al_set_sample_instance_length - Allegro 5 API

       Set  the  length  of  the  sample  instance in sample values.  This can be used to play only parts of the
       underlying sample.  Be careful not to exceed the actual length of the sample data, though.

       Return true on success, false on failure.  Will fail if the sample instance is currently playing.

       al_set_sample_instance_length - Allegro 5 API

al_get_sample_instance_length(3alleg5)

Allegro reference manual                                                  al_set_sample_instance_length(3alleg5)

              #include <allegro5/allegro_audio.h>

              bool al_set_sample_instance_length(ALLEGRO_SAMPLE_INSTANCE *spl,
                 unsigned int val)