[MPlayer-users] 2 pass encoding / encode sound twice?

D Richard Felker III dalias at aerifal.cx
Tue Apr 20 15:40:43 CEST 2004

On Tue, Apr 20, 2004 at 11:15:16AM +0200, Tomasz Bury wrote:
> D Richard Felker III wrote:
> >The problem you'll get isn't A/V desync. The problem is that the 2pass
> >stats will be WRONG, which will defeat the purpose of doing 2pass.
> > 
> >
> Could you explain this, please?
> I was testing this some time ago. The log file created in the the 1-st 
> pass somehow depends on the sound, but I don't understand how. There are 
> VIDEO encoder statistisc in this log, it should depend on the video 
> encoder params but not on audio stream. The fact is the log depends on 
> audio so I'm clearly overlooking something...

Which frames get dropped or duplicated depends on the sound, because
mencoder has a very stupid model for A/V sync. If you have a different
sequence of frames, the bitrate statistics from the first pass have
nothing to do with the bitrate needs for the second.


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