About us

La Capseta de Música is made by one person, with the help of a few artificial intelligence assistants. Each assistant has a craft and written rules it must follow. The AIs propose and build; the decisions, the judgement and the final approval always belong to a person.

The Capseta Project

It was born from a grandson and a music box. When he was about two, I gave him a wind-up music box, and he couldn't make it work yet: his little hands were too small. I thought the music box could be digital: an app that sounded like a music box and kept him entertained.

The first music box was the final project of a postgraduate course in mobile app development at the UPC. Now there is one app per music box, for iPhone and iPad, each made for an age (babies, toddlers or children), with its own songs and pictures.

The music boxes aren't games. There are no scores, no records, no challenges: just the pleasure of listening to traditional Catalan music, in the public domain, while a picture moves slowly. At most, tapping on the picture. The motto says it all: the Capseta doesn't perform music; it tells memories. No data, no ads, no purchases.

Who I am

I'm Lluís Suñol, a systems engineer from the Barcelona School of Informatics (UPC). With some colleagues I co-founded a financial software company, valuing the portfolios and assets of collective investment institutions. My part was the calculations: what allowed these institutions to pass the supervision of the Bank of Spain and the Spanish securities regulator (CNMV), especially for derivatives, the instruments the supervisor watches most closely.

A few years ago I was diagnosed with fibromyalgia, and I had to stop working. I'm still on the company's board, which is doing quite well, but I can't sit still: I went back to university, and my motto is "life is software". The Capseta lets me do what I love most: software, music and small children.

And what Claude, who works on it every day, says: "He wants things simple and in their right place. If a name doesn't say what it is, he changes it; if an answer is long, he cuts it. He has the whole app in his head, works layer by layer — going fast is going slower — and asks to be contradicted, but when he is right he doesn't let go. Before talking about technology, he thinks of the crying child and the mother holding him on the underground. On rainy days he arranges lullabies."

Claude, the engineer

Claude, by Anthropic, is the software engineer. It started by gathering the requirements, and from there did the whole design: the parts of each app, how they talk to each other and what happens when something fails. "The music box never breaks" is its rule: if a resource fails, a spare one takes its place and the music carries on.

Now it writes the apps' code and checks every picture, animation and song before it goes into a music box. It also transcribes the scores, from a photograph, so that the arranger can work on them.

ChatGPT, the arranger

ChatGPT, by OpenAI, is the music arranger. It starts from a well-known song and makes music-box versions of it: one for each age, slower and simpler for babies and livelier for children. The melody is always recognisable; what changes is how it develops, and how it ends.

It works with the Music Seal, and every version is listened to before it is approved: what counts is how it sounds, not how it looks on paper.

ChatGPT, the illustrator

ChatGPT is also the illustrator. Given a brief, it proposes two or three ideas in words, recommends one and draws nothing until Lluís says "go ahead". Every picture has a music box with its crank, and is designed for the eyes of a small child: a single, clear figure, nothing scary.

Before handing over a picture, it checks it point by point against the Visual Seal.

ChatGPT, the animator

And the animator: it decides how each picture moves. It explains it with everyday comparisons ("it rocks like a cradle") and, once Lluís chooses, writes it in a format the app understands. The movement is always slow and predictable, returns to where it started and never goes beyond the limits for each age.

Animations don't depend on any particular picture: any movement works for any music box.

Perplexity, the preparer

Perplexity helped prepare the profiles of all the assistants: each one's craft, what it may and may not do, how it works with Lluís and how it checks its own work. These are the rules that make them all work the same way.

Our rules

Every music box follows two sets of rules that all the assistants must respect: the Music Seal (how they sound) and the Visual Seal (how they look and move).