media_preview_generator

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About

Generates video preview thumbnails for Plex, Emby, and Jellyfin. These are the small images you see when scrubbing through videos in any of those servers.

The Problem: Built-in preview generation has gaps depending on the server you run:

• Plex generates thumbnails single-threaded on the CPU (no GPU support).
• Emby has no GPU support for thumbnail generation at all.
• Jellyfin does support hardware-accelerated trickplay, but it shares CPU/GPU with playback — and on a busy server that’s resources you’d rather give to the player.

The Solution: This tool runs preview generation off the media server on a machine of your choosing, uses every GPU it finds, and processes files in parallel. When two or more servers contain the same file, FFmpeg runs only once — the result is then written out in each server’s own expected format, automatically.

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Features

One FFmpeg pass, every server. Point it at Plex, Emby, Jellyfin — any mix, any number — and a single generation run writes the right output format to each (Plex BIF bundle, Emby sidecar BIF, Jellyfin trickplay tiles). See the multi-server guide for how the dispatcher routes one file to every server that owns it.

Automation that just works. Radarr / Sonarr / Tdarr / FileFlows webhooks, Plex direct (Plex Pass), Recently Added polling, cron & interval schedules — all share one universal inbound URL with vendor auto-detection. A 5-step backoff retry (30 s → 2 m → 5 m → 15 m → 60 m) handles files your server hasn’t indexed yet. Source-aware dedup re-runs automatically when a file is swapped (e.g. a Sonarr/Radarr quality upgrade) and skips when nothing changed. Need to (re)generate something by hand? Manual Generation lets you search your servers by title — pick a show to cover every episode, or a movie, episode, folder, or single file — or browse your media tree, no path-typing required.

Hardware you already have. NVIDIA, AMD, Intel — per-GPU worker counts and FFmpeg threads, automatic in-place CPU retry if a codec fails on the GPU, and HDR / Dolby Vision tone mapping (including Profile 5 via libplacebo). A Previews Readiness panel on each server audits every flag that affects whether your previews actually show up, with one-click toggles and typed confirmation for destructive changes.

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Screenshots

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Quick Start

Docker (Recommended)

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:ro \
  -v /path/to/plex/config:/plex:rw \
  -v /path/to/app/config:/config:rw \
  -v /etc/localtime:/etc/localtime:ro \
  stevezzau/media_preview_generator:latest

Replace /path/to/media, /path/to/plex/config, and /path/to/app/config with your actual paths.

Timezone: The /etc/localtime mount ensures log timestamps and scheduled jobs use your local time. Alternatively, use -e TZ=America/New_York (replace with your timezone).

Then open http://YOUR_IP:8080, retrieve the authentication token from container logs, and complete the setup wizard.

For Docker Compose, Unraid, and GPU-specific setup:

• Getting Started
• Configuration & API Reference

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Installation

Method	Best For	Guide
Docker	Most users, easy GPU setup	Getting Started
Docker Compose	Managed deployments	docker-compose.example.yml
Unraid	Unraid servers	Getting Started — Unraid

• Web UI only: The Docker image runs the web interface. There is no CLI; all configuration and job management is done via the web UI.
• PyPI: The package is no longer published on PyPI; use Docker or install from source.

[!IMPORTANT] The Docker Hub image is published as stevezzau/media_preview_generator — the double z is the author’s Docker Hub username (not a typo). stevezzau/media_preview_generator on Docker Hub.

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GPU Support

Platform	Supported GPUs	Via
Linux (Docker)	NVIDIA, AMD, Intel	CUDA/NVENC, VAAPI, QuickSync
Windows (native)	NVIDIA, AMD, Intel	CUDA, D3D11VA
macOS (native)	Apple Silicon, Intel	VideoToolbox
Linux / Windows / macOS	No GPU	CPU workers only

On Docker Desktop (Windows/WSL2 and macOS) the container runs inside a Linux VM, so D3D11VA and VideoToolbox aren’t reachable — Docker on those platforms processes on CPU. For GPU acceleration on Windows or macOS, install from source.

See Getting Started — GPU Acceleration for per-vendor setup, tuning, and detection. Detected GPUs are shown in the web UI under Settings or Setup.

GPU + CPU Fallback

CPU fallback is automatic and built into every GPU worker — there is no separate “fallback” pool to configure. If a file fails on the GPU for any reason (unsupported codec, hardware error, driver crash), the same worker automatically retries it on the CPU and the dashboard shows a yellow CPU fallback badge so you know it happened.

If you have a lot of content that never decodes on the GPU, raise CPU Workers above 0 so that those files route straight to dedicated CPU workers instead of blocking a GPU worker each time.

See Automatic GPU → CPU Fallback for details.

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Documentation

Document	What’s there
Documentation Hub	Pick the right doc for your task
Getting Started	Install with Docker, GPU setup, Unraid, networking
Guides	Web UI, schedules, webhooks, HDR handling, troubleshooting
Reference	Config options, env vars, REST API, WebSocket events
FAQ	Common questions about setup, performance, and compatibility

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Built With

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Contributing

Contributions are welcome. See CONTRIBUTING.md for local setup, tests, code style, and the PR workflow.

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License

Distributed under the MIT License. See LICENSE for details.

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Acknowledgments

• Plex for the media server
• FFmpeg for video processing
• LinuxServer.io for the Docker base image
• Rich for beautiful terminal output
• All contributors and users

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