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'Clipped' mp3?
StephenPG
post Mar 1 2012, 16:49
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As you can see from these Audacity screen-shots, some pretty nasty clipping, but the original wav file is fine, as is the lossless copy I use for playback.

I'm guessing this is one of those 'funny' things lossy encoding slips up on?

clip2

clip1

Oh, it's a track from 'Das Rheingold' the Solti version. 1997 CD release, but the same track from the excerpts disc from the big Decca box does the same thing when converted to mp3.
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greynol
post Mar 1 2012, 17:03
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It doesn't look that nasty to me. Are you able to ABX the difference, and if so are you confident that it is due to the clipping?

To answer your question, yes clipping can occur from the lossy process, but is a product of decoding rather than encoding.


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pdq
post Mar 1 2012, 17:13
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Just to clarify, the encoder generates a file which, when decoded, results in data points that exceed the maximum range of integer PCM data. This is not the fault of the decoder...it was told to do that.
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dhromed
post Mar 1 2012, 17:15
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Audacity's redlining is absolutely meaningless, especially at such a zoomed-out level. It only marks samples that hit 1. It does not demonstrate clipping, it only provides possible places where clipping may have occurred.

The lines in your screenshots are far from nasty. If you zoom in, you'll find that the big red band starts to break apart.

This post has been edited by dhromed: Mar 1 2012, 17:17
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StephenPG
post Mar 1 2012, 17:21
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So you're saying it's Audacity causing it?

I'll try ABXing them.

Thanks dhromed, still a bit of an Audacity newb! smile.gif

Ok ABX was a bust, after 4 passes I knew I was guessing... I can do all 20 and post the log, but I think it'd be pointless.

Thanks all for the replies.



This post has been edited by StephenPG: Mar 1 2012, 17:27
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DVDdoug
post Mar 1 2012, 19:51
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QUOTE
So you're saying it's Audacity causing it?
The MP3 encoder/decoder is not part of Audacity.

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