third_party/WebKit/LayoutTests/webaudio/sample-accurate-scheduling.html

   1 <!DOCTYPE html>
   2
   3 <!--
   4 Tests that we are able to schedule a series of notes to playback with sample-accuracy.
   5 We use an impulse so we can tell exactly where the rendering is happening.
   6 -->
   7
   8 <html>
   9 <head>
  10 <script src="../resources/js-test.js"></script>
  11 <script src="resources/compatibility.js"></script>
  12 <script type="text/javascript" src="resources/audio-testing.js"></script>
  13 <script type="text/javascript" src="resources/buffer-loader.js"></script>
  14 </head>
  15
  16 <body>
  17
  18 <div id="description"></div>
  19 <div id="console"></div>
  20
  21 <script>
  22 description("Tests sample-accurate scheduling.");
  23
  24 var sampleRate = 44100.0;
  25 var lengthInSeconds = 4;
  26
  27 var context = 0;
  28 var bufferLoader = 0;
  29 var impulse;
  30
  31 // See if we can render at exactly these sample offsets.
  32 var sampleOffsets = [0, 3, 512, 517, 1000, 1005, 20000, 21234, 37590];
  33
  34 function createImpulse() {
  35     // An impulse has a value of 1 at time 0, and is otherwise 0.
  36     impulse = context.createBuffer(2, 512, sampleRate);
  37     var sampleDataL = impulse.getChannelData(0);
  38     var sampleDataR = impulse.getChannelData(1);
  39     sampleDataL[0] = 1.0;
  40     sampleDataR[0] = 1.0;
  41 }
  42
  43 function playNote(time) {
  44     var bufferSource = context.createBufferSource();
  45     bufferSource.buffer = impulse;
  46     bufferSource.connect(context.destination);
  47     bufferSource.start(time);
  48 }
  49
  50 function checkSampleAccuracy(event) {
  51     var buffer = event.renderedBuffer;
  52
  53     var bufferDataL = buffer.getChannelData(0);
  54     var bufferDataR = buffer.getChannelData(1);
  55
  56     var success = true;
  57     var impulseCount = 0;
  58     var badOffsetCount = false;
  59
  60     // Go through every sample and make sure it's 0, except at positions in sampleOffsets.
  61     for (var i = 0; i < buffer.length; ++i) {
  62         // Make sure left == right
  63         if (bufferDataL[i] != bufferDataR[i]) {
  64             testFailed("Rendered buffer left and right channels are not identical.");
  65             success = false;
  66             break;
  67         }
  68
  69         if (bufferDataL[i] != 0) {
  70             // Make sure this index is  in sampleOffsets
  71             var found = false;
  72             for (var j = 0; j < sampleOffsets.length; ++j) {
  73                 if (sampleOffsets[j] == i) {
  74                     found = true;
  75                     break;
  76                 }
  77             }
  78             ++impulseCount;
  79             if (!found) {
  80                 testFailed("Non-zero sample found at sample offset " + i);
  81                 success = false;
  82                 ++badOffsetCount;
  83             }
  84         }
  85     }
  86
  87     if (impulseCount == sampleOffsets.length) {
  88         if (badOffsetCount == 0) {
  89             testPassed("Expected number of events found.");
  90         } else {
  91             testFailed("Expected number of events found, but " + badOffsetCount + " are at incorrect offsets.");
  92             success = false;
  93         }
  94     } else {
  95         testFailed("Expected " + sampleOffsets.length + " impulses but only found " + impulseCount);
  96         success = false;
  97     }
  98
  99     if (success) {
 100         testPassed("All events rendered with sample-accuracy.");
 101     } else {
 102         testFailed("Events NOT rendered with sample-accuracy.");
 103     }
 104
 105     finishJSTest();
 106 }
 107
 108 function runTest() {
 109     if (window.testRunner) {
 110         testRunner.dumpAsText();
 111         testRunner.waitUntilDone();
 112     }
 113
 114     window.jsTestIsAsync = true;
 115
 116     // Create offline audio context.
 117     context = new OfflineAudioContext(2, sampleRate * lengthInSeconds, sampleRate);
 118     createImpulse();
 119
 120     for (var i = 0; i < sampleOffsets.length; ++i) {
 121         var timeInSeconds = sampleOffsets[i] / sampleRate;
 122         playNote(timeInSeconds);
 123     }
 124
 125     context.oncomplete = checkSampleAccuracy;
 126     context.startRendering();
 127 }
 128
 129 runTest();
 130
 131 </script>
 132
 133 </body>
 134 </html>