[FFmpeg-devel] [PATCH] dvd vob input fps detect wrong

Michael Niedermayer michaelni
Fri Sep 7 16:37:22 CEST 2007


On Fri, Sep 07, 2007 at 08:46:04PM +0800, Lance Wang wrote:
> Hi,
> > mpeg2video with 30000/1001 fps can through the use of the repeat first field
> > and top field first flags have frames start at any point in a 60000/1001
> > timebase so the code is correct your change breaks it
> Thanks for your explain, I haven't understand your point. I think
> interlaced mpeg2video
> frame rate is 30000/1001, but field rate is 60000/1001, so why it
> looks the fps as 6000/1001
> after calculated?

as ive said the FRAME timebase is 60000/1001 go read the mpeg2 spec if
you dont belive it

>  If I force the fps to 30000/1001 manually and
> convert it h264, the result is OK also. 

no it is NOT, all timestamps will be wrong

> Any comment to fix the issue?

what issue? you posted a broken patch not a bugreport

> By my test, if I transcode 1000frame, the duplicate frame will
> 1000frame also.

use -vsync 1 and preferably dont use .avi

and as ive said thousends of times already
r_frame_rate is NOT the average frame rate it is the largest framerate
with which all timestamps can accurately be represented

if you want a average_framerate send a patch which adds such a field
but dont hijack a field with a different definition
(and yes an avarage framerate might make sense for transcoding to AVI
but it is wrong for normal containers which have timestamps)


Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

If a bugfix only changes things apparently unrelated to the bug with no
further explanation, that is a good sign that the bugfix is wrong.
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