Audio sync problem

[francks]

I have been using dvd2svcd to convert divx files to vcds using the kvcd matrice with some success. However some files end up the audio out of sync. In some cases, I was able to fix the problem by remuxing the vcd file into an svcd file with tmpgenc (svcd header but mpeg1 stream). There are a couple of cases where I have been unable to fix the problem.

BTW those files have a VBR mp3 stream but even using the EnsureVBRMP3Sync() in the avi script won't does not help.

I tried to align the sound in bbpmeg and tmpgenc but here again without much success (I used the amount of skew displayed by VirtualDub).

Any help would be appreciated :confused:

[markrb]

Have you tried a search?

Mark

[francks]

I think I tried every single suggestion on the various forums.

[markrb]

I believe the issue is with the VBR audio. I think your only solution is to convert it to CBR.
I am pretty sure Vdub will do this.

Mark

[francks]

That's the first thing I did after ready multiple post recommeding that. It did not work but then again I was not very optimistic as DVD2SVC is already doing that for me in the first place :mad:

[markrb]

Your only choice then seem to manually adjusting the delay in BBmpeg. Other then that if Vdub didn't fix it I can see no solution.
Maybe it just can't be converted with DVD2SVCD.
If nothing else works try doing it all in TMPG without DVD2SVCD.

Mark

[francks]

I tried that but without much success either. I'not sure I do the right thing here.

[hoozdapimp]

hmm..weird.

1)figure out number of frames in the movie using vdub. Write this number down.

2)Divide #frames/framerate (note, be very precise with your framerate and final answer. Get at least 3 decimal precision). Write this number down.

3)extract audio as wav in virtual dub.

4)open your wav file with cool edit or some other good wav editing tool. Choose time stretch and strech it to the total found in step 2. (this may be a very small difference but could make the difference in the end between in synch and out of synch. this is why step 2 needs to be very precise). Save this new wav file.

5)remux the video with your new wav file from step 4 in vdub.

6)process in dvd2svcd

Hope this works for ya! :)
Scott

[rolonzos2]

This might help (I guess it might not too though).

http://forum.doom9.org/showthread.php?s=&threadid=44559

[francks]

Scott, let me get Cool Edit and report back to you.

BTW when I open the file with vdub, I get the vbr message that there is a 31910ms skew and when i look at file properties it shows a preload skew of 1.39s.

Not very consistent. And when I apply either skew in BBmpeg, I still have a sync pb. :(

[hoozdapimp]

everytime i have a synch problem, cool edit is able to fix the problem :)

[francks]

Ok, I finally solve the problem for one of the videos. I checked the lenghts of the mpv and mp2 and there was a 8s difference (sound shorter). Adding a 8s silence at the beginning converting back to mp2 and remuxing did the trick.

The funny part is why would this happen in that case when other cases are fine or can be solved by remuxing into SVCD format.

Also, I still have another case unresolved, but I suspect that it might be due to bad video frames. Again, why would the DIVX be able to deal with it and not the MPEG1 I don't know.

Any insight would be appreciated. :)