1. Frequency Modulation

envelope 없는 간단한 FM의 예제
(
var carrierFreq = 400, modFreq = 50, deviation = 100;
{        SinOsc.ar(carrierFreq + SinOsc.ar(modFreq, mul: deviation),
                        mul: 0.3);
}.scope
)

같은것을 다음과 같이 간단화 시킬수 있다.
(
var carrierFreq = 400, modFreq = 50, deviation = 100;
{        SinOsc.ar(SinOsc.ar(modFreq, mul:deviation, add: carrierFreq),
                        mul:0.3);
}.scope
)

2. Phase Modulation

PM은 FM과 비슷하지만, frequency 대신 Phase가 modulate된다.

PMOsc가 사용된다;
PMOsc.ar(carfreq, modfreq, index, modphase, mul, add)
        index는 radian에서의  modulation index
        modphase는 radians에서 modulator를 위한 modulation input.

{ PMOsc.ar(Line.kr(600, 900, 5), 600, 3, 0, 0.1)}.play// modulation carfreq
{ PMOsc.ar(300, Line.kr(600, 900, 5),3,0,0.1)}.play// modulate modfreq
{ PMOsc.ar(300, 550, Line.ar(0,20,8), 0, 0.1)}.scope// modulate index

(
var carrierFreq = 400, modFreq = 50, index = 3, decayTime = 5;
{ EnvGen.kr(Env.perc(0.001, decayTime, 0.2), 1, doneAction:2) * PMOsc.ar(carrierFreq, modFreq, index,0);
}.scope
)

calculate modFreq from cmRatio:
(
var carrierFreq = 400, modFreq, cmRatio = 1.5, index = 3, decayTime = 5;
modFreq = (carrierFreq * cmRatio.reciprocal).postln;
{        EnvGen.kr(Env.perc(0.001, decayTime, 0.2), 1, doneAction: 2) *
        PMOsc.ar(carrierFreq, modFreq, index, 0);
}.scope
)

– as SynthDef

SynthDef(name, {function})
load, send, writeDef, play

SynthDef는 반드시 Output bus 에 무엇인가를 보내야 한다;
Out.ar(bus, value)

(
SynthDef(pmgrain, {
        |carrierFreq = 400, cmRatio = 1.5, index = 3, decayTime = 0.01, amp = 1|
        
        var signal, modFreq;
        
        modFreq = (carrierFreq * cmRatio.reciprocal);
        signal =
                EnvGen.kr(Env.perc(0.001, decayTime, 0.2),1,amp, doneAction: 2) *
                PMOsc.ar(carrierFreq, modFreq, index, 0);
        
        Out.ar(0, signal)
}).load(s)
)

//위의 구문을 실행햐여 정의를 내린다.
//아래와 같은 방법으로 불러낸다.
//definition내의 arguments들의 값을 다음과 같이 변경시킬수 있다.

Synth(pmgrain, [decayTime, 5])
Synth(pmgrain, [decayTime, 1, carrierFreq, 200])

-with Routines

Routine({function})
//random carrierFreqs and random offset between events
//loops indefinitely

(
Routine({
        {Synth(pmgrain, [carrierFreq, rrand(1000.0,5100)]);
                rrand(0.001,0.1).wait;
        }.loop
        }).play(SystemClock)
)
        
//with more layers
(
a= {Routine({
        {Synth(pmgrain, [carrierFreq, rrand(1000.0,5100)]);
                rrand(0.5,0.8).wait;
        }.loop
        })
        } ! 10// be careful how many layers are used
)

play the array of routines
a.do({|i| i.play(SystemClock)})
stop the array of routines:
a.do({|i| i.stop})
reset and play the array of routines
   a.do({|i| i.reset.play(SystemClock)})

//——————————————
http://csound.x-y.net
Ji Youn Kang,
Csound Max Community