[FFmpeg-devel] [PATCH][RFC] set codec time base to format time base at the end

[Michael Niedermayer]

On Thu, May 28, 2009 at 06:04:22PM -0700, Baptiste Coudurier wrote:
> Hi
> 
> $subject,
> 
> This will leave codec timebase unset and therefore being unreliable,
> which is the case IMHO, but I'm not sure of the implications.

iam not sure either but i fear that this may have unexpected sideeffects
but then maybe not ...


> 
> wrong_framerate.mov on mplayerhqhu which is detected as 59.94 instead of
> 29.97 because the first frame duration has 150 duration instead of 100
> on a 2997 timescale.

strictly speaking 59.94 is more correct for this one


> 
> This is problematic when transcoding to mpeg2.

yes and this is what i think i discussed with reimar IIRC

which is the guessed timebase really depends on what it is used for
For transcoding to mpeg2 it must be one of a small fixed set, no matter
what
And for avi it can be an arbitrary fraction but it is very strongly
preferred for that fraction to be a large value (like 1/30 or 1001/24000
but not 1/24000)

In that sense i belive the timbase guessing code should be extended by
a few flags or something that tell it what the user app really wants 

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

I hate to see young programmers poisoned by the kind of thinking
Ulrich Drepper puts forward since it is simply too narrow -- Roman Shaposhnik
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