Patent ID: 7747141

Claim:
A playback method for reproducing video data recorded on a medium, said video data comprising a plurality of video units which each include an intra coded I-picture, a predictive coded P-picture including a group of blocks predicted from one picture and a bidirectionally-predictive coded B-picture including a group of blocks predicted from two pictures, at least one of said video units including an access point P-picture coded by motion compensation prediction using an I-picture located at the beginning of a video unit or a selected preceding P-picture, wherein a P-picture or a B-picture following said access point P-picture is coded without referring to any picture located before said access point P-picture, said medium containing access unit information used for accessing said access point P-picture, said access unit information including a list of data for identifying a location of video information units designated as access units on said medium, each of said access units comprising at least one video unit, said access unit information specifying a start point of a first video unit presented in each access unit; said method comprising steps of: reading said access unit information to identify a location of said access unit which includes a start picture to display, in the case of starting playback from said start picture; identifying said access unit using said access unit information to decode a closest access point P-picture preceding said start picture; and decoding said start picture using decoded access point P-picture as a reference picture, wherein said start picture is decoded without referring to any picture located before said access point P-picture.