Audio software+DVD+VHS=problem?

[Paul D]

I have used Cool Edit (mix of filtering and noise reduction) to tidy up traffic rumble etc from a project which I have mastered to DVD.
The DVD Master is being used to run off VHS copies, but there are several sequences of bird song and on the VHS copies each song is accompanied by deep, fluttery background noises.

There's nothing audible on the DVD master, but if I disable Hifi playback on the VHS machines (and just leave a mono soundtrack) the problem disappears, so it does seem to be something to do with the Hifi soundtrack.

A friend has suggested that Cool Edit has left behind artefacts which are inaudible to me, but which nevertheless interfere with Hifi playback. Having checked tape stock, leads, machines etc this is the only suggestion that fits.

Does anyone have any experience which would confirm that this is the problem?

And more importantly can anyone suggest a solution? I have to get some clean VHS copies out shortly, so this is an urgent problem and any assistance would be very welcome.

[EddyH]

i did notice that recording mp3s onto audio cassettes (for walkman, car..) seemed to accentuate the compression artifacts in the files, even making some audible that sounded perfect before... dunno how to fix it though. In this situation all I can suggest is maybe re-doing the audio but only applying the low frequency filter (traffic rumble) if anything at all, and leaving the noise reduction out on all but the very noisiest scenes - VHS has a much higher noise level than DVD (and the odd rumble probably wouldnt be too noticable either) - and perhaps storing as LPCM rather than AC3 if you're not already doing so.

erm

maybe check on the spectrograph in cooledit too for high-frequency sounds/artifacts, above 16 or 22khz or so... there may be sounds in the DVD-exclusive 22-24khz range that interfere with your VHS recording equipment (eg its tuned for 32 or 44khz..).... and so the bad quality resampling/oversampling stress leads to low frequency noises - or as they're calling in the AM radio world, beats... hm..