3 of 3 replaced http://superuser.com/ with https://superuser.com/

Here's how using ffmpeg:

$ ./ffmpeg -i testing.m4v -b:a 192K -vn testing.mp3

Or variable bit-rate:

$ ./ffmpeg -i testing.m4v -q:a 0 -map a testing.mp3

ffmpeg version

$ ./ffmpeg -version
ffmpeg version N-56896-ga927276
built on Oct  5 2013 05:42:36 with gcc 4.6 (Debian 4.6.3-1)
configuration: --prefix=/root/ffmpeg-static/64bit --extra-cflags='-I/root/ffmpeg-static/64bit/include -static' --extra-ldflags='-L/root/ffmpeg-static/64bit/lib -static' --extra-libs='-lxml2 -lexpat -lfreetype' --enable-static --disable-shared --disable-ffserver --disable-doc --enable-bzlib --enable-zlib --enable-postproc --enable-runtime-cpudetect --enable-libx264 --enable-gpl --enable-libtheora --enable-libvorbis --enable-libmp3lame --enable-gray --enable-libass --enable-libfreetype --enable-libopenjpeg --enable-libspeex --enable-libvo-aacenc --enable-libvo-amrwbenc --enable-version3 --enable-libvpx
libavutil      52. 46.100 / 52. 46.100
libavcodec     55. 34.100 / 55. 34.100
libavformat    55. 19.100 / 55. 19.100
libavdevice    55.  3.100 / 55.  3.100
libavfilter     3. 88.101 /  3. 88.101
libswscale      2.  5.100 /  2.  5.100
libswresample   0. 17.103 /  0. 17.103
libpostproc    52.  3.100 / 52.  3.100

References