<!doctype html>
<html>
  <head>
    <title>
      Test Basic Oscillator Sine Wave Test
    </title>
    <script src="/resources/testharness.js"></script>
    <script src="/resources/testharnessreport.js"></script>
    <script src="/webaudio/resources/audit-util.js"></script>
    <script src="/webaudio/resources/audit.js"></script>
  </head>

  <body>
    <script>
      // Don't change the sample rate.  The tests below depend on this sample
      // rate to cover all the cases in Chrome's implementation.  But the tests
      // are general and apply to any browser.
      const sampleRate = 44100;

      // Only need a few samples for testing, so just use two renders.
      const durationFrames = 2 * RENDER_QUANTUM_FRAMES;

      let audit = Audit.createTaskRunner();

      // The following tests verify that the oscillator produces the same
      // results as the mathematical oscillators.  We choose sine wave and a
      // custom wave because we know they're bandlimited and won't change with
      // the frequency.
      //
      // The tests for 1 and 2 Hz are intended to test Chrome's interpolation
      // algorithm, but are still generally applicable to any browser.

      audit.define(
          {label: 'Test 0', description: 'Sine wave: 100 Hz'},
          async (task, should) => {
            let context = new OfflineAudioContext(
                {length: durationFrames, sampleRate: sampleRate});

            const freqHz = 100;

            let src =
                new OscillatorNode(context, {type: 'sine', frequency: freqHz});
            src.connect(context.destination);

            src.start();

            let renderedBuffer = await context.startRendering();
            checkResult(should, renderedBuffer, context, {
              freqHz: freqHz,
              a1: 0,
              b1: 1,
              prefix: 'Sine',
              threshold: 1.8045e-6,
              snrThreshold: 118.91
            });
            task.done();
          });

      audit.define(
          {label: 'Test 1', description: 'Sine wave: -100 Hz'},
          async (task, should) => {
            let context = new OfflineAudioContext(
                {length: durationFrames, sampleRate: sampleRate});

            const freqHz = -100;

            let src =
                new OscillatorNode(context, {type: 'sine', frequency: freqHz});
            src.connect(context.destination);

            src.start();

            let renderedBuffer = await context.startRendering();
            checkResult(should, renderedBuffer, context, {
              freqHz: freqHz,
              a1: 0,
              b1: 1,
              prefix: 'Sine',
              threshold: 4.7684e-7,
              snrThreshold: 130.95
            });
            task.done();
          });

      audit.define(
          {label: 'Test 2', description: 'Sine wave: 2 Hz'},
          async (task, should) => {
            let context = new OfflineAudioContext(
                {length: durationFrames, sampleRate: sampleRate});

            const freqHz = 2;

            let src =
                new OscillatorNode(context, {type: 'sine', frequency: freqHz});
            src.connect(context.destination);

            src.start();

            let renderedBuffer = await context.startRendering();
            checkResult(should, renderedBuffer, context, {
              freqHz: freqHz,
              a1: 0,
              b1: 1,
              prefix: 'Sine',
              threshold: 1.4516e-7,
              snrThreshold: 119.93
            });
            task.done();
          });

      audit.define(
          {label: 'Test 3', description: 'Sine wave: 1 Hz'},
          async (task, should) => {
            let context = new OfflineAudioContext(
                {length: durationFrames, sampleRate: sampleRate});

            const freqHz = 1;

            let src =
                new OscillatorNode(context, {type: 'sine', frequency: freqHz});
            src.connect(context.destination);

            src.start();

            let renderedBuffer = await context.startRendering();
            checkResult(should, renderedBuffer, context, {
              freqHz: freqHz,
              a1: 0,
              b1: 1,
              prefix: 'Sine',
              threshold: 1.4157e-7,
              snrThreshold: 112.22
            });
            task.done();
          });

      audit.define(
          {label: 'Test 4', description: 'Custom wave: 100 Hz'},
          async (task, should) => {
            let context = new OfflineAudioContext(
                {length: durationFrames, sampleRate: sampleRate});

            const freqHz = 100;

            let wave = new PeriodicWave(
                context,
                {real: [0, 1], imag: [0, 1], disableNormalization: true});
            let src = new OscillatorNode(
                context,
                {type: 'custom', frequency: freqHz, periodicWave: wave});
            src.connect(context.destination);

            src.start();

            let renderedBuffer = await context.startRendering();
            checkResult(should, renderedBuffer, context, {
              freqHz: freqHz,
              a1: 1,
              b1: 1,
              prefix: 'Custom',
              threshold: 1.8478e-6,
              snrThreshold: 122.43
            });
            task.done();
          });

      audit.define(
          {label: 'Test 5', description: 'Custom wave: 1 Hz'},
          async (task, should) => {
            let context = new OfflineAudioContext(
                {length: durationFrames, sampleRate: sampleRate});

            const freqHz = 1;

            let wave = new PeriodicWave(
                context,
                {real: [0, 1], imag: [0, 1], disableNormalization: true});
            let src = new OscillatorNode(
                context,
                {type: 'custom', frequency: freqHz, periodicWave: wave});
            src.connect(context.destination);

            src.start();

            let renderedBuffer = await context.startRendering();
            checkResult(should, renderedBuffer, context, {
              freqHz: freqHz,
              a1: 1,
              b1: 1,
              prefix: 'Custom',
              threshold: 4.7684e-7,
              snrThreshold: 138.76
            });
            task.done();
          });

      audit.run();

      function waveForm(context, freqHz, a1, b1, nsamples) {
        let buffer =
            new AudioBuffer({length: nsamples, sampleRate: context.sampleRate});
        let signal = buffer.getChannelData(0);
        const omega = 2 * Math.PI * freqHz / context.sampleRate;
        for (let k = 0; k < nsamples; ++k) {
          signal[k] = a1 * Math.cos(omega * k) + b1 * Math.sin(omega * k);
        }

        return buffer;
      }

      function checkResult(should, renderedBuffer, context, options) {
        let {freqHz, a1, b1, prefix, threshold, snrThreshold} = options;

        let actual = renderedBuffer.getChannelData(0);

        let expected =
            waveForm(context, freqHz, a1, b1, actual.length).getChannelData(0);

        should(actual, `${prefix}: ${freqHz} Hz`).beCloseToArray(expected, {
          absoluteThreshold: threshold
        });

        let snr = 10 * Math.log10(computeSNR(actual, expected));

        should(snr, `${prefix}: SNR (db)`).beGreaterThanOrEqualTo(snrThreshold);
      }
    </script>
  </body>
</html>
