[sdiy] Expo converters, lin log etc.

[Tom Wiltshire]

On 1 Feb 2007, at 00:28, John Mahoney wrote:

> As for stepping artifacts, do we need to exceed the pitch resolution 
> of MIDI? (That's a question, not a challenge.)

So what exactly _is_ the the pitch resolution of MIDI?

The basic note numbers give us a range of 127 notes, in semitones. The 
pitch bend specification gives us 14 bit data over +/-2 semitones, or 
an accuracy of 1/8192th of a semitone. Wikipedia claims that "The human 
ear cannot hear the difference between adjacent pure tones that differ 
by less than 1/20 semitone" (and we all know that wikipedia never 
lies...).
This is essentially a 20-bit definition of pitch (7+14 with 1 bit 
'overlap'). 24-bit ADC/DACs are fairly commonplace and cheap. So my 
answer to the question is "No, we probably don't need to exceed the 
pitch resolution of MIDI, but while we're at it, we might as well use 
24 bits not 20."


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