this beta version @ Plex Media Server will let you disable transcoding (still a work in progress) for the whole server.
It is NOT possible to disable transcoding for one library.
Again, disabling transcoding will not make the videos play. It will make them NOT play.
The only way to avoid transcoding is to play content on devices that are compatible with the video codec (ie hevc), the audio codec (ie truehd/ac3/dts), and subtitles if enabled (srt/pgs/etc).
