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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)
protected
function InitializeAudioPlaybackEngine(): boolean; override;
function StartAudioPlaybackEngine(): boolean; override;
procedure StopAudioPlaybackEngine(); override;
public
function GetName: String; override;
procedure MixBuffers(dst, src: PChar; size: Cardinal; volume: Integer); override;
end;
var
singleton_AudioPlaybackSDL : IAudioPlayback;
{ 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.InitializeAudioPlaybackEngine(): boolean;
var
desiredAudioSpec, obtainedAudioSpec: TSDL_AudioSpec;
err: integer;
begin
result := false;
SDL_InitSubSystem(SDL_INIT_AUDIO);
FillChar(desiredAudioSpec, sizeof(desiredAudioSpec), 0);
with desiredAudioSpec do
begin
freq := 44100;
format := AUDIO_S16SYS;
channels := 2;
samples := Ini.SDLBufferSize;
callback := @SDLAudioCallback;
userdata := Self;
end;
if(SDL_OpenAudio(@desiredAudioSpec, @obtainedAudioSpec) = -1) then
begin
Log.LogStatus('SDL_OpenAudio: ' + SDL_GetError(), 'UAudioPlayback_SDL');
exit;
end;
FormatInfo := TAudioFormatInfo.Create(
obtainedAudioSpec.channels,
obtainedAudioSpec.freq,
asfS16
);
Log.LogStatus('Opened audio device', 'UAudioPlayback_SDL');
result := true;
end;
function TAudioPlayback_SDL.StartAudioPlaybackEngine(): boolean;
begin
SDL_PauseAudio(0);
result := true;
end;
procedure TAudioPlayback_SDL.StopAudioPlaybackEngine();
begin
SDL_CloseAudio();
end;
procedure TAudioPlayback_SDL.MixBuffers(dst, src: PChar; size: Cardinal; volume: Integer);
begin
// Note: (volume * SDL_MIX_MAXVOLUME) may exceed High(Integer)
// if SDL_MIX_MAXVOLUME (=128 at the moment) changes
SDL_MixAudio(PUInt8(dst), PUInt8(src), size, volume * SDL_MIX_MAXVOLUME div 100);
end;
initialization
singleton_AudioPlaybackSDL := TAudioPlayback_SDL.create();
AudioManager.add( singleton_AudioPlaybackSDL );
finalization
AudioManager.Remove( singleton_AudioPlaybackSDL );
end.
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