[PR] [release/9.0] avcodec/pthread_frame: sync decoded side data to all worker threads (PR #24150)

PR #24150 opened by ffmpeg-devel
URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/24150
Patch URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/24150.patch

**Backport:** https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/23989

Previously only the first thread's context and the user-facing one had
it, so frames decoded by the remaining worker threads were missing
global side data whenever the per-frame state could not provide it, e.g.
extradata-derived HDR metadata after avcodec_flush_buffers().


From eee63b86fae4a719ad83a1ccb8856bf464512ab4 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Kacper=20Michaj=C5=82ow?= <[email protected]>
Date: Sun, 2 Aug 2026 22:22:58 +0200
Subject: [PATCH] avcodec/pthread_frame: sync decoded side data to all worker
 threads
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Previously only the first thread's context and the user-facing one had
it, so frames decoded by the remaining worker threads were missing
global side data whenever the per-frame state could not provide it, e.g.
extradata-derived HDR metadata after avcodec_flush_buffers().

Signed-off-by: Kacper Michajłow <[email protected]>
(cherry picked from commit c48230eb86ff02246f6a14fa1475a0d9398363b4)
---
 libavcodec/pthread_frame.c | 19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/libavcodec/pthread_frame.c b/libavcodec/pthread_frame.c
index e6dcc23c15..1814ab2768 100644
--- a/libavcodec/pthread_frame.c
+++ b/libavcodec/pthread_frame.c
@@ -882,17 +882,18 @@ static av_cold int init_thread(PerThreadContext *p, int *threads_to_free,
     }
     p->thread_init = NEEDS_CLOSE;
 
-    if (first) {
+    if (first)
         update_context_from_thread(avctx, copy, 1);
 
-        av_frame_side_data_free(&avctx->decoded_side_data, &avctx->nb_decoded_side_data);
-        for (int i = 0; i < copy->nb_decoded_side_data; i++) {
-            err = av_frame_side_data_clone(&avctx->decoded_side_data,
-                                           &avctx->nb_decoded_side_data,
-                                           copy->decoded_side_data[i], 0);
-            if (err < 0)
-                return err;
-        }
+    const AVCodecContext *src = first ? copy : avctx;
+    AVCodecContext       *dst = first ? avctx : copy;
+    av_frame_side_data_free(&dst->decoded_side_data, &dst->nb_decoded_side_data);
+    for (int i = 0; i < src->nb_decoded_side_data; i++) {
+        err = av_frame_side_data_clone(&dst->decoded_side_data,
+                                       &dst->nb_decoded_side_data,
+                                       src->decoded_side_data[i], 0);
+        if (err < 0)
+            return err;
     }
 
     atomic_init(&p->debug_threads, (copy->debug & FF_DEBUG_THREADS) != 0);
-- 
2.52.0

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