Revert "avcodec/mpeg12dec: Do not alter avctx->rc_buffer_size"

This reverts commit eb88ccb92e05018b1060cf8126b30eeeff551d3b.

AVCodecContext fields are the proper place for a decoder to export such values.
This change is in preparation for the following commits.

4 files changed, 10 insertions, 8 deletions

diff --git a/doc/APIchanges b/doc/APIchanges
index dbaec30aac..ff0e543403 100644
--- a/doc/APIchanges
+++ b/doc/APIchanges
@@ -2,6 +2,9 @@ The last version increases of all libraries were on 2023-02-09
 
 API changes, most recent first:
 
+2023-09-06 - xxxxxxxxxx - lavc 60.25.101 - avcodec.h
+  AVCodecContext.rc_buffer_size may now be set by decoders.
+
 2023-09-02 - xxxxxxxxxx - lavu 58.19.100 - executor.h
   Add AVExecutor API
 
diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
index 070e36795d..1f477209b0 100644
--- a/libavcodec/avcodec.h
+++ b/libavcodec/avcodec.h
@@ -1260,7 +1260,7 @@ typedef struct AVCodecContext {
     /**
      * decoder bitstream buffer size
      * - encoding: Set by user.
-     * - decoding: unused
+     * - decoding: May be set by libavcodec.
      */
     int rc_buffer_size;
 
diff --git a/libavcodec/mpeg12dec.c b/libavcodec/mpeg12dec.c
index 36461a9ae6..2290a90778 100644
--- a/libavcodec/mpeg12dec.c
+++ b/libavcodec/mpeg12dec.c
@@ -76,7 +76,6 @@ typedef struct Mpeg1Context {
     unsigned aspect_ratio_info;
     AVRational save_aspect;
     int save_width, save_height, save_progressive_seq;
-    int rc_buffer_size;
     AVRational frame_rate_ext;  /* MPEG-2 specific framerate modificator */
     unsigned frame_rate_index;
     int sync;                   /* Did we reach a sync point like a GOP/SEQ/KEYFrame? */
@@ -1392,7 +1391,7 @@ static void mpeg_decode_sequence_extension(Mpeg1Context *s1)
     bit_rate_ext = get_bits(&s->gb, 12);  /* XXX: handle it */
     s->bit_rate += (bit_rate_ext << 18) * 400LL;
     check_marker(s->avctx, &s->gb, "after bit rate extension");
-    s1->rc_buffer_size += get_bits(&s->gb, 8) * 1024 * 16 << 10;
+    s->avctx->rc_buffer_size += get_bits(&s->gb, 8) * 1024 * 16 << 10;
 
     s->low_delay = get_bits1(&s->gb);
     if (s->avctx->flags & AV_CODEC_FLAG_LOW_DELAY)
@@ -1405,7 +1404,7 @@ static void mpeg_decode_sequence_extension(Mpeg1Context *s1)
     s->codec_id = s->avctx->codec_id = AV_CODEC_ID_MPEG2VIDEO;
 
     if (cpb_props = ff_add_cpb_side_data(s->avctx)) {
-        cpb_props->buffer_size = s1->rc_buffer_size;
+        cpb_props->buffer_size = s->avctx->rc_buffer_size;
         if (s->bit_rate != 0x3FFFF*400)
             cpb_props->max_bitrate = s->bit_rate;
     }
@@ -1414,7 +1413,7 @@ static void mpeg_decode_sequence_extension(Mpeg1Context *s1)
         av_log(s->avctx, AV_LOG_DEBUG,
                "profile: %d, level: %d ps: %d cf:%d vbv buffer: %d, bitrate:%"PRId64"\n",
                s->avctx->profile, s->avctx->level, s->progressive_sequence, s->chroma_format,
-               s1->rc_buffer_size, s->bit_rate);
+               s->avctx->rc_buffer_size, s->bit_rate);
 }
 
 static void mpeg_decode_sequence_display_extension(Mpeg1Context *s1)
@@ -2104,7 +2103,7 @@ static int mpeg1_decode_sequence(AVCodecContext *avctx,
         return AVERROR_INVALIDDATA;
     }
 
-    s1->rc_buffer_size = get_bits(&s->gb, 10) * 1024 * 16;
+    s->avctx->rc_buffer_size = get_bits(&s->gb, 10) * 1024 * 16;
     skip_bits(&s->gb, 1);
 
     /* get matrix */
@@ -2152,7 +2151,7 @@ static int mpeg1_decode_sequence(AVCodecContext *avctx,
 
     if (s->avctx->debug & FF_DEBUG_PICT_INFO)
         av_log(s->avctx, AV_LOG_DEBUG, "vbv buffer: %d, bitrate:%"PRId64", aspect_ratio_info: %d \n",
-               s1->rc_buffer_size, s->bit_rate, s1->aspect_ratio_info);
+               s->avctx->rc_buffer_size, s->bit_rate, s1->aspect_ratio_info);
 
     return 0;
 }
diff --git a/libavcodec/version.h b/libavcodec/version.h
index a744e7469f..aa3a484c51 100644
--- a/libavcodec/version.h
+++ b/libavcodec/version.h
@@ -30,7 +30,7 @@
 #include "version_major.h"
 
 #define LIBAVCODEC_VERSION_MINOR  25
-#define LIBAVCODEC_VERSION_MICRO 100
+#define LIBAVCODEC_VERSION_MICRO 101
 
 #define LIBAVCODEC_VERSION_INT  AV_VERSION_INT(LIBAVCODEC_VERSION_MAJOR, \
                                                LIBAVCODEC_VERSION_MINOR, \