What causes waveforms that look like this?

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Xenu
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What causes waveforms that look like this?

Postby Xenu » Fri Jan 28, 2005 7:01 pm

I've seen a few such waveforms in my time, but have never been entirely sure what process generates 'em/modifies them.

This is the single mix of Original Love's "Treasure Island." Neither the album mix, nor the acapella version of the single mix have this odd presentation. It doesn't seem to affect the sound, as far as I can tell.Image

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Postby Rspaight » Fri Jan 28, 2005 7:53 pm

I'm tempted to blame the activity depicted in your avatar.

Seriously, I have no idea. Something funky with the tape alignment, maybe? Though you'd think that would be quite audible.

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Postby Xenu » Fri Jan 28, 2005 8:57 pm

What it looks like is that the waveform has been limited at the bottom of its peak, but not at the top. Buh? I'm wracking my brain trying to figure out where I've seen something similar.

And I'm pretty sure that's tobacco.

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Postby CitizenDan » Fri Jan 28, 2005 9:16 pm

I get that sometimes with .wav files made from dodgy sources such as cassette or poorly ripped MP3. And it's always at the bottom, never the top, and it never produces a consistent sound, or lack thereof. In other words, I dunno, but I wouldn't mind finding out.
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Postby sparkgap » Sat Jan 29, 2005 12:06 pm

DC Offset perhaps? That could shift the baseline so that one half gets clipped.

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Postby lukpac » Sat Jan 29, 2005 12:27 pm

Yeah, that's what I was thinking, although it's unclear where in the process this would/could have happened. It's almost as if an offset was applied going in to the compressor, then removed coming out. Because the parts of the waveforms that are not compressed seem correctly centered.

That's strange.
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Postby Xenu » Sat Jan 29, 2005 3:27 pm

They *are* correctly centered, as correcting the offset does nothing.
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Postby lukpac » Sat Jan 29, 2005 3:33 pm

lukpac wrote:Because the parts of the waveforms that are not compressed seem correctly centered.
"I know because it is impossible for a tape to hold the compression levels of these treble boosted MFSL's like Something/Anything. The metal particulate on the tape would shatter and all you'd hear is distortion if even that." - VD

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Postby damianm » Sat Jan 29, 2005 3:54 pm

It looks like it could have been some component with a push-pull design (where positive and negative halves of the signal are split and amplified independently) malfunctioning during recording/mixing.

I suppose that could cause the output signal to look asymmetrical like the one you posted.

Just a wild guess as I really don't have any background in electronics.

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Postby Xenu » Sat Jan 29, 2005 8:08 pm

Luke, yes, I know, I was just confirming that you were in fact correct.
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Postby Ba Rock » Mon Jun 19, 2006 4:47 pm

I had it with the single 'Shadow' by the Lurkers (and the b-side too). It could be that we are actually seeing the bottom of the groove. And that the vinyl wasn't cut right.