| 摘要 |
Methods and systems for providing random access of structured media content are described. One aspect provides a novel file structure or "Vfile", and method of using the same, for organizing and managing portions of a structured media content file that are or can be downloaded from a content provider such as a multimedia content server. The Vfile is configured to emulate a server file structure that a server uses to store structured media content files. The Vfile is established at a client location when a client accesses a structured media content file and is used to buffer and cache structured media content file portions. In addition to having an infrastructure that emulates the server's file structure, the Vfile includes one or more media management tags. The tags are used by the client to manage a cache of structured media content file portions that are downloaded from the server. Exemplary tags include, but are not limited to (1) a validity tag that indicates whether a particular portion of a structured media content file is available in the Vfile cache, (2) a hit count tag that gives an indication of how many times a particular portion has been accessed, (3) an importance tag that gives a weight to the hit count and determines how long the portion can stay in cache, and (4) a lock tag that indicates whether or not to lock selected structured media content file portions in the Vfile. Cache management strategies make use of the management tags to ensure that relevant portions of the media file are maintained by the client for as long as they are needed. Those file portions that are needed, but which are not present in the Vfile, can be streamed to the client by the server while those file portions that are present are used to render a view for the user.
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