Motion prediction method and video encoding method

Patent metadata

Field	Value
Publication number	US-9008182-B2
Application number	US-96241110-A
Country	US
Kind code	B2
Filing date	Dec 7, 2010
Priority date	Jan 18, 2010
Publication date	Apr 14, 2015
Grant date	Apr 14, 2015

Abstract

The invention provides a motion prediction method. First, a plurality of motion vector predictors is obtained to be included in a candidate set for motion prediction of a current unit of a current frame. Whether the current frame is a non-reference frame which is not referred to by other frames for motion prediction is then determined. When the current frame is not the non-reference frame, any motion vector predictor corresponding to a previously coded frame is removed from the candidate set, and a motion vector of the current unit is predicted according to the motion vector predictors of the candidate set.

First claim

What is claimed is:

1. A motion prediction method, comprising:
(a) obtaining a plurality of motion vector predictors to be included in a candidate set for motion prediction of a current unit of a current frame, wherein the plurality of motion vector predictors comprises at least a spatial motion vector predictor of an adjacent block of the current unit, and at least a temporal motion vector predictor from a collocated unit of the current unit in a previous coded frame;
(b) determining whether the current frame is a non-reference frame which is not referred to by other frames for motion prediction;
(c) when the current frame is not the non-reference frame, adjusting the candidate set by removing the temporal motion vector predictor corresponding to the previously coded frame from the candidate set to avoid parsing error propagation;
(d) when the motion vector predictors are equal to each other, adding at least one backup motion vector predictors until a different backup motion vector predictor is obtained:
(e) selecting a final motion vector predictor from the adjusted candidate set by applying rate-distortion optimization; and
(f) predicting a motion vector of the current unit according to the final motion vector predictor of the adjusted candidate set.

2. The motion prediction method as claimed in claim 1 , wherein determination of whether the current frame is the non-reference frame comprises:
determining a frame type of the current frame;
when the frame type is an I frame or a P frame, determining that the current frame is not a non-reference frame; and
when the frame type is a B frame, determining that the current frame is a non-reference frame.

3. The motion prediction method as claimed in claim 1 , wherein determination of whether the current frame is the non-reference frame comprises:
determining a frame type of the current frame;
when the frame type is a non-reference B frame, determining that the current frame is a non-reference frame.

4. The motion prediction method as claimed in claim 1 , wherein removing any motion vector predictor from the candidate set comprises:
determining whether the candidate set comprises at least one target motion vector predictor corresponding to a unit which is not in the current frame; and
when the target motion vector predictor exists in the candidate set, removing the target motion vector predictor from the candidate set.

5. The motion prediction method as claimed in claim 1 , wherein obtaining of the motion vector predictors comprises:
determining a plurality of units from units located in the current frame or a previously coded frame;
selecting a plurality of candidate units from the units; and
obtaining motion vectors of the candidate units as the motion vector predictors of the candidate set.

6. The motion prediction method as claimed in claim 5 , wherein selection of the candidate units is according to a fixed decision rule or an adaptive selection rule.

7. The motion prediction method as claimed in claim 1 , wherein the method further comprises:
generating a control flag to indicate whether inter-frame entropy coding is allowed for a segment of a video datastream;
when the control flag indicates that inter-frame entropy coding is not allowed, performing the steps of (a), (b), (c), (d) and (e) for motion prediction; and
when the control flag indicates that inter-frame entropy coding is allowed, predicting the motion vector of the current unit according to the motion vector predictors of the candidate set without removing the motion vector predictor from the candidate set no matter whether the current frame is the non-reference frame.

8. A motion prediction method, comprising:
(a) obtaining a plurality of motion vector predictors to be included in a candidate set for motion prediction of a current unit of a current frame;
(b) comparing the motion vector predictors of the candidate set with each other to determine if the motion vector predictors are equal to each other;
(c) when the motion vector predictors of the candidate set are equal to each other, selecting at least one backup motion vector predictor;
(d) adding the backup motion vector predictor to the candidate set; and
(e) predicting a motion vector of the current unit according to the motion vector predictors of the candidate set.

9. The motion prediction method as claimed in claim 8 , wherein the prediction of the motion vector of the current unit comprises:
selecting a final motion vector predictor from the motion vector predictors of the candidate set; and
predicting the motion vector of the current unit according to the final motion vector predictor.

10. The motion prediction method as claimed in claim 9 , wherein the method further comprises:
generating an index of the final motion vector predictor as prediction information for the current unit; and
encoding prediction information in a bitstream.

11. The motion prediction method as claimed in claim 8 , wherein selection of the backup motion vector predictor comprises:
selecting a target motion vector predictor from a plurality of predetermined motion vector predictors;
comparing the target motion vector predictor with the motion vector predictors of the candidate set;
when the target motion vector predictor is different from the motion vector predictors of the candidate set, determining the target motion vector predictor to be the backup motion vector predictor; and
when the target motion vector predictor is equal to the motion vector predictors of the candidate set, repeating selection of the target motion vector predictor and comparison of the target motion vector predictor and the candidate set until the target motion vector predictor is different from the motion vector predictors of the candidate set to determine the target motion vector predictor to be the backup motion vector predictor.

12. The motion prediction method as claimed in claim 8 , wherein obtaining of the motion vector predictors comprises:
determining a plurality of units from units located in the current frame or a previously coded frame;
selecting a plurality of candidate units from the units; and
obtaining motion vectors of the candidate units as the motion vector predictors of the candidate set.

13. The motion prediction method as claimed in claim 12 , wherein selection of the candidate units is according to a decision rule determined in a sequence level.

14. The motion prediction method as claimed in claim 8 , wherein the method further comprises:
generating a control flag to indicate whether inter-frame entropy coding is allowed in a segment of a video datastream;
when the control flag indicates that inter-frame entropy coding is not allowed, performing the steps of (a), (b), (c), (d), and (e) for motion prediction; and
when the control flag indicates that inter-frame entropy coding is allowed, predicting the motion vector of the current unit according to the motion vector predictors of the candidate set without removing the motion vector predictor in the candidate set no matter whether the motion vector predictors of the candidate set are equal to each other.

Assignees

• Tsai Yu-Pao
• Fu Chih-Ming
• Lin Jian-Liang
• Huang Yu-Wen
• Lei Shaw-Min
• Mediatek Inc

Inventors

• Tsai Yu-Pao
• Fu Chih-Ming
• Lin Jian-Liang
• Huang Yu-Wen
• Lei Shaw-Min

Classifications

• H04N19/172

  the region being a picture, frame or field · CPC title

• H04N19/513

  Processing of motion vectors · CPC title

• H04N19/56 Primary

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