Convert .ogv to .mp3

Refer to https://superuser.com/questions/164334/command-line-to-convert-ogv-to-mp4-video-files

Use ffmpeg

For x264 encoded .mp4

$ ffmpeg -i INPUT -vcodec libx264 "OUTPUT.mp4"

For VP8.webm

$ ffmpeg -i "INPUT" -vcodec libvpx -acodec libvorbis -f webm "OUTPUT.mp4"