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 method for decoding encoded data obtained by a motion compensated prediction interframe encoding, the method comprising: 
 receiving the coded data including encoded video picture data, first encoded identification information indicating a plurality of picture groups of hierarchical layers to which the video picture data are assigned and second encoded identification information indicating reference picture data used in a motion compensated prediction interframe encoding and a prediction mode of motion compensated prediction interframe encoding;    decoding the first encoded identification information and the second encoded identification information to generate first decoded identification information and second decoded identification information; and    decoding the video picture data by a motion compensated prediction decoding scheme, using one of first reference picture data belonging to a picture group of same hierarchical layer as that of the video picture data and second reference picture data belonging to a picture group of hierarchical layer lower than that of the video picture and the prediction mode according to the first decoded identification information and the second decoded identification information. (See page 20, lines 1-8, page 22, line 26 to page 23, line 7)    
   
   
       2 . The method according to  claim 1 , wherein the decoding the video picture data includes decoding the video picture using one of the first reference picture, the second reference picture and a linear sum of the first reference picture and the second reference picture. (See page 20, line 9)  
   
   
       3 . The method according to  claim 1 , further including performing a smooth fast-forward playback by playing back the video picture data belonging to the lower picture group at a frame rate of plural times of an original frame rate. (See page 21, lines 21-23)  
   
   
       4 . The method according to  claim 1 , wherein the decoding the video picture data includes decoding only the video picture data of the picture group of lower hierarchical layer and playing back the video picture data at an original frame rate. (See page 22, lines 15-18)  
   
   
       5 . The method according to  claim 1 , wherein the picture groups of hierarchical layers includes a first picture group, a second picture group and a third picture group in order of decreasing hierarchical layer, and the decoding the video picture data includes decoding all encoded pictures not more than the third picture group to perform a normal playback, decoding the encoded pictures not more than the second picture group to play back pictures ½ of the normal playback, and decoding the encoded pictures not more than the first picture group to play back pictures ¼ of the normal playback. (See page 23, lines 24 to page 24, line3)  
   
   
       6 . A video decoding apparatus which decodes encoded data obtained by a motion compensated prediction interframe encoding, the apparatus comprising: 
 a receiving unit configured to receive coded data including encoded video picture data, first encoded identification information indicating plural picture groups to which the video picture data are assigned and second encoded identification information indicating reference picture data used in a motion compensated prediction interframe encoding and a prediction mode of motion compensated prediction interframe encoding;    a first decoder which decodes the first encoded identification information and the second encoded identification information to generate first decoded identification information and second decoded identification information; and    a second decoder which decodes the video picture data by a motion compensated prediction decoding scheme, using one of first reference picture data belonging to a picture group of same hierarchical layer as that of the video picture data and reference picture data belonging to a picture group of hierarchical layer lower than that of the video picture data and the prediction mode according to the first decoded identification information and the second decoded identification information.    
   
   
       7 . The apparatus according to  claim 6 , wherein the second decoder is configured to decode the video picture using one of the first reference picture, the second reference picture and a linear sum of the first reference picture and the second reference picture.  
   
   
       8 . The apparatus according to  claim 6 , further including a playback unit configured to perform a smooth fast-forward playback by playing back the video picture data belonging to the lower picture group at a frame rate of plural times of an original frame rate.  
   
   
       9 . The apparatus according to  claim 6 , wherein the second decoder includes a decoder which decodes only the video picture data of the picture group of lower hierarchical layer and playing back the video picture data at an original frame rate.  
   
   
       10 . The apparatus according to  claim 6 , wherein the picture groups of hierarchical layers includes a first picture group, a second picture group and a third picture group in order of decreasing hierarchical layer, and the second decoder is configured to decode all encoded pictures not more than the third picture group to perform a normal playback, decoding the encoded pictures not more than the second picture group to play back pictures ½ of the normal playback, and decoding the encoded pictures not more than the first picture group to play back pictures ¼ of the normal playback.