Get the number of bytes of still-queued audio.
Uint32 SDL_GetQueuedAudioSize(SDL_AudioDeviceID dev);
the device ID of which we will query queued audio size
Returns the number of bytes (not samples!) of queued audio.
For playback devices: this is the number of bytes that have been queued for playback with SDL_QueueAudio(), but have not yet been sent to the hardware.
Once we've sent it to the hardware, this function can not decide the exact byte boundary of what has been played. It's possible that we just gave the hardware several kilobytes right before you called this function, but it hasn't played any of it yet, or maybe half of it, etc.
For capture devices, this is the number of bytes that have been captured by the device and are waiting for you to dequeue. This number may grow at any time, so this only informs of the lower-bound of available data.
You may not queue or dequeue audio on a device that is using an application-supplied callback; calling this function on such a device always returns 0. You have to use the audio callback or queue audio, but not both.
You should not call SDL_LockAudio() on the device before querying; SDL handles locking internally for this function.
This function is available since SDL 2.0.4.