From 985a26be28f838e47cf2208e0254a7edf731ab41 Mon Sep 17 00:00:00 2001
From: Lynne <dev@lynne.ee>
Date: Tue, 8 Apr 2025 05:45:16 +0000
Subject: [PATCH] vulkan_ffv1: shortcut +-1 coeffs in symbol reading

Slightly faster, and allows for further optimizations.
---
 libavcodec/vulkan/ffv1_dec.comp | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/libavcodec/vulkan/ffv1_dec.comp b/libavcodec/vulkan/ffv1_dec.comp
index 4cc3b9987f..fd9b98023c 100644
--- a/libavcodec/vulkan/ffv1_dec.comp
+++ b/libavcodec/vulkan/ffv1_dec.comp
@@ -119,7 +119,10 @@ int get_isymbol(inout RangeCoder c, uint64_t state)
     for (e = 0; e < 32; e++)
         if (!get_rac(c, state + min(e, 9)))
             break;
-    if (e > 31) {
+
+    if (e == 0) {
+        return get_rac(c, state + 10) ? -1 : 1;
+    } else if (e > 31) {
         corrupt = true;
         return 0;
     }