1 files changed, 3 insertions, 0 deletions
diff --git a/libavfilter/internal.h b/libavfilter/internal.h
index 26059c927b..c08e00bcb8 100644
--- a/libavfilter/internal.h
+++ b/libavfilter/internal.h
@@ -69,6 +69,9 @@ struct AVFilterPad {
      * picture inside the link structure.
      *
      * Input video pads only.
+     *
+     * @return >= 0 on success, a negative AVERROR on error. picref will be
+     * unreferenced by the caller in case of error.
      */
     void (*start_frame)(AVFilterLink *link, AVFilterBufferRef *picref);