### Post-processing Options:
--extract-audio convert video files to audio-only files (requires
- ffmpeg and ffprobe)
+ ffmpeg or avconv and ffprobe or avprobe)
--audio-format FORMAT "best", "aac", "vorbis", "mp3", "m4a", or "wav";
best by default
- --audio-quality QUALITY ffmpeg audio bitrate specification, 128k by default
+ --audio-quality QUALITY ffmpeg/avconv audio bitrate specification, 128k by
+ default
-k, --keep-video keeps the video file on disk after the post-
processing; the video is erased by default