Ffmpeg

For FFmpeg with Constant Bitrate Encoding (CBR):

ffmpeg -i video.mp4 -vn \
       -acodec libmp3lame -ac 2 -ab 160k -ar 48000 \
        audio.mp3

or if you want to use Variable Bitrate Encoding (VBR):

ffmpeg -i video.mp4 -vn \
       -acodec libmp3lame -ac 2 -qscale:a 4 -ar 48000 \
        audio.mp3

The VBR example has a target bitrate of 165 Kbit/s with a bitrate range of 140...185.