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

Movie AtomsTrack AtomsFigure 2-18 (page 74) shows the layout of a track reference atom.Figure 2-18The layout of a track reference atomTrack reference atomAtom sizeType = 'tref'Bytes44Track reference type atomAtom sizeType = (see table)44Track IDsVariableA track reference atom contains the following data elements.SizeA 32-bit integer that specifies the number of bytes in this track reference atom.TypeA 32-bit integer that identifies the atom type; this field must be set to 'tref'.Track reference type atomsA list of track reference type atoms containing the track reference information. These atoms are describednext.Each track reference atom defines relationships with tracks of a specific type. The reference type implies a tracktype. Table 2-2 (page 74) shows the track reference types and their descriptions.Table 2-2Track reference typesReference type'chap''clcp'DescriptionChapter or scene list. Usually references a text track.Closed caption. In any track, this identifies a closed captioning track that containstext that is appropriate for the referring track. See “Closed Captioning Media” (page198) for more information.2012-08-14 | © 2004, 2012 Apple Inc. All Rights Reserved.74