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<title>WaveShaperNode interface - Curve tests | WebAudio</title>
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var sampleRate=44100.0;
var tolerance=0.01;
/*
Testing that -1, 0 and +1 map correctly to curve (with 1:1 correlation)
=======================================================================
From the specification:
The input signal is nominally within the range -1 -> +1.
Each input sample within this range will index into the shaping curve with a signal level of zero corresponding
to the center value of the curve array.
*/
(function() {
var threeElementCurve=[2.0, -3.0, 4.0];
var inputData=[-1.0, 0, 1.0];
var expectedData=[2.0, -3.0, 4.0];
executeTest(threeElementCurve, inputData, expectedData, "Testing that -1, 0 and +1 map correctly to curve (with 1:1 correlation)");
})();
/*
Testing interpolation (where inputs don't correlate directly to curve elements)
===============================================================================
From the specification:
The implementation must perform linear interpolation between adjacent points in the curve.
*/
(function() {
var threeElementCurve=[2.0, -3.0, 4.0];
var inputData=[-0.5, +0.5, +0.75];
var expectedData=[-0.5, +0.5, +2.25];
executeTest(threeElementCurve, inputData, expectedData, "Testing interpolation (where inputs don't correlate directly to curve elements)");
})();
/*
Testing out-of-range inputs (should be mapped to the first/last elements of the curve)
======================================================================================
From the specification:
Any sample value less than -1 will correspond to the first value in the curve array.
Any sample value greater than +1 will correspond to the last value in the curve array.
*/
(function() {
var threeElementCurve=[2.0, -3.0, 4.0];
var inputData=[-1.5, +1.5];
var expectedData=[2.0, 4.0];
executeTest(threeElementCurve, inputData, expectedData, "Testing out-of-range inputs (should be mapped to the first/last elements of the curve)");
})();
/*
Testing a 2-element curve (does not have a middle element)
==========================================================
From the specification:
Each input sample within this range will index into the shaping curve with a signal level of zero corresponding
to the center value of the curve array.
The implementation must perform linear interpolation between adjacent points in the curve.
*/
(function() {
var twoElementCurve=[2.0, -2.0];
var inputData=[-1.0, 0, 1.0];
var expectedData=[2.0, 0.0, -2.0];
executeTest(twoElementCurve, inputData, expectedData, "Testing a 2-element curve (does not have a middle element)");
})();
/*
Testing a 4-element curve (does not have a middle element)
==========================================================
From the specification:
Each input sample within this range will index into the shaping curve with a signal level of zero corresponding
to the center value of the curve array.
The implementation must perform linear interpolation between adjacent points in the curve.
*/
(function() {
var fourElementCurve=[1.0, 2.0, 4.0, 7.0];
var inputData=[-1.0, 0, 1.0];
var expectedData=[1.0, 3.0, 7.0];
executeTest(fourElementCurve, inputData, expectedData, "Testing a 4-element curve (does not have a middle element)");
})();
/*
Testing a huge curve
====================
From the specification:
Each input sample within this range will index into the shaping curve with a signal level of zero corresponding
to the center value of the curve array.
*/
(function() {
var bigCurve=[];
for(var i=0;i<=60000;i++) { bigCurve.push(i/3.5435); }
var inputData=[-1.0, 0, 1.0];
var expectedData=[bigCurve[0], bigCurve[30000], bigCurve[60000]];
executeTest(bigCurve, inputData, expectedData, "Testing a huge curve");
})();
/*
Testing single-element curve (boundary condition)
=================================================
From the specification:
Each input sample within this range will index into the shaping curve with a signal level of zero corresponding
to the center value of the curve array.
Any sample value less than -1 will correspond to the first value in the curve array.
Any sample value greater than +1 will correspond to the last value in the curve array.
The implementation must perform linear interpolation between adjacent points in the curve.
*/
/*
Testing null curve (should return input values)
===============================================
From the specification:
Initially the curve attribute is null, which means that the WaveShaperNode will pass its input to its output
without modification.
*/
(function() {
var inputData=[-1.0, 0, 1.0, 2.0];
var expectedData=[-1.0, 0.0, 1.0, 2.0];
executeTest(null, inputData, expectedData, "Testing null curve (should return input values)");
})();
/**
* Function that does the actual testing (using an asynchronous test).
* @param {?Array.<number>} curveData - Array containing values for the WaveShaper curve.
* @param {!Array.<number>} inputData - Array containing values for the input stream.
* @param {!Array.<number>} expectedData - Array containing expected results for each of the corresponding inputs.
* @param {!string} testName - Name of the test case.
*/
function executeTest(curveData, inputData, expectedData, testName) {
var stTest=async_test("WaveShaperNode - "+testName);
stTest.step(function() {
// Create offline audio context.
var ac=new OfflineAudioContext(1, inputData.length, sampleRate);
// Create the WaveShaper and its curve.
var waveShaper=ac.createWaveShaper();
if(curveData!=null) {
var curve=new Float32Array(curveData.length);
for(var i=0;i<curveData.length;i++) { curve[i]=curveData[i]; }
waveShaper.curve=curve;
}
waveShaper.connect(ac.destination);
// Create buffer containing the input values.
var inputBuffer=ac.createBuffer(1, Math.max(inputData.length, 2), sampleRate);
var d=inputBuffer.getChannelData(0);
for(var i=0;i<inputData.length;i++) { d[i]=inputData[i]; }
// Play the input buffer through the WaveShaper.
var src=ac.createBufferSource();
src.buffer=inputBuffer;
src.connect(waveShaper);
src.start();
// Test the outputs match the expected values.
ac.oncomplete=stTest.step_func_done(function(ev) {
var d=ev.renderedBuffer.getChannelData(0);
for(var i=0;i<expectedData.length;i++) {
var curveText="null";
if(curve!=null) {
if(curveData.length<20) {
curveText=curveData.join(",");
} else {
curveText="TooBigToDisplay ("+(curveData.length-1)+" elements)";
}
}
var comment="Input="+inputData[i]+", Curve=["+curveText+"] >>> ";
assert_approx_equals(d[i], expectedData[i], tolerance, comment);
}
});
ac.startRendering();
});
}
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