audio async with video when capturing in virtual dub

[mydan]

Hi,

I don't know if this has been touched on before, sorry if it has, but these archives are a bit to big to search through manually...

Im capturing from a digital satellite receiver using virtual dub at 320x240 using divx 3, (and mpeg 3 audio at 112kbps) and when I capture, it seems that the fps changes each refresh (1 second i believe) by about +/- 1fps, which means that every second in the final avi there's a jutter in the sound while it the sound catches up to the video.

The video input is in PAL (25fps) and coming in through video-composite, audio is through line in of sound card. In settings I've set it to 25fps, this is close, but ultimately not close enough.

I've also tried it with "lock video stream to audio" both checked and unchecked, no difference.

Is there any way fix to this problem, cos it'd be rediculous to faff around with decimals of fps to get it right (and it varies channel to channel i believe)

Thanks a lot,

dan

[Pojken Purken]

Yes, this subject has been around before but since it was a long time since I last saw it - here we go... ;-)

Rule #1 - Never capture audio to a compressed format. Always use uncompressed PCM (preferrably 44100Hz, 16 bit stereo) and compress it afterwards. You will almost certainly end up with syncproblems if you compress the audio directly (don't ask me why).

Rule #2 - No more rules (for now) ;-)

25fps is the way to go (if you capture PAL). Don't fiddle around with the decimals. It is normal behaviour for VirtualDub to deviate from this value during capture, nothing to worry about.
The "lock audio to video" in VirtualDub should be unchecked. It only applies to compatibility capture mode and will cause unnecessary dropped frames if used in normal capture mode.

Regards
PP