Automatic video transcoding service for Jellyfin media streaming

---

jellyfin-encoder monitors your media library and automatically transcodes videos to optimized 720p HEVC, H.264, or AV1 for bandwidth-efficient mobile and remote streaming. It runs as a Docker container, supports NVIDIA NVENC and Intel QSV hardware acceleration with automatic software fallback, and uses polling-based observation compatible with NFS, CIFS, and other network filesystems.

Features

• Automatic folder monitoring -- watches source directories for new and deleted files using polling (NFS/CIFS compatible)
• Hardware-accelerated encoding -- NVIDIA NVENC and Intel Quick Sync Video (QSV), with transparent software fallback (libx265 / libx264 / libsvtav1)
• Smart skip logic -- detects files already at 720p or lower via filename heuristics and ffprobe resolution analysis
• Jellyfin multi-version support -- creates version symlinks so Jellyfin presents both original and transcoded copies to the user
• H.264 / AAC / MP4 output -- set ENCODING_CODEC: "h264" for MP4 output that Jellyfin clients direct play without transcoding, and without re-encoding the library you already have (see H.264, AAC and MP4 Output)
• Audio normalization -- re-encodes audio for consistent playback: AAC keeping up to 5.1 for MP4, stereo AC3 at 192 kbps for MKV
• Subtitle preservation -- copies MKV-native subtitle codecs and converts incompatible ones (MOV text, WebVTT) to SRT; converts text subtitles to mov_text for MP4
• Guarded automatic cleanup -- periodically removes orphaned encodes and stale symlinks with mount-health checks to prevent mass deletion (see Safety & Cleanup below)
• Temp-file workflow -- encodes to .tmp and atomically renames on success, so Jellyfin never indexes incomplete files (note: no cross-container locking — avoid pointing two encoders at the same destination subfolder)
• Configurable quality presets -- LOW, MEDIUM, and HIGH profiles with per-codec CQ/CRF tuning

Quick Start

Docker Compose

services:
  jellyfin-encoder:
    image: drumsergio/jellyfin-encoder:1.1.4
    container_name: jellyfin-encoder
    devices:
      - /dev/dri:/dev/dri  # Intel QSV -- remove if using NVIDIA or software encoding
    volumes:
      - /path/to/source:/app/source
      - /path/to/destination:/app/destination
    environment:
      ENABLE_HW_ACCEL: "true"
      HW_ENCODING_TYPE: "intel"   # nvidia | intel
      ENCODING_QUALITY: "LOW"     # LOW | MEDIUM | HIGH
      ENCODING_CODEC: "hevc"      # hevc | av1
    restart: always

    # For NVIDIA GPU support, replace the devices block above with:
    # deploy:
    #   resources:
    #     reservations:
    #       devices:
    #         - capabilities: [gpu]

Docker CLI

docker run -d \
  --name jellyfin-encoder \
  --device /dev/dri:/dev/dri \
  -v /path/to/source:/app/source \
  -v /path/to/destination:/app/destination \
  -e ENABLE_HW_ACCEL=true \
  -e HW_ENCODING_TYPE=intel \
  -e ENCODING_CODEC=hevc \
  -e ENCODING_QUALITY=LOW \
  --restart always \
  drumsergio/jellyfin-encoder:1.1.4

Configuration

All settings are controlled via environment variables.

Variable	Default	Description
SOURCE_FOLDER	/app/source	Path to the directory containing original videos
DEST_FOLDER	/app/destination	Path to the directory for encoded output
ENABLE_HW_ACCEL	true	Enable hardware-accelerated encoding
HW_ENCODING_TYPE	nvidia	Hardware encoder: nvidia or intel
ENCODING_CODEC	hevc	Output codec: hevc, h264, or av1
OUTPUT_CONTAINER	auto	Container: auto (MP4 for H.264, MKV otherwise), mkv, or mp4
ENCODING_QUALITY	LOW	Quality preset: LOW, MEDIUM, or HIGH
AUDIO_CODEC	auto	Audio codec: auto (AAC for MP4, AC3 for MKV), aac, or ac3
AUDIO_BITRATE	auto	Bitrate per audio track: auto (192k stereo, 384k multichannel) or a value such as 256k
AUDIO_CHANNELS	auto	Channels per audio track: auto (AAC keeps up to 5.1, AC3 downmixes to stereo) or a count such as 2
SYMLINK_TARGET_PREFIX	(empty)	Absolute path prefix for Jellyfin version symlinks (same-host mode)
SYMLINK_MANIFEST_TARGET	(empty)	Path prefix for cross-host manifest-based symlinks (see Cross-Host Setup)
SYMLINK_VERSION_SUFFIX	- 720p	Suffix appended to symlink filenames
CLEANUP_INTERVAL_HOURS	6	Hours between automatic orphan cleanup runs

Quality Presets

Each preset defines constant-quality (CQ) values for hardware encoding and constant rate factor (CRF) values for software fallback.

Preset	HEVC CQ / CRF	H.264 CQ / CRF	AV1 CQ / CRF	Intended Use
LOW	32 / 30	28 / 26	45 / 40	Mobile devices, minimal storage footprint
MEDIUM	26 / 26	24 / 23	35 / 35	Balanced quality and file size
HIGH	22 / 22	21 / 20	28 / 28	Higher fidelity, larger files

H.264, AAC and MP4 Output

Set ENCODING_CODEC: "h264" and new encodes come out as H.264 video with AAC audio in an MP4 container. Nothing else about the setup changes.

Aspect	What you get
Video encoder	h264_qsv (Intel), h264_nvenc (NVIDIA), libx264 (software fallback)
Container	.mp4, with the index written at the front so players can start before reading the whole file
Audio	AAC, source channel layout up to 5.1, at 192 kbps stereo or 384 kbps multichannel
Pixel format	Forced to 8-bit yuv420p, so 10-bit sources encode instead of failing on hardware H.264

hevc and av1 still produce .mkv with the stereo AC3 audio they always have. To pair a codec with a different container, set OUTPUT_CONTAINER explicitly.

Switching codec never re-encodes what you already have

Changing ENCODING_CODEC on a library that is already encoded produces zero re-encodes.

An output on disk counts as done whatever container it is in. If your destination is full of Movie - 720p.mkv files and you switch to ENCODING_CODEC: "h264", the encoder leaves those files alone. It picks up only the titles that have no encode at all, and those come out as .mp4. Switching back to hevc works the same way in reverse, respecting the .mp4 outputs you already have.

The skip check, orphan cleanup, the symlink manifest, and source-deletion handling all match on the filename stem rather than the extension. A destination folder holding a mix of .mkv and .mp4 works fine, so the two formats can coexist for as long as you like.

Subtitles in MP4

MP4 carries text subtitles only. The encoder converts text tracks (SRT, ASS/SSA, WebVTT) to mov_text and drops bitmap tracks (PGS, DVB), which have no MP4 equivalent. Keep external .srt sidecars next to the encode if you need those. If FFmpeg fails with subtitles mapped, the encoder retries once without them. A subtitle track FFmpeg cannot handle costs you the subtitles, never the encode.

Hardware Acceleration

NVIDIA (NVENC)

Requires the NVIDIA Container Toolkit. Add a GPU reservation to your Compose file:

deploy:
  resources:
    reservations:
      devices:
        - capabilities: [gpu]

Set HW_ENCODING_TYPE: "nvidia". Supported encoders: hevc_nvenc, h264_nvenc, av1_nvenc.

Intel (Quick Sync Video)

Pass the render device into the container:

devices:
  - /dev/dri:/dev/dri

Set HW_ENCODING_TYPE: "intel". Supported encoders: hevc_qsv, h264_qsv, av1_qsv.

Software Fallback

If hardware acceleration is disabled or unavailable, the encoder falls back to libx265 (HEVC), libx264 (H.264), or libsvtav1 (AV1) using CRF-based quality control. Worker count scales to the number of available CPU cores.

Safety & Cleanup

The encoder periodically removes orphaned encodes (files in DEST_FOLDER with no matching source) and stale version symlinks. Several safety rails prevent accidental mass deletion:

Guard	Scope	Behavior
Source not accessible	cleanup_destination, cleanup_orphaned_symlinks	Aborts if SOURCE_FOLDER is not a directory
Empty source	cleanup_destination	Aborts if zero video files are found in source
Persisted count (primary)	cleanup_destination, cleanup_orphaned_symlinks	After each successful cleanup, the source video count is written to DEST_FOLDER/.encoder_source_count. If the current count drops below 50% of the persisted value, cleanup is refused. To reset after intentionally shrinking the library, delete the .encoder_source_count file.
Source vs destination ratio (secondary)	cleanup_destination, cleanup_orphaned_symlinks	If source video count is less than 50% of destination encode count, cleanup is refused
Mount health on delete events	VideoHandler.on_deleted	Before trusting a file-delete event from the polling observer, the handler verifies the source mount is responsive. If not, the event is ignored.
Growing tmp files	cleanup_destination	.tmp files are kept if they are still being written

Same-folder mode (SOURCE_FOLDER == DEST_FOLDER): versioned output filenames (e.g., Movie - 720p.mkv or Movie - 720p.mp4) are recognized as valid encodes and excluded from orphan cleanup.

Delete-event rate limiter: If more than 50 delete events fire within 60 seconds, further deletes are suppressed. This prevents mount outages from cascading into mass encode deletion. The limit resets automatically after the window expires.

Limitations: The persisted-count and ratio guards use a 50% threshold. A mount that exposes more than half its files will pass both guards, potentially allowing cleanup of files in invisible subtrees. After bulk intentional deletions, you may need to delete DEST_FOLDER/.encoder_source_count to reset the baseline — cleanup will refuse to run until the persisted count is reset or the source count recovers above 50%.

Upgrading from < 1.1.0

Starting with v1.1.0, encoded outputs always include the version suffix (e.g., Movie - 720p.mkv instead of Movie.mkv). Existing encodes without the suffix will be re-encoded. To avoid this, rename them before upgrading:

# Dry-run (shows what would be renamed)
docker exec jellyfin-encoder python /app/scripts/migrate_encode_names.py

# Apply renames
docker exec jellyfin-encoder python /app/scripts/migrate_encode_names.py --apply

Cross-Host Manifest Mode

When the encoder and Jellyfin run on different hosts (e.g., encoder on a NAS, Jellyfin on another server connected via CIFS/SMB), real symlinks cannot be created over the network mount. The manifest mode solves this:

1. Encoder writes a .symlink-manifest.json to DEST_FOLDER listing all encoded files and their Jellyfin container target paths.
2. Jellyfin host reads the manifest via a CIFS mount and creates real local symlinks.

Encoder Configuration

Set SYMLINK_MANIFEST_TARGET to the path prefix as seen inside the Jellyfin container:

services:
  jellyfin-encoder:
    image: drumsergio/jellyfin-encoder:1.1.4
    environment:
      SYMLINK_MANIFEST_TARGET: "/media-720/Peliculas"  # Jellyfin container path
      # ...other settings

The manifest is updated on encode, delete, and cleanup, and fully rebuilt at startup.

Jellyfin Host

Install scripts/symlink-from-manifest.sh on the Jellyfin host and run it via cron:

# Copy script to Jellyfin host
cp scripts/symlink-from-manifest.sh /boot/config/symlink-from-manifest.sh
chmod +x /boot/config/symlink-from-manifest.sh

# Add cron (runs every 5 minutes)
echo '*/5 * * * * /boot/config/symlink-from-manifest.sh' | crontab -

Edit the script's configuration variables (REMOTE_ROOT, MEDIA_ROOT, LIBRARIES) to match your setup. The script creates symlinks in MEDIA_ROOT pointing to the Jellyfin container path from the manifest, and removes orphaned symlinks not present in the manifest.

Manifest Format

{
  "version": 1,
  "symlinks": {
    "Movie (2024)/Movie (2024) - 720p.mkv": "/media-720/Peliculas/Movie (2024)/Movie (2024) - 720p.mkv"
  }
}

Same-Host vs Cross-Host

Mode	Variable	Use Case
Same-host	SYMLINK_TARGET_PREFIX	Encoder and Jellyfin share a filesystem — encoder creates real symlinks directly
Cross-host	SYMLINK_MANIFEST_TARGET	Encoder and Jellyfin on different hosts — encoder writes manifest, Jellyfin host creates symlinks

Both modes can coexist. If only SYMLINK_MANIFEST_TARGET is set, symlinks are managed exclusively via the manifest.

Architecture

Source folder (polling observer)
        |
        v
  New file detected ──> Wait for file completion (size-stable for 60s)
        |
        v
  Resolution check ──> Skip if <= 720p
        |
        v
  FFmpeg transcode ──> scale to 720p, encode video and audio, copy/convert subtitles
        |
        v
  Verify output (ffprobe duration check)
        |
        v
  Atomic rename .tmp -> .mkv/.mp4 ──> Create Jellyfin version symlink (optional)

Key design decisions:

• Polling observer (watchdog.PollingObserver) instead of inotify, ensuring compatibility with NFS, CIFS, and other network filesystems.
• Temp-file workflow -- encodes to a .tmp file first and atomically renames on success, preventing Jellyfin from indexing incomplete files.
• File-growth detection -- before deleting stale .tmp files, the cleanup routine checks whether the file is still being written by another instance.
• ProcessPoolExecutor -- one worker for hardware encoding (GPU is the bottleneck), multiple workers for software encoding (CPU-bound).
• Container-agnostic output lookup -- an encode is located by filename stem across every container the tool writes, so changing codec or container never re-encodes a library that is already done.

Utilities

compare_encodes.py

A standalone diagnostic script that compares source and destination folders to report encoding coverage.

# Command-line usage
python scripts/compare_encodes.py --source /media/movies --dest /media/movies-720p

# Inside a running container
docker exec jellyfin-encoder python /app/scripts/compare_encodes.py

# Output as JSON or CSV
python scripts/compare_encodes.py -s /media/movies -d /media/movies-720p --format json
python scripts/compare_encodes.py -s /media/movies -d /media/movies-720p --format csv

# Include files that were skipped (already 720p or lower)
python scripts/compare_encodes.py -s /media/movies -d /media/movies-720p --show-skipped

Option	Env Variable	Description
-s, --source	SOURCE_FOLDER	Source folder with original videos
-d, --dest	DEST_FOLDER	Destination folder with encoded videos
-f, --format	OUTPUT_FORMAT	Output format: text, json, csv
--show-skipped	SHOW_SKIPPED	Include skipped low-quality files in the report
--ignore	IGNORE_PATTERNS	Additional regex patterns to ignore (comma-separated)

Example output

================================================================================
ENCODING COMPARISON REPORT
================================================================================

Source folder:      /media/movies
Destination folder: /media/movies-720p

----------------------------------------
SUMMARY
----------------------------------------
Total source files:     4,463
Total destination files: 4,440
Matched (encoded):      4,420
Missing encodes:        23
Orphaned encodes:       20
Skipped (low quality):  20

----------------------------------------
MISSING ENCODES (23 files, 45.2 GiB total)
----------------------------------------
  [   2.1 GiB] Movie Title (2024) [BDRemux 1080p].mkv
  [   1.8 GiB] Another Movie (2023) [UHD 2160p].mkv
  ...

================================================================================
STATUS: Issues found - 23 missing encodes, 20 orphaned files
================================================================================

Other Jellyfin Projects by GeiserX

• quality-gate — Restrict users to specific media versions based on filename regex patterns
• smart-covers — Cover extraction for books, audiobooks, comics, magazines, and music libraries with online fallback
• whisper-subs — Automatically generates subtitles using local AI models powered by Whisper
• jellyfin-telegram-channel-sync — Sync Jellyfin access with Telegram channel membership

Related Music Pipeline Tools

• telegram-slskd-local-bot — Automated music discovery and download via Telegram
• slskd-transform — Bulk upgrade lossy to lossless FLAC via Soulseek
• audio-transcode-watcher — Automated multi-format audio transcoding

Contributing

Contributions are welcome. Please open an issue to discuss proposed changes before submitting a pull request.

1. Fork the repository
2. Create a feature branch (git checkout -b feature/my-change)
3. Commit your changes
4. Open a pull request against main

License

This project is licensed under the GPL-3.0 License.