1 files changed, 15 insertions, 0 deletions
diff --git a/libass/ass_render.c b/libass/ass_render.c
index 0d774dd987..ded1d56c2f 100644
--- a/libass/ass_render.c
+++ b/libass/ass_render.c
@@ -1943,6 +1943,21 @@ static void shift_event(event_images_t* ei, int shift)
 	ass_image_t* cur = ei->imgs;
 	while (cur) {
 		cur->dst_y += shift;
+		// clip top and bottom
+		if (cur->dst_y < 0) {
+			int clip = - cur->dst_y;
+			cur->h -= clip;
+			cur->bitmap += clip * cur->stride;
+			cur->dst_y = 0;
+		}
+		if (cur->dst_y + cur->h >= frame_context.height) {
+			int clip = cur->dst_y + cur->h - frame_context.height;
+			cur->h -= clip;
+		}
+		if (cur->h <= 0) {
+			cur->h = 0;
+			cur->dst_y = 0;
+		}
 		cur = cur->next;
 	}
 	ei->top += shift;