michael@0: var sampleRate = 44100.0;
michael@0: 
michael@0: var renderLengthSeconds = 8;
michael@0: var pulseLengthSeconds = 1;
michael@0: var pulseLengthFrames = pulseLengthSeconds * sampleRate;
michael@0: 
michael@0: function createSquarePulseBuffer(context, sampleFrameLength) {
michael@0:     var audioBuffer = context.createBuffer(1, sampleFrameLength, context.sampleRate);
michael@0: 
michael@0:     var n = audioBuffer.length;
michael@0:     var data = audioBuffer.getChannelData(0);
michael@0: 
michael@0:     for (var i = 0; i < n; ++i)
michael@0:         data[i] = 1;
michael@0: 
michael@0:     return audioBuffer;
michael@0: }
michael@0: 
michael@0: // The triangle buffer holds the expected result of the convolution.
michael@0: // It linearly ramps up from 0 to its maximum value (at the center)
michael@0: // then linearly ramps down to 0.  The center value corresponds to the
michael@0: // point where the two square pulses overlap the most.
michael@0: function createTrianglePulseBuffer(context, sampleFrameLength) {
michael@0:     var audioBuffer = context.createBuffer(1, sampleFrameLength, context.sampleRate);
michael@0: 
michael@0:     var n = audioBuffer.length;
michael@0:     var halfLength = n / 2;
michael@0:     var data = audioBuffer.getChannelData(0);
michael@0:     
michael@0:     for (var i = 0; i < halfLength; ++i)
michael@0:         data[i] = i + 1;
michael@0: 
michael@0:     for (var i = halfLength; i < n; ++i)
michael@0:         data[i] = n - i - 1;
michael@0: 
michael@0:     return audioBuffer;
michael@0: }
michael@0: 
michael@0: function log10(x) {
michael@0:   return Math.log(x)/Math.LN10;
michael@0: }
michael@0: 
michael@0: function linearToDecibel(x) {
michael@0:   return 20*log10(x);
michael@0: }
michael@0: 
michael@0: // Verify that the rendered result is very close to the reference
michael@0: // triangular pulse.
michael@0: function checkTriangularPulse(rendered, reference) {
michael@0:     var match = true;
michael@0:     var maxDelta = 0;
michael@0:     var valueAtMaxDelta = 0;
michael@0:     var maxDeltaIndex = 0;
michael@0: 
michael@0:     for (var i = 0; i < reference.length; ++i) {
michael@0:         var diff = rendered[i] - reference[i];
michael@0:         var x = Math.abs(diff);
michael@0:         if (x > maxDelta) {
michael@0:             maxDelta = x;
michael@0:             valueAtMaxDelta = reference[i];
michael@0:             maxDeltaIndex = i;
michael@0:         }
michael@0:     }
michael@0: 
michael@0:     // allowedDeviationFraction was determined experimentally.  It
michael@0:     // is the threshold of the relative error at the maximum
michael@0:     // difference between the true triangular pulse and the
michael@0:     // rendered pulse.
michael@0:     var allowedDeviationDecibels = -129.4;
michael@0:     var maxDeviationDecibels = linearToDecibel(maxDelta / valueAtMaxDelta);
michael@0: 
michael@0:     if (maxDeviationDecibels <= allowedDeviationDecibels) {
michael@0:         testPassed("Triangular portion of convolution is correct.");
michael@0:     } else {
michael@0:         testFailed("Triangular portion of convolution is not correct.  Max deviation = " + maxDeviationDecibels + " dB at " + maxDeltaIndex);
michael@0:         match = false;
michael@0:     }
michael@0: 
michael@0:     return match;
michael@0: }        
michael@0: 
michael@0: // Verify that the rendered data is close to zero for the first part
michael@0: // of the tail.
michael@0: function checkTail1(data, reference, breakpoint) {
michael@0:     var isZero = true;
michael@0:     var tail1Max = 0;
michael@0: 
michael@0:     for (var i = reference.length; i < reference.length + breakpoint; ++i) {
michael@0:         var mag = Math.abs(data[i]);
michael@0:         if (mag > tail1Max) {
michael@0:             tail1Max = mag;
michael@0:         }
michael@0:     }
michael@0: 
michael@0:     // Let's find the peak of the reference (even though we know a
michael@0:     // priori what it is).
michael@0:     var refMax = 0;
michael@0:     for (var i = 0; i < reference.length; ++i) {
michael@0:       refMax = Math.max(refMax, Math.abs(reference[i]));
michael@0:     }
michael@0: 
michael@0:     // This threshold is experimentally determined by examining the
michael@0:     // value of tail1MaxDecibels.
michael@0:     var threshold1 = -129.7;
michael@0: 
michael@0:     var tail1MaxDecibels = linearToDecibel(tail1Max/refMax);
michael@0:     if (tail1MaxDecibels <= threshold1) {
michael@0:         testPassed("First part of tail of convolution is sufficiently small.");
michael@0:     } else {
michael@0:         testFailed("First part of tail of convolution is not sufficiently small: " + tail1MaxDecibels + " dB");
michael@0:         isZero = false;
michael@0:     }
michael@0: 
michael@0:     return isZero;
michael@0: }
michael@0: 
michael@0: // Verify that the second part of the tail of the convolution is
michael@0: // exactly zero.
michael@0: function checkTail2(data, reference, breakpoint) {
michael@0:     var isZero = true;
michael@0:     var tail2Max = 0;
michael@0:     // For the second part of the tail, the maximum value should be
michael@0:     // exactly zero.
michael@0:     var threshold2 = 0;
michael@0:     for (var i = reference.length + breakpoint; i < data.length; ++i) {
michael@0:         if (Math.abs(data[i]) > 0) {
michael@0:             isZero = false; 
michael@0:             break;
michael@0:         }
michael@0:     }
michael@0: 
michael@0:     if (isZero) {
michael@0:         testPassed("Rendered signal after tail of convolution is silent.");
michael@0:     } else {
michael@0:         testFailed("Rendered signal after tail of convolution should be silent.");
michael@0:     }
michael@0: 
michael@0:     return isZero;
michael@0: }
michael@0: 
michael@0: function checkConvolvedResult(trianglePulse) {
michael@0:     return function(event) {
michael@0:         var renderedBuffer = event.renderedBuffer;
michael@0: 
michael@0:         var referenceData = trianglePulse.getChannelData(0);
michael@0:         var renderedData = renderedBuffer.getChannelData(0);
michael@0:     
michael@0:         var success = true;
michael@0:     
michael@0:         // Verify the triangular pulse is actually triangular.
michael@0: 
michael@0:         success = success && checkTriangularPulse(renderedData, referenceData);
michael@0:         
michael@0:         // Make sure that portion after convolved portion is totally
michael@0:         // silent.  But round-off prevents this from being completely
michael@0:         // true.  At the end of the triangle, it should be close to
michael@0:         // zero.  If we go farther out, it should be even closer and
michael@0:         // eventually zero.
michael@0: 
michael@0:         // For the tail of the convolution (where the result would be
michael@0:         // theoretically zero), we partition the tail into two
michael@0:         // parts.  The first is the at the beginning of the tail,
michael@0:         // where we tolerate a small but non-zero value.  The second part is
michael@0:         // farther along the tail where the result should be zero.
michael@0:         
michael@0:         // breakpoint is the point dividing the first two tail parts
michael@0:         // we're looking at.  Experimentally determined.
michael@0:         var breakpoint = 12800;
michael@0: 
michael@0:         success = success && checkTail1(renderedData, referenceData, breakpoint);
michael@0:         
michael@0:         success = success && checkTail2(renderedData, referenceData, breakpoint);
michael@0:         
michael@0:         if (success) {
michael@0:             testPassed("Test signal was correctly convolved.");
michael@0:         } else {
michael@0:             testFailed("Test signal was not correctly convolved.");
michael@0:         }
michael@0: 
michael@0:         finishJSTest();
michael@0:     }
michael@0: }