I built an external GPU-accelerated trickplay/preview generator for Jellyfin server (originally made it for Plex, added Jellyfin support)
Hi All,
I originally wrote this for Plex (its built-in preview generation is single-threaded, CPU-only and slow), and have since added Jellyfin and Emby support. I shared the Plex version over on r/PleX recently and people found it useful, so figured I'd post here for the Jellyfin folks in case anyone has use for it.
Jellyfin already does hardware-accelerated trickplay, which is great.. but it shares CPU/GPU with playback. On a busy server that's resources you'd probably rather give to the player. This runs preview generation on a separate machine, uses every GPU it finds (NVIDIA / AMD / Intel), and processes files in parallel. It writes Jellyfin's trickplay tiles in the format Jellyfin expects and if you also run Plex/Emby on the same files, it does all of them in a single FFmpeg pass.
What it does:
- Off-media generation — point it at your media + Jellyfin config, it writes trickplay tiles without loading your server
- Automation — Sonarr/Radarr/Tdarr/FileFlows webhooks, recently-added polling, cron/interval schedules, all on one inbound URL. Auto re-runs on quality upgrades, skips when nothing changed.
- GPU + automatic CPU fallback — if a codec fails on the GPU it retries on CPU automatically. HDR / Dolby Vision tone mapping included.
- Web UI (Docker-only, no CLI) — manual generation by searching your library: whole show, movie, folder, or single file.
Full transparency on two things:
- This project is AI-assisted (Cursor + Claude). I hand-wrote the original, recent development is AI-assisted, and all changes are reviewed and tested. AI also helped me write this post.
- The Jellyfin support is newer and I haven't done extensive testing across every setup yet — but I'm usually quick to fix bugs if you report them. Just sharing in case it's useful.
GitHub (MIT, Docker): https://github.com/stevezau/media_preview_generator