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

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.

Curious, I asked it to explain the decoy notes.

Apparently PianoDisc adds obfuscation into their format which is handled properly by their decoder, but would leave naively extracted MIDI unplayable on other systems.

Fable created an encoder which adds those decoy notes, and a decoder which removes them.

Am I allowed to publish the decoder? The encoder?

70 points | by jmpman 1 day ago

17 comments

  • Giefo6ah 1 hour ago
    If you live in the USA, the "decoy notes" may be considered an "effective technical measure" from the "Digital Millennium Copyright Act".

    If you live in Europe, this restriction may be considered "gatekeeping" and exempted by the Digital Markets Act.

    Don't bring attention to yourself by asking for permission. Publish your codec, and if the company cares about this they will send a cease and desist.

    If you want the world to benefit from your code but you don't want to be responsible for it, try to adapt the codec to ffmpeg. The ffmpeg project is used to dealing with these matters, and will keep your codec working for eternity.

    • progval 55 minutes ago
      > If you live in Europe, this restriction may be considered "gatekeeping" and exempted by the Digital Markets Act.

      That's not how the DMA works at all, there is no concept of gatekeeping practices. Instead, the EU Commission designates companies that act as gatekeeper for some services (current list here: https://digital-markets-act.ec.europa.eu/gatekeepers-portal_...) which then puts constraints on what they do.

    • Doohickey-d 28 minutes ago
      If you don't want to be responsible for it, another way is to just publish it anonymously: make a GitHub that isn't attached to your real name etc, perhaps using a one-off disposable email address, and put it there. Then you don't have to think about what the lawyers think. Worst case it'll get taken down, but by that point it'll likely be popular enough that there'll be plenty of copies.

      [Pirate flag emoji here]

    • phire 36 minutes ago
      > the "decoy notes" may be considered an "effective technical measure" from the "Digital Millennium Copyright Act".

      I really hope not. My understanding is that to be "effective" it needs to at least be a form of encryption with a secret key. At least, I'm not aware of any case law that allowed anything less than that.

      IMO, "dummy notes" are nothing more than a form of obfuscation. If it's obvious how to filter them out, then I don't think it comes close to meeting the bare minimum of what might count as an "effective technical measure".

      Of course, who knows what way the courts will rule if it ever reached that far.

    • politician 13 minutes ago
      Consider publishing the prompts used to create it.
    • KennyBlanken 39 minutes ago
      Any company would be a fool not to send a C&D given how many people on this site seem to think that "I got a C&D" means "if I don't obey it, I'm gonna get sued."

      Anti-SLAPP laws exist for a reason, and if corps can bully anyone, how is it that corps routinely lose lawsuits on either side of the docket, hmmmm?

      Keep licking that corporate boot, folks. Corps send C&Ds because they cost them all of maybe $100-200 and they're so effective.

      There is a long road between "got a C&D" and "am getting sued." Among other things, a judge is going to want to see that both sides attempted to negotiate. If the company sending the C&D just demands that and then tries to file suit, the judge is going to tell them to go back to step 2 and stop bothering him/her.

      Folks, stop telling people that if they get a C&D they have to just fold. Good chance you never hear from them again because the cost of suing you is nowhere near the damages they will be able to prove in court.

      • DANmode 26 minutes ago
        > There is a long road between "got a C&D" and "am getting sued."

        Sometimes!

  • jdlshore 2 minutes ago
    Don’t ask Hacker News for legal advice. If you really want to know the answer, ask a lawyer.
  • arjie 2 hours ago
    The nature of these tools is that your post and the device should suffice to replicate so in some sense you have already published the encoder and the decoder.
  • reilly3000 28 minutes ago
    Gymnopedie No 1 was one of the pieces I learned as a primary school student as a mediocre and undedicated pianist. The reverse engineering is impressive and generally useful, but really learning that piece all the way through could be even more rewarding, then you can use 10 fingers and two feet to make it sound like YOUR ultimate version, not just your words. Perhaps Claude truly nailed it in your taste and you want to be able to reproduce it reliably without automation: record one phrase at a time and try to minimize the about of variance between yours and the MIDI. Maybe some visual feedback would help and be clever, but usually using your ear is the most productive.
  • brudgers 1 day ago
    You are free to interpret this comment as prohibition or as my blessing, but...

    If it matters, ask your lawyer.

    If it doesn't matter, it doesn't matter.

    Or to put it another way, trademarks (you've mentioned two) and copyrights (it's a crapshoot) are complex. And in some jurisdictions (notably the US) anybody can sue anyone for anything.

    Your risk aversion is yours, not someone else's. Your financial and legal wherewithal is likewise yours.

    • Someone 19 minutes ago
      > And in some jurisdictions (notably the US) anybody can sue anyone for anything.

      That should be the case in all jurisdictions. The justice system exists so that, if I feel treated unfairly, I can go to the state to settle the question whether/how much that is true. If there are issues where I cannot go to court, what am I supposed to do? Go fight you over the issue?

      What differs (a lot) is how effectively the system rejects frivolous/unjust cases, how much time/money it costs you to defend yourself against remaining claims, and what systems there are to prevent people from going to court (having affordable care will prevent people from taking some medical claims to court; obligatory car insurance means most fender bender cases get handled by insurance companies, etc(

    • jmpman 21 hours ago
      I might just email the company. If they object, I won't make my GitHub repo public.
      • ungreased0675 2 hours ago
        This seems like the worst possible advice. It will only bring negative attention and maybe legal repercussions.
      • brudgers 10 hours ago
        They might object to the existence of the software and demand “its destruction.”

        Or sue your ass…or file a DCMA takedown with Github.

        Or all of the above.

        The best likely outcome is probably “no.”

        Because they have lawyers and that’s what lawyers do.

        If you really really want to share the information, you might write a blog post with technical details without linking to any code. Sharing the blog to the “Facebook group” will let you assess community and corporate interest and make an informed decision.

        Keep in mind that they could say yes and still do all that bad stuff anyway.

      • bossyTeacher 13 minutes ago
        HN users are at the same time the brightest and the most clueless. Why on earth do you think they will agree to something that they will perceive as damaging to them in the present or in a possible future?
      • georgemcbay 1 hour ago
        > I might just email the company. If they object, I won't make my GitHub repo public.

        If you do this, I can nearly guarantee they will either never respond as a best case scenario, or they will object.

        There is effectively zero chance a company would give you any indication that you have their blessing. Even if they don't actually care one way or another they will make the assumption that giving you any kind of positive response is nothing but a negative for themselves in terms of future liability, etc

        The phrase that it is "better to ask for forgiveness than permission" exists because of situations like the one you're in.

        Just publish the repo. Don't contact them. If they C&D you, take it down if you don't want to deal with the legal repercussions.

        For all the same reasons that it is easy to predict how they will react if you ask, it is easy to predict how they will react if you don't and they find the repo and object. They will send you a cease and desist letter telling you to take the repo down. You will then take the repo down and face no other legal action because it will not be worth their time to make any bigger deal of it than that.

      • MuffinFlavored 1 hour ago
        Have you ever worked corporate before?

        It is better to ask forgiveness than permission.

  • natch 1 hour ago
    You bought a hardware device and you own that device?

    This decoy notes scheme seems pretty unethical.

    • Gigachad 32 minutes ago
      I wouldn't take claude research at face value. It found something odd, came up with a plausible sounding explanation and confidently presented it to OP. Doesn't mean it is true.
  • NordStreamYacht 1 hour ago
    Why not publish the methodology in detail and leave it at that?
  • NegativeLatency 2 hours ago
    Personally I’d just do it
  • ryandrake 1 hour ago
    Find someone in Europe or Australia, or some other place with non-insane digital laws, and have that person publish it as the “developer.”
  • philosopherNoob 55 minutes ago
    If I ever owned a self-playing piano, figuring out how I could play custom songs of my own creation would be my top priority. It’s awesome you’ve found some success. Jmpman, what your post is missing is motivation. Why are you doing this and what is your goal?

    If you sell your decoder or encoder the company will, eventually, kick your butt. Getting money involved raises the stakes.

    If you distribute a file that is sold by the company, even if it was transformed by a decoder, the company will, eventually, kick your butt. (A recording or sample of how it sounds post-transformation for demonstration purposes would be reasonable.)

    If your software requires files that must be paid for in order to function, then it’s critical that you do not bundle those files with your decoder or encoder. That would be piracy.

    How your software was made matters. Did you have access to non-public information about anything involved? It seems like the answer is no, so you might be fine. It sounds like you legally obtained a copy of the file, hardware that runs it, and figured out how they work.

    What terms of service did you agree to? While not everything listed may hold up in court (which gets determined BY a court IN a court so don’t think that’s an easy win), the company is surely within their rights to ban you from their online service.

    If you want some relevant legal advice, check out the GameCube Dolphin emulator and how the team stays legal. I love learning about how stuff works, so I’ve followed lots of console jailbreaking and reverse engineering news for years. There is a way to do this stuff legally. HN is focused more on finance than hacking. So talk to some hackers (who aren’t trying to break the law).

    I saw you ask about contacting the company. If this was a blog, I’d love a followup about what they say and do, but alas I’ll probably never see it. (I guess the worst outcome is that they spend more money on making their proprietary stuff more locked down?) Regardless of what they say, their word is not the law. Know the law, know your rights, and know when it’s safe to stick your neck out and when it’s not. I am obviously not a lawyer.

    Oh, and which US state you are in and what they are based in will be relevant.

  • franky47 1 hour ago
    typo: did you mean Erik Satie?

    https://en.wikipedia.org/wiki/Erik_Satie

  • Redster 1 day ago
    IANAL, but it might be relevant to others trying to answer what jurisdiction you are in. (US, EU, CN, JP, elsewhere?)

    Also, when you bought from PianoDisc, did you agree to abide by a certain jurisdiction's laws in your use of PianoDisc? And did you explicitly agree to not share any sort of decoder/encoder in any ToS?

    • jmpman 21 hours ago
      US.

      https://store.pianodisc.com/pages/terms-of-service-and-condi...

      I don't see details about them mentioning and decoder or encoder.

      • codingdave 12 hours ago
        > (k) to interfere with or circumvent the security features of the Service

        IANAL. But I think reverse engineering their data structure, identifying a security measure - even one as weak as obfuscation, and publishing code to circumvent it is clearly against your license.

        • Elsewhereindeed 1 hour ago
          I am also NAL, but out of curiosity does OPs post detailing the obfuscation transgress any laws?

          If the security measures exist in plain sight, as they apparently do, are they allowed to be discussed?

          I reckon that if OP posts the encoder/decoder software that'd be against some sort of license clause. However in the age of AI who cares about the software at this point? Anyone can prompt their own private version into existence.

          Just thinking out loud here. I have not considered AIs use as personal "cheat engines".

  • worthless-trash 1 hour ago
    You publish it as the organ-guy piano system for a virtual piano that you've lost the code for.

    On a serious note: reverse engineering is legal in australia, even for DMCA violations.

    • rcgy 58 minutes ago
      Would love for sources / prior case law around this? I'm Australian and involved in reverse engineering insulin pumps and CGMs, and we are constantly worried about getting our butts DMCA'd.
  • xgulfie 2 hours ago
    I'm your lawyer, you should do it
    • worthless-trash 1 hour ago
      why are you on hn, you are billing in 6 minute increments!
  • tmpsvc2695f5 1 day ago
    [dead]
  • dmarinus 1 hour ago
    my experience with LLMs is that when you get answers to questions you didn't ask that it's repeating something that already exists. In other words, it probably regenerated a tool from which it was trained on.