Provided by: libsdl3-doc_3.2.26+ds-2_all 

NAME
SDL_SetAudioDeviceGain - Change the gain of an audio device.
SYNOPSIS
#include <SDL3/SDL_audio.h>
bool SDL_SetAudioDeviceGain(SDL_AudioDeviceID devid, float gain);
DESCRIPTION
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.
FUNCTION PARAMETERS
devid the audio device on which to change gain.
gain the gain. 1.0f is no change, 0.0f is silence.
RETURN VALUE
for more information.
THREAD SAFETY
It is safe to call this function from any thread, as it holds a stream-specific mutex while running.
AVAILABILITY
This function is available since SDL 3.2.0.
SEE ALSO
SDL_GetAudioDeviceGain(3)
Simple Directmedia Layer SDL 3.2.26 SDL_SetAudioDeviceGain(3)