A simple interface for playing raw audio samples via the Web Audio API. Meant to mimic the API from dynamicaudio.js.

webaudio.js.coffee

# The WebAudio object can be used to write raw stereo sound samples.
#
# It has one property, "supported" which returns whether the Web Audio API
# is supported, and one method, "writeStereo" which will play sound samples.
class WebAudio
  constructor: ->
    if window.AudioContext? || window.webKitAudioContext?
      @context = new (window.AudioContext ? window.webKitAudioContext)
      @supported = true
    else
      @supported = false

  # Given two Float32Arrays representing samples for the left
  # and right stereo channel, this will immediately play them.
  writeStereo: (samplesL, samplesR) ->
    bufferSize = samplesL.length
    buffer = @context.createBuffer(2, bufferSize, 44100)

    if buffer.copyToChannel?
      buffer.copyToChannel(samplesL, 0)
      buffer.copyToChannel(samplesR, 1)
    else
      left = buffer.getChannelData(0)
      right = buffer.getChannelData(1)
      for i in [0..bufferSize]
        left[i] = samplesL[i]
        right[i] = samplesR[i]

    source = @context.createBufferSource()
    source.buffer = buffer
    source.connect(@context.destination)
    if source.start?
      source.start(0)
    else
      source.noteOn(0)

window.WebAudio = WebAudio