chromium/third_party/blink/web_tests/webaudio/Analyser/realtimeanalyser-zero.html

<!DOCTYPE html>
<html>
  <head>
    <title>
      Test getFloatFrequencyData With Zero Inputs
    </title>
    <script src="../../resources/testharness.js"></script>
    <script src="../../resources/testharnessreport.js"></script>
    <script src="../resources/audit-util.js"></script>
    <script src="../resources/audit.js"></script>
  </head>
  <body>
    <script id="layout-test-code">
      let sampleRate = 48000;

      // Render enough data to run the test.
      let renderFrames = 2 * 1024;
      let renderDuration = renderFrames / sampleRate;

      let audit = Audit.createTaskRunner();


      // Test that getFloatFrequencyData returns -Infinity when the input is
      // all-zeroes.
      audit.define('zero input', (task, should) => {
        let context = new OfflineAudioContext(1, renderFrames, sampleRate);

        // Constant source of 0's.
        let source = context.createBufferSource();
        source.buffer = createConstantBuffer(context, 1, 0);
        source.loop = true;

        // Create analyser and use some non-default minDecibels value.
        let analyser = context.createAnalyser();
        analyser.minDecibels = -123;

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

        source.start();

        // Suspend after some number of frames and grab the float frequency
        // data.
        context.suspend(1024 / sampleRate)
            .then(function() {
              let f = new Float32Array(analyser.frequencyBinCount);
              analyser.getFloatFrequencyData(f);

              should(f, 'getFloatFrequencyData() with zero-valued input')
                  .beConstantValueOf(-Infinity);
            })
            .then(context.resume.bind(context));

        context.startRendering().then(() => task.done());
      });

      audit.run();
    </script>
  </body>
</html>