Plays audio tracks that sit next to the video instead of inside it.
Drop a .mka, .ac3 or .flac beside your video and Plex lists it among the audio tracks as if it had always been there.
Anime releases with alternative dubs are distributed this way constantly, and Plex cannot handle it: there is no native support for external audio, and no plugin system since 2018.
Tested on Plex 1.43.3, Windows 11: 2247 external tracks across a library of 5212 video files, mapped in twenty seconds.
Two external dubs, listed by Plex as if they were inside the file.
Run the installer.
One UAC prompt and it is done - it finds Plex, the database and ffprobe by itself, swaps in the transcoder wrapper and puts a tray icon in place.
It needs ffprobe, part of ffmpeg, to read your audio files; if your machine has none, the installer downloads one and keeps just that single file.
Uninstalling is the normal Windows way: Apps and features, or Uninstall in the tray menu. Both restore the original Plex transcoder and offer to clear the tracks out of the database. Your audio files are never touched.
Anywhere under the video's own folder, at any depth. The audio file has to be named after the video; the track title comes from the folder it sits in.
Series/
Episode 01.mkv
Episode 01.mka -> track from the file's own tag
RUS Sound/[Group A]/Episode 01.mka -> track "Group A"
RUS Sound/[Group B]/Episode 01.mka -> track "Group B"
A title inside the file wins; failing that the VIDEO.language.Title.ext scheme is used, and failing that the folder name.
The language is a three-letter code in the filename, or a tag inside the file.
The mapper writes rows into Plex's media_streams table with index >= 1000 and url = file://....
Plex takes them for tracks inside the file and duly asks the transcoder for stream 1001.
The wrapper intercepts that, looks the real path up in the database, appends a second -i and repoints -map / -filter_complex at it.
The audio is not re-encoded; Plex handles video by its usual rules.
Two things break this, both silently: a Plex update replaces the transcoder, and a library re-analysis wipes the added rows. A guard runs on a schedule and repairs both.
A re-analysis takes something else with it.
Plex remembers the audio track you picked as a reference to a media_streams.id, and once the row it points at is gone that reference dangles - after which Plex marks no track as selected at all, and its web player dies the moment the audio menu is opened.
So every pass also clears references that lead nowhere.
The colour is the state - green means the wrapper is in place, orange means it is not.
Check does everything in one press: verifies the wrapper, reinstalls it if a Plex update overwrote it, and tops the database back up if rows went missing.
Exit stops the background work too, not just the icon. It cannot unregister the scheduled task without a UAC prompt every time you quit, so it leaves a marker the guard checks on startup. Starting the program clears it. Exit does not put the original transcoder back - that needs administrator rights and would break playback of the tracks already mapped. Uninstalling does that.
The interface follows your Windows display language, and can be set by hand in the menu.
12 languages: English, Russian, Ukrainian, German, French, Spanish, Italian, Polish, Brazilian Portuguese, Turkish, Japanese, Simplified Chinese.
Adding one means dropping a single JSON file into cmd/tray/locales/.
Hovering the icon is usually enough:
For the full picture, including whether the scheduled tasks are alive:
& "C:\Program Files\Plex External Audio\Plex External Audio Guard.exe" -statusEverything it prints is read from the live system, not from saved state.
The same report goes to C:\ProgramData\Plex External Audio\status.txt, and the guard keeps a rotating log beside it.
Go only, no C compiler (CGO_ENABLED=0):
powershell -NoProfile -ExecutionPolicy Bypass -File setup\build.ps1 -InstallerBinaries land in bin\, the installer in installer\Output\.
The work is split so that a port has a small target: internal/plex holds everything that touches the Plex database, internal/probe runs ffprobe, internal/scan finds the sidecar files, and cmd/mapper and cmd/transcoder are thin programs on top.
Those five are portable Go.
cmd/guard and cmd/tray are the Windows-specific half.
Run guardtest\run.py before touching the guard.
It is allowed to delete files in Program Files, and it once deleted the real Plex transcoder: the guard used to identify its own wrapper by a hash from the config, and after a rebuild that hash no longer matched.
Identification is by an embedded marker string now.
The test drives the guard through five scenarios inside a fake Plex directory.
Binaries are deliberately not built with -s -w.
Stripping saves a third of the size and gets them deleted on sight by antivirus heuristics, because that is how most Go malware ships.
Windows only for now. The mapper and the wrapper are portable Go and cross-compile as they are; the guard and the tray icon are not - they speak to the registry, Win32 and the Task Scheduler.
On a Linux or macOS server the tray icon makes little sense anyway, and the guard would be a systemd timer or a launchd job. The pieces that would need writing are small and well isolated. Pull requests for other platforms are very welcome.
- A player that cannot decode the external track makes Plex transcode it.
- Browsers will not play Hi10P or FLAC at all; that re-encode is not ours.
- Files Plex has not analysed yet are skipped and picked up on the next run.
- The installer is unsigned, so SmartScreen will call it an unknown publisher.
Nothing is sent anywhere: no telemetry, no update check, no analytics, no networking code at all. The details are in PRIVACY.md.
How releases are built and who may approve one for signing is in SIGNING.md.
The approach - mapping external files into media_streams and wrapping the transcoder - was first worked out by Saoneth/plex-custom-audio, which has been unmaintained since 2021.
This is an independent implementation of the same idea, written against a specification of how Plex behaves rather than from that code, and sharing none with it.
MIT licensed, see LICENSE.