Opened 4 years ago

Closed 4 years ago

#2075 closed defect (invalid)

Wrong bitrate when transcoding to aac

Reported by: ddnlkd Owned by:
Priority: normal Component: undetermined
Version: 1.0.1 Keywords: libfaac
Cc: Blocked By:
Blocking: Reproduced by developer: no
Analyzed by developer: no

Description

Summary of the bug:
I want to transcode from a mp3 file to aac file, the command line is as following :
ffmpeg -y -v 9 -loglevel 99 -i 10.mp3 -acodec libfaac -ac 2 -ab 32000 10.aac
I Specified the bitrate as 32kbps, but the output file bitrate is 58.5kbits/s.

Following is the output and attach is the oringal file:
ffmpeg version 1.0.1 Copyright (c) 2000-2012 the FFmpeg developers

built on Dec 25 2012 11:55:44 with gcc 3.4.6 (GCC) 20060404 (Red Hat 3.4.6-10)
configuration: --prefix=/usr --enable-gpl --enable-shared --enable-libfaac --enable-nonfree --disable-yasm
libavutil 51. 73.101 / 51. 73.101
libavcodec 54. 59.100 / 54. 59.100
libavformat 54. 29.104 / 54. 29.104
libavdevice 54. 2.101 / 54. 2.101
libavfilter 3. 17.100 / 3. 17.100
libswscale 2. 1.101 / 2. 1.101
libswresample 0. 15.100 / 0. 15.100
libpostproc 52. 0.100 / 52. 0.100

[mp3 @ 0x82f1500] Format mp3 probed with size=131072 and score=51
[mp3 @ 0x82f1500] pad 576 576
[mp3 @ 0x82f1500] File position before avformat_find_stream_info() is 107743
[mjpeg @ 0x82f9100] marker=d8 avail_size_in_buf=45910
[mjpeg @ 0x82f9100] marker parser used 0 bytes (0 bits)
[mjpeg @ 0x82f9100] marker=e0 avail_size_in_buf=45908
[mjpeg @ 0x82f9100] marker parser used 16 bytes (128 bits)
[mjpeg @ 0x82f9100] marker=fe avail_size_in_buf=45890
[mjpeg @ 0x82f9100] marker parser used 60 bytes (480 bits)
[mjpeg @ 0x82f9100] marker=db avail_size_in_buf=45828
[mjpeg @ 0x82f9100] index=0
[mjpeg @ 0x82f9100] qscale[0]: 0
[mjpeg @ 0x82f9100] marker parser used 67 bytes (536 bits)
[mjpeg @ 0x82f9100] marker=db avail_size_in_buf=45759
[mjpeg @ 0x82f9100] index=1
[mjpeg @ 0x82f9100] qscale[1]: 0
[mjpeg @ 0x82f9100] marker parser used 67 bytes (536 bits)
[mjpeg @ 0x82f9100] marker=c0 avail_size_in_buf=45690
[mjpeg @ 0x82f9100] sof0: picture: 240x240
[mjpeg @ 0x82f9100] component 0 2:2 id: 0 quant:0
[mjpeg @ 0x82f9100] component 1 1:1 id: 1 quant:1
[mjpeg @ 0x82f9100] component 2 1:1 id: 2 quant:1
[mjpeg @ 0x82f9100] pix fmt id 22111100
[mjpeg @ 0x82f9100] marker parser used 17 bytes (136 bits)
[mjpeg @ 0x82f9100] marker=c4 avail_size_in_buf=45671
[mjpeg @ 0x82f9100] class=0 index=0 nb_codes=12
[mjpeg @ 0x82f9100] marker parser used 31 bytes (248 bits)
[mjpeg @ 0x82f9100] marker=c4 avail_size_in_buf=45638
[mjpeg @ 0x82f9100] class=1 index=0 nb_codes=251
[mjpeg @ 0x82f9100] marker parser used 181 bytes (1448 bits)
[mjpeg @ 0x82f9100] marker=c4 avail_size_in_buf=45455
[mjpeg @ 0x82f9100] class=0 index=1 nb_codes=12
[mjpeg @ 0x82f9100] marker parser used 31 bytes (248 bits)
[mjpeg @ 0x82f9100] marker=c4 avail_size_in_buf=45422
[mjpeg @ 0x82f9100] class=1 index=1 nb_codes=251
[mjpeg @ 0x82f9100] marker parser used 181 bytes (1448 bits)
[mjpeg @ 0x82f9100] escaping removed 218 bytes
[mjpeg @ 0x82f9100] marker=da avail_size_in_buf=45239
[mjpeg @ 0x82f9100] component: 0
[mjpeg @ 0x82f9100] component: 1
[mjpeg @ 0x82f9100] component: 2
[mjpeg @ 0x82f9100] marker parser used 45020 bytes (360155 bits)
[mjpeg @ 0x82f9100] marker=d9 avail_size_in_buf=0
[mjpeg @ 0x82f9100] decode frame unused 0 bytes
[mp3 @ 0x82f1500] max_analyze_duration 5000000 reached at 5015510
[mp3 @ 0x82f1500] File position after avformat_find_stream_info() is 189663
Input #0, mp3, from '10.mp3':

Metadata:

artist : 曲婉婷
title : 我的歌声里
Tagging time : 2012-09-03T03:39:33
album : 网络新神曲
TYER : 2012-07-20

Duration: 00:03:36.71, start: 0.000000, bitrate: 131 kb/s

Stream #0:0, 194, 1/14112000: Audio: mp3, 44100 Hz, stereo, s16, 128 kb/s
Stream #0:1, 1, 1/90000: Video: mjpeg, yuvj420p, 240x240 [SAR 1:1 DAR 1:1], 1/90000, 90k tbr, 90k tbn, 90k tbc
Metadata:

title : e
comment : Cover (front)

[abuffer @ 0x8369c20] Setting entry with key 'time_base' to value '1/44100'
[abuffer @ 0x8369c20] Setting entry with key 'sample_rate' to value '44100'
[abuffer @ 0x8369c20] Setting entry with key 'sample_fmt' to value 's16'
[abuffer @ 0x8369c20] Setting entry with key 'channel_layout' to value '0x3'
[graph 0 input from stream 0:0 @ 0x83589e0] tb:1/44100 samplefmt:s16 samplerate:44100 chlayout:0x3
[aformat @ 0x836fb60] Setting entry with key 'sample_fmts' to value 's16'
[aformat @ 0x836fb60] Setting entry with key 'channel_layouts' to value '0x3'
Output #0, adts, to '10.aac':

Metadata:

artist : 曲婉婷
title : 我的歌声里
Tagging time : 2012-09-03T03:39:33
album : 网络新神曲
TYER : 2012-07-20
encoder : Lavf54.29.104
Stream #0:0, 0, 1/90000: Audio: aac, 44100 Hz, stereo, s16, 32 kb/s

Stream mapping:

Stream #0:0 -> #0:0 (mp3 -> libfaac)

Press [q] to stop, ? for help
[mp3 @ 0x82f1500] demuxer injecting skip 1105
[mp3 @ 0x82f8380] skip 1105 samples due to side data
[mp3 @ 0x82f8380] skip 1105/1152 samples
EOF on sink link output stream 0:0:default.59.0kbits/s
No more output streams to write to, finishing.
[libfaac @ 0x831b980] Trying to remove 81 more samples than are in the que
size= 1547kB time=00:03:36.71 bitrate= 58.5kbits/s
video:0kB audio:1547kB subtitle:0 global headers:0kB muxing overhead 0.000000%
[AVIOContext @ 0x82f9ae0] Statistics: 3575132 bytes read, 0 seeks

Change History (1)

comment:1 Changed 4 years ago by cehoyos

  • Keywords libfaac added; aac bitrate removed
  • Priority changed from important to normal
  • Resolution set to invalid
  • Status changed from new to closed

Please test the following:
$ ffmpeg -i 10.mp3 10.wav
$ faac -b 32 10.wav
faac's console output will tell you if it was successful reaching the bitrate that you specified. Please reopen this ticket if it works correctly. (libfaac is an external library, the bitrate that you specify is passed to the library, we cannot guarantee that an external library works as expected.)

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