Content based partial download

摘要

The present invention provides a system and method for storing a single file comprising multiple parts of content data and for selectively downloading at least one part thereof, including: the relevant files out of a zip-archive instead of the whole archive; a chapter instead of the whole book; the cover image out of an MP3 file; and the thumbnail of a jpg with exif header. The storing of various parts of data about an entity in a single file also provides the advantage of avoiding inconsistencies between the various parts. Often data and meta-data are combined in one file (this is already done to avoid inconsistencies between the parts). Examples in which this is currently done include: in one file have the whole image and its thumbnail; MP3 files already can contain an image of the CD cover together with the music; JPG files (with exif header) can contain meta-data (e.g. flash used, exposure) about the photograph. Preferably, a file is organized according to the present invention with a table of contents that describes the parts of the file in a way that enables partial download of the parts.