FFMPEG is a great swiss army knife of media conversion and manipulation. This is a tip for future me more than anything because I will probably forget this again next time I need it. My Odroid Go can play audio files (ogg, mp3, FLAC) but there is a bug where the playback is distorted if the file is mono rather than stereo. This isn't usually a problem for music but I like listening to podcasts on my Odroid Go and some of the ones I listen to are mono.
So here is the very simple command to copy the audio track to a second channel thus converting it to stereo and making it playback normally on my Odroid Go. You're welcome future me.
ffmpeg -i input.ogg -ac 2 output.ogg