Video encoding method and video decoding method

• US 8,693,546 B2
• Filed: 06/02/2009
• Issued: 04/08/2014
• Est. Priority Date: 09/29/2008
• Status: Active Grant

• Current Assignee: Maxell, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Takahashi, Masashi, Yamaguchi, Muneaki
• Primary Examiner(s): Kim, Hee-Yong
• Application Number:
  US13/058,560
• Publication Number:
  US 20110142133A1
• Time in Patent Office: 1,771 Days
• Field of Search: 375/240.16
• US Class Current: 375/240.16
• 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:

performing a variable length decoding process on a coded stream including;

acquiring motion vectors of decoded blocks located near a block to be decoded,

selecting one of multiple variable length code tables on the basis of a distribution of the motion vectors of the decoded blocks and added data included in the coded stream which indicates a result of selecting candidate values, and where the selection of the one of the multiple variable length code tables is changed on the basis of the added data, and

decoding a differential motion vector using the selected variable length code table;

calculating a predictive motion vector;

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 the coded stream; and

performing an inter-prediction process using the motion vector calculated in the motion vector calculating step,

wherein, in the predictive motion vector calculating step, a method for calculating the predictive motion vector is switched among methods for calculating the predictive motion vector based on a kind and a number of candidate values which are components of the motion vectors of the group of decoded blocks located near the block to be decoded.