void agl_utils_destroy_null_sink (struct userdata *, struct agl_null_sink *);
pa_sink *agl_utils_get_null_sink (struct userdata *, struct agl_null_sink *);
pa_source *agl_utils_get_null_source (struct userdata *, struct agl_null_sink *);
+void agl_utils_volume_ramp (struct userdata *, struct agl_null_sink *, bool);
/* general helper functions */
const char *agl_utils_get_card_name (pa_card *);