[Ffmpeg-devel] [PATCH] remove drop timecode flag
Mon Apr 16 01:35:01 CEST 2007
On Sun, Apr 15, 2007 at 02:28:56PM -0700, Trent Piepho wrote:
> The SMPTE frame ID "drop-frame" works the same way as the Gregorian
> calendar's leap year "add-day" system. It does not drop or add frames. It
> doesn't effect playback. It just assigns different labels to the frames.
> After '00:00:33;29' comes '00:00:34;00'. After '00:00:59;29' comes
> '00:01:00;02'. After '00:09:59;29' comes '00:10:00;00'. Two frame IDs are
> skipped at the beginning of each minute, except for minutes that are
> multiples of 10. It's like how Feb 29th is skipped except when the year is
> a multiple of 4, except when it is a multiple of 100, except when it is a
> multiple of 400.
The same thing will be accomplished if you perform the standard
timestamp conversion from 1001/30000 timebase ticks (or whatever the
content actually is) to 1/30 timebase ticks, and use the result for
the SMPTE codes. No special-case algorithm for "drop-frame" needs to
be used; this will work with any framerate.
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