Settings — Stream Management

Stream Management controls how Sublarr rewrites your MKV / MP4 containers — the remux mechanics (reflinks, trash retention, pausing Sonarr/Radarr) shared by every feature that touches an embedded track, plus dubtitle detection.

Foreign track removal

Stripping embedded subtitle tracks in languages you don’t want isn’t configured on this page — it lives in two places, both documented in full (config table, keep-set rules, per-series override) under Cleanup → Foreign-Track Removal:

• Settings → Subtitle Automation → Foreign-Track Cleanup — the automatic trigger that runs after a subtitle download or embedded-subtitle extract.
• Settings → Cleanup → Foreign-Track Removal — a manual/scheduled rule you run against your whole library.

Both share the remux mechanics below (reflinks, trash retention) and only ever touch subtitle streams — audio tracks are never removed.

Dubtitle detection

For anime files that ship several English tracks (fansub, dubtitle/CC, signs & songs), Sublarr can identify which one matches the spoken English dub and surface it in the track panel — so you extract or keep the right track instead of the fansub. See Dubtitle Detection for the full workflow and the dubtitle_detection / minimum-match-score settings.

Reflinks

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

Setting	Default	Effect
Use CoW Reflink for Backups	on	Attempts a reflink first; silently falls back to a regular copy if the filesystem doesn’t support it. Turn off only if reflinks cause problems on your storage.

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
Remux backup retention (days)	7	0 or more	How long a pre-remux original stays in the trash before it’s eligible for the Old Backups cleanup operation. 0 keeps backups forever.
Trash directory	.sublarr	relative (to media_path) or absolute path	Where remuxed-away originals land, as <trash_dir>/trash/<date>/<file>.<timestamp>.bak.

.bak.<ext> files written by the subtitle editor are a separate fleet with their own retention setting — see Subtitle Backups.

Pause Sonarr / Radarr during remux

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

FFmpeg / mkvmerge

Both binaries are bundled in the Docker image and discovered via $PATH automatically (mkvmerge is preferred for MKV containers when installed; ffmpeg is the fallback and the only backend for non-MKV containers). There’s no path-override setting — install/replace the binary on $PATH if you need a different build.

Hardlinks and container removal

New in 1.10.0. Two settings guard against remux quietly damaging a library that shares files with a torrent client.

Setting	Default	Values	Effect
remux_hardlink_policy	skip	skip · warn · allow	What to do when the file to remux has more than one hardlink.
embedded_extract_remove_from_container	off	on / off	Whether extracting an embedded subtitle also strips that track from the container.

Why the hardlink policy matters. Remuxing rewrites the file. If your media file is hardlinked into a torrent client’s download directory, rewriting it changes the seeded data — the torrent breaks. skip (the default) leaves such files untouched; warn processes them but records a warning; allow proceeds silently. Only choose allow if you know none of your links are seeded.

Why container removal is opt-in. Extracting a subtitle to a sidecar is non-destructive. Removing the track from the container afterwards is not — the original is gone once the remux completes. It therefore defaults to off, and turning it on means accepting that the embedded track will not be recoverable from that file.

Caution

Both defaults are the safe ones. Change them only after confirming your library is not hardlinked into a seeding client.

Common pitfalls

Symptom	Cause	Fix
Remux reports success but file unchanged	Foreign-track scan found nothing to remove (file already clean, or the container’s language tags don’t match what you expected)	Confirm the language tags inside the MKV — mkvinfo file.mkv or ffprobe -show_streams file.mkv shows them.
Some files refuse to remux	Bitstream + container mismatch, or a corrupt source	Check Logs for mkvmerge/ffmpeg stderr.
Trash fills disk fast	Retention too high for your library churn	Lower Remux backup retention or point Trash directory at a different volume.