From 6aaedb813fa11ba0679c3051bc2eb28646b9506c Mon Sep 17 00:00:00 2001 From: 3gg <3gg@shellblade.net> Date: Sat, 30 Aug 2025 16:53:58 -0700 Subject: Update to SDL3 --- .../simple-playback-callback.c | 115 +++++++++++++++++++++ 1 file changed, 115 insertions(+) create mode 100644 src/contrib/SDL-3.2.20/examples/audio/02-simple-playback-callback/simple-playback-callback.c (limited to 'src/contrib/SDL-3.2.20/examples/audio/02-simple-playback-callback/simple-playback-callback.c') diff --git a/src/contrib/SDL-3.2.20/examples/audio/02-simple-playback-callback/simple-playback-callback.c b/src/contrib/SDL-3.2.20/examples/audio/02-simple-playback-callback/simple-playback-callback.c new file mode 100644 index 0000000..c011c72 --- /dev/null +++ b/src/contrib/SDL-3.2.20/examples/audio/02-simple-playback-callback/simple-playback-callback.c @@ -0,0 +1,115 @@ +/* + * This example code creates a simple audio stream for playing sound, and + * generates a sine wave sound effect for it to play as time goes on. Unlike + * the previous example, this uses a callback to generate sound. + * + * This might be the path of least resistance if you're moving an SDL2 + * program's audio code to SDL3. + * + * 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_AudioStream *stream = NULL; +static int current_sine_sample = 0; + +/* this function will be called (usually in a background thread) when the audio stream is consuming data. */ +static void SDLCALL FeedTheAudioStreamMore(void *userdata, SDL_AudioStream *astream, int additional_amount, int total_amount) +{ + /* total_amount is how much data the audio stream is eating right now, additional_amount is how much more it needs + than what it currently has queued (which might be zero!). You can supply any amount of data here; it will take what + it needs and use the extra later. If you don't give it enough, it will take everything and then feed silence to the + hardware for the rest. Ideally, though, we always give it what it needs and no extra, so we aren't buffering more + than necessary. */ + additional_amount /= sizeof (float); /* convert from bytes to samples */ + while (additional_amount > 0) { + float samples[128]; /* this will feed 128 samples each iteration until we have enough. */ + const int total = SDL_min(additional_amount, SDL_arraysize(samples)); + int i; + + /* generate a 440Hz pure tone */ + for (i = 0; i < total; i++) { + const int freq = 440; + const float phase = current_sine_sample * freq / 8000.0f; + samples[i] = SDL_sinf(phase * 2 * SDL_PI_F); + current_sine_sample++; + } + + /* wrapping around to avoid floating-point errors */ + current_sine_sample %= 8000; + + /* feed the new data to the stream. It will queue at the end, and trickle out as the hardware needs more data. */ + SDL_PutAudioStreamData(astream, samples, total * sizeof (float)); + additional_amount -= total; /* subtract what we've just fed the stream. */ + } +} + +/* This function runs once at startup. */ +SDL_AppResult SDL_AppInit(void **appstate, int argc, char *argv[]) +{ + SDL_AudioSpec spec; + + SDL_SetAppMetadata("Example Simple Audio Playback Callback", "1.0", "com.example.audio-simple-playback-callback"); + + if (!SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO)) { + SDL_Log("Couldn't initialize SDL: %s", SDL_GetError()); + return SDL_APP_FAILURE; + } + + /* we don't _need_ a window for audio-only things but it's good policy to have one. */ + if (!SDL_CreateWindowAndRenderer("examples/audio/simple-playback-callback", 640, 480, 0, &window, &renderer)) { + SDL_Log("Couldn't create window/renderer: %s", SDL_GetError()); + return SDL_APP_FAILURE; + } + + /* We're just playing a single thing here, so we'll use the simplified option. + We are always going to feed audio in as mono, float32 data at 8000Hz. + The stream will convert it to whatever the hardware wants on the other side. */ + spec.channels = 1; + spec.format = SDL_AUDIO_F32; + spec.freq = 8000; + stream = SDL_OpenAudioDeviceStream(SDL_AUDIO_DEVICE_DEFAULT_PLAYBACK, &spec, FeedTheAudioStreamMore, NULL); + if (!stream) { + SDL_Log("Couldn't create audio stream: %s", SDL_GetError()); + return SDL_APP_FAILURE; + } + + /* SDL_OpenAudioDeviceStream starts the device paused. You have to tell it to start! */ + SDL_ResumeAudioStreamDevice(stream); + + return SDL_APP_CONTINUE; /* carry on with the program! */ +} + +/* 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. */ + } + 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) +{ + /* we're not doing anything with the renderer, so just blank it out. */ + SDL_RenderClear(renderer); + SDL_RenderPresent(renderer); + + /* all the work of feeding the audio stream is happening in a callback in a background thread. */ + + return SDL_APP_CONTINUE; /* carry on with the program! */ +} + +/* This function runs once at shutdown. */ +void SDL_AppQuit(void *appstate, SDL_AppResult result) +{ + /* SDL will clean up the window/renderer for us. */ +} + -- cgit v1.2.3