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

Some Useful Examples and ScenariosReferencing Two Data Files With a Single TrackIn this example, the file begins with the movie atom ('moov'), followed by the movie data atom ('mdat'). Inorder to overcome any latencies in sound playback, at least one second of sound data is placed at the beginningof the interleaved data. This means that the sound and video data are offset from each other in the file by onesecond.Referencing Two Data Files With a Single TrackThe data reference index to be used for a given media sample is stored within that sample’s sample description.Therefore, a track must contain multiple sample descriptions in order for that track to reference multiple datafiles. A different sample description must be used whenever the data file changes or whenever the format ofthe data changes. The sample-to-chunk atom determines which sample description to use for a sample.The sample description atom would contain the following data values:Atom sizeAtom typeVersion/FlagsNumber of entries…'stsd'02Sample description size[1]Data formatReservedData reference index(sample data)Sample description size[1]Data formatReservedData reference index(sample data)…'tmcd'01……'tmcd'02…2012-08-14 | © 2004, 2012 Apple Inc. All Rights Reserved.359