Over 25 years later, portions of MIDI introduced early on in the spec remain relevant. And if you want to connect your MIDI-equipped gear to Apple’s iPod touch, iPhone, and iPad mobiles, you will soon have an array of choices.

In iOS 4.2, best known for leveling the playing field between Apple’s handhelds and tablet, you’ll get full-blown MIDI support. It was clear in leaked details from earlier releases that Apple’s Core MIDI framework was finding new life on the mobile OS, but not directly what that would mean for hardware. Now, the hardware picture is clear. The Core MIDI framework appears to support two avenues for MIDI:

1. WiFi MIDI, via Apple’s own (apparently unique) wireless implementation, which should allow communication with other Apple handhelds and Macs, but likely not other devices. (WiFi is a common standard, but the way MIDI is transmitted over it is not necessarily so. That said, I believe the protocol for communication itself is based on documented implementation guidelines – not standards, but at least something someone else could conceivably implement.)

2. USB MIDI support for class-compliant devices, using the iPad Camera Connection Kit’s USB adapter.

More on the details – and other options and features outside just what Apple is giving you:

There’s one significant caveat to USB connections: the Camera Connection doesn’t carry a lot of current, so devices may require an external power source. So far, with multiple hardware adapters, and Apple’s own support for class-compliant audio, there could be a significant surge of hardware use with the iPad. But I haven’t yet seen indications these possibilities have taken the world by storm, even among Apple hardware devotees, perhaps because of the added bulk of the accessories themselves. (See more below.) That’s not to rule it out – I still think it’s pretty cool – but we’ll have to see how it’s received out there and how it works.

Interestingly, word of MIDI adapters has spread rapidly through the general tech press – outlets not normally excited by the vision of a 5-pin MIDI DIN connector. Developer Mike Keller, writing for PC World, has an especially ironic headline:

The Coolest New Feature in iOS 4.2 (That No One’s Talking About!)

So, why isn’t anyone talking about this? Apple’s NDA, which still covers 4.2, is one reason. (If anyone wants to have an existential talk with me about whether I should sign an Apple developer agreement and thus effectively gag myself as a writer, I’m game.) Another is that my sources tell me there aren’t yet code samples for the MIDI features. It could be fun to play with, though – especially with tools like libpd in development, bringing that popular free patching environment to the platform. And the good news is – this is public information – Core MIDI on iOS from the developer perspective should work just as it does on Mac OS. So huge kudos to Apple for high-quality implementation of a de facto standard for musicians.

The big news to me is that power requirements may prevent the use of some of the more compact devices out there — anyone want to test, for instance, the M-Audio Uno? Either way, it appears there may remain some call for specialized devices. Update: no worries! Reader reports suggest that at least the M-Audio Uno works fine, and that should mean other 1×1 devices are okay. (They don’t draw much power.) So, connect one of those suckers into the iPad, and you have a viable alternative to the MIDI Mobilizer. (Bonus: developers won’t have to set up an agreement with a separate hardware maker – for iPad, though you still need the MIDI Mobilizer on iPhone and iPod touch, since as readers note, they don’t support the Camera Connection Kit.)

So, aside from what’s coming in iOS 4.2, what are your options for getting MIDI in and out of Apple’s mobiles – or other mobiles, for that matter? Glad you asked.


2 MIDI in (5-pin DIN)
2 MIDI out (5-pin DIN)
Full 2.1A 5V USB power – enough to charge your iPad
Comes with an interface cable
2-4ms iOS app latency

The iConnectMIDI box is the most serious solution out there, especially with dualing ports. And lest you think it’s rendered irrelevant by the coming features in iOS 4.2, think again. Its dedicated connector cable and power specs should make it more useful with iPad than a stock class-compliant device. Buried in the specs document, too, is this gem: “iOS Core MIDI framework support, if and when allowed, is expected to further decrease latency for iOS applications.”

So it may get more useful, not less, with the 4.2 release.

Availability: Not yet. Stay tuned for NAMM.

Cost: Not known. I’m guessing $999/EUR1299. Kidding.

Development: Partner SDK, “as required” by Apple. That means there’s a test and verification process that you have to go through with iConnectMIDI and then you can submit to Apple and go through it again with them. I’m hoping that gets nixed with 4.2, but there’s absolutely no word soon (not even if you break NDA).

Line 6 MIDI Mobilizer

1x in MIDI DIN, 1x out MIDI DIN (via 5-foot breakout cables – they use a 2.5mm connector on their actual box)
Specialized hardware adapter
Includes a free app for recording, exchanging via email and WiFi
iPhone, iPod touch, iPad (a nice handheld option on the former two)
Already supported by a handful of apps, including Line 6’s own MIDI Surface
Developer program open to anyone; see above

Availability: Now
Cost: US$70 street

The MIDI Mobilizer has the advantage of being relatively portable, though as some readers have pointed out, it still adds some bulk to Apple’s svelte handhelds. It’s also costly given what computer users are accustomed to paying for similar interfaces. But once you’ve got it, it’s a powerful, handheld tool. The big question mark has been app support, so watch, again, to see if what we get via 4.2 is standard support in place of individually reviewing apps.

See also SonicState’s review:

WiFi MIDI, OSC, etc.

Readers gripe that the big problem with MIDI adapters is that they kill the portability of the device, thus, erm, defeating the purpose. After all, for $200 these days you can get a netbook and add a $30 MIDI adapter with a lot less fuss, if you want a more portable MIDI rig.

That makes wireless Internet look more appealing, not only on iOS, but potentially other mobiles, too – like Android or even game gadgets.

One example:

DSMI, the DS Music Interface, is free software that has been ported to iOS and enables wireless MIDI communication not just with the Mac, but Windows and Linux, too. (I’ll be interested to see if new implementations of the WiFi MIDI used in 4.2 for those platforms can do the same.)

And that’s to say nothing of various wireless OSC implementations, enabling cool apps like the one we saw earlier this week. If you don’t mind a computer as a go-between, that’s another solution for MIDI right now:

Bluetooth? (on Android?)

What about Bluetooth? Recent conversations I’ve had with engineers on the phone suggest that latency and jitter should no longer be a problem with modern chipsets. That could make Bluetooth an ideal way to enable both mobile platforms and hardware wirelessly.

Just one problem — iOS’ restrictions on device pairing appear to rule out the use of this technique on Apple platforms.

Android is another question; I’ve already seen a couple of proof of concept tests that suggest that this would work really well on Android.

Here’s hoping eventually Apple allows something similar, even via Core MIDI. In the meantime, it could be worth trying on Android. That’d open the possibility of cross-platform mobile-friendly apps that used WiFi and cables on iOS and WiFi and Bluetooth on Android.

Who Cares?

So, why bother keeping track of this? I think there are a few scenarios that get interesting with these devices:

  • Mobile music: Get away from your desktop computer and its distractions and work in any environment. (Hey, even the original Nintendo Game Boy can be adapted to MIDI I/O.)
  • Alternative sequencers: Since touch control has often been relatively lacking on desktops – and laptop form factors in particular don’t lend themselves to touch in their standard hinged form factor – touch-based software on a system like the iPad (and soon, other tablets) benefits from these approaches.
  • Mobile interfacing with gear: Imagine you’re in a studio full of vintage synths and want to record something, without finding a place to balance your laptop.

There’s also just the simple fact that an iPhone, an Android phone or tablet, and an iPad are all computers. Part of what we’re seeing really is reinventing the wheel – in a good way. We’re getting the standards for interoperability and actual music making we’d expect on any computing device.

Stay tuned for when the 4.2 NDA is lifted (and we have the 4.2.1 NDA to contend with instead). And for discussing non-NDA platforms, or iOS once its NDA is lifted, I hope you’ll join us in these groups on Noisepages:
Next-gen Mobile Music + Visual Dev Hack Group
Pd Everywhere

Meanwhile, if you want to see MIDI on traditional computers, a couple of us have found that the good old-fashioned MIDI multi-port hub has some utility, for reasons I’ll explain soon. And yes, you can still buy them – check out the M-Audio MIDISPORT 4×4. So, no, I’m not only about the mobile stuff.