Percussa micro super signal processor

Ready to cut the cord and go wireless? With mobile gadgets getting involved in music-making, it seems a logical solution – maybe not reason to throw away your MIDI cabling, but worth at least trying. Bluetooth could be an answer. In fact, it could work even without all those pesky, pricey mobile tablets and phones lying around, just with good, old-fashioned MIDI gear. (‘Bout time.)

Bluetooth and MIDI are a logical match; the big surprise is that these two haven’t paired off (cough) much earlier. We’ve seen the occasional implementation or paper or rant, but not much real-world usage. That could be about to change – that is, provided ample real-world testing.

Bluetooth mobile sync: First off, owners of Korg iOS software just got a Bluetooth-based update that provides sync. (See video below, shot by tipster and reader Danny Fluck.) Entitled “Wireless Sync-Start Technology,” KORG promises their Bluetooth feature now enables two iPads running iElectribe or iMS-20 to sync with one another with zero latency. (The update also includes perhaps more widely-useful features – SoundCloud support and AudioCopy, says Synthtopia.)

The name suggests that what the “sync-start” technique does is actually to match any latency between the two devices so that they start at the same time. That’s how multiplayer gaming typically works, and it applies easily to musical applications: you ping connected devices, then delay the start points of each of them to match the slowest device so that they sound together. (I think I’m saying that correctly and clearly; it’s Friday.)

Danny reports that it works perfectly and “instantaneously.”

Okay, so cool, as long as you only use iPads, and you’re lucky enough to have two iPads handy, and you only use KORG apps, you’ve got a nifty solution – but that’s a little limiting.

Bluetooth MIDI on Android or any hardware device. A bit further-reaching is something Peter Brinkmann, primary author of libpd, has been testing. (See video, top, which is much snappier than my explanation.) Now, Peter is no MIDI fanboy; when several of us talked about adding MIDI to libpd – an embeddable version of the open source patching environment – he described MIDI as a “plague upon humanity.” (I don’t recall seeing that quote anywhere on the MIDI Manufacturing Association website.)

But here’s the thing: MIDI is obsessively compact and simple, and absurdly easy to implement even on the cheapest microcontroller. That makes it ideally suited as a means of making inexpensive hardware inter-operate, and without using up lots of power or bandwidth – just as MIDI was designed to do.

Furthermore, as Apple tablets and phones demonstrated USB MIDI connections, it got Peter (and some of the rest of us) thinking. Yes, it’s too bad that Android devices lack key USB host capabilities that would let them talk to hardware. On the other hand, once you start attaching lots of cables to a device, you might as well use a (more powerful, more flexible) computer in place of the tablet. So low-power, efficient wireless – like Bluetooth – seems the way to go.

Like a good engineer, Peter went and hacked the solution he wanted himself. Partially inspired by Lady Ada’s own, well-documented Bluetooth MIDI experiments, Peter started documenting the process on his blog.

In his first blog post, he describes his hardware setup. (He later updated the rig and moved it off the bread board.

In part 2, he describes latency and jitter. Here’s what I’ve been told by mobile engineers to whom I talked: performance has greatly improved in Bluetooth implementations in recent years. That means that part of the reason Bluetooth MIDI may have been adapted is that, when people first began testing this a few years ago, the implementations weren’t yet good enough – and no one has checked since. (Until now, that is.)

Since then, Peter has released free software for the Android platform, all under a free Apache license, so anyone can try it out. And since it works natively with Pd for Android, this means you can very quickly hook up a Pd patch to Bluetooth support on any Android device. There’s even a sample patch and code to get you started!

As far as I know, Apple doesn’t let you implement a similar solution on iOS, so this would remain Android-only. (Hey, come on – iOS can’t have all the fun.) I’m curious to hear if I have that correct, though, so please do share.

The next step: refining the hardware rig and interface design and most importantly, testing. Correction: I claimed that the MIDI interface was not opto-isolated; it actually is.

Hacklab and testing: With that spirit in mind, on Saturday April 2 from 1p – 6p, we’ll have a free, open hacklab in New York. It’s mainly an informal get-together, but there will be short demos as we go. It’s the first step in broader testing and experimentation with these ideas. If you’re in the NYC area, you can RSVP on Facebook. (just went up, so it may be quiet) The plan is to play a bit with hardware and software and different Android devices.

All are welcome to the hacklab, regardless of experience.

This isn’t just an Android thing, though. Part of the reason to use Bluetooth in place of WiFi is that it’s much simpler and cheaper to implement, and has more modest power requirements. As such, providing Bluetooth MIDI interfaces for other music gear is more manageable than it would be with WiFi.

More resources:

A 2005 IEEE conference presentation describes early work, though this research could use a modern update.

A 2003 open letter encouraging Bluetooth MIDI use.

Meanwhile, in the Land of WiFi

Synthtopia reports on iOS MIDI WiFi, in the case of MoDrum and Bassline, using Apple’s own network MIDI framework. I’m assuming it claims it’s the most extensive such implementation because of the sync functionality.

SoundPrism Pro, in the trailer below, also recently added network (as well as wired) MIDI compatibility.

Incidentally, there are already compatible frameworks for Windows and Linux (in addition to Mac, of course), and no reason Android couldn’t also do WiFi MIDI, too. The advantage of Bluetooth remains doing so with less power consumption, and as direct serial communication over the wireless link.

More resources on the WiFi side…

From January:
New Solutions for Wireless MIDI, MIDI+OSC; Developers Answer Questions

And yes, devices like The Missing Link provide this kind of functionality over WiFi – though the Bluetooth radio could be cheaper and more power efficient. (As for performance, we just have to do more testing.)

Just don’t forget, all of this is a plague upon humanity and an abomination, so try to keep that in mind. Have a good weekend!