[linux-audio-dev] Aeolus and OSC - comments requested

Albert Graef Dr.Graef at t-online.de
Fri May 13 08:16:41 UTC 2005

Steve Harris wrote:
> My preferred form would be something like
> /std_prefix/inst_name/base_freq f   <base-frequecy>
> /std_prefix/inst_name/note_on   iff <note-id> <octave> <velocity>
> /std_prefix/inst_name/note_off  if  <note-id> <velocity>

Hmm, what would the note-id be? And the octave is the log_2 of the 
frequency, right?

Occam also seems to be a reasonable way for a 1-1 OSC-MIDI mapping, 
thanks for the link. (But is that what we actually want in OSC?)

At least for modular synthesizers I'd guess that a standard way of 
communicating notes would be a message to set the parameters of a synth 
voice, something like this:

/set <voice> <gate> <freq> <gain>

<voice> would be the identifier of the voice to play, <gate> would be 1 
to start playing the note (trigger the attack) and 0 to stop it (trigger 
the release), <freq> would be the frequency in some convenient unit 
(usually either Hz, octaves, semitones or cent) and <gain> the 
amplification (velocity, if you prefer).

In many synths you would also be able to modify each of these parameters 
(and probably some more) individually, while the note is already 
playing. In the case of Aeolus the <freq> parameter could just be a MIDI 
note number, as it cannot play arbitrary frequencies "on the fly".

The disadvantage of this fairly basic scheme is of course that the 
client has to dispatch the voices himself.


Dr. Albert Gr"af
Dept. of Music-Informatics, University of Mainz, Germany
Email:  Dr.Graef at t-online.de, ag at muwiinfa.geschichte.uni-mainz.de
WWW:    http://www.musikwissenschaft.uni-mainz.de/~ag

More information about the Linux-audio-dev mailing list