[FFmpeg-trac] #2075(undetermined:new): Wrong bitrate when transcoding to aac

FFmpeg trac at avcodec.org
Fri Dec 28 07:31:20 CET 2012


#2075: Wrong bitrate when transcoding to aac
-------------------------------------+-------------------------------------
             Reporter:  ddnlkd       |                     Type:  defect
               Status:  new          |                 Priority:  important
            Component:               |                  Version:  1.0.1
  undetermined                       |               Blocked By:
             Keywords:  aac bitrate  |  Reproduced by developer:  0
             Blocking:               |
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
 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

-- 
Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/2075>
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