Video encoding/decoding method and apparatus for motion compensation prediction

Abstract

A video encoding method and apparatus to select one combination, for each block of an input video signal, from a plurality of combinations. Each combination includes a predictive parameter and at least one reference picture number determined in advance for the reference picture. A prediction picture signal is generated in accordance with the reference picture number and predictive parameter of the selected combination. A predictive error signal is generated representing an error between the input video signal and the prediction picture signal. Encoding the predictive error signal, information of the motion vector, and index information indicating the selected combination is included.

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) one combination of a plurality of combinations comprising (a) a weighting factor for each luminance and for each of two color differences, (b) an offset for each luminance and for each of two color differences, (c) a flag indicating presence or non-presence of the weighting factor and the offset concerning luminance and (d) a flag indicating presence or non-presence of the weighting factors and the offsets concerning the two color differences and (B) a reference image;   generating a prediction image by multiplying the reference image by the weighting factors and adding the offsets;   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 quantized orthogonal transform coefficient and (2) the index and encoding, for one or more to-be-encoded blocks, the plurality of combinations;   wherein two possible values of the index correspond to different reference images, and indicate an identical combination of the weighting factors and the offsets, and a value obtained by arithmetic-shifting right one of the two possible 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 for 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) one combination of a plurality of combinations comprising (a) a weighting factor for each luminance and for each of two color differences, (b) an offset for each luminance and for each of two color differences, (c) a flag indicating presence or non-presence of the weighting factor and the offset concerning luminance and (d) a flag indicating presence or non-presence of the weighting factors and the offsets concerning the two color differences and (B) a reference image;   a generator configured to generate a prediction image by multiplying the reference image by the weighting factors and adding the offsets;   a generator configured to generate a prediction error signal by calculating an error between the input video image and the prediction image;   a 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 quantized orthogonal transform coefficient and (2) the index and encode, for one or more to-be-encoded blocks, the plurality of combinations;   wherein two possible values of the index correspond to different reference images, and indicate an identical combination of the weighting factors and the offsets, and a value obtained by arithmetic-shifting right one of the two possible values by one bit is identical to a value obtained by arithmetic-shifting right the other value by one bit.