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  <head>
    <title>
      Test Convolver Channel Outputs for Response with 4 channels
    </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>
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    <script id="layout-test-code">
      // Test various convolver configurations when the convolver response has
      // a four channels.

      // Fairly arbitrary sample rate, except that we want the rate to be a
      // power of two so that 1/sampleRate is exactly respresentable as a
      // single-precision float.
      let sampleRate = 8192;

      // A fairly arbitrary number of frames, except the number of frames should
      // be more than a few render quanta.
      let renderFrames = 10 * 128;

      let audit = Audit.createTaskRunner();

      // Convolver response
      let response;

      audit.define(
          {
            label: 'initialize',
            description: 'Convolver response with one channel'
          },
          (task, should) => {
            // Convolver response
            should(
                () => {
                  response = new AudioBuffer(
                      {numberOfChannels: 4, length: 8, sampleRate: sampleRate});
                  // Each channel of the response is a simple impulse (with
                  // different delay) so that we can use a DelayNode to simulate
                  // the convolver output.  Channel k is delayed by k+1 frames.
                  for (let k = 0; k < response.numberOfChannels; ++k) {
                    response.getChannelData(k)[k + 1] = 1;
                  }
                },
                'new AudioBuffer({numberOfChannels: 2, length: 4, sampleRate: ' +
                    sampleRate + '})')
                .notThrow();

            task.done();
          });

      audit.define(
          {label: '1-channel input', description: 'produces 2-channel output'},
          (task, should) => {
            fourChannelResponseTest({numberOfInputs: 1, prefix: '1'}, should)
                .then(() => task.done());
          });

      audit.define(
          {label: '2-channel input', description: 'produces 2-channel output'},
          (task, should) => {
            fourChannelResponseTest({numberOfInputs: 2, prefix: '2'}, should)
                .then(() => task.done());
          });

      audit.define(
          {
            label: '3-channel input',
            description: '3->2 downmix producing 2-channel output'
          },
          (task, should) => {
            fourChannelResponseTest({numberOfInputs: 3, prefix: '3'}, should)
                .then(() => task.done());
          });

      audit.define(
          {
            label: '4-channel input',
            description: '4->2 downmix producing 2-channel output'
          },
          (task, should) => {
            fourChannelResponseTest({numberOfInputs: 4, prefix: '4'}, should)
                .then(() => task.done());
          });

      audit.define(
          {
            label: '5.1-channel input',
            description: '5.1->2 downmix producing 2-channel output'
          },
          (task, should) => {
            fourChannelResponseTest({numberOfInputs: 6, prefix: '5.1'}, should)
                .then(() => task.done());
          });

      audit.define(
          {
            label: 'delayed buffer set',
            description: 'Delayed set of 4-channel response'
          },
          (task, should) => {
            // Don't really care about the output for this test.  It's to verify
            // we don't crash in a debug build when setting the convolver buffer
            // after creating the graph.
            let context = new OfflineAudioContext(1, renderFrames, sampleRate);
            let src = new OscillatorNode(context);
            let convolver =
                new ConvolverNode(context, {disableNormalization: true});
            let buffer = new AudioBuffer({
              numberOfChannels: 4,
              length: 4,
              sampleRate: context.sampleRate
            });

            // Impulse responses for the convolver aren't important, as long as
            // it's not all zeroes.
            for (let k = 0; k < buffer.numberOfChannels; ++k) {
              buffer.getChannelData(k).fill(1);
            }

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

            // Set the buffer after a few render quanta have passed.  The actual
            // value must be least one, but is otherwise arbitrary.
            context.suspend(512 / context.sampleRate)
                .then(() => convolver.buffer = buffer)
                .then(() => context.resume());

            src.start();
            context.startRendering()
                .then(audioBuffer => {
                  // Just make sure output is not silent.
                  should(
                      audioBuffer.getChannelData(0),
                      'Output with delayed setting of convolver buffer')
                      .notBeConstantValueOf(0);
                })
                .then(() => task.done());
          });

      function fourChannelResponseTest(options, should) {
        // Create an 4-channel offline context.  The first two channels are for
        // the stereo output of the convolver and the next two channels are for
        // the reference stereo signal.
        let context = new OfflineAudioContext(4, renderFrames, sampleRate);
        context.destination.channelInterpretation = 'discrete';

        // Create oscillators for use as the input.  The type and frequency is
        // arbitrary except that oscillators must be different.
        let src = new Array(options.numberOfInputs);
        for (let k = 0; k < src.length; ++k) {
          src[k] = new OscillatorNode(
              context, {type: 'square', frequency: 440 + 220 * k});
        }

        // Merger to combine the oscillators into one output stream.
        let srcMerger =
            new ChannelMergerNode(context, {numberOfInputs: src.length});

        for (let k = 0; k < src.length; ++k) {
          src[k].connect(srcMerger, 0, k);
        }

        // Convolver under test.
        let conv = new ConvolverNode(
            context, {disableNormalization: true, buffer: response});
        srcMerger.connect(conv);

        // Splitter to get individual channels of the convolver output so we can
        // feed them (eventually) to the context in the right set of channels.
        let splitter = new ChannelSplitterNode(context, {numberOfOutputs: 2});
        conv.connect(splitter);

        // Reference graph consists of a delays node to simulate the response of
        // the convolver.  (The convolver response is designed this way.)
        let delay = new Array(4);
        for (let k = 0; k < delay.length; ++k) {
          delay[k] = new DelayNode(context, {
            delayTime: (k + 1) / context.sampleRate,
            channelCount: 1,
            channelCountMode: 'explicit'
          });
        }

        // Gain node to mix the sources to stereo in the desired way.  (Could be
        // done in the delay node, but let's keep the mixing separated from the
        // functionality.)
        let gainMixer = new GainNode(
            context, {channelCount: 2, channelCountMode: 'explicit'});
        srcMerger.connect(gainMixer);

        // Splitter to extract the channels of the reference signal.
        let refSplitter =
            new ChannelSplitterNode(context, {numberOfOutputs: 2});
        gainMixer.connect(refSplitter);

        // Connect the left channel to the first two nodes and the right channel
        // to the second two as required for "true" stereo matrix response.
        for (let k = 0; k < 2; ++k) {
          refSplitter.connect(delay[k], 0, 0);
          refSplitter.connect(delay[k + 2], 1, 0);
        }

        // Gain nodes to sum the responses to stereo
        let gain = new Array(2);
        for (let k = 0; k < gain.length; ++k) {
          gain[k] = new GainNode(context, {
            channelCount: 1,
            channelCountMode: 'explicit',
            channelInterpretation: 'discrete'
          });
        }

        delay[0].connect(gain[0]);
        delay[2].connect(gain[0]);
        delay[1].connect(gain[1]);
        delay[3].connect(gain[1]);

        // Final merger to bring back the individual channels from the convolver
        // and the reference in the right order for the destination.
        let finalMerger = new ChannelMergerNode(
            context, {numberOfInputs: context.destination.channelCount});

        // First two channels are for the convolver output, and the next two are
        // for the reference.
        splitter.connect(finalMerger, 0, 0);
        splitter.connect(finalMerger, 1, 1);
        gain[0].connect(finalMerger, 0, 2);
        gain[1].connect(finalMerger, 0, 3);

        finalMerger.connect(context.destination);

        // Start the sources at last.
        for (let k = 0; k < src.length; ++k) {
          src[k].start();
        }

        return context.startRendering().then(audioBuffer => {
          // Extract the various channels out
          let actual0 = audioBuffer.getChannelData(0);
          let actual1 = audioBuffer.getChannelData(1);
          let expected0 = audioBuffer.getChannelData(2);
          let expected1 = audioBuffer.getChannelData(3);

          // Verify that each output channel of the convolver matches
          // the delayed signal from the reference
          should(actual0, options.prefix + ': Channel 0')
              .beEqualToArray(expected0);
          should(actual1, options.prefix + ': Channel 1')
              .beEqualToArray(expected1);
        });
      }

      audit.run();
    </script>
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