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Ask HN: Fable hacked my piano, can I release the results?

read original get Dover Erik Satie: Gymnopédies and Other Works for Piano → more articles
Why This Matters

A hobbyist asked an AI model to analyze proprietary PianoDisc player-piano files and it not only reverse-engineered the MP3-embedded MIDI format but also spotted and stripped the 'decoy note' obfuscation the vendor uses to keep files locked to its own hardware. It's a concrete example of how cheap LLM-assisted reverse engineering has become, and it revives thorny DMCA questions about publishing tools that defeat technical protection measures.

Key Takeaways
Worth a Look

Dover Erik Satie: Gymnopédies and Other Works for Piano — If all this talk of rubato, fermatas and sustain pedal technique in Gymnopédie No. 1 has you curious, this Dover collection puts Satie's actual notation in your hands so you can play it yourself and hear where the interpretive choices live. It's a classic, sturdy edition that pairs perfectly with tinkering on a self-playing piano — compare the printed score against whatever your MIDI files are doing.

See Dover Erik Satie: Gymnopédies and Other Works for Piano on Amazon → Affiliate link — we may earn a commission on purchases, at no extra cost to you. Product picked by AI based on this article; it is not a tested recommendation.

I have a self playing piano, using a system called PianoDisc Protigy. They have an online store which sells music for their system, from various modern artists along with classics such as Bach and Beethoven. Last night I saw they had released some music from Eric Satre, a 19th century French composer, which I bought. Curious if I could have just used AI to create these files, I began experimenting with Astra and Fable. Feeding the output of one into the other to critique. After an hour of LLM discussion of Rubato and fermata, solenoid response times and proper sustain pedal technique, they settled on their ultimate version of Gymnopedie No 1.

I then asked Fable to compare it to the open source version I'd downloaded from Mutopia, which it promptly ripped apart. No sustain, zero rubato, upside down balance.

Ok, what about the version I'd just bought?

The PianoDisc versions are mp3s encoded with the right channel carrying MIDI to be played on the piano, and the left channel containing any accompanying music to be played through attached speakers (who doesn't want the harmonica on Piano Man?)

I gave the mp3 to Fable, which promptly decoded the format, identifying the right channel carrying MIDI using a 2004.5 Hz square wave.

It then went on to analyze the nuance of pedal lift and melody relative to the chords.

Fable then asked if I wanted it to build an encoder to write my own MIDI files into the right channel of mp3s.

Sounds great, and I instructed it to write the encoder.

What it came back with was a python encoder PLUS a decoder.

In the verbose explanation, it mentioned decoy notes.

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