1 files changed, 160 insertions, 0 deletions
diff --git a/src/media/UAudioPlayback_SDL.pas b/src/media/UAudioPlayback_SDL.pas
new file mode 100644
index 00000000..deef91e8
--- /dev/null
+++ b/src/media/UAudioPlayback_SDL.pas
@@ -0,0 +1,160 @@
+unit UAudioPlayback_SDL;
+
+interface
+
+{$IFDEF FPC}
+  {$MODE Delphi}
+{$ENDIF}
+
+{$I switches.inc}
+
+
+uses
+  Classes,
+  SysUtils,
+  UMusic;
+
+implementation
+
+uses
+  sdl,
+  UAudioPlayback_SoftMixer,
+  ULog,
+  UIni,
+  UMain;
+
+type
+  TAudioPlayback_SDL = class(TAudioPlayback_SoftMixer)
+    private
+      Latency: double;
+      function EnumDevices(): boolean;
+    protected
+      function InitializeAudioPlaybackEngine(): boolean; override;
+      function StartAudioPlaybackEngine(): boolean;      override;
+      procedure StopAudioPlaybackEngine();               override;
+      function FinalizeAudioPlaybackEngine(): boolean;   override;
+      function GetLatency(): double;                     override;
+    public
+      function GetName: String;                          override;
+      procedure MixBuffers(dst, src: PChar; size: Cardinal; volume: Single); override;
+  end;
+
+  
+{ TAudioPlayback_SDL }
+
+procedure SDLAudioCallback(userdata: Pointer; stream: PChar; len: integer); cdecl;
+var
+  Engine: TAudioPlayback_SDL;
+begin
+  Engine := TAudioPlayback_SDL(userdata);
+  Engine.AudioCallback(stream, len);
+end;
+
+function TAudioPlayback_SDL.GetName: String;
+begin
+  Result := 'SDL_Playback';
+end;
+
+function TAudioPlayback_SDL.EnumDevices(): boolean;
+begin
+  // Note: SDL does not provide Device-Selection capabilities (will be introduced in 1.3)
+  ClearOutputDeviceList();
+  SetLength(OutputDeviceList, 1);
+  OutputDeviceList[0] := TAudioOutputDevice.Create();
+  OutputDeviceList[0].Name := '[SDL Default-Device]';
+  Result := true;
+end;
+
+function TAudioPlayback_SDL.InitializeAudioPlaybackEngine(): boolean;
+var
+  DesiredAudioSpec, ObtainedAudioSpec: TSDL_AudioSpec;
+  SampleBufferSize: integer;
+begin
+  Result := false;
+
+  EnumDevices();
+
+  if (SDL_InitSubSystem(SDL_INIT_AUDIO) = -1) then
+  begin
+    Log.LogError('SDL_InitSubSystem failed!', 'TAudioPlayback_SDL.InitializeAudioPlaybackEngine');
+    Exit;
+  end;
+
+  SampleBufferSize := IAudioOutputBufferSizeVals[Ini.AudioOutputBufferSizeIndex];
+  if (SampleBufferSize <= 0) then
+  begin
+    // Automatic setting default
+    // FIXME: too much glitches with 1024 samples
+    SampleBufferSize := 2048; //1024;
+  end;
+
+  FillChar(DesiredAudioSpec, SizeOf(DesiredAudioSpec), 0);
+  with DesiredAudioSpec do
+  begin
+    freq := 44100;
+    format := AUDIO_S16SYS;
+    channels := 2;
+    samples := SampleBufferSize;
+    callback := @SDLAudioCallback;
+    userdata := Self;
+  end;
+
+  // Note: always use the "obtained" parameter, otherwise SDL might try to convert
+  // the samples itself if the desired format is not available. This might lead
+  // to problems if for example ALSA does not support 44100Hz and proposes 48000Hz.
+  // Without the obtained parameter, SDL would try to convert 44.1kHz to 48kHz with
+  // its crappy (non working) converter resulting in a wrong (too high) pitch.
+  if(SDL_OpenAudio(@DesiredAudioSpec, @ObtainedAudioSpec) = -1) then
+  begin
+    Log.LogStatus('SDL_OpenAudio: ' + SDL_GetError(), 'TAudioPlayback_SDL.InitializeAudioPlaybackEngine');
+    Exit;
+  end;
+
+  FormatInfo := TAudioFormatInfo.Create(
+    ObtainedAudioSpec.channels,
+    ObtainedAudioSpec.freq,
+    asfS16
+  );
+
+  // Note: SDL does not provide info of the internal buffer state.
+  // So we use the average buffer-size.
+  Latency := (ObtainedAudioSpec.samples/2) / FormatInfo.SampleRate;
+
+  Log.LogStatus('Opened audio device', 'TAudioPlayback_SDL.InitializeAudioPlaybackEngine');
+
+  Result := true;
+end;
+
+function TAudioPlayback_SDL.StartAudioPlaybackEngine(): boolean;
+begin
+  SDL_PauseAudio(0);
+  Result := true;
+end;
+
+procedure TAudioPlayback_SDL.StopAudioPlaybackEngine();
+begin
+  SDL_PauseAudio(1);
+end;
+
+function TAudioPlayback_SDL.FinalizeAudioPlaybackEngine(): boolean;
+begin
+  SDL_CloseAudio();
+  SDL_QuitSubSystem(SDL_INIT_AUDIO);
+  Result := true;
+end;
+
+function TAudioPlayback_SDL.GetLatency(): double;
+begin
+  Result := Latency;
+end;
+
+procedure TAudioPlayback_SDL.MixBuffers(dst, src: PChar; size: Cardinal; volume: Single);
+begin
+  SDL_MixAudio(PUInt8(dst), PUInt8(src), size, Round(volume * SDL_MIX_MAXVOLUME));
+end;
+
+
+initialization
+  MediaManager.add(TAudioPlayback_SDL.Create);
+
+end.