MP4 isn’t the best option - unless you have devices that won’t direct play MKVs. The TV has very little to do with the whole deal, unless you’re running an old Plex App that may be installed on it.
Image based subs like ASS, PGS, Other are more than likely going to need ‘burning in’ (transcoding) while Text Based Subs (UTF-8) are likely to Direct Play.
When that annoying H.264 to H.264 message comes up in ‘Now Playing’ - you don’t know what’s happening - unless it specifically says: Direct Play. Depending on your Devices, seeing what the stream is actually doing may be better in the Device. An Android Device, for instance, has a very nice ‘Display Information’ feature (basically it’s only redeeming value) that when enabled, will inform you exactly what is happening and tell you why something is transcoding. A Roku is a little less informative, but you can see the condition of the streams.
Since Plex Development sees very little need to let the user know what the stream is actually doing in ‘Now Playing’ and if you aren’t using an Android App, or a Roku, digging tirelessly through logs is the only way to reveal exactly what is going on… unfortunately.
At my house I use Plex Media Player, Roku and AFTVs (that get very little use, except troubleshooting via Display Information), due to there being no real AFTV Design Team. Whatever the Android Team vomits out is what the AFTV gets and seeing as how in SIX YEARS Plex hasn’t been able to develop a working Plex App for an AFTV, mine doesn’t see much Plex Use - if any.
I do create ALL the material - or re-create it, if it won’t Direct Play - so ALL my 720x480 material Direct Plays at 480p, not 400p and looks pretty good, considering it’s only 480p, but there’s nothing wrong with a good strong 480p video stream. There’s a LOT wrong with a 400p video stream, but unfortunately Plex doesn’t know how to program their transcoder.
If it won’t Direct Play - it will by the time I’m done with it and 480p stuff MUST Direct Play, or Plex will annihilate it.
Handbrake Guide in my sig - in case you need it.