[FFmpeg-cvslog] lavc/aac_ac3_parser: improve the raw AAC file bit rate calculation
Jun Zhao
git at videolan.org
Fri Jun 26 04:56:50 EEST 2020
ffmpeg | branch: master | Jun Zhao <barryjzhao at tencent.com> | Sun May 17 12:10:05 2020 +0800| [60d79b1df9d4c6030010ccb0c134ede9e33158c2] | committer: Jun Zhao
lavc/aac_ac3_parser: improve the raw AAC file bit rate calculation
Now we just use one ADTS raw frame to calculate the bit rate, it's
lead to a larger error when get the duration from bit rate, the
improvement cumulate Nth ADTS frames to get the average bit rate.
e,g used the command get the duration like:
ffprobe -show_entries format=duration -i fate-suite/aac/foo.aac
before this improvement dump the duration=2.173935
after this improvement dump the duration=1.979267
in fact, the real duration can be get by command like:
ffmpeg -i fate-suite/aac/foo.aac -f null /dev/null with time=00:00:01.97
Also update the fate-adtstoasc_ticket3715.
Signed-off-by: Jun Zhao <barryjzhao at tencent.com>
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=60d79b1df9d4c6030010ccb0c134ede9e33158c2
---
libavcodec/aac_ac3_parser.c | 9 +++++++--
libavcodec/aac_ac3_parser.h | 2 ++
tests/ref/fate/adtstoasc_ticket3715 | 2 +-
3 files changed, 10 insertions(+), 3 deletions(-)
diff --git a/libavcodec/aac_ac3_parser.c b/libavcodec/aac_ac3_parser.c
index 54e459844f..0746798dab 100644
--- a/libavcodec/aac_ac3_parser.c
+++ b/libavcodec/aac_ac3_parser.c
@@ -97,8 +97,13 @@ get_next:
avctx->audio_service_type = s->service_type;
}
- if (avctx->codec_id != AV_CODEC_ID_EAC3)
- avctx->bit_rate = s->bit_rate;
+ /* 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;
+ }
}
return i;
diff --git a/libavcodec/aac_ac3_parser.h b/libavcodec/aac_ac3_parser.h
index c2506a5bfd..b04041f69d 100644
--- a/libavcodec/aac_ac3_parser.h
+++ b/libavcodec/aac_ac3_parser.h
@@ -55,6 +55,8 @@ typedef struct AACAC3ParseContext {
uint64_t state;
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
index 49fa3eb8d9..3b473ee99e 100644
--- a/tests/ref/fate/adtstoasc_ticket3715
+++ b/tests/ref/fate/adtstoasc_ticket3715
@@ -1,4 +1,4 @@
-4110be924e21846d0e174fac679b062e *tests/data/fate/adtstoasc_ticket3715.mov
+3e63cbb6bb6ec756d79fab2632fef305 *tests/data/fate/adtstoasc_ticket3715.mov
33324 tests/data/fate/adtstoasc_ticket3715.mov
#extradata 0: 2, 0x00340022
#tb 0: 1/44100
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