Personally, I regard this as a bug, since it causes data loss in normal operation.
Sonarr will quite happily overwrite a 720p video file with multi-channel audio with a 1080p video file with stereo audio.
I realize it’s not important for consumption on mobile devices, but if you’re watching on a home-theater setup, it most certainly is.
I can understand not wanting to try to crack the problem of scoring audio encodings to figure out what is an ‘upgrade’, but IMHO going from 5.1 to 2 channels is a significant loss of information, and Sonarr shouldn’t automatically replace a file with one that has fewer audio channels.
To me, that’s the crux of the issue, we don’t need a sophisticated subsystem to ‘score’ a DTS Master soundtrack higher than an AC3 one, or take bitrates into account. Just don’t decrease audio channel count (unless told to).
I have yet to find a way to leave Sonarr on ‘full auto’ that doesn’t risk losing a 5.1 mix for a stereo one.
If there were versions of the ‘quality’ categories that had ‘-stereo’ and ‘-multichannel’ suffixes, that would solve the problem, e.g. ‘hdtv-720p-multichannel’ could be ordered with a higher priority than ‘webdl-1080p-stereo’ in a profile.
Hope you’ll give this some consideration. Thanks for a great piece of software,