Video encoding/decoding method and apparatus

Abstract

A video encoding method comprises selecting one combination, for each block of an input video signal, from a plurality of combinations each including a predictive parameter and at least one reference picture number determined in advance for the reference picture, generating a prediction picture signal in accordance with the reference picture number and predictive parameter of the selected combination, generating a predictive error signal representing an error between the input video signal and the prediction picture signal, and encoding the predictive error signal, information of the motion vector, and index information indicating the selected combination.

1 . A video encoding method for subjecting an input video image having luminance and two color differences to prediction encoding, comprising:
 obtaining, for a to-be-encoded block, an index indicating (A) a combination comprising (a) a weighting factor for every luminance and two color differences and (b) an offset for every luminance and two color differences and (B) a reference image;   generating a prediction image by multiplying the reference image by the weighting factor and adding the offset, based on a motion vector;   generating a prediction error signal by calculating an error between the input video image and the prediction image;   generating a quantized orthogonal transform coefficient by subjecting the prediction error signal to orthogonal transform and quantization; and   encoding, for the to-be-encoded block, (1) the quantization orthogonal transform coefficient, (2) information of the motion vector and (3) the index;   wherein two values of the indexes corresponding to different reference images indicate an identical combination of the weighting factor and the offset, and a value obtained by arithmetic-shifting right one of the two values by one bit is identical to a value obtained by arithmetic-shifting right the other value by one bit.   
     
     
         2 . A video encoding apparatus of subjecting an input video image having luminance and two color differences to prediction encoding, comprising:
 an obtaining module configured to obtain, for a to-be-encoded block, an index indicating (A) a combination comprising (a) a weighting factor for every luminance and two color differences and (b) an offset for every luminance and two color differences and (B) a reference image;   a first generator configured to generate a prediction image by multiplying the reference image by the weighting factor and adding the offset, based on a motion vector;   a second generator configured to generate a prediction error signal by calculating an error between the input video image and the prediction image;   a third generator configured to generate a quantized orthogonal transform coefficient by subjecting the prediction error signal to orthogonal transform and quantization; and   an encoder configured to encode, for the to-be-encoded block, (1) the quantization orthogonal transform coefficient, (2) information of the motion vector and (3) the index;   wherein two values of indexes corresponding to different reference images indicate an identical combination of the weighting factor and the offset, and a value obtained by arithmetic-shifting right one of the two values by one bit is identical to a value obtained by arithmetic-shifting right the other value by one bit.