avcodec/mpeg12dec: Do not alter avctx->rc_buffer_size

Signed-off-by: Anton Khirnov <anton@khirnov.net>

libavcodec/mpeg12dec.c

@@ -64,6 +64,7 @@ typedef struct Mpeg1Context {
     int slice_count;
     AVRational save_aspect;
     int save_width, save_height, save_progressive_seq;
+    int rc_buffer_size;
     AVRational frame_rate_ext;  /* MPEG-2 specific framerate modificator */
     int sync;                   /* Did we reach a sync point like a GOP/SEQ/KEYFrame? */
     int tmpgexs;
@@ -1417,7 +1418,7 @@ 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");
-    s->avctx->rc_buffer_size += get_bits(&s->gb, 8) * 1024 * 16 << 10;
+    s1->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)
@@ -1433,7 +1434,7 @@ 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,
-               s->avctx->rc_buffer_size, s->bit_rate);
+               s1->rc_buffer_size, s->bit_rate);
 }
 
 static void mpeg_decode_sequence_display_extension(Mpeg1Context *s1)
@@ -2118,7 +2119,7 @@ static int mpeg1_decode_sequence(AVCodecContext *avctx,
         return AVERROR_INVALIDDATA;
     }
 
-    s->avctx->rc_buffer_size = get_bits(&s->gb, 10) * 1024 * 16;
+    s1->rc_buffer_size = get_bits(&s->gb, 10) * 1024 * 16;
     skip_bits(&s->gb, 1);
 
     /* get matrix */
@@ -2167,7 +2168,7 @@ 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",
-               s->avctx->rc_buffer_size, s->bit_rate, s->aspect_ratio_info);
+               s1->rc_buffer_size, s->bit_rate, s->aspect_ratio_info);
 
     return 0;
 }