add m4a/aac, ogg audio codec support

[yuzujin99]

aac, ogg have much higher quality and lower size compared to mp3, and they are widely supported by almost all the podcast client.

[mxpv]

Could you please provide an example of youtube-dl configuration you use?

[sean89503]

For m4a youtube-dl -f 140 https://www.youtube.com/watch?v=7E-cwdnsiow

[reactorcoremeltdown]

For better audio quality something like youtube_dl_args = [ "--audio-quality", "192K" ] could help maybe? This tells ffmpeg which bitrate to use for encoding (there's no mp3 hosted on youtube anyways).