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

Some Useful Examples and ScenariosPlaying with Edit ListsPlaying with Edit ListsA segment of a movie can be repeated without duplicating media data by using edit lists. Suppose you havea single-track movie whose media time scale is 100 and track duration is 1000 (10 seconds). For this examplethe movie’s time scale is 600. If there are no edits in the movie, the edit atom would contain the data valueslisted in Table 6-5 (page 356).Table 6-5Atom sizeAtom typeExample edit atom data values36'edts'Atom sizeAtom typeVersion/FlagsNumber of entriesTrack durationMedia timeMedia rate28'elst'026000 (10 seconds)01.0Because this is a single-track move, the track’s duration in the track header atom is 6000 and the movie’sduration in the movie header atom is 6000.If you change the track to play the media from time 0 to time 2 seconds, and then play the media from time0 to time 10 seconds, the edit atom would now contain these data values:Atom sizeAtom type48'edts'Atom sizeAtom typeVersion/FlagsNumber of entriesTrack duration[1]40'elst'021200 (2 seconds)2012-08-14 | © 2004, 2012 Apple Inc. All Rights Reserved.356