-int check_filter_arg(char *filter_arg, void **conf);
-void print_filter_helps(int detailed);
-void generic_filter_pre_select(struct sched *s, struct task *t);
+int check_filter_arg(const char *fa, void **conf);
+void print_filter_helps(unsigned flags);
+void generic_filter_pre_select(struct sched *s, void *context);
+int decoder_execute(const char *cmd, unsigned sample_rate, unsigned channels,
+ char **result);