[FFmpeg-devel] [PATCH] avcodec/gifenc: avoid redundant local color table when global palette is used (PR #20897)

[FFmpeg-devel] [PATCH] avcodec/gifenc: avoid redundant local color table when global palette is used (PR #20897)

[damitha via ffmpeg-devel]

PR #20897 opened by damitha
URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/20897
Patch URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/20897.patch

Addressing the fact that first frame has a LCT when global palette is used for pal8.
issue: [#20896](https://code.ffmpeg.org/FFmpeg/FFmpeg/issues/20896)




>From 66ba0e8c08668f1796469058024db4cd182289ec Mon Sep 17 00:00:00 2001
From: Damitha Gunawardena <damitha.gunawardena@gmail.com>
Date: Wed, 12 Nov 2025 15:12:07 +1100
Subject: [PATCH] avcodec/gifenc: avoid redundant local color table when global
 palette is used

Addressing the fact that first frame has a LCT when global pallette is used for pal8.
issue: #20896
---
 libavcodec/gif.c           | 2 ++
 tests/ref/fate/gifenc-pal8 | 2 +-
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/libavcodec/gif.c b/libavcodec/gif.c
index c11cad8d38..132ce07e6c 100644
--- a/libavcodec/gif.c
+++ b/libavcodec/gif.c
@@ -492,6 +492,8 @@ static int gif_encode_frame(AVCodecContext *avctx, AVPacket *pkt,
             memcpy(s->palette, palette, AVPALETTE_SIZE);
             s->transparent_index = get_palette_transparency_index(palette);
             s->palette_loaded = 1;
+            if (s->use_global_palette)
+                palette = NULL;
         } else if (!memcmp(s->palette, palette, AVPALETTE_SIZE)) {
             palette = NULL;
         }
diff --git a/tests/ref/fate/gifenc-pal8 b/tests/ref/fate/gifenc-pal8
index 1a074b8fd8..d4a42b03b2 100644
--- a/tests/ref/fate/gifenc-pal8
+++ b/tests/ref/fate/gifenc-pal8
@@ -3,7 +3,7 @@
 #codec_id 0: gif
 #dimensions 0: 217x217
 #sar 0: 0/1
-0,          0,          0,        1,     2109, 0x39642b3d
+0,          0,          0,        1,     1341, 0xe4e2af18
 0,          1,          1,        1,      236, 0x332769fd, F=0x0
 0,          2,          2,        1,      186, 0x770d5061, F=0x0
 0,          3,          3,        1,      208, 0x55784c8f, F=0x0
-- 
2.49.1

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