third_party/WebKit/LayoutTests/webaudio/audioparam-summingjunction.html

   1 <!DOCTYPE html>
   2
   3 <!--
   4 Tests that multiple audio-rate signals (AudioNode outputs) can be connected to an AudioParam
   5 and that these signals are summed, along with the AudioParams intrinsic value.
   6 -->
   7
   8 <html>
   9 <head>
  10 <script src="resources/compatibility.js"></script>
  11 <script src="resources/audio-testing.js"></script>
  12 <script src="resources/mix-testing.js"></script>
  13 <script src="../resources/js-test.js"></script>
  14
  15 </head>
  16 <body>
  17
  18 <script>
  19
  20 var sampleRate = 44100.0;
  21 var lengthInSeconds = 1;
  22
  23 var context = 0;
  24
  25 // Buffers used by the two gain controlling sources.
  26 var linearRampBuffer;
  27 var toneBuffer;
  28 var toneFrequency = 440;
  29
  30 // Arbitrary non-zero value.
  31 var baselineGain = 5;
  32
  33 // Allow for a small round-off error.
  34 var maxAllowedError = 1e-6;
  35
  36 function checkResult(event) {
  37     var renderedBuffer = event.renderedBuffer;
  38     var renderedData = renderedBuffer.getChannelData(0);
  39
  40     // Get buffer data from the two sources used to control gain.
  41     var linearRampData = linearRampBuffer.getChannelData(0);
  42     var toneData = toneBuffer.getChannelData(0);
  43
  44     var n = renderedBuffer.length;
  45
  46     if (n == linearRampBuffer.length) {
  47         testPassed("Rendered signal is of correct length.");
  48     } else {
  49         testFailed("Rendered signal is not of correct length.");
  50     }
  51
  52     // Check that the rendered result exactly matches the sum of the intrinsic gain plus the two sources used to control gain.
  53     // This is because we're changing the gain of a signal having constant value 1.
  54     var success = true;
  55     for (var i = 0; i < n; ++i) {
  56         var expectedValue = baselineGain + linearRampData[i] + toneData[i];
  57         var error = Math.abs(expectedValue - renderedData[i]);
  58
  59         if (error > maxAllowedError) {
  60             success = false;
  61             break;
  62         }
  63     }
  64
  65     if (success) {
  66         testPassed("Rendered signal matches sum of two audio-rate gain changing signals plus baseline gain.");
  67     } else {
  68         testFailed("Rendered signal differs from the sum of two audio-rate gain changing signals plus baseline gain.");
  69     }
  70
  71     finishJSTest();
  72 }
  73
  74 function runTest() {
  75     if (window.testRunner) {
  76         testRunner.dumpAsText();
  77         testRunner.waitUntilDone();
  78     }
  79
  80     window.jsTestIsAsync = true;
  81
  82     var sampleFrameLength = sampleRate * lengthInSeconds;
  83
  84     // Create offline audio context.
  85     context = new OfflineAudioContext(1, sampleFrameLength, sampleRate);
  86
  87     // Create buffer used by the source which will have its gain controlled.
  88     var constantOneBuffer = createConstantBuffer(context, sampleFrameLength, 1);
  89     var constantSource = context.createBufferSource();
  90     constantSource.buffer = constantOneBuffer;
  91
  92     // Create 1st buffer used to control gain (a linear ramp).
  93     linearRampBuffer = createLinearRampBuffer(context, sampleFrameLength);
  94     var gainSource1 = context.createBufferSource();
  95     gainSource1.buffer = linearRampBuffer;
  96
  97     // Create 2st buffer used to control gain (a simple sine wave tone).
  98     toneBuffer = createToneBuffer(context, toneFrequency, lengthInSeconds, 1);
  99     var gainSource2 = context.createBufferSource();
 100     gainSource2.buffer = toneBuffer;
 101
 102     // Create a gain node controlling the gain of constantSource and make the connections.
 103     var gainNode = context.createGain();
 104
 105     // Intrinsic baseline gain.
 106     // This gain value should be summed with gainSource1 and gainSource2.
 107     gainNode.gain.value = baselineGain;
 108
 109     constantSource.connect(gainNode);
 110     gainNode.connect(context.destination);
 111
 112     // Connect two audio-rate signals to control the .gain AudioParam.
 113     gainSource1.connect(gainNode.gain);
 114     gainSource2.connect(gainNode.gain);
 115
 116     // Start all sources at time 0.
 117     constantSource.start(0);
 118     gainSource1.start(0);
 119     gainSource2.start(0);
 120
 121     context.oncomplete = checkResult;
 122     context.startRendering();
 123 }
 124
 125 runTest();
 126 successfullyParsed = true;
 127
 128 </script>
 129
 130 </body>
 131 </html>