[FFmpeg-trac] #4055(ffmpeg:new): MP3 encoding bitrates go above 320Kbps

[FFmpeg]

#4055: MP3 encoding bitrates go above 320Kbps
-------------------------------------+-------------------------------------
             Reporter:  fidalgo      |                     Type:  defect
               Status:  new          |                 Priority:  normal
            Component:  ffmpeg       |                  Version:  2.1.5
             Keywords:  mp3          |               Blocked By:
  encoding bitrate                   |  Reproduced by developer:  0
             Blocking:               |
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
 Summary of the bug: When I encode an mp3 using the guide in documentation,
 I'll get frames with bitrate higher than 320Kbps.
 How to reproduce:
 {{{
 % ffmpeg -i 2L38_01_96kHz.flac -codec:a libmp3lame -qscale:a 0
 2L38_01_96kHz.mp3
 }}}


 The file used is from here:
 http://www.lindberg.no/hires/test/2L38_01_96kHz.flac

 I'm using ffmpeg from rpm-fusion in Fedora 20:

 {{{
  ffmpeg version 2.1.5 Copyright (c) 2000-2014 the FFmpeg developers
   built on Jul  8 2014 20:44:17 with gcc 4.8.3 (GCC) 20140624 (Red Hat
 4.8.3-1)
   configuration: --prefix=/usr --bindir=/usr/bin
 --datadir=/usr/share/ffmpeg --incdir=/usr/include/ffmpeg
 --libdir=/usr/lib64 --mandir=/usr/share/man --arch=x86_64 --optflags='-O2
 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-
 strong --param=ssp-buffer-size=4 -grecord-gcc-switches -m64
 -mtune=generic' --enable-bzlib --disable-crystalhd --enable-frei0r
 --enable-gnutls --enable-libass --enable-libcdio --enable-libcelt
 --enable-libdc1394 --disable-indev=jack --enable-libfreetype --enable-
 libgsm --enable-libmp3lame --enable-openal --enable-libopencv --enable-
 libopenjpeg --enable-libopus --enable-libpulse --enable-libschroedinger
 --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libvorbis
 --enable-libv4l2 --enable-libvpx --enable-libx264 --enable-libxvid
 --enable-x11grab --enable-avfilter --enable-avresample --enable-postproc
 --enable-pthreads --disable-static --enable-shared --enable-gpl --disable-
 debug --disable-stripping --shlibdir=/usr/lib64 --enable-runtime-cpudetect
   libavutil      52. 48.101 / 52. 48.101
   libavcodec     55. 39.101 / 55. 39.101
   libavformat    55. 19.104 / 55. 19.104
   libavdevice    55.  5.100 / 55.  5.100
   libavfilter     3. 90.100 /  3. 90.100
   libavresample   1.  1.  0 /  1.  1.  0
   libswscale      2.  5.101 /  2.  5.101
   libswresample   0. 17.104 /  0. 17.104
   libpostproc    52.  3.100 / 52.  3.100
 Hyper fast Audio and Video encoder
 }}}

 For reference there is a note in wikipedia in bitrate section:
 [http://en.wikipedia.org/wiki/MP3]

 Non-standard bit rates up to 640 kbit/s can be achieved with the LAME
 encoder and the freeformat option, although few MP3 players can play those
 files. According to the ISO standard, decoders are only required to be
 able to decode streams up to 320 kbit/s

--
Ticket URL: <https://trac.ffmpeg.org/ticket/4055>
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