Ffmpeg

http://www.tecmint.com/ffmpeg-commands-for-video-audio-and-image-conversion-in-linux/

https://trac.ffmpeg.org/wiki/CompilationGuide/Ubuntu

mp3
https://superuser.com/questions/704493/ffmpeg-convert-m4a-files-to-mp3-without-significant-loss-of-information-quali

https://trac.ffmpeg.org/wiki/Encode/MP3

https://coderwall.com/p/zbevoq/convert-m4a-to-mp3-with-ffmpeg

https://rg3.github.io/youtube-dl/download.html

See Tahoe for stripping metadata.

links

 * Gist code
 * http://libav.org/ ffmpeg fork http://blog.pkh.me/p/13-the-ffmpeg-libav-situation.html
 * Gprs_and_wifi_streaming and Cctv_cameras modding, rooting webcams.