From a1154b74a4a3635e4106aba9b1c4c0efdd35e07c Mon Sep 17 00:00:00 2001
From: Lynne <dev@lynne.ee>
Date: Sun, 23 Nov 2025 19:49:01 +0100
Subject: [PATCH] ffv1dec: call ff_get_format if the EC coding changes

Decoders need to track all state that hwaccels may be intersted in,
and trigger a reconfiguration if it changes.
---
 libavcodec/ffv1.h    | 1 +
 libavcodec/ffv1dec.c | 5 ++++-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/libavcodec/ffv1.h b/libavcodec/ffv1.h
index adf76b0644..8a48e8e682 100644
--- a/libavcodec/ffv1.h
+++ b/libavcodec/ffv1.h
@@ -140,6 +140,7 @@ typedef struct FFV1Context {
     enum AVPixelFormat pix_fmt;
     enum AVPixelFormat configured_pix_fmt;
     int configured_width, configured_height;
+    int configured_ac;
 
     const AVFrame *cur_enc_frame;
     int plane_count;
diff --git a/libavcodec/ffv1dec.c b/libavcodec/ffv1dec.c
index a70cd74af4..630a60595d 100644
--- a/libavcodec/ffv1dec.c
+++ b/libavcodec/ffv1dec.c
@@ -509,13 +509,15 @@ static int read_header(FFV1Context *f, RangeCoder *c)
 
     if (f->configured_pix_fmt != f->pix_fmt ||
         f->configured_width != f->avctx->width ||
-        f->configured_height != f->avctx->height) {
+        f->configured_height != f->avctx->height ||
+        f->configured_ac != f->ac) {
         f->avctx->pix_fmt = get_pixel_format(f);
         if (f->avctx->pix_fmt < 0)
             return AVERROR(EINVAL);
         f->configured_pix_fmt = f->pix_fmt;
         f->configured_width = f->avctx->width;
         f->configured_height = f->avctx->height;
+        f->configured_ac = f->ac;
     }
 
     ff_dlog(f->avctx, "%d %d %d\n",
@@ -921,6 +923,7 @@ static int update_thread_context(AVCodecContext *dst, const AVCodecContext *src)
     fdst->colorspace          = fsrc->colorspace;
     fdst->pix_fmt             = fsrc->pix_fmt;
     fdst->configured_pix_fmt  = fsrc->configured_pix_fmt;
+    fdst->configured_ac       = fsrc->configured_ac;
 
     fdst->ec                  = fsrc->ec;
     fdst->intra               = fsrc->intra;