Using miniaudio with pl_mpeg

[jarroddavis68]

Hi, I'm trying to figure out the best way to use ma to playback the audio from pl_mpeg. I'm currently using the high level api and would like to be able to use that if possible. What would be the best way to do this? If there is an example somewhere, kindly point me and I will check it out. I've been searching but not found anything so far.

[jarroddavis68]

Ok, so this seems to work. Not sure it's the best way to do it. Any feedback appreciated.

var
  ringBuffer: TRingBuffer<Single>;
  device: ma_device;
  plm: Pplm_t;
  dataReady: Boolean = False;
  CurrentVolume: Single = 0.5;

procedure ma_data_callback(pDevice: Pma_device; pOutput: Pointer; pInput: Pointer; frameCount: ma_uint32); cdecl;
var
  readPointer: PSingle;
  framesNeeded: Integer;
  i: Integer;
  output: PSingle;
begin
  framesNeeded := frameCount * 2;
  if ringbuffer.AvailableBytes >= framesNeeded then
    begin
      readPointer := ringBuffer.DirectReadPointer(framesNeeded);
      output := PSingle(pOutput);
      for i := 0 to framesNeeded - 1 do
      begin
        output^ := readPointer^ * UnitToScalarValue(CurrentVolume, 1);
        Inc(readPointer);
        Inc(output);
      end;
    end
  else
    begin
      FillChar(pOutput^, framesNeeded * SizeOf(Single), 0);
    end;
end;

procedure audio_decode_callback(plm: Pplm_t; samples: Pplm_samples_t; user: Pointer); cdecl;
begin
  ringBuffer.Write(samples^.interleaved, samples^.count*2);
end;

procedure Test05;
var
  lastTime,targetTime,currentTime,elapsedTime,remainingTime,lastFPSTime, endtime: double;
  frameCount: integer;
  framerate: integer;
  laudio: TAudio;
begin
  glfwInit;
  lastTime := glfwGetTime();
  lastFPSTime := lasttime;
  targetTime := 1.0 / 60;
  frameCount := 0;
  framerate :=0;
  endtime := 0;

  ringBuffer := TRingBuffer<Single>.Create(44100);


  var deviceConfig: ma_device_config := ma_device_config_init(ma_device_type_playback);
  deviceConfig.playback.format := ma_format_f32;
  deviceConfig.playback.channels := 2;
  deviceConfig.sampleRate := 44100;
  deviceConfig.dataCallback := @ma_data_callback;

  if ma_device_init(nil, @deviceConfig, @device) <> MA_SUCCESS then begin
    ringbuffer.free;
    exit;
  end;
  ma_device_start(@device);

  plm := plm_create_with_filename('arc/videos/GameKit.mpg');
  if plm = nil then begin
   ma_device_uninit(@device);
   ringbuffer.free;
   exit;
  end;

  plm_set_audio_decode_callback(plm, @audio_decode_callback, nil);

  while true do
  begin
    // start frame
    currentTime := glfwGetTime();
    elapsedTime := currentTime - lastTime;

    if AnyKeyPressed then Break;

    plm_decode(plm, targetTime);

    if plm_has_ended(plm) = MA_TRUE then
      break;

    // end frame
    Inc(frameCount);
    if (currentTime - lastFPSTime >= 1.0) then
    begin
      framerate := framecount;
      lastFPSTime := currentTime;
      frameCount := 0;
    end;
    lastTime := currentTime;
    remainingTime := targetTime - (currentTime - lastTime);
    if (remainingTime > 0) then
     begin
        endTime := currentTime + remainingTime;
        while glfwGetTime() < endTime do
        begin
          // Busy-wait for the remaining time
        end;
      end;
  end;

  plm_destroy(plm);
  ma_device_uninit(@device);
  laudio.Free;
  ringbuffer.Free;
  glfwTerminate;
end;