Predictor candidates for motion compensation

Patent metadata

Field	Value
Publication number	US-2025317596-A1
Application number	US-202519242477-A
Country	US
Kind code	A1
Filing date	Jun 18, 2025
Priority date	Oct 5, 2017
Publication date	Oct 9, 2025
Grant date	—

Abstract

Different implementations are described, particularly implementations for determining a set of predictor candidates for affine merge coding mode from neighboring blocks for motion compensation of a picture block based on a motion model. The motion model, may be, e.g., an affine model in a merge mode or AMVP mode for a video content encoder or decoder. The motion model, may be, e.g., an affine model based on top-left/top-right control point motion vectors or an affine model based on top-left/bottom-left control point motion vectors. Such affine model may be signaled by a flag. In an embodiment, predictor candidates are sorted in the set based on a criterion such as, e.g., a validity check or a vectors coherence cost. In an embodiment, a predictor candidate is selected from the set based on a motion model for each of the multiple predictor candidates, and may be based on a criterion such as, e.g., a rate distortion cost. The corresponding motion field is determined based on, e.g., one or more corresponding control point motion vectors for the block being encoded or decoded. The corresponding motion field of an embodiment identifies motion vectors used for prediction of sub-blocks of the block being encoded or decoded.

First claim

1 . A method for video encoding, comprising:
determining, for a block being encoded in affine merge mode, a top-left list of spatial neighboring blocks, the top-left list comprising neighboring blocks of a top-left corner of the block, a top-right list of spatial neighboring blocks of the block, the top-right list comprising neighboring blocks of a top-right corner of the block, a bottom-left list of spatial neighboring blocks of the block, the bottom-left list comprising neighboring blocks of a bottom-left corner of the block; determining, for the block being encoded, a set of predictor candidates for affine merge mode based on the top-left list, top-right list and bottom-left list, wherein the set of predictor candidates for affine merge mode comprises:
a first predictor candidate on condition that a reference picture of a first spatial neighboring block of the top-left list is the same as a reference picture of a second spatial neighboring block of the top-right list wherein:
a motion vector of the first spatial neighboring block of the top-left list is used as a first control point motion vector of the first predictor candidate;
a motion vector of the second spatial neighboring block of the top-right list is used as a second control point motion vector of first predictor candidate; and
the reference picture of the first spatial neighboring block of the top-left list is used as reference picture of the first predictor candidate; and

a second predictor candidate on condition that a reference picture of a first spatial neighboring block of the top-left list is the same as a reference picture of a second spatial neighboring block of the bottom-left list:
a motion vector of the first spatial neighboring block of the top-left list is used as the first control point motion vector of the second predictor candidate;
a motion vector of the second spatial neighboring block of the bottom-left list and the motion vector of the first spatial neighboring block of the top-left list are used to derive a second control point motion vector of the second predictor candidate; and
the reference picture of the first spatial neighboring block of the top-left list is used as a reference picture of the second predictor candidate;

determining, for the block being encoded and for each predictor candidate, a motion field based on a motion model and on the one or more control point motion vectors of the predictor candidate, wherein the motion field identifies motion vectors used for prediction of sub-blocks of the block being encoded; selecting a predictor candidate from the set of predictor candidates based on a rate distortion determination between predictions responsive to the motion field determined for each predictor candidate; and encoding the block based on the motion field for the selected predictor candidate.

2 . The method of claim 1 , wherein motion information associated to at least one of the spatial neighboring blocks comprises translational motion information.

3 . The method of claim 1 , wherein motion information associated to at least one of the spatial neighboring blocks comprises affine motion information.

4 . The method of claim 1 , wherein the set of predictor candidates for affine merge mode comprises:
a third predictor candidate on condition that a reference picture of a first spatial neighboring block of the top-left list is the same as a reference picture of a second spatial neighboring block of the top-right list and as a reference picture of a third spatial neighboring block of the bottom-left list wherein:
a motion vector of the first spatial neighboring block of the top-left list is used as a first control point motion vector of the third predictor candidate;
a motion vector of the second spatial neighboring block of the top-right list is used as a second control point motion vector of third predictor candidate;
a motion vector of the third spatial neighboring block of the bottom-left list is used as a third control point motion vector of the third predictor candidate; and
the reference picture of the first spatial neighboring block of the top-left list is used as reference picture of the third predictor candidate.

5 . An apparatus for video encoding, comprising:
a memory and one or more processors configured for:
determining, for a block being encoded in affine merge mode, a top-left list of spatial neighboring blocks, the top-left list comprising neighboring blocks of a top-left corner of the block, a top-right list of spatial neighboring blocks of the block, the top-right list comprising neighboring blocks of a top-right corner of the block, a bottom-left list of spatial neighboring blocks of the block, the bottom-left list comprising neighboring blocks of a bottom-left corner of the block;
determining, for the block being encoded, a set of predictor candidates for affine merge mode based on the top-left list, top-right list and bottom-left list, wherein the set of predictor candidates for affine merge mode comprises:
a first predictor candidate on condition that a reference picture of a first spatial neighboring block of the top-left list is the same as a reference picture of a second spatial neighboring block of the top-right list wherein:
a motion vector of the first spatial neighboring block of the top-left list is used as a first control point motion vector of the first predictor candidate;
a motion vector of the second spatial neighboring block of the top-right list is used as a second control point motion vector of first predictor candidate; and
the reference picture of the first spatial neighboring block of the top-left list is used as reference picture of the first predictor candidate; and

a second predictor candidate on condition that a reference picture of a first spatial neighboring block of the top-left list is the same as a reference picture of a second spatial neighboring block of the bottom-left list:
a motion vector of the first spatial neighboring block of the top-left list is used as the first control point motion vector of the second predictor candidate;
a motion vector of the second spatial neighboring block of the bottom-left list and the motion vector of the first spatial neighboring block of the top-left list are used to derive a second control point motion vector of the second predictor candidate; and
the reference picture of the first spatial neighboring block of the top-left list is used as a reference picture of the second predictor candidate;

determining, for the block being encoded and for each predictor candidate, a motion field based on a motion model and on the one or more control point motion vectors of the predictor candidate, wherein the motion field identifies motion vectors used for prediction of sub-blocks of the block being encoded; selecting a predictor candidate from the set of predictor candidates based on a rate distortion determination between predictions responsive to the motion field determined for each predictor candidate; and encoding the block based on the motion field for the selected predictor candidate.

6 . The apparatus of claim 5 , wherein motion information associated to at least one of the spatial neighboring blocks comprises translational motion information.

7 . The apparatus of claim 5 , wherein motion information associated to at least one of the spatial neighboring blocks comprises affine motion information.

8 . The apparatus of claim 5 , wherein the set of predictor candidates for affine merge mode comprises:
a third predictor candidate on condition that a reference picture of a first spatial neighboring block of the top-left list is the same as a reference picture of a second spatial neighboring block of the top-right list and as a reference picture

Assignees

• Interdigital Vc Holdings Inc

Inventors

• Poirier Tangi
• Robert Antoine
• Leleannec Fabrice

Classifications

• H04N19/105

  Selection of the reference unit for prediction within a chosen coding or prediction mode, e.g. adaptive choice of position and number of pixels used for prediction · CPC title

• H04N19/54

  using feature points or meshes · CPC title

• H04N19/567

  Motion estimation based on rate distortion criteria · CPC title

• H04N19/56

  Motion estimation with initialisation of the vector search, e.g. estimating a good candidate to initiate a search · CPC title

• H04N19/176

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