void hb_downmix_set_level( hb_downmix_t * downmix, hb_sample_t clev, hb_sample_t slev, hb_sample_t level );
void hb_downmix_adjust_level( hb_downmix_t * downmix );
void hb_downmix_set_bias( hb_downmix_t * downmix, hb_sample_t bias );
void hb_downmix_set_level( hb_downmix_t * downmix, hb_sample_t clev, hb_sample_t slev, hb_sample_t level );
void hb_downmix_adjust_level( hb_downmix_t * downmix );
void hb_downmix_set_bias( hb_downmix_t * downmix, hb_sample_t bias );