curve-tests.html - mozsearch

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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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