Mix

A graph element that mixes the channels of a signal together. It works like the sclang counterpart.

The Mix companion object contains various useful mixing idioms:

• Mix.tabulate(n: Int)(fun: Int => GE): corresponds to Seq.tabulate and to Array.fill in sclang.
• Mix.fill(n: Int)(thunk: => GE): corresponds to Seq.fill.
• Mix.seq(elems: GE*): A shortcut for Mix(GESeq(elems: _*)).

A separate graph element is Mix.mono. Mix.mono(elem: GE) flattens all channels of the input element before summing them, guaranteeing that the result is monophonic.

Finally, Mix.fold is an idiom that not actually adds elements, but recursively folds them. Thus, Mix.fold(elem: GE, n: Int)(fun: GE => GE) is equivalent to

(1 to n).foldLeft(elem) { (res, _) => fun(res) }

Mix.fold is often used in the SuperCollider examples to apply a filtering process such as reverberation several times. For cases where the iteration index is needed, the full form as shown above can be used instead.

===Examples===

// non-nested multi-channel signal reduced to mono (1)
play {
 Mix(SinOsc.ar(440 :: 660 :: Nil)) * 0.2 // --> SinOsc.ar(440) + SinOsc.ar(660)
}

// non-nested multi-channel signal reduced to mono (2)
play {
 Mix(Pan2.ar(SinOsc.ar)) * 0.2 // --> left + right
}

// mix inner channels
play {
 // --> [left(440) + left(660), right(440) + right(660)]
 Mix(Pan2.ar(SinOsc.ar(440 :: 660 :: Nil))) * 0.2
}

// enforce monophonic mix
play {
 // --> left(440) + left(660) + right(440) + right(660)
 Mix.mono(Pan2.ar(SinOsc.ar(440 :: 660 :: Nil))) * 0.2
}

// combine Mix(), Mix.fill(), Mix.fold()
// from original SC examples: reverberated sine percussion
play {
 val d = 6    // number of percolators
 val c = 5    // number of comb delays
 val a = 4    // number of allpass delays

 // sine percolation sound :
 val s = Mix.fill(d) { Resonz.ar(Dust.ar(2.0 / d) * 50, Rand(200, 3200), 0.003) }

 // reverb pre-delay time :
 val z = DelayN.ar(s, 0.048)

 // 'c' length modulated comb delays in parallel :
 val y = Mix(CombL.ar(z, 0.1, LFNoise1.kr(Seq.fill(c)(Rand(0, 0.1))).madd(0.04, 0.05), 15))

 // chain of 'a' allpass delays on each of two channels (2 times 'a' total) :
 val x = Mix.fold(y, a) { in =>
   AllpassN.ar(in, 0.050, Seq(Rand(0, 0.050), Rand(0, 0.050)), 1)
 }

 // add original sound to reverb and play it :
 s + 0.2 * x
}

// Mix.tabulate usage
// from original SC examples: harmonic swimming
play {
 val f = 50       // fundamental frequency
 val p = 20       // number of partials per channel
 val offset = Line.kr(0, -0.02, 60, doneAction = freeSelf) // causes sound to separate and fade
 Mix.tabulate(p) { i =>
   FSinOsc.ar(f * (i+1)) * // freq of partial
     LFNoise1.kr(Seq(Rand(2, 10), Rand(2, 10)))  // amplitude rate
     .madd(
       0.02,     // amplitude scale
       offset    // amplitude offset
     ).max(0)    // clip negative amplitudes to zero
 }
}