-int setup_writer_node(const char *arg, struct btr_node *parent,
- struct writer_node *wn);
-int get_btr_samplerate(struct btr_node *btrn, int32_t *result);
-int get_btr_channels(struct btr_node *btrn, int32_t *result);
+void get_btr_sample_rate(struct btr_node *btrn, int32_t *result);
+void get_btr_channels(struct btr_node *btrn, int32_t *result);
+void get_btr_sample_format(struct btr_node *btrn, int32_t *result);