[MPlayer-dev-eng] r32056 Causes Loss of A/V Sync with VOB files

[Steaphan Greene]

On 06/18/2011 07:49 AM, Ivan Kalvachev wrote:
> I suspect that the sample may have something to do with soft telecine or
> at least with field repeat flags. Maybe the move interfered with
> libmpdemux/video.c pts calculations.

Yes, I believe you are correct.  All the VOBs I've confirmed this with
do seem to be NTSC encoded with telecine framerate oddities.


> Anyway... The code in mplayer.c looks kind of fishy... For one, if the
> purpose of the code is to smooth the framerate change, then we should
> use 2 set of variables one for the original pts and one for the
> smoothed. The most interesting part is that there are 2 sets, last_pts
> and pts, but they are both set to same (in)'corrected' value.

Yes, I believe that is the case.  Once it hits the case of (in the words
of this code's comments) "not too close and not too far", it seems to
permanently corrupt the sync timings.

I would send a patch to just remove this, as it doesn't make sense to
me.  But it was added for a reason, and, until I understand that reason,
I can't be sure it doesn't also do something important.

So, now I am reading through old mailing list archives.

-- 
Steaphan Greene <sgreene at cs.binghamton.edu>
Lecturer, Computer Science, Binghamton University
GPG public key: http://www.cs.binghamton.edu/~sgreene/gpg.key.txt