[PD] editing pd silence

Mathieu Bouchard matju at artengine.ca
Sun Oct 23 20:20:38 CEST 2011

Le 2011-10-22 à 15:29:00, martin brinkmann a écrit :
> On 10/22/2011 02:39 PM, saskia diez wrote:
>> I just discover this since i bought a nice speakers, before i
>> havent realize that sound editors add that hiss.
> i could hardly believe that, but you are right! i have just created a
> file with writesf~, ensured that it contained only zeros (hexeditor),
> loaded it in audacity, exported as 16bit wav, and after normalizing,
> there was a lot of noise.

How much is a lot ? What's the amplitude in the noise ? If it's something 
like 1/65536 of the maximum level, that's not what I'd call « a lot »...

It could appear because of different conceptions of where the home volume 
is. Lots of code assumes that in a range going from -32768 to +32767, the 
middle is 0 ; but it's also possible to assume that the middle is -½, 
which is the average of -32768 and +32767. The latter makes it impossible 
to make a completely empty signal. However, that signal is still DC. It 
needs some kind of misinterpretation of 0 (using two different conceptions 
at once) to think that 0 really means ½ and that ½ has to be dithered 
because it's not a whole number.

Personally, I don't understand what's the point of dither in audio. Maybe 
it's just an evil plot to make CD quality sound like 8-track cartridges.

| Mathieu BOUCHARD ----- téléphone : +1.514.383.3801 ----- Montréal, QC

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