src/sound/sdl2_s.cpp

   1 /*
   2  * This file is part of OpenTTD.
   3  * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
   4  * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
   5  * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
   6  */
   7
   8 /** @file sdl2_s.cpp Playing sound via SDL2. */
   9
  10 #ifdef WITH_SDL2
  11
  12 #include "../stdafx.h"
  13
  14 #include "../mixer.h"
  15 #include "sdl_s.h"
  16 #include <SDL.h>
  17
  18 #include "../safeguards.h"
  19
  20 /** Factory for the SDL sound driver. */
  21 static FSoundDriver_SDL iFSoundDriver_SDL;
  22
  23 /**
  24  * Callback that fills the sound buffer.
  25  * @param stream   The stream to put data into.
  26  * @param len      The length of the stream in bytes.
  27  */
  28 static void CDECL fill_sound_buffer(void *, Uint8 *stream, int len)
  29 {
  30         MxMixSamples(stream, len / 4);
  31 }
  32
  33 std::optional<std::string_view> SoundDriver_SDL::Start(const StringList &parm)
  34 {
  35         SDL_AudioSpec spec;
  36         SDL_AudioSpec spec_actual;
  37
  38         /* Only initialise SDL if the video driver hasn't done it already */
  39         int ret_code = 0;
  40         if (SDL_WasInit(SDL_INIT_EVERYTHING) == 0) {
  41                 ret_code = SDL_Init(SDL_INIT_AUDIO);
  42         } else if (SDL_WasInit(SDL_INIT_AUDIO) == 0) {
  43                 ret_code = SDL_InitSubSystem(SDL_INIT_AUDIO);
  44         }
  45         if (ret_code == -1) return SDL_GetError();
  46
  47         spec.freq = GetDriverParamInt(parm, "hz", 44100);
  48         spec.format = AUDIO_S16SYS;
  49         spec.channels = 2;
  50         spec.samples = GetDriverParamInt(parm, "samples", 1024);
  51         spec.callback = fill_sound_buffer;
  52         SDL_AudioDeviceID dev = SDL_OpenAudioDevice(nullptr, 0, &spec, &spec_actual, SDL_AUDIO_ALLOW_FREQUENCY_CHANGE);
  53         MxInitialize(spec_actual.freq);
  54         SDL_PauseAudioDevice(dev, 0);
  55         return std::nullopt;
  56 }
  57
  58 void SoundDriver_SDL::Stop()
  59 {
  60         SDL_CloseAudio();
  61         SDL_QuitSubSystem(SDL_INIT_AUDIO);
  62         if (SDL_WasInit(SDL_INIT_EVERYTHING) == 0) {
  63                 SDL_Quit(); // If there's nothing left, quit SDL
  64         }
  65 }
  66
  67 #endif /* WITH_SDL2 */