.

10 . The method of claim 9 , wherein N is two.

11 . The method of claim 9 , wherein, where adaptive motion vector resolution is not used for the current block of video data and the predictor block is not included in the current picture, and wherein determining the value of the motion vector comprises:
adding the motion vector predictor to the representation of the difference between the motion vector predictor and the motion vector that identifies the predictor block.

12 . The method of claim 7 , wherein storing the value of the motion vector at fractional-pixel resolution comprises storing the value of the motion vector at quarter-pixel resolution regardless of whether adaptive motion vector resolution is used for the current block of video data and regardless of whether the predictor block is included in the current picture.

13 . A device for decoding video data, the device comprising:
a memory configured to store a portion of the video data; and one or more processors configured to:
obtain, from a coded video bitstream, a representation of a difference between a motion vector predictor and a motion vector that identifies a predictor block for a current block of video data in a current picture;
obtain, from the coded video bitstream, a syntax element that indicates whether adaptive motion vector resolution is used for the current block of video data;
determine, based on the representation of the difference between the motion vector predictor and the motion vector that identifies the predictor block, a value of the motion vector;
store the value of the motion vector at fractional-pixel resolution regardless of whether adaptive motion vector resolution is used for the current block of video data and regardless of whether the predictor block is included in the current picture;
determine, based on the value of the stored motion vector, pixel values of the predictor block; and
reconstruct the current block based on the pixel values of the predictor block.

14 . The device of claim 13 , wherein, to determine the pixel values of the predictor block based on the value of the motion vector, the one or more processors are configured to:
identify, without scaling the value of the stored motion vector and regardless of whether the predictor block is included in the current picture, the predictor block.

15 . The device of claim 14 , wherein, where the syntax element indicates that adaptive motion vector resolution is used for the current block of video data or the predictor block is included in the current picture, and wherein, to determine the value of the motion vector, the one or more processors are configured to:
right-shift the motion vector predictor by N; and left-shift the sum of the right-shifted motion vector predictor and the representation of the difference between the motion vector predictor and the motion vector that identifies the predictor block by N.

16 . The device of claim 15 , wherein

Assignees

• Qualcomm Inc

Inventors

• Pang Chao
• Rapaka Krishnakanth
• Seregin Vadim
• Karczewicz Marta
• Joshi Rajan Laxman

Classifications

• H04N19/182

  the unit being a pixel · CPC title

• H04N19/52 Primary

  by predictive encoding · CPC title

• H04N19/176

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

• H04N19/70 Primary

  characterised by syntax aspects related to video coding, e.g. related to compression standards · CPC title

• H04N19/42

  characterised by implementation details or hardware specially adapted for video compression or decompression, e.g. dedicated software implementation (H04N19/635 takes precedence) · CPC title