diff --git a/examples/CMakeLists.txt b/examples/CMakeLists.txt index b886ba5df..85621449a 100644 --- a/examples/CMakeLists.txt +++ b/examples/CMakeLists.txt @@ -139,6 +139,7 @@ add_sdl_example_executable(renderer-debug-text SOURCES renderer/18-debug-text/de add_sdl_example_executable(audio-simple-playback SOURCES audio/01-simple-playback/simple-playback.c) add_sdl_example_executable(audio-simple-playback-callback SOURCES audio/02-simple-playback-callback/simple-playback-callback.c) add_sdl_example_executable(audio-load-wav SOURCES audio/03-load-wav/load-wav.c DATAFILES ${CMAKE_CURRENT_SOURCE_DIR}/../test/sample.wav) +add_sdl_example_executable(audio-multiple-streams SOURCES audio/04-multiple-streams/multiple-streams.c) add_sdl_example_executable(camera-read-and-draw SOURCES camera/01-read-and-draw/read-and-draw.c) add_sdl_example_executable(pen-drawing-lines SOURCES pen/01-drawing-lines/drawing-lines.c) add_sdl_example_executable(demo-snake SOURCES demo/01-snake/snake.c) diff --git a/examples/audio/04-multiple-streams/README.txt b/examples/audio/04-multiple-streams/README.txt new file mode 100644 index 000000000..cdbc0202b --- /dev/null +++ b/examples/audio/04-multiple-streams/README.txt @@ -0,0 +1,5 @@ +This example code loads .wav files dropped onto the app window, puts +them in an audio stream and binds them for playback. This shows several +streams mixing into a single playback device. + +Drag several files while one is still playing! diff --git a/examples/audio/04-multiple-streams/multiple-streams.c b/examples/audio/04-multiple-streams/multiple-streams.c new file mode 100644 index 000000000..b2c494f88 --- /dev/null +++ b/examples/audio/04-multiple-streams/multiple-streams.c @@ -0,0 +1,151 @@ +/* + * This example code loads .wav files dropped onto the app window, puts + * them in an audio stream and binds them for playback. This shows several + * streams mixing into a single playback device. + * + * This code is public domain. Feel free to use it for any purpose! + */ + +#define SDL_MAIN_USE_CALLBACKS 1 /* use the callbacks instead of main() */ +#include +#include + +/* We will use this renderer to draw into this window every frame. */ +static SDL_Window *window = NULL; +static SDL_Renderer *renderer = NULL; +static SDL_AudioDeviceID audio_device = 0; +static SDL_AudioStream **streams = NULL; +static int num_streams = 0; + +/* This function runs once at startup. */ +SDL_AppResult SDL_AppInit(void **appstate, int argc, char *argv[]) +{ + SDL_SetAppMetadata("Example Audio Multiple Streams", "1.0", "com.example.audio-multiple-streams"); + + if (!SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO)) { + SDL_Log("Couldn't initialize SDL: %s", SDL_GetError()); + return SDL_APP_FAILURE; + } + + if (!SDL_CreateWindowAndRenderer("examples/audio/multiple-streams", 640, 480, 0, &window, &renderer)) { + SDL_Log("Couldn't create window/renderer: %s", SDL_GetError()); + return SDL_APP_FAILURE; + } + + /* open the default audio device in whatever format it prefers; our audio streams will adjust to it. */ + audio_device = SDL_OpenAudioDevice(SDL_AUDIO_DEVICE_DEFAULT_PLAYBACK, NULL); + if (audio_device == 0) { + SDL_Log("Couldn't open audio device: %s", SDL_GetError()); + return SDL_APP_FAILURE; + } + + return SDL_APP_CONTINUE; /* carry on with the program! */ +} + +static void load_wav_file(const char *fname) +{ + int idx; + SDL_AudioSpec spec; + Uint8 *wav_data = NULL; + Uint32 wav_data_len = 0; + + /* Find an unused element in the streams array... */ + for (idx = 0; idx < num_streams; idx++) { + if (streams[idx] == NULL) { + break; + } + } + + /* No space? Grow the array. */ + if (idx == num_streams) { + void *ptr = SDL_realloc(streams, (num_streams + 1) * sizeof (*streams)); + if (!ptr) { + SDL_Log("Out of memory!"); + return; // oh well. + } + streams = (SDL_AudioStream **) ptr; + streams[idx] = NULL; + num_streams++; + } + + /* Load the new .wav file */ + if (!SDL_LoadWAV(fname, &spec, &wav_data, &wav_data_len)) { + SDL_Log("Failed to load '%s': %s", fname, SDL_GetError()); + return; // oh well. + } + + /* Create an audio stream. Set the source format to the wav's format (what + we'll input), leave the dest format NULL here (it'll change to what the + device wants once we bind it). */ + streams[idx] = SDL_CreateAudioStream(&spec, NULL); + if (!streams[idx]) { + SDL_Log("Couldn't create audio stream: %s", SDL_GetError()); + } else if (!SDL_BindAudioStream(audio_device, streams[idx])) { /* once bound, it'll start playing when there is data available! */ + SDL_Log("Failed to bind '%s' stream to device: %s", fname, SDL_GetError()); + } else if (!SDL_PutAudioStreamData(streams[idx], wav_data, (int) wav_data_len)) { + SDL_Log("Failed to put '%s' data into stream: %s", fname, SDL_GetError()); + } else { + /* tell SDL we won't be sending more data to this stream, so don't hold back for resampling. */ + SDL_FlushAudioStream(streams[idx]); + } + + SDL_free(wav_data); +} + +/* This function runs when a new event (mouse input, keypresses, etc) occurs. */ +SDL_AppResult SDL_AppEvent(void *appstate, SDL_Event *event) +{ + if (event->type == SDL_EVENT_QUIT) { + return SDL_APP_SUCCESS; /* end the program, reporting success to the OS. */ + } else if (event->type == SDL_EVENT_DROP_FILE) { + load_wav_file(event->drop.data); + } + return SDL_APP_CONTINUE; /* carry on with the program! */ +} + +/* This function runs once per frame, and is the heart of the program. */ +SDL_AppResult SDL_AppIterate(void *appstate) +{ + int winw = 640, winh = 480; + const char *text = "--> Drag and drop .wav files here <--"; + float x, y; + int i; + + /* see if any streams have finished; destroy them if so. */ + for (i = 0; i < num_streams; i++) { + if (streams[i] && (SDL_GetAudioStreamAvailable(streams[i]) == 0)) { + SDL_DestroyAudioStream(streams[i]); + streams[i] = NULL; + } + } + + SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255); + SDL_RenderClear(renderer); + SDL_GetWindowSize(window, &winw, &winh); + x = (((float) winw) - (SDL_strlen(text) * SDL_DEBUG_TEXT_FONT_CHARACTER_SIZE)) / 2.0f; + y = (((float) winh) - SDL_DEBUG_TEXT_FONT_CHARACTER_SIZE) / 2.0f; + SDL_SetRenderDrawColor(renderer, 255, 255, 255, 255); + SDL_RenderDebugText(renderer, x, y, text); + SDL_RenderPresent(renderer); + + return SDL_APP_CONTINUE; /* carry on with the program! */ +} + +/* This function runs once at shutdown. */ +void SDL_AppQuit(void *appstate, SDL_AppResult result) +{ + int i; + + SDL_CloseAudioDevice(audio_device); + + /* see if any streams have finished; destroy them if so. */ + for (i = 0; i < num_streams; i++) { + if (streams[i]) { + SDL_DestroyAudioStream(streams[i]); + } + } + + SDL_free(streams); + + /* SDL will clean up the window/renderer for us. */ +}