Provided by: allegro5-doc_5.2.9.1+dfsg-1.1build4_all 

NAME
al_set_mixer_postprocess_callback - Allegro 5 API
SYNOPSIS
#include <allegro5/allegro_audio.h>
bool al_set_mixer_postprocess_callback(ALLEGRO_MIXER *mixer,
void (*pp_callback)(void *buf, unsigned int samples, void *data),
void *pp_callback_userdata)
DESCRIPTION
Sets a post-processing filter function that’s called after the attached streams have been mixed. The
buffer’s format will be whatever the mixer was created with. The sample count and user-data pointer is
also passed.
Note: The callback is called from a dedicated audio thread.
Allegro reference manual al_set_mixer_postprocess_callback(3alleg5)