Which codec and format are Audible downloads? Files downloaded with the Audible Download Manager are stored with the .aax file extension, but the information I can find about this format seem to vary.
Regarding this source, the files are stored in the M4B container (MPEG-4 Part 14), also a quick look into the file header of the .aax files reveals aax M4B mp42isom.
Furthermore, regarding this source, the audio is encoded with the ACELP codec.
If I would decrypt the .aax files DRM with my Audible authentication code without converting the audio, which format and codec would the audio be in?
(Also I'm not sure if this belongs here or in &quot;Sound Design&quot;.)
As this post over at the apple stackexchange says, .aax files from Audible are indeed encrypted m4b files, which means that if I would decode an .aax file without converting it, I would get a .m4b file.
This is possible with the following command:
ffmpeg.exe -activation_bytes XXXXXX -i input.aax -c copy output.m4b

The -c copy ensures that the data will not be converted.