third_party/WebKit/LayoutTests/webaudio/audiochannelmerger-cycle.html

   1 <!DOCTYPE html>
   2 <html>
   3
   4 <head>
   5   <script src="../resources/js-test.js"></script>
   6   <script src="resources/compatibility.js"></script>
   7   <script src="resources/audio-testing.js"></script>
   8 </head>
   9
  10 <body>
  11   <script>
  12     description("Test if ChannelMergerNode runs correctly in a cycle.");
  13     window.jsTestIsAsync = true;
  14
  15     // This specific sample rate is chosen to avoid the round/truncation error
  16     // in delay time. See: crbug.com/448801
  17     var sampleRate = 32768;
  18
  19     // Web Audio API's rendering quantum.
  20     var renderingQuantum = 128;
  21
  22     // 4x of rendering quantum. This is to make the rendered result long enough
  23     // so that we can observe the delayed output.
  24     var renderLength = renderingQuantum * 4;
  25
  26     // 1x rendering quantum of delay.
  27     var delayTime = renderingQuantum / sampleRate;
  28
  29     // Use 2 channels as a test case.
  30     var numberOfChannels = 2;
  31
  32     var audit = Audit.createTaskRunner();
  33
  34     audit.defineTask('merger-cyclic-graph', function (done) {
  35
  36       var context = new OfflineAudioContext(
  37         numberOfChannels, renderLength, sampleRate
  38       );
  39       var merger = context.createChannelMerger(2);
  40       var delay = context.createDelay();
  41       var source = context.createBufferSource();
  42
  43       // Create a mono source buffer filled with '1'.
  44       source.buffer = createTestingAudioBuffer(context, 1, renderLength);
  45
  46       delay.delayTime.value = delayTime;
  47
  48       // Connect the source to input 0 of the merger. Connect the output of
  49       // the merger to a delay node whose output is then connected to input 1
  50       // of the merger. See: crbug.com/442925
  51       source.connect(merger, 0, 0);
  52       delay.connect(merger, 0, 1);
  53       merger.connect(delay);
  54       merger.connect(context.destination);
  55       source.start();
  56
  57       context.startRendering().then(function (buffer) {
  58         // Expected output values: the output of delay node will be a stereo
  59         // signal of [1, 0]. When it feeds back to the 2nd input of merger node,
  60         // the stereo channel will be summed to mono resulting in 0.5.
  61         var expected_left = [];
  62         var expected_right = [];
  63
  64         for (var i = 0; i < renderLength; i++) {
  65           // Note that the delayed channel will be zero for the first 128 samples
  66           // due to the cyclic audio graph, the second 128 sample will be also
  67           // zero because of 128 samples delay.
  68           expected_left[i] = 1.0;
  69           expected_right[i] = (i < renderingQuantum * 2) ? 0.0 : 0.5;
  70         }
  71
  72         for (i = 0; i < buffer.numberOfChannels; i++) {
  73           var actual_left = buffer.getChannelData(0);
  74           var actual_right = buffer.getChannelData(1);
  75           for (var j = 0; j < renderLength; j++) {
  76             if (expected_left[j] !== actual_left[j]) {
  77               testFailed('The value ' + actual_left[j] +
  78                 'in the left channel did not match the expected value ' +
  79                 expected_left[j] + ' at the index ' + j + '.');
  80               done();
  81               return;
  82             }
  83             if (expected_right[j] !== actual_right[j]) {
  84               testFailed('The value ' + actual_left[j] +
  85                 'in the right channel did not match the expected value ' +
  86                 expected_left[j] + ' at the index ' + j + '.');
  87               done();
  88               return;
  89             }
  90           }
  91         }
  92
  93         testPassed("ChannerMergerNode passed cyclic audio graph test.");
  94         done();
  95       });
  96
  97     });
  98
  99     audit.defineTask('finish', function (done) {
 100       finishJSTest();
 101       done();
 102     });
 103
 104     audit.runTasks(
 105       'merger-cyclic-graph',
 106       'finish'
 107     );
 108
 109     successfullyParsed = true;
 110   </script>
 111 </body>
 112
 113 </html>