/**
* Open one instance of this filter.
*
- * This should allocate the output buffer of the given filter node and do any
- * other filter-specific preparations like initializing the private_data member
- * of \a fn suitably. The open function is assumed to succeed.
+ * This should allocate the output buffer of the given filter node and
+ * do any other filter-specific preparations like initializing the
+ * private_data member of \a fn suitably. The open function is
+ * optional, If it is provided, it is assumed to succeed.
*/
void (*open)(struct filter_node *fn);
/**
* Close one instance of this filter.
*
- * Free all resources of associated with \a fn that were previously allocated
- * by the open() function. It's OK to leave this alone if the filter does not
- * need any cleanups.
+ * Free all resources associated with \a fn that were previously
+ * allocated by the open() function. It's OK to set this to NULL if the
+ * filter does not need to perform any cleanup operation.
*/
void (*close)(struct filter_node *fn);
/**
/**
* Set scheduler timeout and add file descriptors to fd sets.
*
- * This function is used to control the timeout value for select. It
- * only allowed to decrease the current value. The second purpose of
- * this function is to set file descriptors to be watched by the
- * subsequent select call to the two fd sets.
+ * This function controls the timeout value for the next call to
+ * select(2). It may decrease the current timeout but shall never
+ * increase it. The second purpose of this function is to add file
+ * descriptors to the two fd sets of the sched structure. The
+ * descriptors in these sets will be watched by the subsequent
+ * select(2) call.
*/
void (*pre_select)(struct sched *s, void *context);
/**
};
void filter_init(void);
-int check_filter_arg(char *filter_arg, void **conf);
+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,
DECLARE_FILTER_INITS
-/** Iterate over the array of supported filters. */
-#define FOR_EACH_SUPPORTED_FILTER(j) for (j = 0; j < NUM_SUPPORTED_FILTERS; j++)
-
-/** The filter array, one structure for each supported filter. */
-extern struct filter filters[NUM_SUPPORTED_FILTERS];
+const struct filter *filter_get(int filter_num);