It is also worth noting other pieces out of man youtube-dl (a online copy can be found here): You can list the available format with youtube-dl -F Resulting in an m4a file or youtube-dl -f bestaudio -extract-audio -embed-thumbnail -add-metadata So, if quality and file size matter to you, you should avoid re-encoding and stay with Youtube's native music formats: youtube-dl -f bestaudio -embed-thumbnail -add-metadata The default is 5 and might be a better choice depending on the source quality. The -audio-quality 0 uses the highest encoding quality but can increase your file size unnecessarily. So your command could be: youtube-dl -f bestaudio -extract-audio -audio-format mp3 -audio-quality 0 audio-quality QUALITY Specify ffmpeg/avconv audio quality, insert a value between 0 (better) and 9 (worse) for VBR or a specific bitrate like 128K (default

audio-format FORMAT Specify audio format: 'best', 'aac', 'vorbis', 'mp3', 'm4a', 'opus', or 'wav' 'best' by default

From man youtube-dl: -x, -extract-audio Convert video files to audio-only files (requires ffmpeg or avconv and ffprobe or avprobe)

Youtubedl download playlist