«experiments in detecting fast onsets with Amplitude UGens» by julian.rohrhuber

on 19 Dec'15 20:57 in amplitudeanalysisexperimenttrigger

A series of consecutive experiments (all results visualised as plots) that try to detect onsets in a noisy signal.

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// single Amplitude UGen
// attackTime:0.01, releaseTime:0.01
// too soft to follow
(
{
	var sig, amp, gate, trig;
	sig = LFSaw.ar(-200) * SinOsc.kr(20).range(0, 1);
	amp = Amplitude.ar(sig, attackTime:0.01, releaseTime:0.01);
	gate = amp > 0.2;
	trig = Trig1.ar(HPZ1.ar(gate), 0.001); //  create a trigger signal
	[sig, amp, trig]
}.plot(0.1, bounds:Rect(0, 0, 800, 800), maxval:1.1)
)

// attackTime:0, releaseTime:0.0002
// follows well
(
{
	var sig, amp, gate, trig;
	sig = LFSaw.ar(-200) * SinOsc.kr(20).range(0, 1);
	amp = Amplitude.ar(sig, attackTime:0, releaseTime:0.0002);
	gate = amp > 0.1;
	trig = Trig1.ar(HPZ1.ar(gate), 0.001);
	[sig, amp, trig]
}.plot(0.1, bounds:Rect(0, 0, 800, 800), maxval:1.1)
)

// attackTime:0, releaseTime:0.0002
// follows well, but: for a bit of noise causes false positives ...
(
{
	var sig, amp, gate, trig;
	sig = LFSaw.ar(-200) * SinOsc.kr(20).range(0, 1) + LFNoise2.ar(4000, 0.2);
	amp = Amplitude.ar(sig, attackTime:0, releaseTime:0.0002);
	gate = amp > 0.2;
	trig = Trig1.ar(HPZ1.ar(gate), 0.001);
	[sig, amp, trig]
}.plot(0.1, bounds:Rect(0, 0, 800, 800), maxval:1.1)
)


// ... comparison of multiple time scales may help
// attackTime:0.001, releaseTime:0.0002
// attackTime:0.01, releaseTime:0.01
(
{
	var sig, amp1, amp2, gate, trig;
	sig = LFSaw.ar(-200) * SinOsc.kr(20).range(0, 1) + LFNoise2.ar(4000, 0.2);
	amp1 = Amplitude.ar(sig, attackTime:0.0002, releaseTime:0.0002);
	amp2 = Amplitude.ar(sig, attackTime:0.01, releaseTime:0.01);
	gate = (amp2 - amp1) > 0.2;
	trig = Trig1.ar(HPZ1.ar(gate), 0.001);
	[sig, amp1, amp2, trig]
}.plot(0.1, bounds:Rect(0, 0, 800, 800), maxval:1.1)
)

// with slowly increasing noise
// attackTime:0.001, releaseTime:0.0002
// attackTime:0.01, releaseTime:0.01
(
{
	var sig, amp1, amp2, gate, trig;
	sig = LFSaw.ar(-200) * SinOsc.kr(20).range(0, 1) + LFNoise2.ar(4000, Line.kr(0.1, 0.6, 0.1));
	amp1 = Amplitude.ar(sig, attackTime:0.0002, releaseTime:0.0002);
	amp2 = Amplitude.ar(sig, attackTime:0.01, releaseTime:0.01);
	gate = (amp2 - amp1) > 0.2;
	trig = Trig1.ar(HPZ1.ar(gate), 0.001);
	[sig, amp1, amp2, trig]
}.plot(0.1, bounds:Rect(0, 0, 800, 800), maxval:1.1)
)

// for a lagged and little bit noisy signal
// attackTime:0.001, releaseTime:0.0002
// attackTime:0.01, releaseTime:0.01
// loses the first peaks
(
{
	var sig, amp1, amp2, gate, trig;
	sig = LFSaw.ar(-200).range(0, 1).lag(0.01) * SinOsc.kr(20).range(0, 1) + LFNoise2.ar(4000, 0.02);
	amp1 = Amplitude.ar(sig, attackTime:0.0002, releaseTime:0.0002);
	amp2 = Amplitude.ar(sig, attackTime:0.01, releaseTime:0.01);
	gate = (amp2 - amp1) > 0.1;
	trig = Trig1.ar(HPZ1.ar(gate), 0.001);
	[sig, amp1, amp2, trig]
}.plot(0.1, bounds:Rect(0, 0, 800, 800), maxval:1.1)
)

// with slowly increasing noise
// attackTime:0.001, releaseTime:0.0002
// attackTime:0.01, releaseTime:0.01
(
{
	var sig, amp1, amp2, gate, trig;
	sig = LFSaw.ar(-200).range(0, 1).lag(0.01) * SinOsc.kr(20).range(0, 1) + LFNoise2.ar(4000, Line.kr(0.01, 0.2, 0.1));
	amp1 = Amplitude.ar(sig, attackTime:0.0002, releaseTime:0.0002);
	amp2 = Amplitude.ar(sig, attackTime:0.01, releaseTime:0.01);
	gate = (amp2 - amp1) > 0.1;
	trig = Trig1.ar(HPZ1.ar(gate), 0.001);
	[sig, amp1, amp2, amp2 - amp1, trig]
}.plot(0.1, bounds:Rect(0, 0, 800, 800), maxval:1.1)
)


// with slowly increasing noise
// attackTime:0.001, releaseTime:0.0002
// attackTime:0.01, releaseTime:0.01
(
{
	var sig, amp1, amp2, floor, floorThresh, gate, trig;
	sig = LFSaw.ar(-200).range(0, 1).lag(0.01) * SinOsc.kr(20).range(0, 1) + LFNoise2.ar(4000, Line.kr(0.01, 0.2, 0.1));
	amp1 = Amplitude.ar(sig, attackTime:0.0002, releaseTime:0.0002);
	amp2 = Amplitude.ar(sig, attackTime:0.001, releaseTime:0.01);
	floor = Amplitude.ar(sig, attackTime:0.01, releaseTime:0.03);
	floorThresh = amp2 > 0.3;
	gate = (amp1 - amp2) > 0.01 * floorThresh;
	trig = Trig1.ar(HPZ1.ar(gate), 0.001);
	[sig, trig]
}.plot(0.1, bounds:Rect(0, 0, 800, 800), maxval:1.1)
)



// different randomly chosen time scales
(
{
	var sig, amp1, amp2, floor, floorThresh, gate, trig;
	var f0 = rrand(40, 540);
	var tmul = 200/f0;
	var noiseLevel = Line.kr(0.01, 0.2, 0.1);

	"********* frequency: % **********".format(f0).postln;

	sig = LFSaw.ar(f0.neg).range(0, 1).lag(0.5/f0) * SinOsc.kr(20).range(0, 1);
	sig = sig + LFNoise2.ar(f0 * 20, noiseLevel);
	amp1 = Amplitude.ar(sig, attackTime:0.0002 * tmul, releaseTime:0.0002 * tmul);
	amp2 = Amplitude.ar(sig, attackTime:0.001 * tmul, releaseTime:0.01 * tmul);
	floor = Amplitude.ar(sig, attackTime:0.01 * tmul, releaseTime:0.03 * tmul);
	floorThresh = amp2 > 0.3;
	gate = (amp1 - amp2) > 0.01 * floorThresh;
	trig = Trig1.ar(HPZ1.ar(gate), 0.001);
	[sig, amp1, amp2, trig]
}.plot(0.1, bounds:Rect(0, 0, 800, 800), maxval:1.1)
)

// sweep
(
{
	var sig, amp1, amp2, floor, floorThresh, gate, trig;
	var f0 = XLine.kr(40, 1540);
	var noiseLevel = 0.1;
	var tmul = 200/f0;
	sig = LFSaw.ar(f0.neg).range(0, 1).lag(0.5/f0) * SinOsc.kr(20).range(0, 1);
	sig = sig + LFNoise2.ar(f0 * 15, noiseLevel);
	amp1 = Amplitude.ar(sig, attackTime:0.0002 * tmul, releaseTime:0.0002 * tmul);
	amp2 = Amplitude.ar(sig, attackTime:0.001 * tmul, releaseTime:0.01 * tmul);
	floor = Amplitude.ar(sig, attackTime:0.01 * tmul, releaseTime:0.03 * tmul);
	floorThresh = amp2 > 0.3;
	gate = (amp1 - amp2) > 0.01 * floorThresh;
	trig = Trig1.ar(HPZ1.ar(gate), 0.001);
	[sig, amp1, amp2, trig]
}.plot(0.5, bounds:Rect(0, 0, 1200, 800), maxval:1.1)
)


// postscript:
// for a lagged and little bit noisy signal
// trying out the Onsets UGen: not good at all for what we are trying, however other settings may help.

(
{
	var sig, fft, gate, trig;
	sig = LFSaw.ar(-200).range(0, 1).lag(0.01) * SinOsc.kr(20).range(0, 1) + LFNoise2.ar(4000, 0.02);
	gate = Onsets.kr(FFT(LocalBuf(1024), sig),threshold:0.2,relaxtime:0.01,floor:0.01, mingap:0.001);
	trig = Trig1.kr(HPZ1.kr(gate), 0.001);
	[sig, trig]
}.plot(0.1, bounds:Rect(0, 0, 800, 800), maxval:1.1)
)
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reception
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