third_party/WebKit/LayoutTests/webaudio/realtimeanalyser-fft-scaling.html - chromium/src.git - Git at Google

 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
 <html>
   <head>
     <script src="../resources/js-test.js"></script>
     <script src="resources/compatibility.js"></script>
     <script src="resources/audio-testing.js"></script>
   </head>

   <body>
     <div id="description"></div>
     <div id="console"></div>

     <script>
       description("Test scaling of FFT data for AnalyserNode");

       // The number of analysers. We have analysers from size for each of the possible sizes of 32,
       // 64, 128, 256, 512, 1024 and 2048 for a total of 7.
       var numberOfAnalysers = 7;
       var sampleRate = 44100;
       var nyquistFrequency = sampleRate / 2;

       // Frequency of the sine wave test signal.  Should be high enough so that we get at least one
       // full cycle for the 32-point FFT.  This should also be such that the frequency should be
       // exactly in one of the FFT bins for each of the possible FFT sizes.
       var oscFrequency = nyquistFrequency/16;

       // The actual peak values from each analyser.  Useful for examining the results in Chrome.
       var peakValue = new Array(numberOfAnalysers);

       // For a 0dBFS sine wave, we would expect the FFT magnitude to be 0dB as well, but the
       // analyzer node applies a Blackman window (to smooth the estimate).  This reduces the energy
       // of the signal so the FFT peak is less than 0dB.  The threshold value given here was
       // determined experimentally.
       //
       // See https://code.google.com/p/chromium/issues/detail?id=341596.
       var peakThreshold = [-14.43, -13.56, -13.56, -13.56, -13.56, -13.56, -13.56];

       var allTestsPassed = true;

       function checkResult(order, analyser) {
           return function () {
               var index = order - 5;
               var fftSize = 1 << order;
               var fftData = new Float32Array(fftSize);
               analyser.getFloatFrequencyData(fftData);

               // Compute the frequency bin that should contain the peak.
               var expectedBin = analyser.frequencyBinCount * (oscFrequency / nyquistFrequency);

               // Find the actual bin by finding the bin containing the peak.
               var actualBin = 0;
               peakValue[index] = -1000;
               for (k = 0; k < analyser.frequencyBinCount; ++k) {
                   if (fftData[k] > peakValue[index]) {
                       actualBin = k;
                       peakValue[index] = fftData[k];
                   }
               }

               var success = true;

               if (actualBin == expectedBin) {
                   testPassed("Actual FFT peak in the expected position (" + expectedBin + ").");
               } else {
                   success = false;
                   testFailed("Actual FFT peak (" + actualBin + ") differs from expected (" + expectedBin + ").");
               }

               if (peakValue[index] >= peakThreshold[index]) {
                   testPassed("Peak value is near " + peakThreshold[index] + " dBFS as expected.");
               } else {
                   success = false;
                   testFailed("Peak value of " + peakValue[index]
                              + " is incorrect.  (Expected approximately "
                              + peakThreshold[index] + ").");
               }

               if (success) {
                   testPassed("Analyser correctly scaled FFT data of size " + fftSize);
               } else {
                   testFailed("Analyser incorrectly scaled FFT data of size " + fftSize);
               }
               allTestsPassed = allTestsPassed && success;

               if (fftSize == 2048) {
                   if (allTestsPassed) {
                       testPassed("All Analyser tests passed.");
                   } else {
                       testFailed("At least one Analyser test failed.");
                   }

                   finishJSTest();
               }
           }
       }

       function runTests() {
           if (window.testRunner) {
               testRunner.dumpAsText();
               testRunner.waitUntilDone();
           }

           window.jsTestIsAsync = true;

           // Test each analyser size from order 5 (size 32) to 11 (size 2048).
           for (order = 5; order < 12; ++order) {
               // Create a new offline context for each analyser test with the number of samples
               // exactly equal to the fft size.  This ensures that the analyser node gets the
               // expected data from the oscillator.
               var context = new OfflineAudioContext(1, 1 << order, sampleRate);
               // Use a sine wave oscillator as the reference source signal.
               var osc = context.createOscillator();
               osc.type = "sine";
               osc.frequency.value = oscFrequency;
               osc.connect(context.destination);

               var analyser = context.createAnalyser();
               // No smoothing to simplify the analysis of the result.
               analyser.smoothingTimeConstant = 0;
               analyser.fftSize = 1 << order;
               osc.connect(analyser);

               osc.start();
               context.oncomplete = checkResult(order, analyser);
               context.startRendering();
           }
       }

       runTests();
       successfullyParsed = true;
     </script>
   </body>
 </html>
	<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
	<html>
	<head>
	<script src="../resources/js-test.js"></script>
	<script src="resources/compatibility.js"></script>
	<script src="resources/audio-testing.js"></script>
	</head>

	<body>
	<div id="description"></div>
	<div id="console"></div>

	<script>
	description("Test scaling of FFT data for AnalyserNode");

	// The number of analysers. We have analysers from size for each of the possible sizes of 32,
	// 64, 128, 256, 512, 1024 and 2048 for a total of 7.
	var numberOfAnalysers = 7;
	var sampleRate = 44100;
	var nyquistFrequency = sampleRate / 2;

	// Frequency of the sine wave test signal. Should be high enough so that we get at least one
	// full cycle for the 32-point FFT. This should also be such that the frequency should be
	// exactly in one of the FFT bins for each of the possible FFT sizes.
	var oscFrequency = nyquistFrequency/16;

	// The actual peak values from each analyser. Useful for examining the results in Chrome.
	var peakValue = new Array(numberOfAnalysers);

	// For a 0dBFS sine wave, we would expect the FFT magnitude to be 0dB as well, but the
	// analyzer node applies a Blackman window (to smooth the estimate). This reduces the energy
	// of the signal so the FFT peak is less than 0dB. The threshold value given here was
	// determined experimentally.
	//
	// See https://code.google.com/p/chromium/issues/detail?id=341596.
	var peakThreshold = [-14.43, -13.56, -13.56, -13.56, -13.56, -13.56, -13.56];

	var allTestsPassed = true;

	function checkResult(order, analyser) {
	return function () {
	var index = order - 5;
	var fftSize = 1 << order;
	var fftData = new Float32Array(fftSize);
	analyser.getFloatFrequencyData(fftData);

	// Compute the frequency bin that should contain the peak.
	var expectedBin = analyser.frequencyBinCount * (oscFrequency / nyquistFrequency);

	// Find the actual bin by finding the bin containing the peak.
	var actualBin = 0;
	peakValue[index] = -1000;
	for (k = 0; k < analyser.frequencyBinCount; ++k) {
	if (fftData[k] > peakValue[index]) {
	actualBin = k;
	peakValue[index] = fftData[k];
	}
	}

	var success = true;

	if (actualBin == expectedBin) {
	testPassed("Actual FFT peak in the expected position (" + expectedBin + ").");
	} else {
	success = false;
	testFailed("Actual FFT peak (" + actualBin + ") differs from expected (" + expectedBin + ").");
	}

	if (peakValue[index] >= peakThreshold[index]) {
	testPassed("Peak value is near " + peakThreshold[index] + " dBFS as expected.");
	} else {
	success = false;
	testFailed("Peak value of " + peakValue[index]
	+ " is incorrect. (Expected approximately "
	+ peakThreshold[index] + ").");
	}

	if (success) {
	testPassed("Analyser correctly scaled FFT data of size " + fftSize);
	} else {
	testFailed("Analyser incorrectly scaled FFT data of size " + fftSize);
	}
	allTestsPassed = allTestsPassed && success;

	if (fftSize == 2048) {
	if (allTestsPassed) {
	testPassed("All Analyser tests passed.");
	} else {
	testFailed("At least one Analyser test failed.");
	}

	finishJSTest();
	}
	}
	}

	function runTests() {
	if (window.testRunner) {
	testRunner.dumpAsText();
	testRunner.waitUntilDone();
	}

	window.jsTestIsAsync = true;

	// Test each analyser size from order 5 (size 32) to 11 (size 2048).
	for (order = 5; order < 12; ++order) {
	// Create a new offline context for each analyser test with the number of samples
	// exactly equal to the fft size. This ensures that the analyser node gets the
	// expected data from the oscillator.
	var context = new OfflineAudioContext(1, 1 << order, sampleRate);
	// Use a sine wave oscillator as the reference source signal.
	var osc = context.createOscillator();
	osc.type = "sine";
	osc.frequency.value = oscFrequency;
	osc.connect(context.destination);

	var analyser = context.createAnalyser();
	// No smoothing to simplify the analysis of the result.
	analyser.smoothingTimeConstant = 0;
	analyser.fftSize = 1 << order;
	osc.connect(analyser);

	osc.start();
	context.oncomplete = checkResult(order, analyser);
	context.startRendering();
	}
	}

	runTests();
	successfullyParsed = true;
	</script>
	</body>
	</html>