(This is the legacy documentation for SDL2, the previous stable version; SDL3 is the current stable version.)

SDL_QueueAudio

Queue more audio on non-callback devices.

Header File

Syntax

int SDL_QueueAudio(SDL_AudioDeviceID dev, const void *data, Uint32 len);

Function Parameters

SDL_AudioDeviceID	dev	the device ID to which we will queue audio.
const void *	data	the data to queue to the device for later playback.
Uint32	len	the number of bytes (not samples!) to which `data` points.

Return Value

(int) Returns 0 on success or a negative error code on failure; call SDL_GetError() for more information.

Remarks

If you are looking to retrieve queued audio from a non-callback capture device, you want SDL_DequeueAudio() instead. SDL_QueueAudio() will return -1 to signify an error if you use it with capture devices.

SDL offers two ways to feed audio to the device: you can either supply a callback that SDL triggers with some frequency to obtain more audio (pull method), or you can supply no callback, and then SDL will expect you to supply data at regular intervals (push method) with this function.

There are no limits on the amount of data you can queue, short of exhaustion of address space. Queued data will drain to the device as necessary without further intervention from you. If the device needs audio but there is not enough queued, it will play silence to make up the difference. This means you will have skips in your audio playback if you aren't routinely queueing sufficient data.

This function copies the supplied data, so you are safe to free it when the function returns. This function is thread-safe, but queueing to the same device from two threads at once does not promise which buffer will be queued first.

You may not queue audio on a device that is using an application-supplied callback; doing so returns an error. You have to use the audio callback or queue audio with this function, but not both.

You should not call SDL_LockAudio() on the device before queueing; SDL handles locking internally for this function.

Note that SDL2 does not support planar audio. You will need to resample from planar audio formats into a non-planar one (see SDL_AudioFormat) before queuing audio.

Version

This function is available since SDL 2.0.4.