src/third_party/web_platform_tests/webaudio/the-audio-api/the-gainnode-interface/test-gainnode.html - cobalt - Git at Google

 <!doctype html>

 <!--
 Tests that GainNode is properly scaling the gain.
 We'll render 11 notes, starting at a gain of 1.0, decreasing in gain by 0.1.
 The 11th note will be of gain 0.0, so it should be silent (at the end in the rendered output).

 Based on a test from the WebKit test suite
 (https://github.com/WebKit/webkit/blob/master/LayoutTests/webaudio/gain.html)
 -->

 <html class="a">
  <head>
   <title>GainNode interface</title>
   <script src="/resources/testharness.js"></script>
   <script src="/resources/testharnessreport.js"></script>
   <script src="/webaudio/js/lodash.js"></script>
   <script src="/webaudio/js/vendor-prefixes.js"></script>
   <script src="/webaudio/js/helpers.js"></script>
   <script src="/webaudio/js/buffer-loader.js"></script>
  </head>
  <body class="a">
   <div id="log"></div>
   <script>
 var gainNodeTest = async_test("GainNode");

 var sampleRate = 44100.0;
 var bufferDurationSeconds = 0.125;
 var numberOfNotes = 11;
 var noteSpacing = bufferDurationSeconds + 0.020; // leave 20ms of silence between each "note"
 var lengthInSeconds = numberOfNotes * noteSpacing;

 var context = 0;
 var expectedBuffer = 0;
 var actualBuffer = 0;
 var sinWaveBuffer = 0;

 function createSinWaveBuffer(lengthInSeconds, frequency) {
   var audioBuffer = context.createBuffer(2, lengthInSeconds * sampleRate, sampleRate);

   var n = audioBuffer.length;
   var channelL = audioBuffer.getChannelData(0);
   var channelR = audioBuffer.getChannelData(1);

   for (var i = 0; i < n; ++i) {
     channelL[i] = Math.sin(frequency * 2.0*Math.PI * i / sampleRate);
     channelR[i] = channelL[i];
   }

   return audioBuffer;
 }

 function playNote(time, gain) {
   var source = context.createBufferSource();
   source.buffer = sinWaveBuffer;

   var gainNode = context.createGain();
   gainNode.gain.value = gain;

   source.connect(gainNode);
   gainNode.connect(context.destination);

   source.start(time);
 }

 function loadExpectedBuffer(event) {
   actualBuffer = event.renderedBuffer;

   bufferLoader = new BufferLoader(
     context,
     ['/webaudio/the-audio-api/the-gainnode-interface/gain-expected.wav'],
     bufferLoadCompleted
   );
   bufferLoader.load();
 };

 function bufferLoadCompleted(buffer) {
   compareExpectedWithActualBuffer(buffer);
 };

 setup( function() {
   // Create offline audio context.
   context = new OfflineAudioContext(2, sampleRate * lengthInSeconds, sampleRate);

   // Create a buffer for a short "note".
   sinWaveBuffer = createSinWaveBuffer(bufferDurationSeconds, 880.0);

   // Render 11 notes, starting at a gain of 1.0, decreasing in gain by 0.1.
   // The last note will be of gain 0.0, so shouldn't be perceptible in the rendered output.
   for (var i = 0; i < numberOfNotes; ++i) {
     var time = i * noteSpacing;
     var gain = 1.0 - i / (numberOfNotes - 1);
     playNote(time, gain);
   }

   context.oncomplete = loadExpectedBuffer;
   context.startRendering();
 }, {timeout: 10000});

 function compareExpectedWithActualBuffer(expected) {
   var expectedBuffer = expected[0];

   gainNodeTest.step(function() {
     assert_array_approx_equals(expectedBuffer.getChannelData(0),
                                actualBuffer.getChannelData(0),
                                1e-4,
                                "comparing expected and rendered buffers (channel 0)");
   });

   gainNodeTest.step(function() {
     assert_array_approx_equals(expectedBuffer.getChannelData(1),
                                actualBuffer.getChannelData(1),
                                1e-4,
                                "comparing expected and rendered buffers (channel 1)");
   });

   gainNodeTest.done();
 };
   </script>
  </body>
 </html>
	<!doctype html>

	<!--
	Tests that GainNode is properly scaling the gain.
	We'll render 11 notes, starting at a gain of 1.0, decreasing in gain by 0.1.
	The 11th note will be of gain 0.0, so it should be silent (at the end in the rendered output).

	Based on a test from the WebKit test suite
	(https://github.com/WebKit/webkit/blob/master/LayoutTests/webaudio/gain.html)
	-->

	<html class="a">
	<head>
	<title>GainNode interface</title>
	<script src="/resources/testharness.js"></script>
	<script src="/resources/testharnessreport.js"></script>
	<script src="/webaudio/js/lodash.js"></script>
	<script src="/webaudio/js/vendor-prefixes.js"></script>
	<script src="/webaudio/js/helpers.js"></script>
	<script src="/webaudio/js/buffer-loader.js"></script>
	</head>
	<body class="a">
	<div id="log"></div>
	<script>
	var gainNodeTest = async_test("GainNode");

	var sampleRate = 44100.0;
	var bufferDurationSeconds = 0.125;
	var numberOfNotes = 11;
	var noteSpacing = bufferDurationSeconds + 0.020; // leave 20ms of silence between each "note"
	var lengthInSeconds = numberOfNotes * noteSpacing;

	var context = 0;
	var expectedBuffer = 0;
	var actualBuffer = 0;
	var sinWaveBuffer = 0;

	function createSinWaveBuffer(lengthInSeconds, frequency) {
	var audioBuffer = context.createBuffer(2, lengthInSeconds * sampleRate, sampleRate);

	var n = audioBuffer.length;
	var channelL = audioBuffer.getChannelData(0);
	var channelR = audioBuffer.getChannelData(1);

	for (var i = 0; i < n; ++i) {
	channelL[i] = Math.sin(frequency * 2.0Math.PI i / sampleRate);
	channelR[i] = channelL[i];
	}

	return audioBuffer;
	}

	function playNote(time, gain) {
	var source = context.createBufferSource();
	source.buffer = sinWaveBuffer;

	var gainNode = context.createGain();
	gainNode.gain.value = gain;

	source.connect(gainNode);
	gainNode.connect(context.destination);

	source.start(time);
	}

	function loadExpectedBuffer(event) {
	actualBuffer = event.renderedBuffer;

	bufferLoader = new BufferLoader(
	context,
	['/webaudio/the-audio-api/the-gainnode-interface/gain-expected.wav'],
	bufferLoadCompleted
	);
	bufferLoader.load();
	};

	function bufferLoadCompleted(buffer) {
	compareExpectedWithActualBuffer(buffer);
	};

	setup( function() {
	// Create offline audio context.
	context = new OfflineAudioContext(2, sampleRate * lengthInSeconds, sampleRate);

	// Create a buffer for a short "note".
	sinWaveBuffer = createSinWaveBuffer(bufferDurationSeconds, 880.0);

	// Render 11 notes, starting at a gain of 1.0, decreasing in gain by 0.1.
	// The last note will be of gain 0.0, so shouldn't be perceptible in the rendered output.
	for (var i = 0; i < numberOfNotes; ++i) {
	var time = i * noteSpacing;
	var gain = 1.0 - i / (numberOfNotes - 1);
	playNote(time, gain);
	}

	context.oncomplete = loadExpectedBuffer;
	context.startRendering();
	}, {timeout: 10000});

	function compareExpectedWithActualBuffer(expected) {
	var expectedBuffer = expected[0];

	gainNodeTest.step(function() {
	assert_array_approx_equals(expectedBuffer.getChannelData(0),
	actualBuffer.getChannelData(0),
	1e-4,
	"comparing expected and rendered buffers (channel 0)");
	});

	gainNodeTest.step(function() {
	assert_array_approx_equals(expectedBuffer.getChannelData(1),
	actualBuffer.getChannelData(1),
	1e-4,
	"comparing expected and rendered buffers (channel 1)");
	});

	gainNodeTest.done();
	};
	</script>
	</body>
	</html>