PLIdev | 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 PLIdev object.

Arguments:

pattern	Symbol or PIdev pattern arg. The source value pattern to start search from. If a Symbol is passed, a pattern/value can be assigned to an envir variable later on. Can be dynamically replaced by Patterns or Streams.
maxLookBack	Integer, the maximum lookback span. Fixed, defaults to 3.
loDev	Symbol or PIdev loDev arg. Determines the current low deviation for the search. If a Symbol is passed, a pattern/value can be assigned to an envir variable later on. Can be dynamically replaced by Patterns or Streams. Defaults to -3.
hiDev	Symbol or PIdev hiDev arg. Determines the current high deviation for the search. If a Symbol is passed, a pattern/value can be assigned to an envir variable later on. Can be dynamically replaced by Patterns or Streams. Defaults to 3.
lookBack	Symbol or PIdev lookBack arg. 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. If a Symbol is passed, a pattern/value can be assigned to an envir variable later on. Can be dynamically replaced by Patterns or Streams. Defaults to nil.
thr	Symbol or PIdev thr arg. Threshold for equality comparison. If a Symbol is passed, a pattern/value can be assigned to an envir variable later on. Can be dynamically replaced by Patterns or Streams. Defaults to 1e-3.
length	Symbol or PIdev length arg. Number of repeats. If a Symbol is passed, a value can be assigned to an envir variable later on. Defaults to inf.
envir	Dictionary or one of the Symbols \top, \t (topEnvironment), \current, \c (currentEnvironment). Dictionary to be taken for variable reference. Defaults to \current.

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 PLIdev

(
~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;
~maxLookBack = 5; // fixed !
~lookBack = 2;

// be careful not to exceed index bounds
~src = Pseg(Pseq([~loDev.abs, ~rhythmNum - ~hiDev - 1], inf), 10, \sin, inf).round;

p = Pbind(
    \instrument, \noise_grain,
    \rel, Pexprand(0.05, 0.15),
    \dur, PLIdev(\src, ~maxLookBack, \loDev, \hiDev, \lookBack).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;
)

// more variation by larger deviation from fixed source and larger lookBack

(
~src = 3;
~loDev = -3;
~hiDev = 2;
~lookBack = 4;
)

// fixed cycle with these bounds and lookBack == 1

(
~loDev = -1;
~hiDev = 0;
~lookBack = 1;
)

// other fixed cycle

~src = 2;

p.stop

Ex. 8: Proof of concept

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

PLIdevExtension

.new

Arguments:

PLIdev
Extension