MPE (Mid polyphonic expression)

DSP, Plug-in and Host development discussion.
Markus Krause
KVRist
76 posts since 2 Jul, 2018

Post Wed Aug 21, 2019 1:15 am

Today i ordered a MPE-controller. I got mixed feelings about implementing the MPE specification. My opinion is that it is not very well-designed and looks more like a dirty hack. Why?

- It only supports 16 voices properly
- It opens the door for bugs
- I can create incompatibilities between manufacturers
- It breaks the midi specification
- If a midi device is disconnected and re-connected it will play wrong notes, because the midi-in device can't know that MPE mode is currently used
- Why do they not use NRPNs?
- Why is "polyphonic key pressure / aftertouch" not used which does exactly the same and is a well-defined midi command?

What do you think?

Jeff McClintock
KVRist
300 posts since 30 Jan, 2005 from New Zealand

Re: MPE (Mid polyphonic expression)

Post Thu Aug 22, 2019 7:37 pm

Markus Krause wrote:
Wed Aug 21, 2019 1:15 am
The MPE specification looks more like a dirty hack. Why?
Short answer: It is a dirty hack.

Long answer: Polyphonic expression was LONG overdue, and Roli did the best they could within the limitation of MIDI 1.0 to finally support it. I suspect also that MPE goaded the big companies into releasing the MIDI 2.0 spec (after many years of procrastination). MIDI 2 is "MPE done right" and doesn't suffer the same limitations.

I'm guessing Roli are now working on MIDI 2.0 support for Roli keyboards, and perhaps it's wiser make preparations for supporting MIDI 2.0 at this point (in addition to MIDI 1.0 of course).

Jeff McClintock
KVRist
300 posts since 30 Jan, 2005 from New Zealand

Re: MPE (Mid polyphonic expression)

Post Thu Aug 22, 2019 7:40 pm

[double-post, ignore]
Last edited by Jeff McClintock on Thu Aug 22, 2019 7:42 pm, edited 1 time in total.

Jeff McClintock
KVRist
300 posts since 30 Jan, 2005 from New Zealand

Re: MPE (Mid polyphonic expression)

Post Thu Aug 22, 2019 7:41 pm

[double-post, ignore]

dusted william
KVRAF
4794 posts since 18 Dec, 2000

Re: MPE (Mid polyphonic expression)

Post Thu Aug 22, 2019 9:03 pm

I love mpe I No way I could go back. I hope you do it!

Markus Krause
KVRist
76 posts since 2 Jul, 2018

Re: MPE (Mid polyphonic expression)

Post Fri Aug 23, 2019 4:16 am

If the spec of MIDI2 different from the MPE spec that Roli uses?

jussi_neuraldsp
KVRer
3 posts since 24 Oct, 2018

Re: MPE (Mid polyphonic expression)

Post Fri Aug 23, 2019 5:06 am

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Markus Krause wrote:
Fri Aug 23, 2019 4:16 am
If the spec of MIDI2 different from the MPE spec that Roli uses?
MIDI 2.0 is quite different comparent to MIDI 1.0 (and it's extensions like MPE).

https://www.midi.org/articles-old/detai ... y-exchange (https://www.midi.org/articles-old/details-about-midi-2-0-midi-ci-profiles-and-property-exchange)

Markus Krause
KVRist
76 posts since 2 Jul, 2018

Re: MPE (Mid polyphonic expression)

Post Fri Aug 23, 2019 8:02 am

Thanks for the link. So

Midi 2.0 != Midi 1.0 + MPE

Midi 2.0 = Midi 1.0 + Systex for Midi 2.0 data + bidirectional communication

The Midi 2.0 specification seems to be a lot better than the 'MPE hack' with midi channels.

From what i can read Midi 2.0 should work with the existing interfaces. Will it work also with VST 2.4 ?

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