4 Oct
2009
4 Oct
'09
4:21 a.m.
Hi,
Many thanks for all feedback on my original posting about what
features you would like to see in an open midi controller...
Based on your "requests" I've started experimenting a bit with adding
rotary encoders and a 20x4 lcd display. I've changed to a more
powerful (but still cheap and easy to work with) microcontroller
atmega128 (from atmega16). If you're not familiar with
microcontrollers you might be familiar with the arduino platform which
also uses an atmega (but the lesses atmega168).
Now to my question: Does anyone have some sample velocity curves, like
a mapping from key velocity to midi velocity for different instruments
(grand piano etc)? There doesn't seem to be any convention on how to
handle velocity data?? Does some synths expect linear mapping and does
the "mapping" in software??
--Albin
4 Oct
4 Oct
12:50 p.m.
söndag 04 oktober 2009 10:21:09 skrev Albin Stigo:
Hi,
Many thanks for all feedback on my original posting about what
features you would like to see in an open midi controller...
Based on your "requests" I've started experimenting a bit with adding
rotary encoders and a 20x4 lcd display. I've changed to a more
powerful (but still cheap and easy to work with) microcontroller
atmega128 (from atmega16). If you're not familiar with
microcontrollers you might be familiar with the arduino platform which
also uses an atmega (but the lesses atmega168).
I have a few Atmel MCUs lying around, actually... :-)
I should start playing around with them some time. Any year now... :-D
Now to my question: Does anyone have some sample
velocity curves, like
a mapping from key velocity to midi velocity for different instruments
(grand piano etc)? There doesn't seem to be any convention on how to
handle velocity data??
Don't know... I would expect the velocity (as in m/s) to have a rather non-
linear relation to the MIDI velocity values. I mean, kinetic energy is
velocity squared, so one would expect double actual speed (ie m/s) to add 12
dB to the resulting output level, assuming the instrument response is linear.
But, I'm only guessing! I suspect it'll come down to trial and error, finding
something that "feels good".
Does some synths expect linear mapping and does the
"mapping" in software??
Well, I don't know about linearity, or how linear MIDI velocity is actually
supposed to be, but it's common to at least have various ways of scaling
velocity. Many (most?) synths will support mapping of velocity per voice to
create "analog" layers (crossfade rather than switch at a distinct velocity),
and to exaggerate, reduce or disable velocity response and things like that.
I have a faint memory of the Roland JV-1080 having some sort of programmable
exponential velocity mapping as well, but I could be wrong... Don't have mine
here, so I can't check.
--
//David Olofson - Developer, Artist, Open Source Advocate
.--- Games, examples, libraries, scripting, sound, music, graphics ---.
| http://olofson.net http://kobodeluxe.com http://audiality.org |
| http://eel.olofson.net http://zeespace.net http://reologica.se |
'---------------------------------------------------------------------'
1:46 p.m.
On Sun, Oct 04, 2009 at 06:50:38PM +0200, David Olofson wrote:
Well, I don't know about linearity, or how linear
MIDI velocity is actually
supposed to be, but it's common to at least have various ways of scaling
velocity. Many (most?) synths will support mapping of velocity per voice to
create "analog" layers (crossfade rather than switch at a distinct velocity),
and to exaggerate, reduce or disable velocity response and things like that.
The first question to ask is what is acually measured
and how, and with which resolution.
Then a range of these values must be mapped to 0..127,
so the first thing to be decided is the limits of this
range, next what kind of function maps it to the MIDI
range.
Ciao,
--
FA
Io lo dico sempre: l'Italia è troppo stretta e lunga.
6:48 p.m.
söndag 04 oktober 2009 19:43:38 skrev Fons Adriaensen:
On Sun, Oct 04, 2009 at 06:50:38PM +0200, David
Olofson wrote:
Most likely the time elapsed from the first key switch is made to the second.
(IIRC from cleaning mine, the Fatars have the usual "bubbles" with conductive
rubber switches; two per key. I also had some small Roland controller way
back: Same design.)
Well, I don't know about linearity, or how
linear MIDI velocity is
actually supposed to be, but it's common to at least have various ways of
scaling velocity. Many (most?) synths will support mapping of velocity
per voice to create "analog" layers (crossfade rather than switch at a
distinct velocity), and to exaggerate, reduce or disable velocity
response and things like that.
The first question to ask is what is acually measured
and how, and with which resolution. Then a range of these values must be mapped to
0..127,
so the first thing to be decided is the limits of this
range,
I suppose 0 would be somewhere around where a real piano would make no audible
noise whatsoever, whereas 127 would be somewhere between where your fingers
start hurting and where the hardware breaks. :-)
This would be the absolute limits *before* mapping. One would most likely want
to map only a part of this range to MIDI velocity in the normal case. One just
wants to avoid random zero velocities when playing very softly, as well as an
obvious dynamic "brickwall" when playing real hard.
next what kind of function maps it to the MIDI range.
The original Studiologic MCU has two integer parameters for this in the user
interface; SHAPE [-4,4] and VELOCITY [1-8], where the former selects the
mapping function and the latter scales the dynamic range of that function.
Unfortunately, I don't know how this is related to actual key velocities, and
I'm quite sure one can't make it out from the instruction manual. ;-)
--
//David Olofson - Developer, Artist, Open Source Advocate
.--- Games, examples, libraries, scripting, sound, music, graphics ---.
| http://olofson.net http://kobodeluxe.com http://audiality.org |
| http://eel.olofson.net http://zeespace.net http://reologica.se |
'---------------------------------------------------------------------'
6 Oct
6 Oct
8:07 a.m.
Fons Adriaensen wrote:
On Sun, Oct 04, 2009 at 06:50:38PM +0200, David
Olofson wrote:
1 to 127, because note on velocity 0 is a note off command.
Well, I don't know about linearity, or how
linear MIDI velocity is actually
supposed to be, but it's common to at least have various ways of scaling
velocity. Many (most?) synths will support mapping of velocity per voice to
create "analog" layers (crossfade rather than switch at a distinct velocity),
and to exaggerate, reduce or disable velocity response and things like that.
The first question to ask is what is acually measured
and how, and with which resolution.
Then a range of these values must be mapped to 0..127,
5349
days inactive
5351
days old
linux-audio-dev@lists.linuxaudio.org
4 comments
4 participants
participants (4)
-
Albin Stigo -
David Olofson -
Fons Adriaensen -
Ralf Mardorf