Software decoding is ffmpeg.
Kodi v21 will give a much newer version of ffmpeg (6.x vs 4.x in Kodi v20).
I’ll have test builds up on the forum shortly after we release Kodi v20.5 at the end of the month.
Keep an eye on this and let me know you get on.
I can provide a Kodi v21 test build earlier to you if you’re interested.
Sam