audio.ml

open Core

type ('a, 'b, 'c, 'd) t =
    { stream : ('a, 'b, 'c, 'd) Portaudio.stream
    ; num_samples_per_read : int }

let dump_available_devices () =
  let num = Portaudio.get_device_count () in
  List.iter (List.range 0 num) ~f:(fun i ->
    let info = Portaudio.get_device_info i in
    eprintf "%d: %s\n" i info.Portaudio.d_name)

let init ~hz ~num_samples_per_read ~sound_dev =
  Portaudio.init ();
  let num_devices = Portaudio.get_device_count () in
  match
    List.find (List.range 0 num_devices) ~f:(fun device_no ->
      let device_info = Portaudio.get_device_info device_no in
      String.(=) device_info.Portaudio.d_name sound_dev)
  with
  | None ->
    eprintf "*** Couldn't find device.  List of available devices:\n%!";
    dump_available_devices ();
    exit 1
  | Some pulse_device_no ->
    let stream =
      let instream =
        { Portaudio.channels = 1
        ; device = pulse_device_no
        ; sample_format = Portaudio.format_int16
        ; latency = 0.00001 }
      in
      Portaudio.open_stream (Some instream) None ~interleaved:true (Float.of_int hz) num_samples_per_read []
    in
    Portaudio.start_stream stream;
    let t = { stream; num_samples_per_read } in
    t

let read t bbuf =
  Portaudio.read_stream t.stream bbuf 0 t.num_samples_per_read