anchor: RecordingDevice:start
  Begins recording audio using this device.
  success = RecordingDevice:start( samplecount, samplerate, bitdepth, channels )
  samplecount number The maximum number of samples to store in an internal ring buffer when recording. RecordingDevice:getData clears the internal buffer when called.
  samplerate (8000) number The number of samples per second to store when recording.
  bitdepth (16) number The number of bits per sample.
  channels (1) number Whether to record in mono or stereo. Most microphones don't support more than 1 channel.
  success boolean True if the device successfully began recording using the specified parameters, false if not.