SDL Wiki
(This is the documentation for SDL3, which is under heavy development and the API is changing! SDL2 is the current stable version!)


Set a callback that runs when data is added to an audio stream.


int SDL_SetAudioStreamPutCallback(SDL_AudioStream *stream, SDL_AudioStreamCallback callback, void *userdata);

Function Parameters

stream the audio stream to set the new callback on.
callback the new callback function to call when data is added to the stream.
userdata an opaque pointer provided to the callback for its own personal use.

Return Value

Returns 0 on success, -1 on error. This only fails if stream is NULL.


This callback is called after the data is added to the stream, giving the callback the chance to obtain it immediately.

The callback can (optionally) call SDL_GetAudioStreamData() to obtain audio from the stream during this call.

The callback's approx_request argument is how many bytes of converted data (in the stream's output format) was provided by the caller, although this may underestimate a little for safety. This value might be less than what is currently available in the stream, if data was already there, and might be less than the caller provided if the stream needs to keep a buffer to aid in resampling. Which means the callback may be provided with zero bytes, and a different amount on each call.

The callback may call SDL_GetAudioStreamAvailable to see the total amount currently available to read from the stream, instead of the total provided by the current call.

The callback is not required to obtain all data. It is allowed to read less or none at all. Anything not read now simply remains in the stream for later access.

Clearing or flushing an audio stream does not call this callback.

This function obtains the stream's lock, which means any existing callback (get or put) in progress will finish running before setting the new callback.

Setting a NULL function turns off the callback.

Thread Safety

It is safe to call this function from any thread.


This function is available since SDL 3.0.0.


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