BaseAudioContext: createScriptProcessor() method

createScriptProcessor(bufferSize, numberOfInputChannels, numberOfOutputChannels)

const myScript = document.querySelector("script");
const myPre = document.querySelector("pre");
const playButton = document.querySelector("button");

// Create AudioContext and buffer source
const audioCtx = new AudioContext();
const source = audioCtx.createBufferSource();

// Create a ScriptProcessorNode with a bufferSize of 4096 and a single input and output channel
const scriptNode = audioCtx.createScriptProcessor(4096, 1, 1);
console.log(scriptNode.bufferSize);

// load in an audio track via XHR and decodeAudioData

function getData() {
  request = new XMLHttpRequest();
  request.open("GET", "viper.ogg", true);
  request.responseType = "arraybuffer";
  request.onload = () => {
    const audioData = request.response;

    audioCtx.decodeAudioData(
      audioData,
      (buffer) => {
        myBuffer = buffer;
        source.buffer = myBuffer;
      },
      (e) => console.error(`Error with decoding audio data: ${e.err}`)
    );
  };
  request.send();
}

// Give the node a function to process audio events
scriptNode.onaudioprocess = (audioProcessingEvent) => {
  // The input buffer is the song we loaded earlier
  const inputBuffer = audioProcessingEvent.inputBuffer;

  // The output buffer contains the samples that will be modified and played
  const outputBuffer = audioProcessingEvent.outputBuffer;

  // Loop through the output channels (in this case there is only one)
  for (let channel = 0; channel < outputBuffer.numberOfChannels; channel++) {
    const inputData = inputBuffer.getChannelData(channel);
    const outputData = outputBuffer.getChannelData(channel);

    // Loop through the 4096 samples
    for (let sample = 0; sample < inputBuffer.length; sample++) {
      // make output equal to the same as the input
      outputData[sample] = inputData[sample];

      // add noise to each output sample
      outputData[sample] += (Math.random() * 2 - 1) * 0.2;
    }
  }
};

getData();

// Wire up the play button
playButton.onclick = () => {
  source.connect(scriptNode);
  scriptNode.connect(audioCtx.destination);
  source.start();
};

// When the buffer source stops playing, disconnect everything
source.onended = () => {
  source.disconnect(scriptNode);
  scriptNode.disconnect(audioCtx.destination);
};