[theora] Impossible to encode this file in sync

®om rom at rom1v.com
Tue Mar 2 04:04:07 PST 2010

Le lundi 01 mars 2010 à 22:49 -0500, xiphmont at xiph.org a écrit :
> > In your opinion, is there a way to encode it in theora in sync? Maybe
> > transmuxing or doing any preparation on the input file before encoding
> > in theora?
> I don't know why ffmpeg2theora is not encoding it in sync, but it
> seems to me like it would just be a bug..
> The mplayer/y4oi route was using container timestamps to calculate
> sync (the strategy it always uses for mpeg).  I don't have tools to
> see if the mpeg file had conflicting information confusing
> ffmpeg2theora.  All I know is that alternate toolchain I tend to use
> myself had no trouble.  To encode in sync you either need to drop
> audio or pad video at the beginning.  The audio is starting
> considerably before the video.  Aside from the initial offset, there's
> nothing odd about the file timing.
> In a sense dumping the raw yuv/audio from mplayer and using y4oi is
> 'preparation' before encoding, it's just all happening in a pipe.
> Monty

Doesn't ffmpeg2theora just ignore the delay between video and audio? In
that case, it would be noticeable only for high values (a delay of 80ms
is quite hard to detect by an human).

In many dvd I think the delay is 80ms (I used to have this value in a
old windows software few years ago, dvddecrypter, I don't know how to
get this value on gnu/linux).

I don't have "y4oi" package on my distribution (ubuntu), what does this
tool do?

Thank you for your time, I appreciate.


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