For those who would like to decode an Audible AAX file with the FFmpeg binary itself, you may do so with the following:

    ffmpeg -activation_bytes 1CEB00DA -i test.aax -vn -c:a copy output.mp4

Taken from the docs. (http://ffmpeg.org/ffmpeg-all.html#Audible-AAX)

I've downloaded so much junk from the internet trying to do this but just couldn't and now I find it's so simple! Again, Thanks for sharing it. Who would have thought it would be so simple.

Is it reversible though?

THANK YOU!!! I have been wanting to backup my extensive audible library for years but could never find an easy solution.

edit: I have not tried it yet, but this script seems to extract the key from audible

https://github.com/inAudible-NG/audible-activator/blob/maste...