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lavc/aac_ac3_parser: improve the raw AAC file bit rate calculation

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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@tencent.com>
This commit is contained in:
Jun Zhao 2020-05-17 12:10:05 +08:00
parent a8fb7612a9
commit 60d79b1df9
3 changed files with 10 additions and 3 deletions
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9
libavcodec/aac_ac3_parser.c
View File

@ -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;

2
libavcodec/aac_ac3_parser.h
View File

@ -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;

2
tests/ref/fate/adtstoasc_ticket3715
View File

@ -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