delay-test.html - mozsearch

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

<!doctype html>

<html>

  <head>

    <title>Test DelayNode Delay</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>

      let audit = Audit.createTaskRunner();

      audit.define(

          {label: 'test0', description: 'Test delay of 3 frames'},

          async (task, should) => {

            // Only need a few outputs samples.  The sample rate is arbitrary.

            const context =

                new OfflineAudioContext(1, RENDER_QUANTUM_FRAMES, 8192);

            let src;

            let delay;

            should(

                () => {

                  src = new ConstantSourceNode(context);

                  delay = new DelayNode(context);

},

                'Creating ConstantSourceNode(context) and DelayNode(context)')

                .notThrow();

            // The number of frames to delay for the DelayNode.  Should be a

            // whole number, but is otherwise arbitrary.

            const delayFrames = 3;

            should(() => {

              delay.delayTime.value = delayFrames / context.sampleRate;

            }, `Setting delayTime to ${delayFrames} frames`).notThrow();

            src.connect(delay).connect(context.destination);

            src.start();

            let buffer = await context.startRendering();

            let output = buffer.getChannelData(0);

            // Verify output was delayed the correct number of frames.

            should(output.slice(0, delayFrames), `output[0:${delayFrames - 1}]`)

                .beConstantValueOf(0);

            should(

                output.slice(delayFrames),

                `output[${delayFrames}:${output.length - 1}]`)

                .beConstantValueOf(1);

            task.done();

});

      audit.run();

    </script>

  </body>

</html>