Audio shift problem in Avidemux

[sir_ken]

Hi,
after using XviD4PSP to rip a DVD into an FLV i discovered a 21 second difference in video/audio sync.
Apparently there was a 21 sec chapter in the beginning of the DVD that didn't have any sound. This resulted in the (negative) audio delay.

I tried to use Avidemux to fix the problem, and it did, sort of...

The audio still starts 21 seconds too early, i e in the absolute beginning of the movie. However, after the 21 seconds have passed the audio starts over again and now of course it's in sync...
I would like to know if there is a way to truely shift the audio by 21 seconds, not copy it, but move it and have silence in the beginning.
Is there anyone who knows of a way to accomplish this?

//Erik

[guns1inger]

AVI Demux should not have duplicated the audio, but added silence to the beginning. I certainly haven't seen it do what you are describing, but then I don't believe I have ever used it to fix audio skew in an FLV file before.

There are very few tools that work with FLV files. AVI Demux is probably the best of them.

One alternative would be to output the audio only to an uncompressed WAV file, load it into Audacity, add your skew silence, then save it again. Load this into AVI Demux to replace the current audio.

[sir_ken]

Thanks!
I did it the way you suggested and it worked beautifully.
I must agree with you that it seems very strange that Avidemux should duplicate the audio... But i does.
Anyway, thanks again for the help, next time i think i'll try to get it right from the beginning.

[polycoda]

For the record, I have the same problem with every single FLV video for which I use audio shifting using AviDemux