* which is a way to add filters as a playlist entry - useful only in a multitrack. See FxCut on the wiki.
* \properties \em mix_in
* \properties \em mix_out
+ * \event \em playlist-next The playlist fires this when it moves to the next item in the list.
+ * The listener receives one argument that is the index of the entry that just completed.
*/
struct mlt_playlist_s