third_party/WebKit/LayoutTests/webaudio/waveshaper-limits.html

   1 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
   2 <html>
   3   <head>
   4     <script src="../resources/js-test.js"></script>
   5     <script src="resources/compatibility.js"></script>
   6   </head>
   7
   8   <body>
   9     <div id="description"></div>
  10     <div id="console"></div>
  11
  12     <script>
  13       description("Test WaveShaperNode including values outside the range of [-1,1]");
  14
  15       var context;
  16       var bufferData;
  17       var outputData;
  18       var reference;
  19
  20       var sampleRate = 48000;
  21       // Must be odd so we have an exact middle point.
  22       var testFrames = 23;
  23       var scale = 1 / ((testFrames - 1) / 2 - 1);
  24       // Number of decimal digits to print
  25       var decimals = 6;
  26       // Required accuracy
  27       var diffThreshold = Math.pow(10, -decimals);
  28
  29       // Generate reference data
  30       function generateReference() {
  31         // The curve data is 0, 1, 0, and the input data is a ramp from -1+eps to 1+eps.  Then the
  32         // output is a ramp from 0 to 1 back to 0.
  33         var ref = new Float32Array(testFrames);
  34         var midPoint = (testFrames - 1) / 2;
  35         // First sample is below -1 at -1-scale.
  36         ref[0] = 0;
  37         // Generate ramp up to the mid-point
  38         for (var k = 0; k < midPoint; ++k) {
  39           ref[k + 1] = k * scale;
  40         }
  41         // The value at the mid-point must be 1, from the curve
  42         ref[midPoint] = 1;
  43         // Generate a ramp from 1 down to 0
  44         for (var k = midPoint; k < testFrames - 1; ++k) {
  45            ref[k + 1] = 2 - k * scale;
  46         }
  47         // The last sample is out of range at 1+scale
  48         ref[testFrames - 1] = 0;
  49         return ref;
  50       }
  51
  52       function checkResult (event) {
  53         outputData = event.renderedBuffer.getChannelData(0);
  54         reference = generateReference();
  55         var success = true;
  56         // Verify that every output value matches our expected reference value.
  57         for (var k = 0; k < outputData.length; ++k) {
  58            var diff = outputData[k] - reference[k];
  59            if (Math.abs(diff) <= diffThreshold) {
  60               testPassed(bufferData[k].toFixed(decimals) + " -> " + outputData[k].toFixed(decimals) + ".");
  61            } else {
  62               testFailed(bufferData[k].toFixed(decimals) + " -> " + outputData[k].toFixed(decimals) + ", but expected " + reference[k].toFixed(decimals) + ".");
  63               success = false;
  64            }
  65         }
  66
  67         if (success)
  68           testPassed("All outputs matched expected results.");
  69         else
  70           testFailed("Some outputs did not match expected results.");
  71
  72         finishJSTest();
  73       }
  74
  75       function runTest () {
  76         if (window.testRunner) {
  77           testRunner.dumpAsText();
  78           testRunner.waitUntilDone();
  79         }
  80
  81         window.jsTestIsAsync = true;
  82
  83         context = new OfflineAudioContext(1, testFrames, sampleRate);
  84         // Create input values between -1.1 and 1.1
  85         var buffer = context.createBuffer(1, testFrames, context.sampleRate);
  86         bufferData = buffer.getChannelData(0);
  87         var start = -1 - scale;
  88         for (var k = 0; k < testFrames; ++k) {
  89           bufferData[k] = k * scale + start;
  90         }
  91
  92         var source = context.createBufferSource();
  93         source.buffer = buffer;
  94
  95         // Create simple waveshaper. It should map -1 to 0, 0 to 1, and +1 to 0 and interpolate
  96         // all points in between using a simple linear interpolator.
  97         var shaper = context.createWaveShaper();
  98         var curve = new Float32Array(3);
  99         curve[0] = 0;
 100         curve[1] = 1;
 101         curve[2] = 0;
 102         shaper.curve = curve;
 103         source.connect(shaper);
 104         shaper.connect(context.destination);
 105
 106         source.start();
 107         context.oncomplete = checkResult;
 108         context.startRendering();
 109       }
 110
 111       runTest();
 112       successfullyParsed = true;
 113     </script>
 114   </body>
 115 </html>