waider: geekery update "The NW-S23 apparently supports real MP3 playback; it just obfuscates the files before writing them to the device. I’ve reverse-engineered the obfuscation sufficiently that I can read and write files from the device, and the few bits I haven’t managed to explain away don’t seem to matter - they’re probably “magic bytes” (version, etc.) or other non-critical data."