[vlc-devel] Soft field repeat?

Juha Jeronen juha.jeronen at jyu.fi
Sat Jan 8 18:35:57 CET 2011

Hi again everyone,

I investigated a bit more. It looks like the ffmpeg decoder sometimes 
sends incorrect PTSs when the stream contains field repeats. (I have an 
SVN ffmpeg from mid-December, compiled from sources.)

What happens is that VLC's p_sys->i_pts sometimes gets updated to an 
incorrect value, when p_sys->p_ff_pic->reordered_opaque contains a PTS.

For some reason the PTS obtained from ffmpeg is often, but not always, 
one or sometimes two fields in either direction from the value that 
would be expected by simply summing the the last frame's PTS (from 
decoder output) and expected duration (based on framerate and 
i_nb_fields, like VLC does).

I think I don't have the knowledge required to debug this any further. 
Anyone else want to have a shot at it, or should I approach the ffmpeg devs?

If test data is needed, I can supply an example clip (about 80MB; 
extracted from a VOB on the DVD) that exhibits the problem.


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