Patent ID: 6052417
Filing Date: 2000-04-18
Classification: H04N

Abstract:
A motion image coding apparatus in which each of a plurality of frames constituting a motion image sequence is divided into a plurality of coding blocks, and each of said plurality of frames is coded in accordance with a coding mode, coding block by coding block,said coding mode including a forward prediction mode using prediction based on a past reference frame, a backward prediction mode using prediction based on a future reference frame, a bidirectional prediction mode using as prediction, a mean value of prediction based on the past reference frame and prediction based on the future reference frame, and an intra-frame coding mode not using inter-frame prediction,each said frame being classified as a first frame in which each of said plurality of coding blocks is coded in accordance with said intra-frame coding, a second frame in which each of said plurality of coding blocks is coded in accordance with said forward prediction mode or said intra-frame coding mode, or a third frame in which each of said plurality of coding blocks is coded in accordance with any of said forward prediction mode, said backward prediction mode, said bidirectional prediction mode and said intra-frame coding mode,said apparatus comprising:coding means for coding said first, second and third frames;prediction efficiency calculating means for calculating prediction efficiency of inter-frame prediction, in coding by said coding means using said first or second frame as a reference frame; andreference frame interval determining means for determining a reference frame interval which is a time interval between said first and second frames, a time interval between said second frames, and a time interval between said first frames, in accordance with an output from said prediction efficiency calculating means.