Media Preview Generator

Your media server's slowest jobs, done on your GPU.
Media Preview Generator makes the preview thumbnails and the Skip Intro and Skip Credits markers for Plex, Emby and Jellyfin. It starts the moment Sonarr or Radarr imports a file and sends the results to every server at once.
Self-hosted, one Docker container.

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Quick start · How it compares · Ask a question · Report a bug

!Tears of Steel in the Plex, Jellyfin and Emby web players, each showing a preview thumbnail over the seek bar

_{Plex, Jellyfin and Emby web players on test servers, each paused mid-scrub on the same film. The thumbnails were made by this app. Tears of Steel, (CC) Blender Foundation | mango.blender.org, CC BY 3.0.}

What it does

Plex, Emby and Jellyfin can make preview thumbnails themselves, but they do it inside the server, mostly on the CPU, and mostly on a schedule. On a big library that can take days, and the episode that arrived tonight can sit with a blank timeline until the next maintenance window.

Media Preview Generator makes them on your GPU, for each file as it arrives. When more than one server holds the same file, it decodes it once and writes each server's own format.

It also adds Skip Intro and Skip Credits. It finds each file's intro and end credits once and sends the markers to every server that has the file. When it isn't sure, it sends nothing; you can add or adjust a marker in the Inspector.

What it looks like

| It finds every server with that file | | --- | | !Servers page with one card each for Home Plex, Home Jellyfin and Home Emby, each showing its address and enabled libraries |

| One GPU pass per file | | --- | | !Workers panel as a table: busy GPU and CPU workers with percent, speed and ETA, idle workers folded into one line |

| Each server gets its own format | | --- | | !A completed job's details with the Files tab open: one file marked Generated, with Home Plex, Home Jellyfin and Home Emby listed as its servers |

| It waits for slow servers | | --- | | !The Jobs queue with four rows: Tears of Steel running at 62%, Sintel pending with Retry 2/5 and Retry starting in 4 min, Big Buck Bunny completed, and Elephants Dream pending |

_{App screenshots come from a test setup with made-up servers; the job titles are open films.}

Features

GPU first, CPU when needed

• Every GPU you pass in. NVIDIA, Intel and AMD on Linux; NVIDIA on Windows through WSL2. Choose worker groups for the GPUs passed to the container.
• Named worker groups. Choose each group's devices, their job types and worker counts, and weekly hours. Dashboard +/− changes are saved; reducing capacity lets current files finish. Worker guide.
• CPU fallback built in. A file the GPU can't decode is retried on the CPU by the same worker.
• Key-frame skipping. Jumps between key frames when a file's key-frame spacing allows it.

• Webhooks. Sonarr, Radarr, Sportarr, Tdarr, FileFlows, Plex (Plex Pass), Emby (Premiere) and Jellyfin, or any JSON with a path. Sonarr, Radarr and the three servers can share one URL.
• Schedules. Recently Added polling, plus cron and interval schedules.
• Process a file or folder. Search your servers by title (a whole show, a movie or one episode), or browse the media folders, and make previews for just those.
• Plex without waiting for a scan. File/folder jobs and path-based webhooks generate from the media itself, even while Plex is offline or has not indexed the file.
• Retries and skips. Retries after 1, 2, 5, 15 and 60 minutes by default while a server indexes a new file, and skips files whose previews are current.

• Each server's own format. A BIF in Plex's data folder, a BIF next to the video for Emby, and Jellyfin trickplay tiles (next to the video, or in Jellyfin's data folder with the companion plugin).
• Setup Health. Checks each server's settings and offers fixes one library at a time.

Right colours

• HDR tone mapping. Tone-maps HDR10, HLG and HDR10+, and uses the HDR10 layer of Dolby Vision profiles 7 and 8. Profile 5 needs a GPU with a hardware Vulkan driver.

• Found once, sent to every server. Finds intros and end credits from the file's chapters, online skip databases (TheIntroDB, IntroDB.app, SkipDB), the season's theme song or the credit roll itself (read on the GPU when that's faster), then sends the markers to every server. When it isn't sure, it sends nothing instead of a guess; you can add or adjust a marker in the Inspector. Off until you turn it on for a server.
• Yours to correct. Tools → Inspector adjusts, adds and locks a file's markers by hand, and Setup Health checks each server's Intro & Credits setup.
• Plex. Needs Plex Pass on the server, and for viewers (or their Plex Home). The app runs on the Plex machine, or next to it through the Plex marker agent.
• Jellyfin. Jellyfin 10.11 or 12.0, with the Media Preview Bridge plugin (the one trickplay uses).
• Emby. Emby 4.9 or 4.10, with the Media Preview Bridge for Emby plugin. Skip Intro needs Emby Premiere; Skip Credits doesn't.

• Normalize Loudness sooner. Analyses audio tracks on CPU worker groups and stores loudness measurements in Plex. Off until you turn it on for a local Plex 1.43.4.x server; independent of Intro & Credits.

Where it fits

The container can run on a separate GPU machine and reuse the same extraction across servers that share a file. Plex chapter thumbnails and loudness analysis are separate CPU tasks: chapter thumbnails can use the Plex helper, while loudness requires this app beside a local Plex 1.43.4.x database and does not support a helper or network-mounted database.

It sits next to Sonarr, Radarr and Tdarr and takes over the media server's own preview job. Once it runs, the server's own generation is the same work done twice. The app's Setup Health tab says which setting to turn off on each server, and which to leave on: switching Jellyfin's trickplay off deletes the tiles this app wrote. If your server's own generator keeps up, you don't need this: see how it compares.

Quick start

You'll need: Docker · Plex, Emby or Jellyfin (Jellyfin 10.10 or newer), reachable from the container · write access where previews go: Plex's data folder, or the media folder for Emby and Jellyfin. A GPU is optional: its driver on the host, plus the NVIDIA Container Toolkit for NVIDIA on Linux.

docker run -d \
  --name media-preview-generator \
  --restart unless-stopped \
  -p 8080:8080 \
  --device /dev/dri:/dev/dri \
  -e PUID=1000 -e PGID=1000 \
  -v /path/to/media:/media \
  -v /path/to/plex/config:/plex \
  -v /path/to/app/config:/config \
  stevezzau/media_preview_generator:latest

• Intel or AMD: --device /dev/dri as above. NVIDIA: --gpus all -e NVIDIA_VISIBLE_DEVICES=all -e NVIDIA_DRIVER_CAPABILITIES=all instead. No GPU, or on Windows or macOS? Delete the --device /dev/dri line.
• Plex writes into /plex, so the media can be :ro. Emby, and Jellyfin in its default layout, write next to each video, so for them the media mount must be read-write. No Plex? Drop the /plex mount.
• Open http://YOUR_IP:8080 and sign in with the token saved in auth.json in your app config folder (or pin your own with -e WEB_AUTH_TOKEN=...), then follow the setup wizard.
• The image is stevezzau/media_preview_generator. The double z is the Docker Hub account's name, not a typo.

Documentation

The docs are also a website: mediapreviewgenerator.dev.

| Page | What's in it | | --- | --- | | Getting started | Docker, GPUs, mounts, Unraid, networking | | How it compares | Plex, Jellyfin and Emby built-in generation, side by side | | Guides | The web UI, webhooks, schedules, troubleshooting | | Multi-server | Plex, Emby and Jellyfin from one instance | | Reference | Every setting, environment variable and API endpoint | | FAQ | Windows, GPUs, RAM, skipped files | | Why Plex previews are slow | What Plex does, and what to change | | Plex previews with a GPU | Moving Plex's preview job to a GPU | | Faster Jellyfin trickplay | Jellyfin's own settings first, then a GPU | | Emby BIF previews with a GPU | Emby BIFs made on a GPU, next to each video | | Previews on Sonarr or Radarr import | Webhooks, quiet period, retries | | HDR and Dolby Vision previews | Tone mapping, and the Dolby Vision 5 caveat | | Skip Intro and Skip Credits | What each server needs, how they're found, limits |

Support the project

It's free and MIT licensed. Helping is optional.

• Star it on GitHub: free, and it's how other server owners find it.
• Buy me a coffee on Ko-fi: no account needed.

Get help

• Previews don't show up? Open the server's Setup Health tab in the app. It names the setting that's in the way.
• Not sure it's a bug? Ask in Discussions.
• Found a bug? Open an issue with the app version and what you tried.

License

MIT, see LICENSE. Development is AI-assisted (Claude); every change is reviewed and tested.

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