Set callbacks that fire around a new iteration of audio device processing.
Defined in <SDL3/SDL_audio.h>
bool SDL_SetAudioIterationCallbacks(SDL_AudioDeviceID devid, SDL_AudioIterationCallback start, SDL_AudioIterationCallback end, void *userdata);| SDL_AudioDeviceID | devid | the ID of an opened audio device. |
| SDL_AudioIterationCallback | start | a callback function to be called at the start of an iteration. Can be NULL. |
| SDL_AudioIterationCallback | end | a callback function to be called at the end of an iteration. Can be NULL. |
| void * | userdata | app-controlled pointer passed to callback. Can be NULL. |
(bool) Returns true on success or false on failure; call SDL_GetError() for more information.
Two callbacks are provided here: one that runs when a device is about to process its bound audio streams, and another that runs when the device has finished processing them.
These callbacks can run at any time, and from any thread; if you need to serialize access to your app's data, you should provide and use a mutex or other synchronization device.
Generally these callbacks are used to apply state that applies to multiple bound audio streams, with a guarantee that the audio device's thread isn't halfway through processing them. Generally a finer-grained lock through SDL_LockAudioStream() is more appropriate.
The callbacks are extremely time-sensitive; the callback should do the least amount of work possible and return as quickly as it can. The longer the callback runs, the higher the risk of audio dropouts or other problems.
This function will block until the audio device is in between iterations, so any existing callback that might be running will finish before this function sets the new callback and returns.
Physical devices do not accept these callbacks, only logical devices created through SDL_OpenAudioDevice() can be.
Setting a NULL callback function disables any previously-set callback. Either callback may be NULL, and the same callback is permitted to be used for both.
It is safe to call this function from any thread.
This function is available since SDL 3.4.0.