Factorio is a factory simulation game that leads its players into many happy hours of building ever more complex factories, but it comes with a snag. Its built-in music is a fairly simple synthesiser, and that doesn’t really cut it for the musical experience. This irked [Nablanaut] to the extent that he created his own MP3 player. Not just any MP3 player, this one is implemented as a Factorio blueprint, using only those in-game speaker elements as output.The synth has a range of built-in instrument voices and not much else, so he had to find a way to reproduce complex sounds using only those tools. As you can imagine, the result looks a lot like Fourier analysis, but with the added complication that those voices are not the discrete tones needed in such a system. The video below the break is a deep dive into the tricks and compromises required to not only play an MP3, but play it well, as we hear the various versions of the output as bit by bit they get better.The blueprint itself isn’t created by hand, of course; instead, it’s generated procedurally by a script. As far as we can see, it contains both the audio samples and the playback logic, making for a very complex factory. We especially like the song at the end of the video.