1 files changed, 9 insertions, 2 deletions
diff --git a/libavfilter/internal.h b/libavfilter/internal.h
index 5f0299cb83..c217883319 100644
--- a/libavfilter/internal.h
+++ b/libavfilter/internal.h
@@ -93,6 +93,9 @@ 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);
 
@@ -119,16 +122,20 @@ struct AVFilterPad {
      * in the link structure during start_frame().
      *
      * Input video pads only.
+     *
+     * @return >= 0 on success, a negative AVERROR on error.
      */
-    void (*end_frame)(AVFilterLink *link);
+    int (*end_frame)(AVFilterLink *link);
 
     /**
      * Slice drawing callback. This is where a filter receives video data
      * and should do its processing.
      *
      * Input video pads only.
+     *
+     * @return >= 0 on success, a negative AVERROR on error.
      */
-    void (*draw_slice)(AVFilterLink *link, int y, int height, int slice_dir);
+    int (*draw_slice)(AVFilterLink *link, int y, int height, int slice_dir);
 
     /**
      * Samples filtering callback. This is where a filter receives audio data