If you have a music keyboard that isn’t one of the most basic, it will probably have MIDI sockets on it. MIDI was invented in the 1980s, and in spite of retaining the limitations of the concepts and technology of the time, it’s still in use today.
The 5-pin connectors look rather oversized now, but that’s good. I like simple, robust designs. They carry a serial communications protocol that runs at 31,250 bits per second. There was a reason for choosing that odd figure, but I forget what it was. Anyway, it’s pretty slow. Nowadays, there are systems to carry MIDI signals over Ethernet or USB, but the old-fashioned direct connection is still the most common.
When you press a key on your keyboard, it sends a “note on” message out of the MIDI connector, and when you release the key, it sends a “note off”. That’s the core of how MIDI works. If you connect up a second keyboard, with “MIDI out” from the first plugged into “MIDI in” of the second, the second keyboard acts like a slave of the other: when it receives “note on”, it plays that note too. Neat! You can play two keyboards at once.
Actually, that’s not all that useful, is it? OK, you can have two different sounds at the same time, but you can only play them in unison. No, the real fun starts when you connect up a computer. Early PCs supported MIDI through spare connecting pins on their “Game port” for joysticks, so you needed a weird 15-pin adaptor thing, but these days you’re more likely to use a USB or FireWire adaptor: under £20.
Software on the computer (a “sequencer”) can record your playing, and can then send it back to the synth later; maybe after you’ve edited out the bum notes, or fixed up the timing with some quantization. Almost all keyboards will support multiple channels and simultaneously play several independent instruments’ sounds when instructed to by the computer. So you really can play more than one instrument at once, by recording each separately.
Sequencers generally have their own file format for saving MIDI sequences, but all of them will also support Standard MIDI Format, generally files with a “.mid” extension. Back in the early days of the Internet (and even before, on the dial-up bulletin boards) you’d get a lot of MIDI files in circulation, when talented musician/programmers would make versions of popular songs and give them away.
Remember, that’s not like MP3s, where you’re illegally swapping the actual sound of a performer. With MIDI files, you’re swapping data that describes how to play the notes. It’s exactly the equivalent of swapping sheet music. Of course, that’s an illegal copyright violation as well.
The copyright holders, the music publishers, did make some ineffectual efforts to prevent material being swapped, but what really killed the free scene was the invention of polyphonic ringtones. A lot of phones could play the MIDI files right off, or conversion was possible if they couldn’t. Free MIDI files disappeared off the net pretty quickly, to reappear as commercial ringtones. Yes, generally the same ones, stolen without credit or profit to the person who made them.
But the phones never really had sound synthesising hardware of any quality, so although they could produce a recognisable version of a tune, it always sounded as if it was being played on a vintage plastic Casio. Cute, maybe, on the first listen, but very annoying after that, even to the owner. More recent phones have the ability to play proper recorded music, as in MP3 or other formats, and polyphonic has largely gone out of fashion.
But that means that there’s no money in it, so free is back in fashion. You can now find loads of MIDI files on the Internet again. Most computers will already know how to play them through the on-board audio hardware. On Mac or Linux, although it’s quite vintage now, a program called Timidity* may be your default one. Or you can find sequencer software so that you can modify the music before it’s played.
Being free, the quality of the files varies from execrable to mediocre. I’m just listening to a rendering of Rock Lobster, downloaded from the Free MIDI File Database. The drumming is pretty good, and the overall structure of the song is accurate, but the instrument sounds of the bass, guitar and organ are very plastic.
So why should I bother? Why listen to a version of the tune on synthesized instruments, with no vocals, when I have the original on the album? For me, two things: I can make changes, say to transpose the key or change the instrumentation (Rock Lobster on the tuba); and I can play along. With a sequencer, you can eliminate any channel — any instrument — so you can add your own real one to the mix. There’s some software that combines MIDI sequencing with recording live audio, so you could even capture it for posterity.
I’ve just downloaded Pick Up The Pieces from the same site, and although the bass and guitar lines in the song are very simple, it’s going to be fun to try playing them with the rest of the virtual band.
*I once fixed a minor bug in Timidity, so my software could be on your computer