QuickTime 4 Reference
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When you export text and text descriptors from a text track, the text component also exports a time stamp for each sample. The time stamp indicates the starting and ending time of the sample, either relative to the start of the movie ( kMovieExportAbsoluteTime ) or to the end of the previous sample ( kMovieExportRelativeTime ). On import, the time stamps maintain the timing positions of the text samples relative to other media in the movie.
[HH:MM:SS.xxx]where HH represents the number of hours, MM represents the number of minutes, SS represents the number of seconds, and xxx represents the mantissa (the fractional part of a second). The mantissa is expressed in the time scale of the text track. For example, if the time scale of the text track is 600, the time stamp [00:00:07.300] is interpreted as 7.5 seconds. If the time scale of the text track is 10, the time stamp [00:00:07.5] is also interpreted as 7.5 seconds. The maximum time scale for a text track is 10000.
When a text export component exports a text sample, it first exports the time stamp, followed by a return character. Then, it exports the sample's text and text descriptors. If a text sample does not contain any text, the text component exports the time stamp and return character, but no text.
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