From 71ebd08406547339a5decd9c61ab3e83739e96b3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Hubert=20G=C5=82uchowski?= <fishhh@fishhh.dev>
Date: Fri, 5 Jun 2026 21:50:26 +0200
Subject: [PATCH] sub/packer: correctly offset instance bitmap pointer in
 `pack_subrandr`

The software scaling code expects this pointer to already be offset
by `src_x` and `src_y` but this function copied a pointer only
offset by the image offset, forgetting about instance offset.
---
 sub/packer.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/sub/packer.c b/sub/packer.c
index 5f4f986d1c..67a8dd766e 100644
--- a/sub/packer.c
+++ b/sub/packer.c
@@ -369,7 +369,9 @@ static bool pack_subrandr(struct mp_sub_packer *p, struct sub_bitmaps *res,
             .w = instance->src_width,  .h = instance->src_height,
             .src_x = image_b->src_x + instance->src_off_x,
             .src_y = image_b->src_y + instance->src_off_y,
-            .bitmap = image_b->bitmap, .stride = byte_stride,
+            .bitmap = (sbr_bgra8 *)image_b->bitmap
+                      + pixel_stride * instance->src_off_y + instance->src_off_x,
+            .stride = byte_stride,
         };
         res->num_parts++;
     }