97 lines
2.7 KiB
Text
97 lines
2.7 KiB
Text
class:: SubsampleOffset
|
|
summary:: Offset from synth start within one sample.
|
|
related:: Classes/ControlRate, Classes/RadiansPerSample, Classes/SampleDur, Classes/SampleRate, Classes/OffsetOut
|
|
categories:: UGens>Info
|
|
|
|
|
|
Description::
|
|
|
|
When a synth is created from a time stamped osc-bundle, it starts
|
|
calculation at the next possible block (normally 64 samples). Using an
|
|
OffsetOut UGen, one can delay the audio so that it matches sample
|
|
accurately.
|
|
|
|
|
|
For some synthesis methods, one needs subsample accuracy. SubsampleOffset
|
|
provides the information where, within the current sample, the synth was
|
|
scheduled. It can be used to offset envelopes or resample the audio
|
|
output.
|
|
|
|
|
|
classmethods::
|
|
|
|
method::ir
|
|
|
|
Examples::
|
|
|
|
code::
|
|
|
|
// example: demonstrate cubic subsample interpolation
|
|
|
|
|
|
// impulse train that can be moved between samples
|
|
(
|
|
SynthDef(\Help_SubsampleOffset, { |out, addOffset|
|
|
var in, dt, sampDur, extraSamples, sampleOffset, resampledSignal;
|
|
in = Impulse.ar(2000, 0, 0.3); // some input.
|
|
sampDur = SampleDur.ir; // duration of one sample
|
|
extraSamples = 4; // DelayC needs at least 4 samples buffer
|
|
sampleOffset = 1 - SubsampleOffset.ir; // balance out subsample offset
|
|
sampleOffset = sampleOffset + MouseX.kr(0, addOffset); // add a mouse dependent offset
|
|
// cubic resampling:
|
|
resampledSignal = DelayC.ar(in,
|
|
maxdelaytime: sampDur * (1 + extraSamples),
|
|
delaytime: sampDur * (sampleOffset + extraSamples)
|
|
);
|
|
OffsetOut.ar(out, resampledSignal)
|
|
}).add;
|
|
)
|
|
|
|
// create 2 pulse trains 1 sample apart, move one relatively to the other.
|
|
// when cursor is at the left, the impulses are adjacent, on the right, they are
|
|
// exactly 1 sample apart.
|
|
|
|
(
|
|
var dt = s.sampleRate.reciprocal; // 1 sample delay
|
|
s.sendBundle(0.2, [9, \Help_SubsampleOffset, s.nextNodeID, 1, 1, \out, 40, \addOffset, 3]);
|
|
s.sendBundle(0.2 + dt, [9, \Help_SubsampleOffset, s.nextNodeID, 1, 1, \out, 40, \addOffset, 0]);
|
|
)
|
|
|
|
s.scope(1, 40, zoom: 0.2);
|
|
|
|
|
|
|
|
|
|
|
|
// example of a subsample accurate sine grain:
|
|
// (I don't hear a difference to normal sample accurate grains, but maybe
|
|
// someone could add an example that shows the effect)
|
|
|
|
(
|
|
SynthDef("Help_Subsample_Grain",
|
|
{ arg out=0, freq=440, sustain=0.005, attack=0.001;
|
|
var env, offset, sig, sd;
|
|
|
|
sd = SampleDur.ir;
|
|
offset = (1 - SubsampleOffset.ir) * sd;
|
|
// free synth after delay:
|
|
Line.ar(1,0, attack + sustain + offset, doneAction: Done.freeSelf);
|
|
env = EnvGen.kr(Env.perc(attack, sustain, 0.2));
|
|
sig = SinOsc.ar(freq, 0, env);
|
|
|
|
sig = DelayC.ar(sig, sd * 4, offset);
|
|
OffsetOut.ar(out, sig);
|
|
}, [\ir, \ir, \ir, \ir]).add;
|
|
)
|
|
|
|
(
|
|
Routine {
|
|
loop {
|
|
s.sendBundle(0.2, [9, \Help_Subsample_Grain, -1, 1, 1, \freq, 1000]);
|
|
rrand(0.001, 0.002).wait;
|
|
}
|
|
}.play;
|
|
)
|
|
|
|
::
|
|
|