1 files changed, 153 insertions, 0 deletions
diff --git a/dom/media/webaudio/test/blink/biquad-testing.js b/dom/media/webaudio/test/blink/biquad-testing.js
new file mode 100644
index 000000000..795adf601
--- /dev/null
+++ b/dom/media/webaudio/test/blink/biquad-testing.js
@@ -0,0 +1,153 @@
+// Globals, to make testing and debugging easier.
+var context;
+var filter;
+var signal;
+var renderedBuffer;
+var renderedData;
+
+var sampleRate = 44100.0;
+var pulseLengthFrames = .1 * sampleRate;
+
+// Maximum allowed error for the test to succeed.  Experimentally determined.
+var maxAllowedError = 5.9e-8;
+
+// This must be large enough so that the filtered result is
+// essentially zero.  See comments for createTestAndRun.
+var timeStep = .1;
+
+// Maximum number of filters we can process (mostly for setting the
+// render length correctly.)
+var maxFilters = 5;
+
+// How long to render.  Must be long enough for all of the filters we
+// want to test.
+var renderLengthSeconds = timeStep * (maxFilters + 1) ;
+
+var renderLengthSamples = Math.round(renderLengthSeconds * sampleRate);
+
+// Number of filters that will be processed.
+var nFilters;
+
+function createImpulseBuffer(context, length) {
+    var impulse = context.createBuffer(1, length, context.sampleRate);
+    var data = impulse.getChannelData(0);
+    for (var k = 1; k < data.length; ++k) {
+        data[k] = 0;
+    }
+    data[0] = 1;
+
+    return impulse;
+}
+
+
+function createTestAndRun(context, filterType, filterParameters) {
+    // To test the filters, we apply a signal (an impulse) to each of
+    // the specified filters, with each signal starting at a different
+    // time.  The output of the filters is summed together at the
+    // output.  Thus for filter k, the signal input to the filter
+    // starts at time k * timeStep.  For this to work well, timeStep
+    // must be large enough for the output of each filter to have
+    // decayed to zero with timeStep seconds.  That way the filter
+    // outputs don't interfere with each other.
+
+    nFilters = Math.min(filterParameters.length, maxFilters);
+
+    signal = new Array(nFilters);
+    filter = new Array(nFilters);
+
+    impulse = createImpulseBuffer(context, pulseLengthFrames);
+
+    // Create all of the signal sources and filters that we need.
+    for (var k = 0; k < nFilters; ++k) {
+        signal[k] = context.createBufferSource();
+        signal[k].buffer = impulse;
+
+        filter[k] = context.createBiquadFilter();
+        filter[k].type = filterType;
+        filter[k].frequency.value = context.sampleRate / 2 * filterParameters[k].cutoff;
+        filter[k].detune.value = (filterParameters[k].detune === undefined) ? 0 : filterParameters[k].detune;
+        filter[k].Q.value = filterParameters[k].q;
+        filter[k].gain.value = filterParameters[k].gain;
+
+        signal[k].connect(filter[k]);
+        filter[k].connect(context.destination);
+
+        signal[k].start(timeStep * k);
+    }
+
+    context.oncomplete = checkFilterResponse(filterType, filterParameters);
+    context.startRendering();
+}
+
+function addSignal(dest, src, destOffset) {
+    // Add src to dest at the given dest offset.
+    for (var k = destOffset, j = 0; k < dest.length, j < src.length; ++k, ++j) {
+        dest[k] += src[j];
+    }
+}
+
+function generateReference(filterType, filterParameters) {
+    var result = new Array(renderLengthSamples);
+    var data = new Array(renderLengthSamples);
+    // Initialize the result array and data.
+    for (var k = 0; k < result.length; ++k) {
+        result[k] = 0;
+        data[k] = 0;
+    }
+    // Make data an impulse.
+    data[0] = 1;
+
+    for (var k = 0; k < nFilters; ++k) {
+        // Filter an impulse
+        var detune = (filterParameters[k].detune === undefined) ? 0 : filterParameters[k].detune;
+        var frequency = filterParameters[k].cutoff * Math.pow(2, detune / 1200); // Apply detune, converting from Cents.
+
+        var filterCoef = createFilter(filterType,
+                                      frequency,
+                                      filterParameters[k].q,
+                                      filterParameters[k].gain);
+        var y = filterData(filterCoef, data, renderLengthSamples);
+
+        // Accumulate this filtered data into the final output at the desired offset.
+        addSignal(result, y, timeToSampleFrame(timeStep * k, sampleRate));
+    }
+
+    return result;
+}
+
+function checkFilterResponse(filterType, filterParameters) {
+    return function(event) {
+        renderedBuffer = event.renderedBuffer;
+        renderedData = renderedBuffer.getChannelData(0);
+
+        reference = generateReference(filterType, filterParameters);
+
+        var len = Math.min(renderedData.length, reference.length);
+
+        var success = true;
+
+        // Maximum error between rendered data and expected data
+        var maxError = 0;
+
+        // Sample offset where the maximum error occurred.
+        var maxPosition = 0;
+
+        // Number of infinities or NaNs that occurred in the rendered data.
+        var invalidNumberCount = 0;
+
+        ok(nFilters == filterParameters.length, "Test wanted " + filterParameters.length + " filters but only " + maxFilters + " allowed.");
+
+        compareChannels(renderedData, reference, len, 0, 0, true);
+
+        // Check for bad numbers in the rendered output too.
+        // There shouldn't be any.
+        for (var k = 0; k < len; ++k) {
+            if (!isValidNumber(renderedData[k])) {
+                ++invalidNumberCount;
+            }
+        }
+
+        ok(invalidNumberCount == 0, "Rendered output has " + invalidNumberCount + " infinities or NaNs.");
+        SimpleTest.finish();
+    }
+}