[FFmpeg-devel] [RFC][PATCH] ticks_per_frame / timebase
Thu Feb 26 16:50:52 CET 2009
On Thu, Feb 26, 2009 at 03:37:53PM +0100, Reimar D?ffinger wrote:
> On Thu, Feb 26, 2009 at 03:15:09PM +0100, Michael Niedermayer wrote:
> > @@ -2322,6 +2322,15 @@
> > * - decoding: Set by libavcodec
> > */
> > struct AVHWAccel *hwaccel;
> > +
> > + /**
> > + * For some codecs, the time base is closer to the field rate than the frame rate.
> > + * Most notably, H.264 and MPEG-2 specify time_base as half of frame duration
> > + * if no telecine is used ...
> > + *
> > + * Set to time_base ticks per frame. Default 1, e.g., H.264/MPEG-2 set it to 2.
> > + */
> Maybe it would be good to note e.g. what differentiates r_frame_rate from
> time_base / ticks_per_frame
r_frame_rate is from libavformat and is our best guess at a minimal timebase
in which all frame durations can be represented.
time_base is the unit in which timestamps / durations are represented
(there are 2 of that, one for lavc & one for lavf)
ticks_per_frame is the factor between the codec time_base and the frame_rate
as defined by mpeg2. It is generally not possible to represent frame durations
or frame timestamps in this unit.
This though happens to be a good guess at the frame duration for a random
frame if no better information is available
iam not sure how i should change the doxy, suggestion welcome
Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
When the tyrant has disposed of foreign enemies by conquest or treaty, and
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some war or other, in order that the people may require a leader. -- Plato
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