sometimes with old vhs tapes, the sound recording brakes down, if I continue then the resulting mpeg file will playback in increased speed e.g 7 minutes instead of 20 minutes.
If during the recording I stop and re-start then the sound is Ok for a while till the next brakedown.
Is there any audio configuration parameter to influence this behaviour, or any other solution ??

If I turn off the audio preview, then the problem disappears. So it seems related to the support for the realtec audio on my acer notebook (Vista)