Saving Youtube Audio for iPhone playback

I'm watching a lot of tutorials these days on Youtube.  A lot of these are fine audio-only, and it would be nice to listen to them on the daily commute.

BUT, unlike the various audio players, the Youtube player pauses when you lock the screen.  So, here's some incantations to grab the audio.

• grab video. I'm using: https://github.com/gantt/downloadyoutube
• ffmpeg -i foo.mp4 -c copy foo.aac
• avconvert  --preset PresetAppleM4VCellular-s foo.aac -o foo.mp3

I think an mp3 codec can be added to ffmpeg.  If anybody knows an easy incantation give me a shout! This may be it:

• ffmpeg -i foo.mp4 -c:a libmp3lame -ac 2 -q:a 2 foo.mp3

blogodex = {"idx" : ["video conversion", "audio extraction", "Youtube"]};