(This is the documentation for SDL3, which is the current stable version. SDL2 was the previous version!)

SDL_SetAudioDeviceGain

Change the gain of an audio device.

Header File

Syntax

bool SDL_SetAudioDeviceGain(SDL_AudioDeviceID devid, float gain);

Function Parameters

SDL_AudioDeviceID	devid	the audio device on which to change gain.
float	gain	the gain. 1.0f is no change, 0.0f is silence.

Return Value

(bool) Returns true on success or false on failure; call SDL_GetError() for more information.

Remarks

The gain of a device is its volume; a larger gain means a louder output, with a gain of zero being silence.

Audio devices default to a gain of 1.0f (no change in output).

Physical devices may not have their gain changed, only logical devices, and this function will always return false when used on physical devices. While it might seem attractive to adjust several logical devices at once in this way, it would allow an app or library to interfere with another portion of the program's otherwise-isolated devices.

This is applied, along with any per-audiostream gain, during playback to the hardware, and can be continuously changed to create various effects. On recording devices, this will adjust the gain before passing the data into an audiostream; that recording audiostream can then adjust its gain further when outputting the data elsewhere, if it likes, but that second gain is not applied until the data leaves the audiostream again.

Thread Safety

It is safe to call this function from any thread, as it holds a stream-specific mutex while running.

Version

This function is available since SDL 3.1.3.