public static extern int avfilter_insert_filter(AVFilterLink* link, AVFilterContext* filt, int filt_srcpad_idx, int filt_dstpad_idx);
 public static extern int avfilter_link_get_channels(AVFilterLink* link);
 public static extern void avfilter_link_set_closed(AVFilterLink* link, int closed);
 public static extern void avfilter_link_free(AVFilterLink** link);