[PD] db and pd

[IOhannes m zmoelnig]

Marc Lavallée wrote:
> Le 22 Mai 2005 15:22, IOhannes m zmoelnig a écrit :
> 
>>dB is a relative measure. +1dBfs == +1dB(midi) == +1dB(16bit) ==
>>+1dB(32bit) == ~ *1.12 (rms)
>>
>>128 midi-values are *not* mapped to a 0..100 dB range; instead they are
>>mapped to a -100..+28 dBfs range.
>>this is what i meant by "28dB headroom" for amplifying low signals.
>>
>>you cannot just map one range to another range.
> 
> 
> I understand now. Thanks!  But midi-dB resolution (1dB) is much too small; 

yes of course. but that has been a midi-problem for ages. (btw. there 
are some 9bit MIDI-interfaces out there, so you get 0.25dB resolution 
which is quite ok)
and you get tons of resolution in a range where you don't need it at all 
(e.g: who cares for 1dB resolution at -90dBfs ??)
i think there is a nice [fadtorms] object in the iemlib, which has some 
very non-linear scale: gives you a lot of resolution around 0dBfs and 
less resolution at very low or very high values.


> interpolation is required to smooth volume transitions from the lowest 
> possible value to a certain level of amplification. 

but i think this might heavily depend on what kind of signals you are 
trying to amplify.

> 
> MIDI is almost obsolete, but I'm not sure we have a fast enough 
> communication link to directly map the full dynamic range of 24/96 audio 
> cards. Maybe with OSC and a UDP ethernet link... (but that's another 
> question).

MIDI is definitely not the choice (unless you really love it); i use 
FUDI most of the time (because i am too lazy to install OSC)

> 
> Le 22 Mai 2005 15:39, Miller Puckette a écrit :
> 
>>I didn't have MIDI in mind at all when making the dbtorms, etc., objects.
> 
> 
> That was my impression. Thanks for setting that straight.

yes, good to kow.

anyhow, it really turned out to be "conveniently enough" usable with MIDI.

mfg.a.sdr
IOhannes