[MEncoder-users] A/V sync problems when encoding to mpeg2 DVD compatible file [hope this is better readable]

[Nico Sabbi]

Jansen wrote:
> This is the same email as the one before. Somehow hotmail/live mail
> totally messes up the hard returns in an email.... Trying Evolution
> now... Sorry, sorry.
> 
> Dear fellow MEncoder fans,
> 
> I always record TV with MEncoder. I allways record to a file that has
> the video in mpeg2 video and the audio as PCM. This is because my
> computer is not fast enough to encode audio AND video on the fly at the
> same time. I use a command like:
> 
> mencoder\ 
> -tv
> driver=v4l2:device=/dev/video0:alsa:adevice=hw.0,0:amode=1:outfmt=yuy2:width=720:height=576:fps=25:audiorate=48000:freq=203.25\
> -o "output_file.mpg"\
> -oac pcm\
> -ovc lavc\
> -lavcopts
> vcodec=mpeg2video:vrc_buf_size=1835:vrc_maxrate=9800:vbitrate=6000:keyint=15:aspect=1.3333\
> tv://
> 
> This results in a *perfectly* audio/video synchronized file, which plays
> just fine in Xine or Mplayer. When I want to convert it to a DVD
> compatible mpeg2 file (to burn it to DVD) id do the following. I encode
> the audio to mp2, stream-copy the video and set the file-format to
> "mpeg". I used to use a command like:
> 
> mencoder\
> "INPUT_FILE.MPG" -o "OUTPUT_FILE.MPG"\
> -oac lavc -ovc copy\-lavcopts acodec=mp2:abitrate=224\
> -of mpeg
> 
> That command used to result in an mpeg2 file that I could author and
> burn to a DVD, and which was in perfect sync. If I played that file in
> Xine or Mplayer the total duration that showed up in the
> on-screen-display was too short, but otherwise it played just fine. But
> now all of a sudden (mplayer upgrade?) it does not work anymore. That
> command produces a load of errors and a file that is out of synch. The
> audio gradually gets out of synch during the recording.So now I use:
> 
> mencoder "INPUT_FILE.MPG" -o "OUTPUT_FILE.MPG"\
> -ovc copy\
> -oac lavc -lavcopts acodec=mp2:abitrate=224\
> -of mpeg -mpegopts format=dvd
> 
> It produces no errors, but that does not help (not even with
> "-forceidx"). Total time too short and Audio/Video is still out of
> synch. Help!
> 
> Best regards, Jansen.
> 
> 

why don't you encode to mpeg in a single pass? re-muxing (especially 
from avi) always implies a potential loss of synchrony

mencoder tv:// -tv \
driver=v4l2:device=/dev/video0:alsa:adevice=hw.0,0:amode=1:outfmt=yuy2:width=720:height=576:fps=25:audiorate=48000:freq=203.25\
-o "output_file.mpg" -of mpeg -mpegopts format=dvd \
-oac lavc   -ovc lavc  -lavcopts \
vcodec=mpeg2video:vrc_buf_size=1835:vrc_maxrate=9800:vbitrate=6000:keyint=15:aspect=4/3:acodec=mp2:abitrate=224