libavfilter: implement avfilter_fill_frame_from_video_buffer_ref()

libavfilter/avcodec.h

@@ -46,6 +46,17 @@ void avfilter_copy_frame_props(AVFilterBufferRef *dst, const AVFrame *src);
  */
 AVFilterBufferRef *avfilter_get_video_buffer_ref_from_frame(const AVFrame *frame, int perms);
 
+/**
+ * Fill an AVFrame with the information stored in picref.
+ *
+ * @param frame an already allocated AVFrame
+ * @param picref a video buffer reference
+ * @return 0 in case of success, a negative AVERROR code in case of
+ * failure
+ */
+int avfilter_fill_frame_from_video_buffer_ref(AVFrame *frame,
+                                              const AVFilterBufferRef *picref);
+
 /**
  * Add frame data to buffer_src.
  *