Outsource your FFmpeg calls to a different machine, with directory mapping
While Outsource allows you to run FFmpeg commands on another host, you need to be aware of the hardware capabilities of both. Outsource is effectively an FFmpeg proxy, not a load-balancer (though this may change in the future). For example, Outsource can be used to enable hardware transcoding for Jellyfin if the host machine doesn't have a GPU. However, if the client is inaccessible or the SSH calls fail and requires the host to fall back to local FFmpeg calls, then that GPU is no longer available and the local calls will fail.
Requirements:
- Lua with luaposix
The host requires Outsource and some way to share directories with the client, such as NFS or SMB. The share is so the output files are accessible back on the host.
Create a symlink from the expected ffmpeg/ffprobe locations to the Outsource wrappers, for example:
/usr/local/jellyfin-ffmpeg/ffmpeg -> /path/to/outsource-ffmpeg
/usr/local/jellyfin-ffmpeg/ffprobe -> /path/to/outsource-ffprobe
Alternatively, set OUTSOURCE_MODE="ffprobe" for FFprobe.
Configure your environment variables. You will need to set OUTSOURCE_SSH_HOST and probably OUTSOURCE_SSH_ID but, depending on your setup, you may not need to set any others.
Host should be in SSH format, eg: OUTSOURCE_SSH_ID="<user>@<host>"
By default, OUTSOURCE_SSH_ID will check in the calling user's $HOME/.ssh for id_ed25519. It just needs an identity that can SSH into the client WITHOUT a password, otherwise the SSH calls will hang. You may need to include a known_hosts file for the SSH call to work.
Host-to-client directory mapping is optional, but requires the OUTSOURCE_MAP_DIRS variable to use.
First, determine where you want to map. You can easily determine this by checking the FFmpeg calls themselves. For example:
This is an FFmpeg input flag -i file:"/data/shows/Breaking Bad/Season 01/S01E01.mkv". If I wanted to map /data/shows on the host to /mnt/NAS/media/shows on the client, then I would set OUTSOURCE_MAP_DIRS="/data/shows//mnt/NAS/media/shows"
Note the double-slash, it is necessary to separate out the host and client paths. If you want to map multiple directories, then separate them with a semicolon (;) like so: /host/location1//client/location1;/host/location2//client/location2
Outsource can also fallback to local FFmpeg if the client fails in any way. Ensure that OUTSOURCE_FFMPEG_ALLBACK_PATH and OUTSOURCE_FFPROBE_FALLBACK_PATH are set to an actual FFmpeg/FFprobe binary on the host system and NOT the Outsource link.
By default, Outsource will attempt to log everything to /tmp/outsource/log.txt (OUTSOURCE_LOG_DIR) and the logging level can be changed with OUTSOURCE_LOG_LEVEL. If you want to disable logging, set the level to "none". Just note that Outsource doesn't manage the size of the logs so you need to ensure they clear automatically.
Install FFmpeg and take note of the binary location. If it is not at /usr/bin/ffmpeg then change OUTSOURCE_FFMPEG_PATH and OUTSOURCE_FFPROBE_PATH accordingly.
Make sure that the user being SSH'd into can run FFmpeg and is in the video group if your hardware needs it.
Mount a share from the host to the client using something like NFS, SMB, etc. All accessed paths on the host must be present on the client but if directory mapping is configured, the locations do not need to be identical. Your destination mappings must be able to access the paths within the share(s).
After the host and client are configured, test the connection:
/path/to/outsource-ffmpeg -version
Verify that the returned version is for the actual FFmpeg binary on the client and not the fallback host binary:
ffmpeg version 7.1.4-Jellyfin Copyright (c) 2000-2026 the FFmpeg developers
built with gcc 15.2.0 (GCC)
| Variable | Default | Details |
|---|---|---|
OUTSOURCE_SSH_PATH |
/usr/bin/ssh |
The path on the host to the SSH binary |
OUTSOURCE_SSH_HOST |
"" (Required) |
The client hostname, eg: user@host |
OUTSOURCE_SSH_ID |
$HOME/.ssh/id_ed25519 |
The path on the host to the SSH identity file, required to initialize an SSH session |
OUTSOURCE_FFMPEG_PATH |
/usr/bin/ffmpeg |
The path on the client to the FFmpeg binary |
OUTSOURCE_FFPROBE_PATH |
/usr/bin/ffprobe |
The path on the client to the FFprobe binary |
OUTSOURCE_FFMPEG_ALLBACK_PATH |
/usr/bin/ffmpeg |
The local path on the host to the FFmpeg binary |
OUTSOURCE_FFPROBE_FALLBACK_PATH |
/usr/bin/ffprobe |
The local path on the host to the FFprobe binary |
OUTSOURCE_MAP_DIRS |
nil |
A list of semicolon (;) separated host-to-client path mappings, eg: /host/location//client/location means map from /host/location to /client/location. The double-slash is where the paths are split. |
OUTSOURCE_LOG_DIR |
/tmp/outsource/log.txt |
The path on the host to log to |
OUTSOURCE_LOG_LEVEL |
info |
The logging level to use. One of debug, info, warn, error, fatal. |
Outsource's creation was inspired by some limitations with rffmpeg.
Currently, rffmpeg will redirect ffmpeg calls verbatim, meaning that input/output paths need to be the same on both systems.
This means that you may need to put NFS shares in a couple places on the clients filesystem to ensure all internal host paths are mapped correctly.
This gets more complicated when used in a Docker container because bind mounts are often at locations like /data or /config, not default root directories.
Rewriting paths solves this by allowing any host directory to point to any client directory, which means that the NFS shares can be put in a more appropriate client-specific location.