retrospective-test.js

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// Create an audio graph on an offline context that consists of a

// constant source and two gain nodes. One of the nodes is the node te

// be tested and the other is the reference node.  The output from the

// test node is in channel 0 of the offline context; the reference

// node is in channel 1.

//

// Returns a dictionary with the context, source node, the test node,

// and the reference node.

function setupRetrospectiveGraph() {

  // Use a sample rate that is a power of two to eliminate round-off

  // in computing the currentTime.

  let context = new OfflineAudioContext(2, 16384, 16384);

  let source = new ConstantSourceNode(context);

  let test = new GainNode(context);

  let reference = new GainNode(context);

  source.connect(test);

  source.connect(reference);

  let merger = new ChannelMergerNode(

      context, {numberOfInputs: context.destination.channelCount});

  test.connect(merger, 0, 0);

  reference.connect(merger, 0, 1);

  merger.connect(context.destination);

  return {context: context, source: source, test: test, reference: reference};