Use with a MIDI controller?

[BenMcLean]

I know the main intended use case for this project is to connect your Raspberry PI to your retro gaming PC via MIDI so you can hear the music.
But it occurs to me that a device like this would be the perfect sound module for MIDI controllers such as the Alesis Vortex keytars like I've got since they are just controllers and don't have onboard sounds.
Would it be possible to effectively control the MT-32 emulator with that?
(later edit) Oh, I see the FAQ mentions being able to use MIDI controllers. That's cool but I'm still not entirely clear on how you make and use this thing.
Like what things would I buy to make this happen? Will I need soldering or can I get parts that'll just snap together?

(later later edit) I think this thing is actually what I'd need to buy? I'm still figuring this out and it's really confusing

...

Oh there's a video -- thank God and everyone who worked on this! I am definitely getting one ASAP!

[icb-]

mt32-pi works great with MIDI instruments!

You'll need to add a real MIDI port to your mt32-pi. The simplest way to do this is to buy a USB MIDI adapter, but there are several custom boards that add both MIDI in and a control interface. @dwhinham is also releasing his own hardware option (expected later this month).

You'll need to pay attention to the channel assignment. Many MIDI instruments will only send to channel 1, that is ignored by the MT32, unless you set a flag in the config file (midi_channels = alternate).

[icb-]

Unless your instrument can be a USB MIDI device (which is unlikely), you would need additional hardware, like the Roland UM-ONE mk2.

Emulating other FM synthesis or video game hardware is out of scope of this project.

If your instrument can send custom SysEx messages, you can control mt32-pi from it.

[BenMcLean]

Unless your instrument can be a USB MIDI device (which is unlikely),

I believe that the Alesis Vortex Wireless 2 receiver does act as a USB MIDI device.

you would need additional hardware, like the Roland UM-ONE mk2.

I do have a USB MIDI adapter in my closet but the MP32L has a MIDI port on it so I suspect that I won't need the USB MIDI adapter for this even if I decide to use a different controller that needs MIDI.

Emulating other FM synthesis or video game hardware is out of scope of this project.

What about just providing an API for others to add custom modes though?

All the work that's been done here to get one synth running on bare metal seems like it would obviously be helpful for other synths too, and it'd be better to be able to switch between them without switching SD cards.

If your instrument can send custom SysEx messages, you can control mt32-pi from it.

I don't know whether that's possible and will have to research it.
Might it be possible to put in some kind of interpretive layer that selectively interprets certain standard MIDI messages into SysEx messages?

[icb-]

Unless your instrument can be a USB MIDI device (which is unlikely),

I believe that the Alesis Vortex Wireless 2 receiver does act as a USB MIDI device.

If that works, it would certainly be an easy way to use the two together.

Emulating other FM synthesis or video game hardware is out of scope of this project.

What about just providing an API for others to add custom modes though?

That would be a question for @dwhinham to answer.

If your instrument can send custom SysEx messages, you can control mt32-pi from it.

I don't know whether that's possible and will have to research it. Might it be possible to put in some kind of interpretive layer that selectively interprets certain standard MIDI messages into SysEx messages?

Sure, it wouldn't be too difficult to write something external that translated certain MIDI messages, e.g. a Teensy and their MIDI library, or even just handling the raw byte stream. MIDI isn't an especially complicated protocol.

[dwhinham]

@BenMcLean I would hope that the Alesis USB MIDI adaptor just presented itself as a class-compliant USB MIDI device. If it does, there's a high chance it should "just work" with mt32-pi.

Haven't you tried mt32-pi yet? You don't actually need any extra hardware to do a basic test, you should get sound out of the Pi's headphone jack if you plug in the USB receiver and send some notes on Channel 2+ in MT-32 mode or 1+ in SoundFont mode.

"API" for synths ... well, there's an abstraction already (the CSynthBase class) that wraps the essentials, and you just implement the synth engine within it. mt32-pi has two synth engines. The code's all there, take a look.

Dynamically-loadable plugins, a la VST/LV2 etc might be too much of a stretch unless someone invests a significant amount of time/research into trying to implement library loading and linking from bare metal.

I am currently looking at Dexed (#239) which should satisfy most FM synth fans' requirements. Adding random sound chip emulators is less interesting to me because then you need to invent some kind of made-up MIDI front-end for them that exposes all their programming possibilities. Simulations of contemporary MIDI modules/synthesizers are a better fit for this project IMO.

Re: re-mapping MIDI controls, this can easily be done with a DAW in the middle, although maybe some kind of lightweight embedded script engine within mt32-pi would be nice, e.g. Lua, for doing this kind of thing in a flexible way. Something to think about.

[BenMcLean]

Haven't you tried mt32-pi yet? You don't actually need any extra hardware, you should get sound out of the Pi's headphone jack if you plug in the USB receiver and send some notes on Channel 2+ in MT-32 mode or 1+ in SoundFont mode.

Haven't tried it yet. Just learned about the existence of this project yesterday.

"API" for synths ... well, there's an abstraction already (the CSynth class) that wraps the essentials, and you just implement the synth engine within it. mt32-pi has two synth engines. The code's all there, take a look.

Definitely a start!

Dynamically-loadable plugins, a la VST/LV2 etc might be too much of a stretch unless someone invests a significant amount of time/research into trying to implement library loading and linking from bare metal.

I was naively thinking you'd need to define your own plugin format just for this. VST seems particularly unsuitable for numerous reasons.

I am currently looking at Dexed (#239) which should satisfy most FM synth fans' requirements.

Never heard of that one but maybe!

Adding random sound chip emulators is less interesting to me because then you need to invent some kind of made-up MIDI front-end for them that exposes all their programming possibilities.

That would be required to make that work, yes. But I believe there are various open source projects around which have done this to one degree or another before so it wouldn't necessarily be starting from scratch for whoever tries it. For example, I happen to know just off the top of my head that a MIDI-to-YM3812 conversion layer was developed for the game Super 3D Noah's Ark back in 1996.

Re: re-mapping MIDI controls, this can easily be done with a DAW in the middle, although maybe some kind of lightweight embedded script engine within mt32-pi would be nice, e.g. Lua, for doing this kind of thing in a flexible way. Something to think about.

The latter is what I was thinking of, although personally I'm not a fan of Lua.

[BenMcLean]

I put the SD card in my Raspberry PI 3 B+ (no MP32L) and got my keytar and a little speaker hooked up for the first time today. Some electric piano sound came out when I pressed the keys. Velocity sensitive, no pitch wheel, no sustain. Some notes held out longer which suggests to me that they are stuck notes. Whenever I connect any MIDI controller (I have a few different ones) to any custom programmed gadget (I have a few different ones of those too) there always seems to be stuck notes. What gives? This doesn't happen on professionally made all-in-one keyboard synths: only when trying to use a controller with a separate synth.

[BenMcLean]

I found some programming information about the Vortex here.