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-rw-r--r--src/media/UAudioPlayback_SDL.pas160
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.