Video encoding method and video decoding method

• US 10,448,045 B2
• Filed: 09/04/2018
• Issued: 10/15/2019
• Est. Priority Date: 09/29/2008
• Status: Active Grant

• Current Assignee: Maxell, Ltd.
• Original Assignee: Maxell, Ltd.
• Inventors: Takahashi, Masashi, Yamaguchi, Muneaki
• Primary Examiner(s): Kim, Hee-Yong
• Application Number:
  US16/120,680
• Publication Number:
  US 20180376163A1
• Time in Patent Office: 406 Days
• Field of Search: 37524016
• CPC Class Codes: G06F 3/0604 Improving or facilitating administration, e.g. storage management
• CPC Class Codes: G06F 3/0655 Vertical data movement, i.e. input-output transfer; data movement between one or more hosts and one or more storage devices
• CPC Class Codes: G06F 3/0673 Single storage device
• CPC Class Codes: G06N 3/04 Architecture, e.g. interconnection topology
• CPC Class Codes: G06N 3/10 Interfaces, programming languages or software development kits, e.g. for simulating neural networks
• CPC Class Codes: H04N 19/13 Adaptive entropy coding, e.g. adaptive variable length coding [AVLC] or context adaptive binary arithmetic coding [CABAC]
• CPC Class Codes: H04N 19/172 the region being a picture, frame or field
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock
• CPC Class Codes: H04N 19/184 the unit being bits, e.g. of the compressed video stream
• CPC Class Codes: H04N 19/51 Motion estimation or motion compensation
• CPC Class Codes: H04N 19/513 Processing of motion vectors
• CPC Class Codes: H04N 19/517 by encoding
• CPC Class Codes: H04N 19/52 by predictive encoding
• CPC Class Codes: H04N 19/577 Motion compensation with bidirectional frame interpolation, i.e. using B-pictures
• CPC Class Codes: H04N 19/61 in combination with predictive coding

Abstract

Provided is a video encoding/decoding technique for improving the compression efficiency by reducing the motion vector code amount. In a video decoding process, the prediction vector calculation method is switched from one to another in accordance with a difference between predetermined motion vectors among a plurality of motion vectors of a peripheral block of a block to be decoded and already decoded. The calculated prediction vector is added to a difference vector decoded from an encoded stream so as to calculate a motion vector. By using the calculated motion vector, the inter-image prediction process is executed.

Claims

1. A video decoding method comprising the steps of:

selecting a prediction mode to be performed among a plurality of prediction modes including an intra-prediction mode and an inter-prediction mode;

calculating a predictive motion vector, in case that the inter-prediction mode is selected as the prediction mode to be performed;

calculating a motion vector by summing the predictive motion vector calculated in the predictive motion vector calculating step and a differential motion vector decoded from a coded stream, in case that the inter-prediction mode is selected as the prediction mode to be performed; and

performing an inter-prediction process of the selected prediction mode using the motion vector calculated in the motion vector calculating step, in case that the inter-prediction mode is selected as the prediction mode to be performed,

wherein the predictive motion vector calculating step includes;

a first process to select a plurality of candidate blocks among blocks decoded prior to a block to be decoded, the candidate blocks are selected from five or more blocks, the five or more blocks including peripheral blocks in the same frame as the block to be decoded and blocks in a different frame from the block to be decoded,

a second process to use any one of a first value and a second value when a difference between the first value and the second value in motion vector values of the plurality of candidate blocks is within a predetermined threshold,

a third process to make a motion vector list listing a plurality of motion vector values including the motion vector value of the first value or the second value selected in the second process and a motion vector value other than the first value and the second value in the motion vector values of the plurality of candidate blocks selected in the first process,

a fourth process to retrieve selection information from the coded stream, and

a fifth process to select one motion vector value among the plurality of motion vector values listed in the motion vector list,

wherein the one motion vector value selected from the plurality of motion vector values listed in the motion vector list is determined based on the selection information regardless of the differential motion vector,

wherein the number of the plurality of motion vector values listed in the motion vector list is smaller than five, and

wherein the peripheral blocks in the same frame as the block to be decoded, referred to in the first process includes a peripheral block, located at an upper side of the block to be decoded and a peripheral block located at a left side of the block to be decoded.

2. A method comprising:

selecting a prediction mode to be performed among a plurality of prediction modes including an intra-prediction mode and an inter-prediction mode;

calculating a predictive motion vector in case the inter-prediction mode is selected as the prediction mode to be performed;

calculating a motion vector by summing the calculated predictive motion vector and a differential motion vector decoded from a coded stream, in case the inter-prediction mode is selected as the prediction mode to be performed; and

performing an inter-prediction process of the selected prediction mode using the calculated motion vector in case the inter-prediction mode is selected as the prediction mode to be performed,

wherein the calculating the predictive motion vector includes;

selecting a plurality of candidate blocks among blocks decoded prior to a block to be decoded, the candidate blocks being selected from five or more blocks, the five or more blocks including peripheral blocks in the same frame as the block to be decoded and blocks in a different frame from the block to be decoded,

using one of a first value or a second value when a difference between the first value and the second value in motion vector values of the plurality of candidate blocks is within a predetermined threshold,

generating a motion vector list listing a plurality of motion vector values including the motion vector value of the first value or the second value, and a motion vector value other than the first value and the second value in the motion vector values of the plurality of candidate blocks,

retrieving selection information from the coded stream, and

selecting one motion vector value among the plurality of motion vector values listed in the motion vector list,

wherein the one motion vector value selected from the plurality of motion vector values listed in the motion vector list is determined based on the selection information regardless of the differential motion vector,

wherein the number of the plurality of motion vector values listed in the motion vector list is smaller than five, and

wherein the peripheral blocks in the same frame as the block to be decoded, referred to in the selecting the plurality of candidate blocks, includes a peripheral block located at an upper side of the block to be decoded and a peripheral block located at a left side of the block to be decoded.