PIdev | SuperCollider 3.13.0 Help

Description

DIdev / PIdef / PLIdev search for numbers with integer distance from a source signal / pattern up to a given deviation. Repetitions within a lookback span are avoided, DIdev / PIdef / PLIdev randomly choose from possible solutions. Intended for search within integer grids (pitches, indices etc.), however applications with non-integer sources are possible, see examples.

NOTE: It's the user's responsibility to pass a combination of deviation and lookback values that allows a possible choice, see examples.

NOTE: In contrast to DIdev, PIdev and PLIdev do *not* need to know maximum deviations (minLoDev, maxHiDev) beforehand. Thus the order of arguments is different (here loDev and hiDev before lookBack).

Class Methods

.new

Creates a new PIdev object.

Arguments:

pattern	The source value pattern to start search from.
maxLookBack	Integer, the maximum lookback span. Fixed, defaults to 3.
loDev	Determines the current low deviation for the search. Defaults to -3.
hiDev	Determines the current high deviation for the search. Defaults to 3.
lookBack	Determines the current lookback span for avoiding repetitions. Can be modulated but must not exceed maxLookBack. If no value is passed, then maxLookBack is taken.
thr	Threshold for equality comparison. Can be modulated, defaults to 1e-3.
length	Number of repeats. Defaults to inf.

Examples

Ex. 1: Basic usage: random choice within region without repetitions

Ex. 2: Variable deviations and lookBack

Ex. 3: Moving source signal

Ex. 4: Dynamic deviation range and lookBack

Ex. 5: Non-integer source

Ex. 6: Multichannel expansion

Ex. 7: Application to other params: rhythm

// if we have indexed data of whatever, we can slide over it,
// groups of durations as items to be streamed by PIdev

(
~rhythmBase = [
    [1, 1],
    [2, 1, 1],
    [1, 1, 2]
].collect(_.normalizeSum);

~rhythms = ~rhythmBase *.x [1, 2];
~rhythmNum = ~rhythms.size;
~rhythms = ~rhythms.scramble;

SynthDef(\noise_grain, { |out = 0, freq = 400, att = 0.005, rel = 0.1, 
    rq = 0.05, pan = 0, amp = 0.1|
    var sig = { WhiteNoise.ar } ! 2;
    sig = BPF.ar(sig, freq, rq) *
        EnvGen.ar(Env.perc(att, rel, amp), doneAction: 2) *
        (rq ** -1) * (250 / (freq ** 0.8));
    OffsetOut.ar(out, Pan2.ar(sig, pan));
}).add;
)

(
// rhythmic variation and partial pitch repetition
// play for a while to note slow sliding caused by Pseg

~loDev = -1;
~hiDev = 1;

p = Pbind(
    \instrument, \noise_grain,
    \rel, Pexprand(0.05, 0.15),
    \dur, PIdev(
        // be careful not to exceed index bounds
        Pseg(Pseq([~loDev.abs, ~rhythmNum - ~hiDev - 1], inf), 10, \sin, inf).round, 
        2, // lookBack span, no repetition within 3 items
        ~loDev, 
        ~hiDev
    ).trace(prefix: "rhythm type: ").collect(~rhythms[_]).flatten * 0.3,
    \midinote, Pstutter(Pwhite(1, 2), Pclump(3, Pxrand((50..100), inf))).flatten + [0, 12],
    \pan, Pstutter(Pwhite(1, 2), Pclump(3, Pwhite(-1.0, 1))).flatten
).play;
)

p.stop

Ex. 8: Proof of concept

helpfile source: HelpSource/Classes/PIdev.schelp
link::miSCellaneous_lib/Classes/PIdev::

PIdevExtension

.new

Arguments:

PIdev
Extension