Sample inversion on 'clipping'

  • Thread starter Thread starter DanielF
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DanielF

New member
G'day all.
I'm new to this forum, though I've been using CEP for several years. I'm still on version 1.2 (yes, you read that right: 1.2 NOT 2.1!).
Has anyone experienced this problem:
Recording digital audio (via a Toslink connection through my Xear 3D card) through CEP, and some of the source audio peaks hit 0dBFS - not really clipped, but just compressed/normalised to maximum level. But if more than one successive sample hits maximum, CEP 'inverts' some of the samples. So instead of getting, say 3 samples of 32767, 32767, 32767 (or 7FFF hex if you prefer), I end up with 32767, -32768, 32767, which sounds horribly crackly!
This is definitely not in the original audio, which sounds perfectly clean when played with the soundcard in 'digital loopback' mode.
Is this a known CEP problem?
Daniel
Sydney, Australia
 
Isn't it simply a matter of getting away with brief clips in some cases but distortion if it goes too far? Any media will rum out of headroom at some point and in this case there is no 'compression to be had.
Wayne
 
Wayne,
No I'm not talking about simple clipping and the distortion that creates. I you read my post carefully you'll see that what's happening is (in the example given) three samples are coming in (via Toslink) at maximum positive level), i.e.
32767, 32767, 32767 (these are the decimal values of successive samples)
but CEP is inverting one or more samples to the maximum negative, e.g.
32767, -32768, 32767 is recorded by CEP.
(This might not have appeared as clearly in the original post, as the line was split at the hyphen [negative sign]!)
Daniel
 
Daniel, I've been in this forum for years, and I don't remember ever hearing about this.
 
Dobro,
Thanks for this info. Maybe I should be looking at my Xear sound card. The digital signals sound fine on Toslink loop-through, but I guess in that configuration the hardware's just passing the signal from the Toslink receiver to the Toslink transmitter. But when it has to process the received digital audio into a PCM stream, maybe it's inverting some of the 'clipped' samples then.
I'll look first for a driver update, but if that's not available or doesn't fix it, I'll start harrassing the manufacturer :-)
Daniel
 
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