background noise after conversion to MPG2

[colojim]

I capture as raw avi or dv (advc50) and clean up the noise at the bottom of the screen, edit etc. and save as avi or convert using TMPGENC to MPG2. I convert AVI files with TMPGENC or ULead Movie factory so that I have MPG2 with bitrates 4000 or 6000 kpbs.

Throughout this the sound is perfect until the MPG2 is created ready for dvd creation. Then on playback there is a hiss sound which gurgles in the background like a low bitrate MP3.

This has been noticeable since putting in a Creative 5.1 sound system.
Could this sound always have been there but was masked by the older stereo speakers I had or could the Creative system decoder be adding this?

If it was the Creative why does it only happen to the MPG2 and not the source files?

Anyone else had this problem or found a solution to it?

[scopophilia]

i assume you use tmpgenc to produce the wav file, too. does that wav file sound bad? in my experience tmpgenc has awful audio capabilities and i had results similar to yours, i now use goldwave to extract audio from avis.

[colojim]

The noise happens even with playback of commerical dvds but when I boot into Win 2000 (was in XP) the problem is not there.

I have installed a Sound blaster live 5.1 to overcome electronic noise from the motherboard sound chip, but first I have to get rid of the background noise (sounds like constant wind) before I get anywhere.

Trouble shooting tonight.