MIDIIn


A popular 80s technology


This document explains technical details of the MIDI hardware interface class, MIDIIn.


Note that the interface in this class has significant limitations. MIDI responders created directly in MIDIIn cannot be created and destroyed dynamically, which significantly limits the ability to create flexible MIDI configurations. For general programming, users should not use the MIDIIn class directly. Instead, use the MIDIResponder classes (see helpfile: MIDIResponder).


Certain MIDI messages are supported only through MIDIIn. These are: polytouch, program, sysex, sysrt, smpte.


See the UsingMIDI helpfile for practical considerations and techniques for using MIDI in SC.


The MIDIIn class


MIDIIn links MIDI input received from the operating system to a set of user defined functions.

Only one set of MIDI input handling functions can be active at a time, they are stored in the

following class variables:


noteOff, noteOn, polytouch, control, program, touch, bend, sysex, sysrt, smpte


The first argument these functions receive is an unique identifier that specifies the source of the data.


Quick start for 1 port:


(

MIDIIn.connect; // init for one port midi interface

// register functions:

MIDIIn.noteOff = { arg src, chan, num, vel; [chan,num,vel / 127].postln; };

MIDIIn.noteOn = { arg src, chan, num, vel; [chan,num,vel / 127].postln; };

MIDIIn.polytouch = { arg src, chan, num, vel; [chan,num,vel / 127].postln; };

MIDIIn.control = { arg src, chan, num, val; [chan,num,val].postln; };

MIDIIn.program = { arg src, chan, prog; [chan,prog].postln; };

MIDIIn.touch = { arg src, chan, pressure; [chan,pressure].postln; };

MIDIIn.bend = { arg src, chan, bend; [chan,bend - 8192].postln; };

MIDIIn.sysex = { arg src, sysex; sysex.postln; };

MIDIIn.sysrt = { arg src, chan, val; [chan,val].postln; };

MIDIIn.smpte = { arg src, chan, val; [chan,val].postln; };

)


Quick start for 2 or more ports:


(

var inPorts = 2;

var outPorts = 2;

MIDIClient.init(inPorts,outPorts); // explicitly intialize the client

inPorts.do({ arg i; 

MIDIIn.connect(i, MIDIClient.sources.at(i));

});

)



class methods:

 

*noteOn_(function)

function is evaluated whenever a MIDI noteOn message is received, it is passed the following arguments:

uid unique identifier of the MIDI port

MIDIchannel ranges from 0 to 15

keyNumber 0 - 127

velocity 0 - 127

*noteOff_(function)

uid unique identifier of the MIDI port

MIDIchannel ranges from 0 to 15

keyNumber 0 - 127

velocity 0 - 127, typically 64 unless noteOff velocity is supported

*polytouch_(function)

uid unique identifier of the MIDI port

MIDIchannel ranges from 0 to 15

keyNumber 0 - 127

pressure 0 - 127

*control_(function)

uid unique identifier of the MIDI port

MIDIchannel ranges from 0 to 15

controllerNumber 0 - 127

value 0 - 127

*program_(function)

uid unique identifier of the MIDI port

MIDIchannel ranges from 0 to 15

programNumber 0 - 127

*touch_(function)

uid unique identifier of the MIDI port

MIDIchannel ranges from 0 to 15

pressure 0 - 127

*bend_(function)

uid unique identifier of the MIDI port

MIDIchannel ranges from 0 to 15

bend 0..16384,   the  midpoint is 8192

*sysex_(function)

uid unique identifier of the MIDI port

system exclusive data an Int8Array (includes f0 and f7) 

see manufacturer references for details

note: The current implementation  assembles a complete system exclusive packet

 before evaluating the function.

*sysrt_(function)

uid unique identifier of the MIDI port

index ranges from 0 to 15

data 0 - 127

index data message

2 14bits song pointer

3 7bits song select

8 midiclock

10 start

11 continue

12 stop


*smpte

uid unique identifier of the MIDI port

index ranges from 0 to 7

data 4 bits

Over MIDI, SMPTE is transmitted at 1/4 frame intervals four times faster than the frame rate.

index data

0 frames low nibble

1 frames hi nibble

2 seconds low nibble

3 seconds hi nibble

4 minutes low nibble

5 minutes hi nibble

6 hours low nibble

7 hours hi bit OR'ed with frameRate

0 -> 24fps

2 -> 25 fps

4 -> 30 fps drop frame

6 -> 30 fps

Nibbles are sent in ascending order, 


(

MIDIIn.connect;

s = Server.local;

s.boot;

s.latency = 0;


SynthDef("sik-goo", { arg freq=440,formfreq=100,gate=0.0,bwfreq=800;

var x;

x = Formant.ar(

SinOsc.kr(0.02, 0, 10, freq), 

formfreq,

bwfreq

);

x = EnvGen.kr(Env.adsr, gate,Latch.kr(gate,gate)) * x;

Out.ar(0, x);

}).send(s);


x = Synth("sik-goo");


//set the action:

MIDIIn.noteOn = {arg src, chan, num, vel;

x.set(\freq, num.midicps / 4.0);

x.set(\gate, vel / 200 );

x.set(\formfreq, vel / 127 * 1000);

};

MIDIIn.noteOff = { arg src,chan,num,vel;

x.set(\gate, 0.0);

};

MIDIIn.bend = { arg src,chan,val;

//(val * 0.048828125).postln;

x.set(\bwfreq, val * 0.048828125 );

};

)






//i used this and got acceptable latency for triggering synths live.

//The latency might actually be less than sc2, but i haven't used it enough

//to tell for sure yet.

//Powerbook G4, 512mb ram.

- matrix6k@somahq.com



writing to the bus rather than directly to the synth


s = Server.local;

s.boot;


(

s.latency = 0;

SynthDef("moto-rev", { arg ffreq=100;

var x;

x = RLPF.ar(LFPulse.ar(SinOsc.kr(0.2, 0, 10, 21), [0,0.1], 0.1),

ffreq, 0.1)

.clip2(0.4);

Out.ar(0, x);

}).send(s);


b = Bus.control(s);


x = Synth("moto-rev");


// map the synth's first input (ffreq) to read

// from the bus' output index

x.map(0,b.index);



MIDIIn.connect;

//set the action:

MIDIIn.noteOn = {arg src, chan, num, vel;

b.value = num.midicps.postln;

};


MIDIIn.control = {arg src, chan, num, val;

[chan,num,val].postln;

};

MIDIIn.bend = {arg src, chan, val;

val.postln;

};

)


// cleanup

x.free;

b.free;




Keyboard Split for two voices

pbend to cutoff, mod to rez, 7 to amp

// - matrix6k@somahq.com

prepare

s.boot;

(

SynthDef("funk",{ arg freq = 700, amp = 0.2, gate = 1, cutoff = 20000, rez = 1, lfospeed=0;

     var e,x,env,range,filterfreq;

e = Env.new([0, 0.1, 0.1, 0], [0, 0.1, 0.1], 'linear', 2);

env=Env.adsr(0.3,1,1,1);

range = cutoff -1;

filterfreq = SinOsc.kr(lfospeed,0, range, cutoff).abs;

x = RLPF.ar(Mix.ar([

Mix.arFill(2, {Saw.ar(freq *2 + 0.2.rand2, amp)}),

Mix.arFill(2, {Saw.ar(freq *4+ 0.2.rand2, amp)})

]),

EnvGen.kr(env,gate)*filterfreq,

rez);

     Out.ar([0,1],x * EnvGen.kr(e, gate, doneAction: 2))


}).send(s);


SynthDef("strings",{ arg freq = 700, amp = 0.2, gate = 1;

     var x,enve;

enve = Env.new([0, 0.1, 0.1, 0], [2, 0.1, 1], 'linear', 2);

x = RLPF.ar(Mix.ar([

Mix.arFill(2, {Saw.ar(freq +2.rand2,0.6)}),

Mix.arFill(2, {Saw.ar(freq *0.5 + 2.rand2,0.6)})

]),

6000,1);

     Out.ar([0,1],x * EnvGen.kr(enve, gate, doneAction: 2))


}).send(s);


)

then...

(

var keys, cutspec, cutbus, rezspec, rezbus, lfospec, lfobus;

keys = Array.newClear(128);


MIDIClient.init;

MIDIIn.connect(0, MIDIClient.sources.at(0));


g = Group.new;


cutspec = ControlSpec(100,10000,\linear,0.001);

cutbus = Bus.new(\control,1,1,s);

cutbus.value = 10000;


rezspec = ControlSpec(1,0,\linear,0.001);

rezbus = Bus.new(\control,2,1,s);

rezbus.value = 1.0;


lfospec = ControlSpec(0,50,\linear,0.001);

lfobus = Bus.new(\control,3,1,s);


MIDIIn.control = {arg src, chan, num, val;

if(num == 1,{

rezbus.value = rezspec.map(val/127.0);

});

if(num == 7,{

lfobus.value = lfospec.map(val/127.0).postln;

});

};

MIDIIn.bend = {arg src, chan, val;

cutbus.value = cutspec.map(val/16383.0);

};


MIDIIn.noteOn = {arg src, chan, num, vel;

var node;

if(num < 60, {

node = Synth.tail(g, "funk", [\freq, num.midicps, \amp, vel/255]);

node.map("cutoff",1,"rez",2,"lfospeed",3);

// node = Synth.basicNew("funk",s);

// s.sendBundle(nil,

// node.addToTailMsg(g,[\freq, num.midicps, \amp, vel/255]),

// node.mapMsg("cutoff",1,"rez",2,"lfospeed",3)

// );

keys.put(num, node)

},{ 

node = Synth.tail(g, "strings", [\freq, num.midicps, \amp, vel/255]);

keys.put(num, node)

});

};


MIDIIn.noteOff = {arg src, chan, num, vel;

    var node;

    node = keys.at(num);

    if (node.notNil, {

        keys.put(num, nil);

        s.sendMsg("/n_set", node.nodeID, "gate", 0);

        // or node.release

        // then free it ... or get the NodeWatcher to do it

    });

};


)











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