[Big2hd]

I'm not sure if you can use the termux ffmpeg without rooting your Shield. You might be able to copy it to a shareable folder.
Find out what architecture your Shield is either by looking at the top of the kodi.log file or using DroidInfo in the play store. It might also just be in the Kodi Settings somewhere. I can't remember.
Then grab the binary of ffmpeg for that architecture from here: https://github.com/Khang-NT/ffmpeg-binary-android
unzip it and point to it in Settings.
It will get copied to the right place to run.
If it doesn't work turn on Settings \ Debug \ Debug menus and run Maintenance \ Delete ffmpeg. Then try a different ffmpeg binary.   

Yeah, that's the first thing I did cause I had no clue lol, but just in case Downloaded both versions(arm64 btw but according to article I can still use arm if wanted to) unpacked and copied contents to an external drive. This where my problems start. In settings under Jobs and Rule, it is asking for "ffmpeg.exe" but the zip/tar only contains ffmpeg file, which I added the .exe extension and still didn't work. Is there some other setting I should be using the file to point it?   

 You don't need to rename it. Just unzip it and point to the unzipped ffmpeg file.
The Setting does say "ffmpeg exe" rather than ffmpeg.exe. Maybe I should have just said "ffmpeg program".

I know it does work on a Shield because I've got one.
@nashnash has one of the later models than mine and he used arm64_v8a_full.
https://forum.kodi.tv/showthread.php?tid...pid2769634
His problem was needing to turn the Settings \ Debug \ Debug off again.
https://forum.kodi.tv/showthread.php?tid...pid2769691

There are more posts about the Shield in this thread that might help.
https://forum.kodi.tv/showthread.php?tid...pid2767246 

Ah I see so ignore the .exe thing gotcha, still giving me "ffmpeg exe not found" no matter what version I use. FFmpeg Debug option doesn't even give me log so yeah. Maybe Kodi log will point in the right direction. gonna set up my Windows machine just to see if I'm just not missing something general here.  I use SPMC fork so maybe that is a problem too gonna RC 18 a whirl while I'm at.  Looked at posts you gave I just don't see my issue in there.