Quicktime File Format (2012-08-14).pdf

Movie AtomsTrack AtomsTypeA 32-bit integer that identifies the atom type; this field must be set to 'elst'.VersionA 1-byte specification of the version of this edit list atom.FlagsThree bytes of space for flags. Set this field to 0.Number of entriesA 32-bit integer that specifies the number of entries in the edit list atom that follows.Edit list tableAn array of 32-bit values, grouped into entries containing 3 values each. Figure 2-16 (page 71) showsthe layout of the entries in this table.Figure 2-16The layout of an edit list table entryTrack duration Media time Media rate4 4 4FieldBytesAn edit list table entry contains the following elements.Track durationA 32-bit integer that specifies the duration of this edit segment in units of the movie’s time scale.Media timeA 32-bit integer containing the starting time within the media of this edit segment (in media timescaleunits). If this field is set to –1, it is an empty edit. The last edit in a track should never be an empty edit.Any difference between the movie’s duration and the track’s duration is expressed as an implicit emptyedit.Media rateA 32-bit fixed-point number that specifies the relative rate at which to play the media corresponding tothis edit segment. This rate value cannot be 0 or negative.Track Load Settings AtomsTrack load settings atoms contain information that indicates how the track is to be used in its movie. Applicationsthat read QuickTime files can use this information to process the movie data more efficiently. Track load settingsatoms have an atom type value of 'load'.2012-08-14 | © 2004, 2012 Apple Inc. All Rights Reserved.71