[LAU] Audacity strange behavior

Folderol folderol at ukfsn.org
Tue Nov 11 14:47:01 EST 2008


On Tue, 11 Nov 2008 19:35:30 +0100
Fons Adriaensen <fons at kokkinizita.net> wrote:

> On Mon, Nov 10, 2008 at 10:58:26PM +0000, Folderol wrote:
> 
> > OK, there are four files:
> > 
> > http://www.musically.me.uk/music/Test1.wav
> > http://www.musically.me.uk/music/Test2.wav
> > http://www.musically.me.uk/music/Test3.wav
> > http://www.musically.me.uk/music/Test4.wav
> 
> I had a closer look. As posted before the difference is
> noise, numerically generated (not analog) and strangely
> lowpass filtered: -3dB at around 8 Khz going down to
> -20dB at Fs/2. 
> 
> The noise power is -81dB FS, which is at least 14 dB
> higher than would be required for any form of dithering
> of 16-bit PCM. At least 2.5 bits are lost. No idea what
> Audacity is trying to do, but it looks quite wrong.
> 
> Ciao,

Thanks for going further into this. It's quite puzzling.

The thing is, where do we go from here? As I said in my previous post I
can confirm the ability to make identical copies directly, and via flac,
but I don't know how relevant the Audacity devs will think this issue
is.

-- 
Will J Godfrey
http://www.musically.me.uk



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