MPE is now official.
The MIDI Manufacturers Association (MMA) has announced the ratification of a new extension to MIDI, MIDI Polyphonic Expression (MPE).
The specification, originally introduced as Multidimensional Polyphonic Expression, has also been rebranded as MIDI Polyphonic Expression.
MPE is a specification, based on MIDI 1.0, that creates a standard way to communicate per-note expressive information among electronic music devices and music software.
Here’s how the MMA describes it:
Prior to MPE, expressive gestures on synthesizers—such as pitch bending or adding vibrato—affected all notes being played. With MPE, every note a musician plays can be articulated individually for much greater expressiveness.
In MPE, each note is assigned its own MIDI Channel, so that Channel-wide expression messages can be applied to each note individually. Music making products (such as the ROLI Seaboard, Moog’s Animoog, and Apple’s Logic) take advantage of this so that musicians can apply multiple dimensions of finger movement control: left and right, forward and back, downward pressure, and more.
MPE is already widely adopted as a preliminary specification, supported by DAWs, like Logic Pro X, Bitwig & Cubase; software synths, like Cycling ’74 Max, Madrona Labs Aalto, NI Reaktor and Kyma; iOS music apps, like Noise, GeoShred, GarageBand & Animoog; and hardware synths, including Deckard’s Dream, the Futuresonus Parva & Modal Electronics’ synthesizers.
In addition, MPE can be used with some older synths that offer multitimbral support.
MPE’s early adoption was driven by the work of Geert Bevin, who wrote the original specification, and Roger Linn, who created the LinnStrument. it quickly became an important feature of iOS music applications, because of the way the iPad’s screen allows for multi-touch control of notes.
The standard’s widespread adoption has been driven by MMA members, including companies like ROLI, who has promoted MPE not just as a standard, but as a new platform for innovation in music.
MPE’s benefits have also been advocated for musically, by performers like Jordan Rudess, Eren Basbug and Marco Parisi, shown here in a 2016 NAMM Show performance:
The MMA highlights these key features of MPE:
- Wherever possible, every sounding note is temporarily assigned its own MIDI Channel between its Note On and Note Off. This allows Control Change and Pitch Bend messages to be addressed to that particular note.
- A Registered Parameter Number is used to establish the range of Channels used for sending or receiving notes. Two messages control the division of MIDI Channel space into sub-spaces called Zones, so that multi-timbral playing is still possible using only one physical MIDI interface.
- When there are more active notes in a Zone than available Channels, two or more notes will have to share the same Channel. Under such circumstances, all notes will continue to sound, but will no longer be uniquely controllable.
- Each Zone has a dedicated extra Channel, called the Master Channel, which conveys common information including Program Change messages, pedal data, and overall Pitch Bend. These messages apply across the entire Zone.
The MPE specification also defines how to handle Pitch Bend, Aftertouch and CC messages to provide maximum interoperability.
The MMA says that the official MPE specification will be available for download in the coming weeks via the MIDI Association site.