lavc/aac_ac3_parser: fix potential overflow when averaging bitrate

The new code is analog to how it's done in our mpegaudio parser. Acked-by: Jun Zhao <[email protected]> Signed-off-by: Alexander Strasser <[email protected]>
lgeek · Aug 12, 2020 · ecd7191 · ecd7191
1 parent 1201687
commit ecd7191
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Showing 3 changed files with 3 additions and 5 deletions.
diff --git a/libavcodec/aac_ac3_parser.c b/libavcodec/aac_ac3_parser.c
@@ -100,9 +100,8 @@ int ff_aac_ac3_parse(AVCodecParserContext *s1,
         /* Calculate the average bit rate */
         s->frame_number++;
         if (avctx->codec_id != AV_CODEC_ID_EAC3) {
-            avctx->bit_rate =
-                (s->last_bit_rate * (s->frame_number -1) + s->bit_rate)/s->frame_number;
-            s->last_bit_rate = avctx->bit_rate;
+            avctx->bit_rate +=
+                (s->bit_rate - avctx->bit_rate) / s->frame_number;
         }
     }
 

diff --git a/libavcodec/aac_ac3_parser.h b/libavcodec/aac_ac3_parser.h
@@ -56,7 +56,6 @@ typedef struct AACAC3ParseContext {
 
     int need_next_header;
     int frame_number;
-    int last_bit_rate;
     enum AVCodecID codec_id;
 } AACAC3ParseContext;
 

diff --git a/tests/ref/fate/adtstoasc_ticket3715 b/tests/ref/fate/adtstoasc_ticket3715
@@ -1,4 +1,4 @@
-3e63cbb6bb6ec756d79fab2632fef305 *tests/data/fate/adtstoasc_ticket3715.mov
+29ef0632a8eb5c336bf45a1d5076626e *tests/data/fate/adtstoasc_ticket3715.mov
 33324 tests/data/fate/adtstoasc_ticket3715.mov
 #extradata 0:        2, 0x00340022
 #tb 0: 1/44100