From 96e8af6c4d031313e42a5dfb5caf2bcab48bf976 Mon Sep 17 00:00:00 2001
From: Anton Khirnov <anton@khirnov.net>
Date: Wed, 10 Jul 2024 17:20:07 +0200
Subject: [PATCH] lavc/ffv1: move ac_byte_count to per-slice context

---
 libavcodec/ffv1.h    | 2 +-
 libavcodec/ffv1dec.c | 6 +++---
 libavcodec/ffv1enc.c | 9 ++++-----
 3 files changed, 8 insertions(+), 9 deletions(-)

diff --git a/libavcodec/ffv1.h b/libavcodec/ffv1.h
index bee7b75614..ae81940073 100644
--- a/libavcodec/ffv1.h
+++ b/libavcodec/ffv1.h
@@ -85,6 +85,7 @@ typedef struct FFV1SliceContext {
     PutBitContext pb;
     RangeCoder c;
 
+    int ac_byte_count;                   ///< number of bytes used for AC coding
     uint64_t rc_stat[256][2];
     uint64_t (*rc_stat2[MAX_QUANT_TABLES])[32][2];
 } FFV1SliceContext;
@@ -109,7 +110,6 @@ typedef struct FFV1Context {
     const AVFrame *cur_enc_frame;
     int plane_count;
     int ac;                              ///< 1=range coder <-> 0=golomb rice
-    int ac_byte_count;                   ///< number of bytes used for AC coding
     int16_t quant_tables[MAX_QUANT_TABLES][MAX_CONTEXT_INPUTS][256];
     int context_count[MAX_QUANT_TABLES];
     uint8_t state_transition[256];
diff --git a/libavcodec/ffv1dec.c b/libavcodec/ffv1dec.c
index 187359c9c6..d171660c85 100644
--- a/libavcodec/ffv1dec.c
+++ b/libavcodec/ffv1dec.c
@@ -323,10 +323,10 @@ static int decode_slice(AVCodecContext *c, void *arg)
     if (f->ac == AC_GOLOMB_RICE) {
         if (f->version == 3 && f->micro_version > 1 || f->version > 3)
             get_rac(&sc->c, (uint8_t[]) { 129 });
-        fs->ac_byte_count = f->version > 2 || (!x && !y) ? sc->c.bytestream - sc->c.bytestream_start - 1 : 0;
+        sc->ac_byte_count = f->version > 2 || (!x && !y) ? sc->c.bytestream - sc->c.bytestream_start - 1 : 0;
         init_get_bits(&gb,
-                      sc->c.bytestream_start + fs->ac_byte_count,
-                      (sc->c.bytestream_end - sc->c.bytestream_start - fs->ac_byte_count) * 8);
+                      sc->c.bytestream_start + sc->ac_byte_count,
+                      (sc->c.bytestream_end - sc->c.bytestream_start - sc->ac_byte_count) * 8);
     }
 
     av_assert1(width && height);
diff --git a/libavcodec/ffv1enc.c b/libavcodec/ffv1enc.c
index a17fdd35ec..b861210462 100644
--- a/libavcodec/ffv1enc.c
+++ b/libavcodec/ffv1enc.c
@@ -1060,10 +1060,10 @@ retry:
         encode_slice_header(f, fs, sc);
     }
     if (f->ac == AC_GOLOMB_RICE) {
-        fs->ac_byte_count = f->version > 2 || (!x && !y) ? ff_rac_terminate(&sc->c, f->version > 2) : 0;
+        sc->ac_byte_count = f->version > 2 || (!x && !y) ? ff_rac_terminate(&sc->c, f->version > 2) : 0;
         init_put_bits(&sc->pb,
-                      sc->c.bytestream_start + fs->ac_byte_count,
-                      sc->c.bytestream_end - sc->c.bytestream_start - fs->ac_byte_count);
+                      sc->c.bytestream_start + sc->ac_byte_count,
+                      sc->c.bytestream_end - sc->c.bytestream_start - sc->ac_byte_count);
     }
 
     if (f->colorspace == 0 && c->pix_fmt != AV_PIX_FMT_YA8) {
@@ -1212,7 +1212,6 @@ static int encode_frame(AVCodecContext *avctx, AVPacket *pkt,
 
     buf_p = pkt->data;
     for (i = 0; i < f->slice_count; i++) {
-        FFV1Context *fs = f->slice_context[i];
         FFV1SliceContext *sc = &f->slices[i];
         int bytes;
 
@@ -1220,7 +1219,7 @@ static int encode_frame(AVCodecContext *avctx, AVPacket *pkt,
             bytes = ff_rac_terminate(&sc->c, 1);
         } else {
             flush_put_bits(&sc->pb); // FIXME: nicer padding
-            bytes = fs->ac_byte_count + put_bytes_output(&sc->pb);
+            bytes = sc->ac_byte_count + put_bytes_output(&sc->pb);
         }
         if (i > 0 || f->version > 2) {
             av_assert0(bytes < pkt->size / f->slice_count);