Hierarchical storage scheme and data playback scheme for enabling random access to realtime stream data

摘要

A hierarchical memory scheme capable of improving a hit rate for the segment containing the random access point rather than improving the overall hit rate of the cache, and a data playback scheme capable of automatically detecting positions that are potentially used as playback start indexes by the user and attaching indexes, are disclosed. The hierarchical storage device stores random access point segment information from which a possibility for each segment to contain a point that can potentially be random accessed in future can be estimated, and controls a selection of the selected segments to be stored in the cache storage device according to the random access point segment information. The data playback device records a plurality of playback start indexes, each playback start index being information regarding a playback position that is determined according to the user input which is recorded when the user input is in a prescribed pattern, and presents the plurality of playback start indexes to a user so as to urge the user to select a desired playback position.