Settings — Stream Management

Stream Management is the page that controls what Sublarr does with the embedded subtitle and audio tracks inside your MKV / MP4 files. The headline feature is foreign-track removal: stripping subtitle tracks in languages you don’t want, so your media server doesn’t show “Russian” and “Polish” in the player UI for an English-language show.

Foreign track removal

When enabled, Sublarr scans every container as part of its post-extract pipeline and removes subtitle tracks that don’t match a “keep” criterion. The original file is preserved in Trash for the configured retention.

Setting	Default	Values	Effect
Enabled	off	toggle	Master switch. Turning on starts a one-shot pass over the library.
Keep mode	target-only	target-only / target+original / whitelist	Which tracks to keep.
Whitelist	empty	comma-separated language codes	When mode is whitelist, only listed languages are kept.
Keep undefined	on	toggle	Tracks tagged und (undefined language) are kept; many releases tag the original audio language as und.
Run on import	off	toggle	Run automatically on every new file Sonarr/Radarr imports.

Mode	Example outcome
target-only (default)	Profile target = de, file has en, de, ja, ko → keeps de.
target+original	Keeps de + the original audio language as detected.
whitelist with de,en,ja	Keeps only those three regardless of profile.

Caution

Foreign track removal rewrites the MKV. The pre-mux file is kept under Trash → MKV Backups for the retention window. Restore from there if anything goes wrong.

Reflinks

When the underlying filesystem supports them (Btrfs, XFS, ZFS, ReFS, OCFS2 with reflink mount), Sublarr can use reflinks for the temporary copy used during remuxing — saving disk on every operation.

Setting	Default	Effect
Use reflinks	auto	When auto, Sublarr probes filesystem capability and uses reflinks if supported. Force on only if you’ve verified your FS, or off to disable for predictable behaviour.

Reflinks aren’t always faster than copies — they save disk but the rename + atomic-replace dance still hits the metadata layer. Benefit is biggest on big files (≥ 5 GB).

Trash retention

Setting	Default	Values	Effect
MKV backup retention (days)	14	0–365	How long the pre-remux file stays in Trash. 0 disables retention (immediate delete).
Subtitle backup retention (days)	14	0–365	Lifetime of .bak files written by the editor. See Subtitle Backups.
Trash directory	/config/trash	absolute path	Where the deleted/replaced files live. Must be writable; should be on the same volume as media to make moves atomic.

Cleanup after extract

When Sublarr extracts an embedded subtitle, the result is a new sidecar file. The container’s embedded track stays in place by default — meaning the same subtitle exists twice (embedded + sidecar):

Setting	Default	Effect
Cleanup after extract	off	When on, foreign-track removal runs immediately after a successful extract, dropping the now-redundant embedded track.

Useful for storage savings; off by default because it modifies the container — a more invasive operation than just writing a sidecar.

Pause Sonarr / Radarr during remux

Setting	Default	Effect
*Pause arr during remux	off	Tells Sonarr/Radarr to ignore filesystem events for the duration of the remux. Prevents the *arr from re-importing the half-finished file.

FFmpeg / mkvtoolnix paths

Both binaries are bundled in the Docker image and discovered automatically. Override only when running outside Docker:

Setting	Default	Effect
ffmpeg path	bundled	Custom binary path; useful for distros without ffmpeg in $PATH.
mkvmerge path	bundled	Same for mkvmerge.
ffmpeg timeout (s)	300	Per-operation timeout. Raise for very long files.

Common pitfalls

Symptom	Cause	Fix
Remux reports success but file unchanged	Foreign-track scan found nothing to remove (file already clean)	Confirm the language tags inside the MKV — mkvinfo file.mkv shows them.
MKV grows in size after remux	New container has different default flags	Disable Reset default flags under advanced.
Some files refuse to remux	Bitstream + container mismatch	Check Logs for mkvmerge stderr; usually a corrupt source.
Trash fills disk fast	Retention too high for your library churn	Lower retention or move trash to a different volume.