Need help in fixing audio delay which builds up as the video goes on ..

[ahmadka]

Hi guys .. I recently did some captures from some old VHS tapes and I'm experiencing a little audio sync problem, although its almost negligible ... At the beginning of the recorded video there's no sync issue ... however the sync linearly builds throughout the video and after 1:53:00 long video, the audio ends about 2 seconds before the video does .. !

I was using HuffYUV and iuVCR for the capture .. iuVCR reported about 700ms audio delay, and I found some tricks through which iuVCR tries to automatically correct this, which is does partly (the delay is removed from the start at least)

iuVCR also reported that there were no frame drops .. !

I also did the same capture twice, just to see if the sync issue repeats, which it does ..

So how can I make the audio slightly slower so that its 2 seconds longer, and ends with the video ?

Also, how can I make sure the HuffYUV is fully installed in my PC ? (because when I open a HuffYUV file in Gspot, it says codec NOT installed) ...

[redwudz]

When the audio sync gradually gets worse during the playback, the most common cause is that the audio and video lengths don't match. That's a different problem from a audio offset delay where the sync error is the same throughout the playback.

You can try dropping the audio into Audacity and shrinking it by two seconds, then mux it back with the video. With Audacity, that's done with 'Effect>Change Tempo'.

[ahmadka]

How can I find out the length of the video with millisecond precision ?

[redwudz]

A video editor should be able to do that. Try AVIDemux.

[Calidore]

I've had this problem and tried Audacity, but Audacity only allows two decimal places of precision, which wasn't enough on a long video. I've had better luck with Virtualdub's stretch and time stretch filters (Audio | Use advanced filtering), which allows five decimals.

Best,

Calidore