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

Movie AtomsMedia AtomsObject IDA 32-bit integer identifying the object.Media AtomsMedia atoms describe and define a track’s media type and sample data. The media atom contains informationthat specifies:●●●●●●The media type, such as sound or videoThe media handler component used to interpret the sample dataThe media timescale and track durationMedia-and-track-specific information, such as sound volume or graphics modeThe media data references, which typically specify the file where the sample data is storedThe sample table atoms, which, for each media sample, specify the sample description, duration, and byteoffset from the data referenceThe media atom has an atom type of 'mdia'. It must contain a media header atom ('mdhd'), and it cancontain a handler reference ('hdlr') atom, media information ('minf') atom, and user data ('udta') atom.Note Do not confuse the media atom ('mdia') with the media data atom ('mdat'). The mediaatom contains only references to media data; the media data atom contains the actual media samples.Figure 2-20 (page 79) shows the layout of a media atom.Figure 2-20The layout of a media atomMedia header atomMedia atomAtom sizeType = 'mdia'Extended language tag atomHandler reference atomMedia information atomUser data atom'mdhd''elng''hdlr''minf''udta'‡‡ Required atom2012-08-14 | © 2004, 2012 Apple Inc. All Rights Reserved.79