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Tip #1274: Where a QuickTime Movie Stores Timecode
Timecode is a separate track stored inside the QuickTime movie container.
We often think of a QuickTime movie as a file. But, it actually isn’t. It’s a container for multiple files – each of which can be different.
Timecode tracks, which are stored inside the QuickTime container, store external timecode information, such as SMPTE timecode. QuickTime provides a timecode media handler that interprets the data in these tracks to track each frame of video.
A movie’s timecode is stored in a timecode track. Timecode tracks contain:
- Source identification information (this identifies the source; for example, a given videotape or digital file)
- Timecode format information (this specifies the characteristics of the timecode and how to interpret the timecode information)
- Frame numbers (these allow QuickTime to map from a given movie time, in terms of QuickTime time values, to its corresponding timecode value)
Apple has defined the information that is stored in the track in a manner that is independent of any specific timecode standard. The format of this information is sufficiently flexible to accommodate all known timecode standards, including SMPTE timecoding.
In essence, you can think of the timecode media handler as providing a link between the digital QuickTime-specific timing information and the original analog timing information from the source material.
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