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FAQ

1. Is Alchemist free?​

Yes. Alchemist is GPLv3 open source. There is no paid tier, license key, private pro build, or commercial-use unlock.

2. Will it ruin my quality?​

No by default. The planner uses BPP analysis and optional VMAF gating to avoid pointless or low-quality transcodes.

3. How much space will I save?​

Typical results are 30–70%, depending on source quality, codec choice, and how much waste is in the original file.

4. Do I need a GPU?​

No. CPU encoding works. GPU encoding is much faster and more power-efficient.

5. Does it work with Plex, Jellyfin, or Emby?​

Yes. Point Alchemist at the same media directories your server already uses.

6. What happens to my originals?​

By default they stay in place. Nothing is deleted unless you enable delete_source.

7. Does it support 4K and HDR?​

Yes. It can preserve HDR metadata or tonemap to SDR.

8. Can I run multiple instances?​

Not against the same SQLite database. Use one Alchemist instance per DB.

9. What is BPP?​

Bits-per-pixel. It is the compression density measurement Alchemist uses to decide whether a file is already efficient.

10. What is VMAF?​

Netflix’s perceptual quality metric. It is optional and slows down post-encode validation.

11. How do I update?​

Direct Linux/macOS binary installs can use the prompted update flow in About when a signed release manifest is available. Alchemist drains active jobs, backs up the database, verifies the release asset, and restarts.

Docker installs should still update the container image:

docker compose pull && docker compose up -d

Homebrew, AUR, Windows, and source installs show the matching package-manager or manual update guidance in the app.

12. What if hardware is not detected?​

CPU fallback is automatic unless you disabled it. Check the hardware probe log to fix the GPU path.

On repeat boots, Alchemist may show a cached hardware result immediately if the runtime fingerprint still matches.

13. Can I control when it runs?​

Yes. Use Settings → Schedule to define allowed windows.

14. Does it handle subtitles?​

Yes. Subtitle mode supports copy, burn, extract, and drop.

15. Why did it skip my file?​

Open the skipped job and read the reason, or start with Skip Decisions.