UBUNTU does not give you the real ffpmeg + lame so CBR will not work download a static binary of ffmpeg http://www.ffmpeg.org/download.html tar -xf ffmpeg.tar.gz mv ffmpeg /usr/bin/ffmpeg ffmpeg -i input.mp4 -b:a 320000 -minrate 320000 -maxrate 320000 output.mp3

mediainfo output.mp3 General Complete name : output.mp3 Format : MPEG Audio File size : 9.91 MiB Duration : 4mn 19s Overall bit rate mode : Constant Overall bit rate : 320 Kbps Writing library : LAME3.99.5 major_brand : mp42 minor_version : 0 compatible_brands : mp42isom3gp63g2a3gp4

Audio Format : MPEG Audio Format version : Version 1 Format profile : Layer 3 Mode : Joint stereo Duration : 4mn 20s Bit rate mode : Constant Bit rate : 320 Kbps Channel count : 2 channels Sampling rate : 44.1 KHz Compression mode : Lossy Stream size : 9.91 MiB (100%) Writing library : LAME3.99.5

sudo apt-get install ubuntu-restricted-extras

The following extra packages will be installed:
  gstreamer0.10-plugins-bad-multiverse libavcodec-extra-53 libfaac0 libmjpegtools-1.9 libopenjpeg2 libquicktime2
Suggested packages:
  libfaad0
The following packages will be REMOVED:
  libavcodec53
The following NEW packages will be installed:
  gstreamer0.10-plugins-bad-multiverse libavcodec-extra-53 libfaac0 libmjpegtools-1.9 libopenjpeg2 libquicktime2 ubuntu-restricted-extras

avconv -i filename.mp4 # get full info

avconv -i filename.mp4 -f mp3 -ab 192000 -vn filename.mp3 avconv -i filename.mp3

NOTE: file filename.mp3 IS NOT ACCURATE as to kbps

sudo apt-get install mediainfo

mediainfo -l filename.mp4

mediainfo -l filename.mp3 General Complete name : test.mp3 Format : MPEG Audio File size : 6.37 MiB Duration : 4mn 38s Overall bit rate mode : Variable Overall bit rate : 192 Kbps Encoded date : UTC 2009-04- 9 12:31:13 Writing library : LAME3.99.5 major_brand : mp42 minor_version : 0 compatible_brands : mp42isom3gp63g2a3gp4

Audio
Format                                   : MPEG Audio
Format version                           : Version 1
Format profile                           : Layer 3
Mode                                     : Joint stereo
Duration                                 : 4mn 38s
Bit rate mode                            : Variable
Bit rate                                 : 192 Kbps
Channel count                            : 2 channels
Sampling rate                            : 44.1 KHz
Compression mode                         : Lossy
Stream size                              : 6.37 MiB (100%)
Writing library                          : LAME3.99.5

sudo apt-get install ffmpeg libavcodec-extra-52

ffmpeg -i filename.mp4 filename.mp3

( ffmpeg -i video.mp4 -f mp3 -ab 192000 -vn music.mp3 )