[MPlayer-users] Syncronization problem

Fabio S. fast at ferrara.linux.it
Mon Dec 20 19:14:15 CET 2004

Hi all,

I have a syncronization problem that I am not able to solve. What seems
strange to me is that it is generated by mencoder itself.

I use mencoder to grab videos from my videocamera. 
Since my machine is not very fast, I use the following strategy: 
1) I grab a  video from my videocam with a very high video bitrate 
and no audio encoding
2) I encode the video obtained in 1) compressing audio in mp3 and then doing a
2pass encoding for the video with a smaller bitrate.

The video I get after step 1) is perfectly syncronized.

After this step the camera is no longer needed and the second step relies 
only on mencoder; nevertheless, the video I get after the second step 
is out of sync and the desyncronization increases from nearly nothing at
the beginning to 3-4 seconds at the end.

Here are the commands I use:

Step 1:
mencoder -endpos 1:00:00 -tv driver=v4l2:input=1 -vf pp=lb -ovc lavc -lavcopts vcodec=mpeg4:v4mv:vbitrate=6000:mbd=2 -oac copy -o "video.avi" tv://

Step 2:
mencoder -oac mp3lame -ovc frameno  video.avi -lameopts cbr -o frameno.avi 
mencoder video.avi -oac copy -ovc lavc -lavcopts vcodec=mpeg4:vbitrate=1600:vpass=1:vhq:mbd=2
mencoder video.avi -oac copy -ovc lavc -lavcopts vcodec=mpeg4:vbitrate=1600:vpass=2:vhq:mbd=2

Any suggestion?

Thank you


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