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

Some Useful Examples and ScenariosPreparing Sound and Subtitle Alternate Groups for Use with Apple Devices// add atoms to spriteData atom containerSetSpriteData (spriteData, &location, nil, nil, &imageIndex);// add the spriteData atom container to sampleerr = AddSpriteToSample (sample, spriteData, 2);// ...// update other sprites// ...// add the sample to the mediaerr = AddSpriteSampleToMedia (newMedia, sample,kSpriteMediaFrameDuration, false);}Preparing Sound and Subtitle Alternate Groups for Use with AppleDevicesAlternate groups are collections of tracks that all serve the same purpose, where any track in the group canbe substituted for another in a movie. Members of the same alternate group have the same identifier value inthe alternate group field in the 'tkhd' (track header) atom; see “Track Reference Atoms” (page 73) for anexample of alternate tracks for different languages.This section provides guidelines for the use of alternate groups in movies to be played on Apple devices.GeneralFor each alternate group:●●●●The group must contain tracks of only one type; for example, only subtitle tracks or only sound tracks.All tracks of the same type must be in a single alternate group.One track in the group must be enabled; that is, the Track Enabled flag must be set (0x0001) in its trackheader ('tkhd').All other tracks in the group must be disabled.2012-08-14 | © 2004, 2012 Apple Inc. All Rights Reserved.334