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Music Tool

Convert the music library to MP3 or 432 Hz, right on the NAS.

Converts lossless music to compact MP3s and creates a second library at 432 Hz, keeping tags and album art. Start it from your phone, and the NAS keeps working while Plex goes on streaming.

A web interface that runs on the NAS and converts the music library without sending files across the network. You start a job from your phone or laptop, close the window and the NAS just keeps working. The results appear as separate libraries in Plex.

What it does

  • To MP3: converts lossless music (FLAC, WAV and AIFF) to MP3 at V0 quality. All tags, featured artists and album art are kept. In practice that saves about 68% of storage, with no audible difference.
  • 440 to 432 Hz: creates a second library that plays slightly slower, like a turntable running a touch slow. No pitch-shift algorithm, so no artefacts. Measured: 431.998 Hz.
  • Automatic: new music dropped into a watch folder is converted by itself, locally or via Nextcloud.
  • Smart source choice: if the same track exists in several formats, the tool picks the best source, with FLAC first.

How it is used

  1. Pick a source and destination folder and click Try 5 files first. How long that sample takes tells you straight away how long the whole library will take.
  2. Click Start all and feel free to close the window.
  3. Interrupted? Start the same job again. Anything already done is skipped.

By default the tool processes only a few files at a time, so Plex keeps streaming without hiccups. At night you can turn that up.

Safe with your library

  • The source folder is read-only. The tool cannot change or delete your originals.
  • Results always go to a separate folder. You switch over yourself, once you are sure.
  • A damaged file does not stop the job; it is listed together with the error.
  • Stopping never leaves half-written files behind.

Technology

A single Python file with no extra libraries and the interface built in. It runs in Docker on the NAS (ARM64), and also as a standalone app on Windows and macOS. The heavy lifting is done by ffmpeg, which the tool fetches itself on first start, in the right build for the processor.