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audio: SDL_AudioStream now has callbacks for Get and Put operations.

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This allows code to feed a stream (or feed from a stream) on-demand,
which is to say: it can efficiently simulate the SDL2 audio callback.
This commit is contained in:
Ryan C. Gordon 2023-05-28 22:39:39 -04:00
parent 905c4fff5b
commit 56b1bc2198
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GPG key ID: FA148B892AB48044
8 changed files with 286 additions and 10 deletions
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34
test/loopwave.c
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@ -33,11 +33,36 @@ static struct
int freq;
Uint8 *sound; /* Pointer to wave data */
Uint32 soundlen; /* Length of wave data */
Uint32 soundpos;
} wave;
static SDL_AudioDeviceID device;
static SDL_AudioStream *stream;
static void SDLCALL
fillerup(SDL_AudioStream *stream, int len, void *unused)
{
Uint8 *waveptr;
int waveleft;
/*SDL_Log("CALLBACK WANTS %d MORE BYTES!", len);*/
/* Set up the pointers */
waveptr = wave.sound + wave.soundpos;
waveleft = wave.soundlen - wave.soundpos;
/* Go! */
while (waveleft <= len) {
SDL_PutAudioStreamData(stream, waveptr, waveleft);
len -= waveleft;
waveptr = wave.sound;
waveleft = wave.soundlen;
wave.soundpos = 0;
}
SDL_PutAudioStreamData(stream, waveptr, len);
wave.soundpos += len;
}
/* Call this instead of exit(), so we can clean up SDL: atexit() is evil. */
static void
quit(int rc)
@ -78,6 +103,8 @@ open_audio(void)
SDL_free(wave.sound);
quit(2);
}
SDL_SetAudioStreamGetCallback(stream, fillerup, NULL);
}
#ifndef __EMSCRIPTEN__
@ -91,12 +118,6 @@ static void reopen_audio(void)
static int done = 0;
static void fillerup(void)
{
if (SDL_GetAudioStreamAvailable(stream) < (wave.soundlen / 2)) {
SDL_PutAudioStreamData(stream, wave.sound, wave.soundlen);
}
}
#ifdef __EMSCRIPTEN__
@ -192,7 +213,6 @@ int main(int argc, char *argv[])
}
}
fillerup();
SDL_Delay(100);
}
#endif