+/**
+ * Prints a listing containing all the codecs supported by the
+ * program.
+ */
+void show_codecs(void);
+
+/**
+ * Prints a listing containing all the filters supported by the
+ * program.
+ */
+void show_filters(void);
+
+/**
+ * Prints a listing containing all the bit stream filters supported by the
+ * program.
+ */
+void show_bsfs(void);
+
+/**
+ * Prints a listing containing all the protocols supported by the
+ * program.
+ */
+void show_protocols(void);
+
+/**
+ * Prints a listing containing all the pixel formats supported by the
+ * program.
+ */
+void show_pix_fmts(void);
+
+/**
+ * Returns a positive value if reads from standard input a line
+ * starting with [yY], otherwise returns 0.
+ */
+int read_yesno(void);
+