I’ve got FireTV 4K units and I normally have no problems playing any video files (I only use 1080p so even acceleration generally isn’t needed), but I have issues with music files “skipping”. I assume it’s an extremely brief WiFi connection issue since local files don’t seem to have the problem and it doesn’t happen all the time with every music file. Some people in some threads elsewhere have suggested the cache buffermode in advancedsettings.xml have helped on their systems, but when I enable it I get no visual indication that it’s caching the music file playback at all (unlike videos where you can see the light grey bar filling in) and I still seem to get audio skips (I plan to test it with larger settings since someone elsewhere suggested the amount of cache used was smaller for smaller files like music). I’ve had to keep older AppleTV units around just for music since unless I want to keep an SD card around with my entire music library on it, I cannot trust Kodi to play music without a skip. I believe AppleTV buffers everything as I normally never get skips with it, but I have had some skips once in awhile with Airplay and an Airport Express that is much closer to the router than the FIreTV unit, indicating even a small hiccup in WiFi streaming with little or no buffer can cause an audio glitch. If there were some way to get Kodi to cache the music files ahead so that any brief interruption wouldn’t have any effect, that would be useful.
Even more bizarre, I discovered while playing with the video cache settings that SOME 1080p video files I have will go into slow-motion followed by re-buffering with the cache buffermode set to 1 (buffer all local network files) while these same files play perfectly fine with the buffermode set to zero. It only seems to be a few 1080p files so far that have this issue but it’s always the same ones so there might be something wrong with those files, but I thought it strange they would play better/perfect without any local cache than with it. So even if the cache settings can be made to work with music files, it would cause issues with a few video files here.