The documentation in this regard is really bad indeed. They apparently want users to use their editor and primarily rely on online sources based upon folder and file name matching. If Plex is (still) anything like Kodi/XBMC here, it relies on FFmpeg to read the MP4 user metadata tags.
| MP4 | FFmpeg (read) | Kodi =? Plex |
|---|---|---|
©nam |
title |
SetTitle |
©com, ©wrt
|
composer |
SetWritingCredits, split at " / "
|
gnre, ©gen
|
genre |
SetGenre, split at " / "
|
©day |
date |
SetYear, parsed as integer |
desc |
description |
SetPlotOutline, toggle tag precedence |
ldes |
synopsis |
SetPlot, toggle tag precedence |
trkn, ©trk
|
track |
m_iTrack, parsed as integer |
©alb |
album |
SetAlbum |
©ART, ©aut
|
artist |
SetArtist |