Re: sequencer: handling non-registered parameter numbers....

[Joern Nettingsmeier <nettings@folkwang-hochschule.de>]

Paul Davis wrote:
>>hello alsa gurus !
>>
>>i have bought a peavey studiomix midi controller on ebay, and it sends 
>>NRPN messages (non-registered parameter numbers). when i move a slider, 
>>it sends the slider number encoded in 98 and 99 and the value in the 
>>DATA ENTRY controllers 6 and 38. i would like to map these to ordinary 
>>midi controllers, or better yet, get nrpn support into ardour.
>>
>>how do i get nrpn controller values from the alsa sequencer without 
>>having to parse the individual events and put them together by hand ?
> 
> 
> ardour doesn't use the sequencer.

i'm aware of that. i was planning to use a virmidi card, which ardour 
could grab raw, and to write a little mapper that maps nrpns to 
arbitrary normal controllers. this can be patched between the midi in 
port and the virtual device with aconnect. (if i have understood virmidi 
devices correctly.)

> and i don't consider the nrpn messages any different from any other
> controller. from libmidi++'s persepective, there are 127 controller
> ID's, each with a value. whatever standard mapping they may have to
> gain, pan, or nrpn is completely ignored.

understood. the problem is, it won't work automatically with nrpn-based 
controllers, since two nrpn "events" and two data entry events (yes, 
both 14 bit) must be grouped together and transmogrified into one 
[controller,value] tuple.

> 14 bit value support is almost impossible to provide: the midi spec is
> just ridiculous for that. 

i wouldn't have dared to say so for lack of experience, but i had this 
creeping feeling it might be the case. :)

maybe i should consider dropping 14-bit resolution (the crappy faders on 
the peavey hardly manage 127 distinct positions) and just use the MSB 
part of the 14bit controller. ardour does perform lowpass filtering of 
controller values, right ?

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Jörn Nettingsmeier
Kurfürstenstr 49, 45138 Essen, Germany
http://spunk.dnsalias.org (my server)
http://www.linuxdj.com/audio/lad/ (Linux Audio Developers)






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