Video encoding method and apparatus, and video decoding method and apparatus

Abstract

A method for encoding a video block using reference blocks comprises assigning the video block to one of first and second prediction groups, and encoding the video block according to a motion compensated prediction encoding mode, using the reference blocks depending on the one of the first and second prediction groups to which the video block is assigned, one of the reference blocks being a decoded block, wherein a first prediction group is obtained by a prediction using the reference blocks belonging to a first prediction group, and a second prediction group is obtained by a prediction using the reference blocks belonging to at least one of the second prediction group and the first prediction group.

1 . A computer readable storage medium storing instructions of a computer program which when executed by a computer results in performance of steps comprising: 
 assigning a video picture to one of a plurality of prediction groups of hierarchical layers including at least a first hierarchical layer and a second hierarchical layer higher than the first hierarchical layer;    encoding the video picture assigned to the prediction group of the first hierarchical layer according to a motion compensated prediction interframe encoding mode, using a reference picture belonging to the prediction group of the first hierarchical layer;    encoding the video picture assigned to the prediction group of the second hierarchical layer according to a motion compensated prediction interframe encoding mode, using a reference picture belonging to either of the prediction group of the first hierarchical layer and the prediction group of the second hierarchical layer;    encoding first identification information indicating the hierarchical layer of the prediction group to which the video picture belongs and second identification information indicating a prediction mode of the motion compensated prediction interframe encoding mode to generate side information;    outputting the side information together with the video picture encoded according to the motion compensated prediction inter-encoding mode;    setting a sum of the reference pictures assigned to the prediction groups to a constant value; and    encoding reference picture number information indicating the number of reference pictures assigned to each of the prediction groups and including the coded reference picture number information in the side information.    
   
   
       2 . The computer readable storage medium according to  claim 1 , wherein the step of assigning the video picture includes steps of encoding the video picture by each of an intraframe encoding mode, a forward prediction interframe encoding mode and a bi-directional prediction interframe encoding mode, and assigning the video picture includes assigning first video pictures encoded by the intraframe encoding mode and the forward prediction interframe encoding mode and the reference pictures corresponding to the first video pictures to the prediction group of the first hierarchical layer, and assigning second video pictures encoded by the bi-directional prediction interframe encoding mode and the reference pictures corresponding to the second video pictures to at least one of the prediction group of the first hierarchical layer and the prediction group of the second hierarchical layer.