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sdl/examples/audio/03-load-wav/load-wav.c

104 lines
4.0 KiB
C

/*
* This example code creates an simple audio stream for playing sound, and
* loads a .wav file that is pushed through the stream in a loop.
*
* This code is public domain. Feel free to use it for any purpose!
*
* The .wav file is a sample from Will Provost's song, The Living Proof,
* used with permission.
*
* From the album The Living Proof
* Publisher: 5 Guys Named Will
* Copyright 1996 Will Provost
* https://itunes.apple.com/us/album/the-living-proof/id4153978
* http://www.amazon.com/The-Living-Proof-Will-Provost/dp/B00004R8RH
*/
#define SDL_MAIN_USE_CALLBACKS 1 /* use the callbacks instead of main() */
#include <SDL3/SDL.h>
#include <SDL3/SDL_main.h>
/* 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 Uint8 *wav_data = NULL;
static Uint32 wav_data_len = 0;
/* This function runs once at startup. */
SDL_AppResult SDL_AppInit(void **appstate, int argc, char *argv[])
{
SDL_AudioSpec spec;
char *wav_path = NULL;
SDL_SetAppMetadata("Example Audio Load Wave", "1.0", "com.example.audio-load-wav");
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/load-wav", 640, 480, 0, &window, &renderer)) {
SDL_Log("Couldn't create window/renderer: %s", SDL_GetError());
return SDL_APP_FAILURE;
}
/* Load the .wav file from wherever the app is being run from. */
SDL_asprintf(&wav_path, "%ssample.wav", SDL_GetBasePath()); /* allocate a string of the full file path */
if (!SDL_LoadWAV(wav_path, &spec, &wav_data, &wav_data_len)) {
SDL_Log("Couldn't load .wav file: %s", SDL_GetError());
return SDL_APP_FAILURE;
}
SDL_free(wav_path); /* done with this string. */
/* Create our audio stream in the same format as the .wav file. It'll convert to what the audio hardware wants. */
stream = SDL_OpenAudioDeviceStream(SDL_AUDIO_DEVICE_DEFAULT_PLAYBACK, &spec, NULL, 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)
{
/* see if we need to feed the audio stream more data yet.
We're being lazy here, but if there's less than the entire wav file left to play,
just shove a whole copy of it into the queue, so we always have _tons_ of
data queued for playback. */
if (SDL_GetAudioStreamAvailable(stream) < (int)wav_data_len) {
/* feed more data to the stream. It will queue at the end, and trickle out as the hardware needs more data. */
SDL_PutAudioStreamData(stream, wav_data, wav_data_len);
}
/* we're not doing anything with the renderer, so just blank it out. */
SDL_RenderClear(renderer);
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)
{
SDL_free(wav_data); /* strictly speaking, this isn't necessary because the process is ending, but it's good policy. */
/* SDL will clean up the window/renderer for us. */
}