diff --git a/libavfilter/avfilter.c b/libavfilter/avfilter.c
index f3dea6e65e..823e1ba9c5 100644
--- a/libavfilter/avfilter.c
+++ b/libavfilter/avfilter.c
@@ -190,7 +190,7 @@ int avfilter_link_get_channels(AVFilterLink *link)
     return link->channels;
 }
 
-static void ff_filter_set_ready(AVFilterContext *filter, unsigned priority)
+void ff_filter_set_ready(AVFilterContext *filter, unsigned priority)
 {
     filter->ready = FFMAX(filter->ready, priority);
 }
diff --git a/libavfilter/filters.h b/libavfilter/filters.h
index d3c4c3085c..72e5676369 100644
--- a/libavfilter/filters.h
+++ b/libavfilter/filters.h
@@ -27,6 +27,18 @@
 
 #include "avfilter.h"
 
+/**
+ * Mark a filter ready and schedule it for activation.
+ *
+ * This is automatically done when something happens to the filter (queued
+ * frame, status change, request on output).
+ * Filters implementing the activate callback can call it directly to
+ * perform one more round of processing later.
+ * It is also useful for filters reacting to external or asynchronous
+ * events.
+ */
+void ff_filter_set_ready(AVFilterContext *filter, unsigned priority);
+
 /**
  * Test and acknowledge the change of status on the link.
  *