audioparam-summingjunction.html

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This WPT test may be referenced by the following Test IDs:
- /webaudio/the-audio-api/the-audioparam-interface/audioparam-summingjunction.html - WPT Dashboard Interop Dashboard

<!DOCTYPE html>

<!--

Tests that multiple audio-rate signals (AudioNode outputs) can be connected to an AudioParam

and that these signals are summed, along with the AudioParams intrinsic value.

-->

<html>

  <head>

    <title>

      audioparam-summingjunction.html

    </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>

    <script src="/webaudio/resources/mix-testing.js"></script>

  </head>

  <body>

    <script id="layout-test-code">

      let audit = Audit.createTaskRunner();

      let sampleRate = 44100.0;

      let lengthInSeconds = 1;

      let context = 0;

      // Buffers used by the two gain controlling sources.

      let linearRampBuffer;

      let toneBuffer;

      let toneFrequency = 440;

      // Arbitrary non-zero value.

      let baselineGain = 5;

      // Allow for a small round-off error.

      let maxAllowedError = 1e-6;

      function checkResult(renderedBuffer, should) {

        let renderedData = renderedBuffer.getChannelData(0);

        // Get buffer data from the two sources used to control gain.

        let linearRampData = linearRampBuffer.getChannelData(0);

        let toneData = toneBuffer.getChannelData(0);

        let n = renderedBuffer.length;

        should(n, 'Rendered signal length').beEqualTo(linearRampBuffer.length);

        // Check that the rendered result exactly matches the sum of the

        // intrinsic gain plus the two sources used to control gain. This is

        // because we're changing the gain of a signal having constant value 1.

        let success = true;

        for (let i = 0; i < n; ++i) {

          let expectedValue = baselineGain + linearRampData[i] + toneData[i];

          let error = Math.abs(expectedValue - renderedData[i]);

          if (error > maxAllowedError) {

            success = false;

            break;

        should(

            success,

            'Rendered signal matches sum of two audio-rate gain changing signals plus baseline gain')

            .beTrue();

      audit.define('test', function(task, should) {

        let sampleFrameLength = sampleRate * lengthInSeconds;

        // Create offline audio context.

        context = new OfflineAudioContext(1, sampleFrameLength, sampleRate);

        // Create buffer used by the source which will have its gain controlled.

        let constantOneBuffer =

            createConstantBuffer(context, sampleFrameLength, 1);

        let constantSource = context.createBufferSource();

        constantSource.buffer = constantOneBuffer;

        // Create 1st buffer used to control gain (a linear ramp).

        linearRampBuffer = createLinearRampBuffer(context, sampleFrameLength);

        let gainSource1 = context.createBufferSource();

        gainSource1.buffer = linearRampBuffer;

        // Create 2st buffer used to control gain (a simple sine wave tone).

        toneBuffer =

            createToneBuffer(context, toneFrequency, lengthInSeconds, 1);

        let gainSource2 = context.createBufferSource();

        gainSource2.buffer = toneBuffer;

        // Create a gain node controlling the gain of constantSource and make

        // the connections.

        let gainNode = context.createGain();

        // Intrinsic baseline gain.

        // This gain value should be summed with gainSource1 and gainSource2.

        gainNode.gain.value = baselineGain;

        constantSource.connect(gainNode);

        gainNode.connect(context.destination);

        // Connect two audio-rate signals to control the .gain AudioParam.

        gainSource1.connect(gainNode.gain);

        gainSource2.connect(gainNode.gain);

        // Start all sources at time 0.

        constantSource.start(0);

        gainSource1.start(0);

        gainSource2.start(0);

        context.startRendering().then(buffer => {

          checkResult(buffer, should);

          task.done();

});

});

      audit.run();

    </script>

  </body>

</html>