[PD] db and pd

IOhannes m zmölnig zmoelnig at iem.at
Sun May 22 11:14:28 CEST 2005


Marc Lavallée wrote:
> Le 21 Mai 2005 13:54, IOhannes m zmoelnig a écrit :
> 
>>Phillip Stearns wrote:
>>
>>>Why not use the dBfs scale (0dB is the clipping
>>>ceiling and everything below is measured negative) if
>>>we're running digital?
>>
>>the most important reason to not use technical dB but dB with an offset
>>is (i think) because of MIDI: MIDI gives us values between 0..127; it is
>>very hard to express negatice numbers with MIDI-values.
> 
> 
> I believe it has more to do with 16 bits digital audio than MIDI.


well, yes: i guess it is, as miller says "conveniently enough" that we 
want to control a range of (at least) 100dB and MIDI gives us 127 values.
the fact that 100dB is just the range that is covered by 16bit audio 
shouldn't have too much effect on whether we use values between -100 and 
0 (which would go neatly with technical dB) or use values 0..100 (which 
is not very technical)
additionally pd has nothing to do with 16bit audio: signals are floating 
point (well, they are 16bit on pdas...); it is just the audio-card that 
will convert it to a fixed point format (like 24bit on the hammerfall)

it just turned out to work very simply and intuitively when using 
midi-dB (i prefer to refer to pd's dB as such) with quite everything 
(this is: human perception, 16bit audio and MIDI)


mfg.a.dr
IOhannes




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