+ pa_idxset* (*get_formats)(pa_sink *s); /* may be NULL */
+
+ /* Called to set the list of formats supported by the sink. Can be
+ * NULL if the sink does not support this. Returns true on success,
+ * false otherwise (for example when an unsupportable format is
+ * set). Makes a copy of the formats passed in. */
+ bool (*set_formats)(pa_sink *s, pa_idxset *formats); /* may be NULL */
+
+ /* Called whenever the sampling frequency shall be changed. Called from
+ * main thread. */
+ int (*update_rate)(pa_sink *s, uint32_t rate);