[RockerC]

Yep. In a first instance, I'd suggest to agree on a single, hardcoded, profile (e.g h264 + aac) to maximize the chances to reach the transcoding goal for most of potential clients.

In that case then might to just copy the Built-In Presets from example HandBrake for specific player clients. Also FFmpeg have have their own iOS compatibility matrix for x264 encoding presets. These preset profiles are pre-configured with resolution, bitrates, and video/audio profiles.

https://trac.handbrake.fr/wiki/BuiltInPresets
https://trac.ffmpeg.org/wiki/Encode/H.264
http://rodrigopolo.com/ffmpeg/cheats.php

Have a drop-down list in Kodi's GUI where the user can manually select one out of ~10 preset profiles, as one preset could use 1080p x264 with AAC and another 720p x264 with MP3. At least then you will meet more people requirements and still being relatively user-friendly without having to automate the process.

So no need to even display the specific encoding specifications in Kodi's GUI, instead only have a simple drop-down list with a few per-configured preset profiles for the most probable commonly occurring clients.

Example of devices as preset profiles that user can select in Kodi's GUI settings

• Universal Low-End Profile
  
• Universal Midrange-End Profile
  
• Universal High-End Profile
  
• iPod
  
• iPhone & iPod Touch
  
• iPad
  
• AppleTV 2
  
• AppleTV 3
  
• Android Phone (Midrange-End)
  
• Android Tablet (High-End)