wip: big refactor

AudioSender.js

@@ -0,0 +1,115 @@
+let audioContext;
+let CHANNELS = [];
+let DESTINATION;
+let ON_START;
+let ON_STOP;
+let ON_SEND;
+let CHANNEL_OSCILLATORS = [];
+let WAVE_FORM;
+
+let stopOscillatorsTimeoutId;
+
+export const changeConfiguration = ({
+  channels,
+  destination,
+  startCallback,
+  stopCallback,
+  sendCallback,
+  waveForm
+}) => {
+  CHANNELS = channels;
+  DESTINATION = destination;
+  ON_START = startCallback;
+  ON_STOP = stopCallback;
+  ON_SEND = sendCallback;
+  WAVE_FORM = waveForm;
+}
+
+export const setAudioContext = ctx => audioContext = ctx;
+
+function getAudioContext() {
+  if(!audioContext) {
+    throw 'Audio context not provided.';
+  }
+  if(audioContext.state === 'suspended') {
+    audioContext.resume();
+  }
+  return audioContext;
+}
+
+const getChannels = () => CHANNELS;
+const getDestination = () => DESTINATION;
+
+export const now = () => getAudioContext().currentTime;
+
+export function beginAt(streamStartSeconds) {
+  stopTimeout();
+  const oscillators = getOscillators();
+  if(oscillators.length !== 0) stop();
+  const audioContext = getAudioContext();
+  const channels = getChannels();
+  const channelCount = channels.length;
+  const destination = getDestination();;
+  // create our oscillators
+  for(let i = 0; i < channelCount; i++) {
+    const oscillator = audioContext.createOscillator();
+    oscillator.connect(destination);
+    oscillator.type = WAVE_FORM;
+    oscillator.start(streamStartSeconds);
+    oscillators.push(oscillator);
+  }
+  callFn(ON_START);
+  return oscillators;
+}
+function getOscillators() {
+  return CHANNEL_OSCILLATORS;
+}
+export function send(bits, startSeconds) {
+  const oscillators = getOscillators();
+  getChannels().forEach((channel, i) => {
+    // send missing bits as zero
+    const isHigh = bits[i] ?? 0;
+    callFn(ON_SEND, isHigh);
+    const oscillator = oscillators[i];
+    // already at correct frequency
+    if(oscillator.on === isHigh) return;
+    oscillator.on = isHigh;
+    const hz = channel[isHigh ? 1 : 0];
+    oscillator.frequency.setValueAtTime(hz, startSeconds);
+  });
+}
+const stopTimeout = () => {
+  if(stopOscillatorsTimeoutId) {
+    window.setTimeout(stopOscillatorsTimeoutId);
+    stopOscillatorsTimeoutId = undefined;
+  }
+}
+export function stopAt(streamEndSeconds) {
+  const channels = getChannels();
+  const oscillators = getOscillators();
+  const channelCount = channels.length;
+  // silence oscillators when done
+  for(let channel = 0; channel < channelCount; channel++) {
+    const oscillator = oscillators[channel];
+    oscillator?.stop(streamEndSeconds);
+  }
+  stopTimeout();
+  stopOscillatorsTimeoutId = window.setTimeout(
+    stop,
+    (streamEndSeconds - now()) * 1000
+  );
+}
+export function stop() {
+  const time = now();
+  const oscillators = getOscillators();
+  oscillators.forEach(
+    oscillator => {
+      oscillator?.stop(time);
+      oscillator?.disconnect();
+    }
+  )
+  oscillators.length = 0;
+  callFn(ON_STOP);
+  stopTimeout();
+}
+const callFn = (fn, ...args) => typeof fn === 'function' ? fn(...args) : 0;