Plex Media Server is the server half of the Plex system. It runs on a Windows, macOS or Linux computer, on supported NAS units from Synology, QNAP, Netgear and others, or on an NVIDIA SHIELD. It takes the video, music and photos stored on that machine and serves them to Plex apps on phones, browsers, smart TVs, streaming boxes and game consoles. The server software is free; an optional Plex Pass subscription unlocks extra server functions and remote video streaming.
Libraries built from folders
Plex Media Server organizes everything into libraries. The owner creates a library for one content type, such as movies, TV shows, music, photos or home video, and points it at one or more folders. The server reads those folders and presents them as a catalog with posters, descriptions and episode lists instead of file names. Plex Media Server accepts common formats such as MKV, MP4, AVI, FLAC, MP3 and RAW photos.
Libraries can stay current without manual refreshes. The server can rescan when the operating system reports a change in a source folder. If desired, it can limit the rescan to the changed folder. It can also scan on a timer for drives where change detection does not work, such as some network mounts.
How Plex identifies files
Scanners decide which movie, episode or album a file represents, relying mainly on folder layout and file names, plus tags and acoustic fingerprints for music. Metadata agents then attach artwork, summaries and cast details to the match.
Naming therefore matters in Plex. Plex reliably matches an episode stored as Show Name (2020)/Season 02/Show Name (2020) - s02e17.mkv. Mixed movie and TV folders often produce wrong results. When a match is ambiguous, an ID in the folder name or a .plexmatch file can steer it. For home videos, a less strict scanner indexes files without looking anything up online.
Background analysis
The server can also process media as scheduled tasks during its regular maintenance period. It creates preview thumbnails for scrubbing along a timeline and measures music loudness so apps can level volume between tracks. With Plex Pass, it detects TV intros, end credits and commercials in recordings, which powers Skip Intro and Skip Credits buttons. Plex Pass also lets the server analyze music for sonic similarity to build track radio and mixes. These jobs are CPU- and disk-heavy, so they can run at lower priority on modest hardware.
Direct Play, Direct Stream and transcoding
When an app requests a title, Plex Media Server compares the file with what that device can decode and picks one of three paths:
- Direct Play: the device supports the file as it is, so the server sends it unchanged.
- Direct Stream: the device can decode the audio and video but not the container, so the server repackages the streams without re-encoding them.
- Transcoding: a track is incompatible, or the connection needs a lower bitrate, so the server converts that track and leaves compatible ones alone.
Transcoding runs on the server’s processor and writes temporary files to disk. An incompatible subtitle forces a full video transcode because the server must burn the text into the picture. Plex Pass adds hardware-accelerated transcoding on supported chips, HDR-to-SDR tone mapping and limits on bandwidth and transcoder use.
Access outside the home network
With Remote Access enabled, Plex Media Server tries to open a router port automatically through UPnP or NAT-PMP. It then has the Plex service confirm that the server is reachable from the internet. If that fails, the owner can forward a port manually and enter it in the server settings. Double NAT and carrier-grade NAT are common blockers.
Playback counts as remote whenever the app cannot see the server on the same local subnet, which VPNs or containers without host networking can also cause. Remote video playback needs a Plex Pass on the server owner’s account, covering everyone who streams from that server, or a Plex Pass or Remote Watch Pass on the viewer’s account. Music in Plexamp and photos in Plex Photos stream remotely for free.
Sharing libraries with family and friends
The owner invites people by Plex username or email address and chooses either the whole server or individual libraries. The owner can later change or revoke access per account. With Plex Pass, the owner can limit shares by content rating or custom labels and block downloads. Plex Pass also lets people join a Plex Home with managed accounts.
Over-the-air TV and recording
With a compatible tuner and antenna connected, Plex Media Server scans channels and matches them to a program guide for the owner’s postal code. It streams live broadcasts to Plex apps. Recording requires Plex Pass and offers HD preference, start and end padding, post-processing scripts and commercial detection that removes ads or marks them for skipping.
What stays free
Without a subscription, Plex Media Server still catalogs media and streams it inside the home to the TV, console, desktop and web apps. The Android and iOS apps play server media in a limited mode until unlocked by a one-time purchase or Plex Pass. Plex Pass also adds offline downloads, trailers and extras for library titles, lyrics, webhooks and early access to new server builds.
