Well, ASS subtitles are the big one for me, because it means video gets transcoded to add them. They have to be embedded, too. External ASS subtitle tracks are completely ignored by the Fire Stick (the client can see them, but they do not play or cause transcoding on the server if you select them, so you just get no subs). These all direct play on the Kodi Plex add-on on the same Fire Stick 4K.
Also AAC 5.1 audio was not working until the release they did just earlier this month (the Fire Stick supports it but there was a bug) – so I guess I can cross that off my list now.
10-bit h264 can be hit or miss. Ironically the player’s lack of support for ASS saves it most of the time (two wrongs make a right). But if it’s using SRT or PGS subs then I have set the Fire Stick to not direct play those sub formats to cause a transcode to watch it.
There was a show I was watching that had Apple Lossless audio on it and the client needed it converted, but in an interesting twist the Plex Server couldn’t transcode it right (stutter/breakup). I just tried that show again now with the newest client and it’s direct playing on the Fire Stick. Audio seems okay, but now video is not playing smoothly. The show plays fine on the Kodi Plex Add-On.
HDR video will not direct play if you have HD audio and subs at the same time. Which makes no sense when it plays fine simply by turning off the subs and the subs are in a format the Fire Stick can direct play.
