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false 0, waveform centered below 0

Posted: Tue Apr 05, 2011 5:22 am
by collwyn
Hi. my problem is that when I record, the waveform isn't centered on 0. it's centered below 0.
If I amplify the waveform, it moves farther into the negative (bottom half of the track).

Has anyone seen this before?
I used audacity for a long time before on this computer. This started somewhat recently, before I upgraded to the new version, and the upgrade didn't fix it.
I'm guessing it's probably a problem with my soundcard, the laptop is old hp pavilion running windowsXP

thanks,
collwyn.

Re: false 0, waveform centered below 0

Posted: Tue Apr 05, 2011 5:51 am
by kozikowski
Like the left-hand side of this illustration...

http://kozco.com/tech/audacity/pix/DCOffset.jpg

That's DC offset and you can get rid of it with the Effect > Normalize tool. Just take the DC out, don't let the tool do anything else. You have to fix this before you start editing with that material. Once you start cutting like that illustration, you can't easily fix those pops and clicks.

You have a broken digitizer or analog to digital converter (or soundcard). In my case, that's a defective ICUSBAUDIO.

http://us.startech.com/product/ICUSBAUD ... io-Adapter

I have three of these and two of them produce that lower than normal wave.

Koz