Mix_Volume -- Change the volume of a channel
#include "SDL_mixer.h" int Mix_Volume(int channel, int volume);
MIx_Volume changes the volume of the channel specified in channel by the amount set in volume. The range of volume is from 0 to MIX_MAX_VOLUME which is 128. Passing -1 to channel will change the volume of all channels. If the specified volume is -1, it will just return the current volume.
Returns the previously set volume of the channel.