MIDI specifications for Multidimensional Polyphonic Expression (MPE)

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MIDI specifications for Multidimensional Polyphonic Expression (MPE)
Since Winter NAMM 2015, I've been working on a new MIDI specification together with many other industry professionals (Apple, Bigwig, Haken Audio, KMI, Madrona Labs, Moog Music, Roger Linn Design, ROLI, ...). We've preliminarily called it Multidimensional Polyphonic Expression, in short: MPE.

The point is very simple: to allow new controllers like the LinnStrument and Eigenharp to have full per-note expressive support in sound generators and DAWs.

We've taken a pragmatic approach where we kept the best of what is already in practical use today and structured in so that adding support for MPE would be the least possible effort, while providing the most possible benefit.

A beta version of the spec is available at http://bit.ly/mpe-spec

Feel free to reach out to let us know what you think of it!

By Geert Bevin   – April 24, 2015


CDM BEST OF SHOW: MIDI Polyphonic Expression – Bitwig, ROLI, Roger Linn, et al.

For all the wonderful things happening with modular, it'd be a sad world if our only interface idea were 1960s telephone patch cords. And that's why MPE (MIDI Polyphonic Expression) matters. It's not a new spec, per se – everything it does it does with the existing MIDI protocol. And it still leaves room for HD MIDI and OpenSoundControl.

But what MPE does finally do is standardize on a way of adding expression to polyphonic controllers. It works with creative new hardware – initially, the LinnStrument, Haken Continuum, ROLI Seaboard, Eigenharp, and SoundPlane. It works with software, like ROLI's new Equator soft synth.

And I was impressed that MPE has a lot of backing, including the likes of Apple (Gerhard Lengeling) and Moog (Amos Gaynes) – not just the usual alternative controller scene.

I eventually took the trophy over to Bitwig for the simple reason that there, you could see the technology in action even outside something like the ROLI booth. A Roger Linn Linnstrument was connected to a Bitwig Studio beta, where it was able to easily control a built-in instrument. Bitwig can record and edit the controller data seamlessly.

And being able to play this sort of data – not just draw it with a mouse – to me really humanizes the performance possibilities. It was also nice to see Bitwig showing a product that was not their own, demonstrating the sort of historical connectivity that marked the first connection of MIDI between Dave Smith's Sequential Circuits and Roland back in the 80s.

So, to all the folks behind MPE – and particularly Bitwig, ROLI, and Roger Linn for making it visible at Messe as a possible future for music making – I'm pleased to award a Best of Show.


K-Board Pro 4 is a four octave MIDI keyboard controller with true X-Y-Z response per key. This gives you velocity, continuous pressure, and both horizontal and vertical position to provide the highest degree of expression ever offered in a keyboard.

k-board-pro-handsSeamlessly go from a traditional piano to the K-Board Pro and instantly play faster and in perfect tune – until you want to add vibrato, modulation or total control over the nature of your sound.

Under each key of K-Board Pro 4 is the patented Smart Sensor Fabric technology that is at the core of all our MIDI control surfaces. Resilient silicone keys and no moving parts ensure our trademark durability.

K-Board Pro 4 is USB powered and class compliant to ensure both portability and compatibility.

Jordan Rudess, legendary keyboardist and Head of Music Experience at ROLI, presented at Design Driven NYC in May 2015. Jordan spoke about designing a new instrument while performing several demonstrations of the ROLI Seaboard Grand.


By Anderton | January 27, 2017
MIDI - The Force Awakens
Everyone's favorite music technology protocol is moving rapidly into the 21st century

By Craig Anderton

A long time ago, in a galaxy far, far away (well actually it was over 30 years ago in Anaheim, California), two synthesizers—one from Roland, one from Sequential Circuits—talked to each other over a MIDI cable. Through a miracle of inter-industry co-operation refreshingly free of politics, the music industry banded together to create a specification that has endured to this day.

But...as the old saying goes, what have you done for us lately? The answer is quite a bit.

When hard disk recording and ADAT hit, digital audio recording entered the spotlight—while MIDI's spotlight dimmed. But then Steinberg introduced Virtual Studio Technology, computers got faster, virtual instruments became a sophisticated alternative to physical instruments, USB made it easy for MIDI to talk to computers, and now, MIDI is more important than ever and actually gaining in importance. With MIDI ramping up to be a part of 2.6 billion devices as it invades the smart phone market, the sky's the limit.


It takes effort to maintain a spec—dealing with multiple music business companies (with an overlay of American/Japanese/European cultural divide) is like herding cats. Friendly cats to be sure...but cats nonetheless. That task, which borders on the thankless, falls to the MIDI Manufacturers Association.

Lately, there's been increased interest and participation from consumer-oriented companies like Apple, Google, and Microsoft, as well as long-time supporters like Yamaha, Roland, Gibson, Korg, and others who recognize the value of being involved with the MIDI specification. By paying their share of the organization's dues, MMA members have the right to help shape the future of MIDI, and vote—with one vote per member, regardless of size—on the various initiatives.

This year's MMA meeting at the Anaheim Marriott started off with a review of what happened in 2016.

Regarding the mechanics of how changes happen to the MIDI spec, the MMA is an all-volunteer organization with the exception of one employee—Tom White, who heads up the MMA. When a company has a proposal for an extension to the spec, working groups of interested parties coalesce to explore how it would work, and eventually, proposals go to a Technical Standards Board for review. After that review happens, it's up to the Executive Board of the MMA to "make it so" (full disclosure: I represent Gibson Brands on the Executive Board.) Also, the MMA works closely with AMEI, its Japanese counterpart. This effectively doubles the available brainpower.

The MMA holds an annual meeting at NAMM, with both public sessions (through invitation to, for example, journalists and educators who work with MIDI) and other sessions that are closed to the public.

Approval of changes is a difficult, lengthy, and time-consuming process. Different manufacturers have different priorities, the MMA's all-volunteer nature means software engineers who are normally very busy in their "day jobs" don't have a lot of spare time, and it's crucial that anything new doesn't "break" anything old.


Although there are several very exciting initiatives on the horizon (more on that later), 2016 brought several extensions to fruition. Some of the higher-visibility ones include:

BLE-MIDI. This allows MIDI to talk to computers over Bluetooth Low Energy, with no special hardware required. Although virtually all aspects of the MIDI spec originated in the music industry, this was originally an Apple standard (spearheaded by Torrey Walker), and was proposed to the MMA. It was then adopted with minor revisions. At NAMM 2017, Cakewalk demoed the Zivix Jamstik working with SONAR (BLE-MIDI support was introduced with Windows 10 Anniversary Edition), despite Zivix itself thinking it wouldn't be possible. Granted, any software needs the right "hooks" for Windows, but there's no doubt other companies will be incorporating BLE-MIDI into their software.

Other other new features, MoForte's GeoShred 2 software instrument now includes MIDI Polyphonic Expression

MPE (MIDI Polyphonic Expression). Championed by ROLI, Roger Linn, and others, this allows expression for individual notes within a polyphonic data stream. It does this by maximizing the use of MIDI channels to allow per-note control of pitch, volume, timbre and more. The bottom line is this brings acoustic instrument-like expressiveness to new electronic controllers, like ROLI's keyboards and the Linnstrument.

Windows 10 Multi-Client Support. This is a fancy way of saying "you can have several MIDI programs running at once." Ever wonder why you couldn't run your sequencer and the editor for your virtual instrument that communicates via MIDI at the same time? Now you can, because Windows has the intelligence to separate individual MIDI data streams. There are also many other Windows 10 enhancements, like MIDI support in PowerShell and the Windows Store.

This doodle generated sound on Chrome using the Web-MIDI API.

Web-MIDI API (Application Program Interface). This is currently supported in Chrome and Opera, and is what allowed you to play a synth on Google's home page as a tribute to Bob Moog on what would have been his 78th birthday. Firefox is also moving toward adoption, albeit slowly. Microsoft and Apple aren't committed to supporting it yet, but it probably won't take long before they figure out this is a really cool feature to have—especially for education.

The MIDI Association gave info on all things MIDI that were happening at the Winter 2017 NAMM show

The MIDI Association. The MMA also established a free, public-facing, user-oriented offshoot at www.midi.org that explains MIDI, presents news about the spec, makes the spec available for download, and has numerous articles as well as a forum on all things MIDI. It's a cool site and well worth checking out.


The MMA is understandably reluctant to reveal what's under consideration. Much of this is to avoid early mentions of something that "seems like a good idea" at the time, but for some reason, doesn't pan out. As a result, although I'd love to give you a peek in to the future, I can't. But the fact that I wish I could probably gives you a hint that there's a lot more bubbling under the surface. What I can say is that both the MMA and AMEI agree on the need to improve MIDI in terms of speed, resolution, and channels, and have a goal of finalizing new extensions to the specification as rapidly as practical.

The challenge is how to bring MIDI into the 21st century without invalidating the huge universe of existing MIDI gear, but the music industry's best minds are on the case...and MIDI looks poised to mean even more in the 21st century than it did in the 20th.


Individuals can join The MIDI Association, a global community of people who work, play, and create with MIDI, for free. Companies that make MIDI products and want to help decide MIDI's future can join the MMA. In either case, visit www.midi.org for more details.


Craig Anderton is Editorial Director of Harmony Central. He has played on, mixed, or produced over 20 major label releases (as well as mastered over a hundred tracks for various musicians), and written over a thousand articles for magazines like Guitar Player, Keyboard, Sound on Sound (UK), and Sound + Recording (Germany). He has also lectured on technology and the arts in 38 states, 10 countries, and three languages.



MIDI evolves, adding more expressiveness and easier configuration
Peter Kirn - February 1, 2018  3 Comments     
It's been a long time coming, but MIDI now officially has added MPE and "capability inquiry," opening up new expression and automatic configuration.

MIDI, of course, is the lingua franca of music gear. AKA "Musical Instrument Digital Interface," the protocol first developed in the early 80s and has been a common feature on computers and gear and quite a few oddball applications ever since. And it's a bit of a myth that MIDI itself hasn't changed since its 80s iteration. Part of that impression is because MIDI has remained backwards compatible, meaning changes haven't been disruptive. But admittedly, the other reason musicians think about MIDI in this way is that the stuff they most use indeed has remained fairly unchanged.

Engineers and musicians alike have clamored for expanded resolution and functionality ever since MIDI's adoption. The announcements made by the MIDI Manufacturers Association aren't what has commonly been called "HD MIDI" – that is, you don't get any big changes to the way data is transmitted. But the announcements are significant nonetheless, because they make official stuff you can use in real musical applications, and they demonstrate the MMA can ratify official changes (with big hardware maker partners onboard). Oh, and they're really cool.

Standardizing on new expressive ways of playing
First, there's MIDI Polyphonic Expression, aka MPE. The name says it all: it allows you to add additional expression to more than one note at a time. So, you've always been able to layer expression on a single note – via aftertouch, for instance – but now instead of just one note and one finger, an instrument can respond to multiple notes and multiple fingers independently. That means every fingertip on an instrument like the ROLI Seaboard can squish and bend, and a connected sound instrument can respond or a DAW can record the results.

Hardware has found ways of hacking in this support, and plug-ins that require complex per-note information (think orchestral sound libraries and the like) have had their own mechanisms. But now there's a single standard, and it's part of MIDI.

MPE is exciting because it's really playable, and it's already got some forward momentum. Major DAWs like Logic and Cubase support it, as do synths like Native Instruments' Reaktor and Moog's Animoog. Hardware like the ROLI gear and Roger Linn's Linnstrument send MPE, but there's now even hardware receiving it, too, and translating to sound – even without a computer. (That's not just weird keyboards, either – Madrona Labs' Soundplane showed this could work with new instrument interfaces, too.)

Making MPE official should improve implementations already out there, and standardize inter-operability. And it means no more excuses for software that hasn't picked it up – yeah, I'm looking at you, Ableton. Those developers could (reasonably) say they didn't want to move forward until everyone agreed on a standard, to avoid implementing the thing twice. Well, now, it's time.

More demos and product compatibility information is in the news, though of course this also means soon we should do a fresh check-in on what MPE is and how to use it, especially with a lot of ROLI hardware out there these days.

MIDI Polyphonic Expression (MPE) Specification Adopted!

Making instruments self-configure and work together
MPE you might have heard of, but there's a good chance you haven't heard about the second announcement, "Capability Inquiry" or MIDI-CI. In some ways, though, MIDI-CI is the really important news here – both in that it's the first time the MIDI protocol would work in a new way, and because it involves the Japanese manufacturers.

MIDI-CI does three things. Here's their official name, plus what each bit means:

1. Profile configuration – "Hey, here's what I am!". Profiles define in advance what a particular instrument does. Early demos included an "Analog Synth" and a "Drawbar Organ" draft. You already know channel 10 will give you drum sounds, and General MIDI drum maps will put a kick and a snare in a particular place, but you haven't been able to easily control particular parameters without going through your rig and setting it up yourself.

2. Property exchange – save and recall. If configuration tells you what a device is and what it does, the "exchange" bit lets you store and recall settings. Last week, manufacturers showed gear from Yamaha, Roland, and Korg having their instrument settings saved and recalled from a DAW.

MMA say the manufacturers demonstrated "total recall." Awesome.

3. Protocol negotiation – the future is coming. Actually, this is probably the most important. Profile configuration and property exchange, we'll need to see in action before we can judge in terms of utility. But protocol negotiation is the bit that will allow gear now to build in the ability to negotiate next-generation protocols coming soon. That's what has been commonly called "HD MIDI," and what hopefully will bring greater data resolution and, ideally, time stamps. Those are features that some have found in alternative protocols like Open Sound Control or in proprietary implementations, but which aren't available in standard MIDI 1.0.

And this "negotiation" part is really important. A future protocol won't break MIDI 1.0 compatibility. Gear built now with protocol negotiation in mind may be able to support the future protocol when it arrives.

As musicians, as hackers, as developers, we're always focused on the here and now. But the protocol negotiation addition to MIDI 1.0 is an essential step between what we have now and what's coming.

No gear left behind
For all the convervatism of musical instruments, it's worth noting how different this is from the rest of electronics. Backwards compatibility is important for musical instruments, because a musical instrument never really becomes outmoded. (Hey, I spent long, happy evenings singing with some violas da gamba. Trust me on this.)

The MIDI-CI adoption process here, while it's not the most exciting thing ever, also indicates more buy-in to the future of MIDI by the big Japanese manufacturers. And that finally means the AMEI is backing the MMA.

Say what?

While even many music nerds know only the MIDI Manufacturers Association, significant changes to MIDI require another organization called the Association of Musical Electronics Industries – AMEI. The latter is the trade group for Japan, and ... well, those Japanese manufacturers make gear on a scale that a lot of the rest of the industry can't even imagine. Keep in mind, while music nerds drool over the Eurorack modular explosion, a whole lot of the world is buying home pianos and metronomes and has no idea about the rest. Plus, you have to calculate not only a different scale and a more corporate culture, but the fact that a Japanese organization involves Japanese culture and language. Yes, there will be a gap between their interests and someone making clever Max/MSP patches back in the States and dreaming of MIDI working differently.

So MIDI-CI is exciting both because it suggests that music hardware will communicate better and inter-operate more effectively, but also in that it promises music humans to do the same.

But here again is where the craft of music technology is really different from industries like digital graphics and video, or consumer electronics, or automobiles, or many other technologies. Decisions are made by a handful of people, very slowly, which then result in mass usage in a myriad of diverse cultural use cases around the world.

The good news is, it seems those decision makers are listening – and the language that underlies digital music is evolving in a way that could impact that daily musical usage.

And it'll do so without breaking the MIDI we've been using since the early 80s.

Watch this space.





Haken Audio ContinuuMini Electronic Instrument now on Kickstarter
The ContinuuMini is the baby sibling of the Continuum Fingerboard a huge multi-dimensional keyboard-like controller and synthesizer. You'd be forgiven for thinking it's an MPE controller but it's actually much more than that because it includes an internal sound engine. So, the ContinuuMini is an instrument all of its own.

The Fingerboard is big and expensive and those are two factors the ContinuuMini hope to address. It takes the same expressive technology as the Fingerboard but reshapes it into a unique playing experience. The playing surface is one continuous strip, it's like a mix of stringed and wind instruments and a ribbon controller with the good old MPE trombone/swanee whistle tendency. Top and bottom of the surface is a strip that indicates musical notes which I imagine is very helpful.

The ContinuuMini has exactly the same sound engine as the big one. It's called the EaganMatrix and was designed specifically for their expressive technology. It is polyphonic but the ContinuuMini can only handle 1 to 2 fingers at a time and you would probably be playing a couple of overlapping notes possibly layering them up as you play. The playing surface certainly doesn't lend itself to chords and it's not pretending to be a piano. And although the sound engine has a software interface it doesn't require a computer to access any of the features or sounds.

Haken Audio ContinuuMini
Haken Audio ContinuuMini

It doesn't have any CV outputs however it does have a bi-directional serial port which, when it's not being used as a foot pedal input, can take the massive Haken CVC 16 output CV expander box.

There are other cool features such as Continuous Sustain while using a pedal to apply dynamics and other modulations within the EaganMatrix structure. It can handle MPE in both directions, letting you connect a ROLI Seaboard to play the internal engine while also playing along on the ContinuuMini.

It's an extraordinary expressive instrument, perfect for solos and developing dynamic and evolving sounds in performance or the studio. It's light, portable and at $599 for an Early Bird preorder it hits the right sort of price point. The Kickstarter funded in a matter of hours but there's plenty of time to get on board if this is your thing. The first few instruments should get to the early adopters by the end of the year, then the next batch should be January and more generally on sale by April.

More information
ContinuuMini Kickstarter page.

Haken Audio website.



MIDI Guitar MPE synth series: U-he Diva & Modartt Pianoteq 8 LoFiLeif

One part of the development of the next generation of MIDI Guitar is the MPE implementation. Many synths are to varying degree MPE compatible, and in this series I've taken it upon myself to present the synths I am testing, describing some of the findings.

This MIDI Guitar (3) software is still in development, and not out as a public beta yet. As there might be changes still to do, this series will just focus on the synths and the issue of their degree of control for now.  I'll try to answer questions you might have on the MPE synths I test in this series ( which for now are going to be):

Pianoteq 8
Falcon (Expressive E, Ircam Solo Instruments 2, VHorns)
Surge XT
Cypher 2

There are a few others that might be included as I go on if there is any interest in those.

Kontakt (Native Instruments - a special case needing an MPE script)
OB-E  (Gforce)
Obsession (Synapse)

0:00 Introduction
0:41 Checklisting U-he Diva
1:02 Setting/Locking Pitch Bend Range = 48
1:35 Making SLIDE work in Diva
2:51 Using a Brightness Envelope for CC74
4:31 Setting up with a Breath Controller for CC74 instead
5:52 Beware - using the learning function erases your earlier input
7:00 Checklisting Modartt Pianoteq 8/Nylon string guitar
8:34 Setting the Pitch Bend Range
9:19 We don't use SLIDE/CC74 
9:37 Outro

This Cliff Notes Series is the abbreviated snapshot version of the full video and is meant to serve as a sample. Some terms or parts referred to might be missing here, so if you are wondering about anything mentioned here in particular I'll be happy to answer you in the comment section below awaiting my putting the full whopper together.

JamOrigin MIDI Guitar


Pianoteq 8

Breath controller