In this bold, new future of computing, we don’t need USB or ports, huh? Wait – scratch that – you may have your iPad and your USB, too, after all. Photo (CC) Teo.

Score one for standards. According to second-hand sources and a post to a public mailing list, the upcoming Apple iPad accessory adapter for cameras, the iPad Camera Connection Kit, will support audio interfaces that are compatible with the USB Audio Class. I don’t have official confirmation from Apple, and the adapter itself appears not to be shipping until later this month, so file this as “likely, but unconfirmed.” But it’s one to watch, and comes as a surprise to me. (Generally, camera accessory kits aren’t a way of providing audio expansion.)

Let’s assume, as these sources suggest, that USB audio devices were available via the standard stereo output (or even input) for the public Apple APIs for audio I/O. In that case, the other good news is that iPad apps would be able to support your third-party hardware without special modification of the software, or a signed hardware license agreement.

Most pro audio interfaces are not class-compliant; it’s more common to use custom drivers, even for USB 1.x-compliant interfaces. Custom drivers would be out of the question. But there are a number of interfaces that do provide class compliance, like the M-Audio Fast Track or Edirol UA-25. (I have a Cakewalk-branded, Roland-manufactured SPS-25 that works as a class-compliant device with the “advanced” mode on the back switched off.)

Incidentally, devices that support this spec will also easily work with Linux, and possibly upcoming updates to Android, if the latter adds similar USB host support. That means there’s now ample incentive for audio interface vendors to investigate providing class support, as it could mean more customers not only from iPad owners, but owners of other slates and tablets, too – including those we don’t yet know about. (Google tablet, anyone?) That further illustrates why up-to-date class descriptions for hardware are so badly needed (though it also, sadly, reminds us how much isn’t covered by these generic classes).

Before you get excited about connecting a MIDI keyboard to your iPad, I don’t know that this will mean support for the MIDI device class. But it’s nothing if not a reminder of the power of standards. (See also the Nintendo Wii remote, which enterprising musicians have used as a controller on multiple operating systems, thanks to its support for the Bluetooth spec.)

And yes, this means the prospects of the iPad becoming an all-in-one, live performance machine are looking brighter. DJs are still likely to be unsatisfied, as I doubt that this will allow separate audio cuing, but given that I didn’t see this coming, who knows?

Supporting evidence:
Re: iPad USB Audio Class 1 and Update on OSX Class 2 [Apple Core Audio API Mailing List]

Thanks to Art Gillespie for pointing this out. He’s got a connection kit coming, so expect a full test.