youtube audio only download code example
Example: youtube-dl download audio
youtube-dl -F http://www.youtube.com/watch?v={video ID} to get available audio
then
youtube-dl -f {number of available audio} http://www.youtube.com/watch?v={video ID}
youtube-dl -F http://www.youtube.com/watch?v={video ID} to get available audio
then
youtube-dl -f {number of available audio} http://www.youtube.com/watch?v={video ID}