[MPlayer-users] [MEncoder] Synchonization lost when using Vorbis in a OGM

[Rodolfo J. Quesada]

Hi,

This is my first post to this list... As I had been looking for a long 
time how to deal with a problem I got recently...

I'm trying to compress some VOBs copied with vobcopy, and after that, 
dump the audio, convert it to Vorbis, and mux it all, with ogmmerge to 
get a nice OGM.

The problem is, that those VOBs after starting mencoder, keeps saying 
that there was duplicate frames, enters and leaves telecine mode, it 
jumps from 23.976 to 29.970 in those changes... All of that things are 
expected by the nature of the DVD, when I got to the final AVI, with an 
AC3 audio track (-oac copy), the A-V sync is always around 0.000, with a 
few tens of milliseconds changes... That's still fine...

Then I dump the PCM audio...

cat *.VOB | mplayer -vc null -vo null -ao pcm -aofile audio.wav

And I get a pretty big PCM file... Then I encode it...

oggenc -q0 audio.wav

And got an audio.ogg file...

Then, I merge it...

ogmmerge -A video.avi audio.ogg -o pelicula.ogm

And when I play it with MPlayer, the sync ratio jumps up to 15 seconds, 
in some scenes where the telecine mode was enabled... It gets 
desynchronized all the way, in the plain old 29.970fps scenes, the audio 
is synced, but not in the 23.976 ones... I tried it in Windows Media 
Player 6.4, and those scenes not synchonized get blurred or stoped, and 
follows the audio synchronizations nicely, but the video quality is not 
appealing at all... Pretty ugly in fact...

So, the question, somebody has faced this problem before? It can be 
solved?... I really love OGM... The audio is so sweet, even at a -q0 
ratio...

These are the lines of the encoding, I have tried the detc filter, and 
othe options as well...

cat *VOB | mencoder -sws 1 -fps 29.970 -ofps 29.970 -sid 0 -vop 
scale=512:384,pp=lb -aid 129 -oac copy -ovc lavc -lavcopts 
vcodec=mpeg4:vhq:v4mv:vbitrate=650:vpass=1:vqscale=2 - -o /dev/null

cat *VOB | mencoder -sws 1 -fps 29.970 -ofps 29.970 -sid 0 -vop 
scale=512:384,pp=lb -aid 129 -oac copy -ovc lavc -lavcopts 
vcodec=mpeg4:vhq:v4mv:vbitrate=650:vpass=2 - -o video.avi

(Any suggestion about those settings will be very apprecied, I try to 
get the best quality!!!)

After hours of trying with no good results at all, I finally decided to 
get the audio in MP3... I was expecting the same problem... But the A-V 
sync ratio was fine!!! And the sound quality its not so bad at all... 
But I just have this doubt... :(

Thanks a lot! ;)


-- 
Rodolfo J. Quesada
Estudiante, Ing. en Computacion
Instituto Tecnologico de Costa Rica
http://www.ic-itcr.ac.cr/~rquesada
E-Mail: rquesada at ic-itcr.ac.cr
IM: rquesada at jabber.org