Salt, RNBO, C++, MIDI...

odokian

Hi, I would like to run a RNBO patch as C++ on my Bela Salt. I'm very comfortable in Max, not so much in C++. I've previously run Pd on Bela/Salt with good success but would rather try RNBO -> C++ for my current use case.

I have created this simple sine-ping test patch in RNBO. (Eventually I'd like to get a MIDI dial into the dial/ pch parameter, but for now just a successful compile would be good.)

In the Bela IDE I cloned the RNBO example patch and replaced the main source file with my sinPing1.cpp export from RNBO. But I'm getting a bunch of errors:

I'm reading this thread and this resource .. I don't understand whether I should have the render.cpp included among my sources or not. And per this thread maybe I need to include RNBO.cpp for good measure?

Thanks in advance for any suggestions...

giuliomoro

the error you report above seems to be due to an incompatibility with the rnbo version that you've used. Can you post here a zip archive of the full export you get from rnbo?

odokian

260824-testcpp.zip

420kB

Here it is

giuliomoro

that's a rnbo 1.1.2 project. Can you update your copy of rnbo? Otherwise, checkout an earlier commit of the rnbo.example.bela repo, e.g.: this is 1.1.0, it mat work: https://github.com/giuliomoro/rnbo.example.bela/tree/8fc7b0c6cd1ac8523834ad097d0b5c406cd1e6b2

odokian

Ok I tried this 3 ways, no dice.

with the older RNBO repo commit, but replacing the main Source .cpp with my own RNBO export
the older RNBO repo commit, as-is
with the current RNBO repo commit, as-is

In all cases the Build process ran for a while and reported successfully building several of the RNBO_(etc).cpp files, but then threw a bunch of errors, like so:

If it's generating those errors from the unchanged repo .zips, then it probably wouldn't be due to my version of RNBO, would it?

giuliomoro

Those displayed are just warnings. Errors will be further up or down in the console. Can you show them? They should have a red backgrouns

odokian

Ok, build working now (not sure what changed, but that's good!)

These were the errors last night, including red X failure icon, and no sound out.

But then today after power-cycling everything, I am getting successful build & sound out. It's also successful to set this as "Run project on boot" and power the Salt independently without USB connection to computer. FWIW this is what I'm seeing, but I guess these yellow/white "errors" don't really matter.

Ok, next step is MIDI implementation. For now I'm using a Korg Nanokontrol2 and simply want to map one potentiometer to the pch (pitch) parameter. I'm aware of the C++ reference and the Bela tutorials such as MIDI part 2, but I'm not clear how to extrapolate that to my situation (tiny RNBO patch becomes 1700 lines in C++). Could you give any pointers on how to get started implementing?

(I realize a full C++ tutorial is outside the scope of this thread. Longterm use case would be to recreate my whole complex Ableton/Max4Live patch in RNBO [which I can confidently do], then map 60+ CC controls from my Midi Fighter Twister to my various parameters. At this time I want to determine whether I can feasibly achieve a "simple" mod [1x midi pot mapping] of C++ code from RNBO, and/or whether this workflow is within Bela's reasonably supported use cases.)

Thanks in advance for any thoughts!

giuliomoro

there is MIDI support there: in render.cpp look for BELA_RNBO_USE_MIDI and you'll see how it works.
Currently it reads from hw:0,0,0, which is the MIDI Interface to the host via the USB cable. Use that, or change to another device here:

               midi.readFrom("hw:0,0,0");

To know the device name of your controller, do amidi -l in the console at the bottom of the IDE with the controller connected. It will probably be hw:1,0,0.
Any MIDI input from the selected interface is then passed on to RNBO:

midiInput.addEvent(RNBO::MidiEvent(0, 0, msg, msgSize));

odokian

I added this code to my patch:

#define BELA_RNBO_USE_MIDI

static RNBO::MidiEventList midiInput; // whether it's actually used or not depends on BELA_RNBO_USE_MIDI
#ifdef BELA_RNBO_USE_MIDI
static bool useMidi = false;
#include <libraries/Midi/Midi.h>
static Midi midi;
#endif // BELA_RNBO_USE_MIDI

#ifdef BELA_RNBO_USE_MIDI
	useMidi = rnbo->getNumMidiInputPorts() > 0;
	if(useMidi)
	{
		midi.readFrom("hw:1,0,0");
		midi.enableParser(true);
	}
#endif // BELA_RNBO_USE_MIDI

#ifdef BELA_RNBO_USE_MIDI
	if(useMidi)
	{
		midiInput.clear();
		int num;
		while((num = midi.getParser()->numAvailableMessages()) > 0)
		{
			MidiChannelMessage message = midi.getParser()->getNextChannelMessage();
			size_t numDataBytes = message.getNumDataBytes();
			size_t msgSize = numDataBytes + 1;
			midi_byte_t msg[msgSize];
			msg[0] = message.getStatusByte();
			for(size_t n = 0; n < numDataBytes; ++n)
				msg[1 + n] = message.getDataByte(n);
			midiInput.addEvent(RNBO::MidiEvent(0, 0, msg, msgSize));
		}
	}
#endif // BELA_RNBO_USE_MIDI`

Which returns these errors.

giuliomoro

you should not have added that code to the rnbo-generated file. That code is already in render.cpp, which must be included with your project and the rnbo-generated source. All you had to do was to locate the existing

		midi.readFrom("hw:0,0,0");

line and adjust it for the device you use.

odokian

Aha, thanks for clarifying! I'm getting successful build now.

This brings me to another issue that I'm experiencing now, and that I have previously experienced when running Pd on Bela or Salt. With the Bela/Salt connected to the computer and midi controller connected to the Bela host port, everything works and I get the full range expected given the midi scalings I've specified in my patch. But when I power my Salt independently, I get limited or no midi range:

Korg Nanokontrol2 = it works in a limited way. My pitch pot should scale to a 4-octave range but only results in a 1-octave range in the middle of the intended span. I also added a gain param [0.,1.], but similarly my gain pot only gives a limited effect approx [0.4,0.6].
Midi Fighter Twister = does not work at all. I've tried running the MFT through a powered USB hub, no luck.

Reading this thread and this thread, I think I might need to re-flash with one of these newer images.

Would you agree that re-flashing would be a useful step here? And can you confirm that it's ok to re-flash the Salt? Based on this page i think it's ok, but I know the Salt modules are quite rare (and certainly I had to save up for a while to acquire it), so I just want to confirm that re-flashing the Salt to improve midi functionality seem like a viable path.

giuliomoro

If you are still using the stock image, definitely do update it.

Get the latest here https://github.com/BelaPlatform/bela-image-builder/releases

odokian

Unfortunately, flashing to the newest image has made things worse. I now have no sound output.

giuliomoro

After you flash a new image, run this command in the console at the bottom of the IDE:

./scripts/make_salt.sh

If you have no sound out of your rnbo example, make sure you do from the Fundamentals/sinetone example.

odokian

Thanks for bearing with me. Yes, I ran that command, did the Fundamentals/sinetone, got a sine out.

When I try to build my own RNBO code, it does say "Build finished" but gives yellow warnings and does not actually run the project. (I'm still using Bela image 1.1.0. I still find that using the more recent image results in errors.)

Only other thing, no idea if this matters. When I went to remove the SD to re-flash it, I realized there was none already in the board, I guess Bela image & all patches etc had been running on onboard RAM. So I just grabbed a random SD I had lying around and flashed that. I hope the bela would know to refer to the SD now? The fact that Fundamentals/sinetone worked makes me think it's ok.

giuliomoro

Yes, if the sd card is inserted and properly flashed, it boots from it.

Those errors may indicate you have possibly multiple copies of the same/similar file in the project. More in general, if the project built correctly before and doesn't now, it is likely because the project is not the exact same as it was before. How did you transfer the project across?

odokian

Aha. For some reason I had an old random .cpp mistakenly placed in Directories. Good, so with the new Bela image I'm successfully getting full MIDI pot scaling as expected when the Salt is independently powered (ditto across Korg Nanokontrol2, and Midi Fighter Twister with or without powered USB hub). That's great, thank you so much for all the tips so far!!

My next step is testing midi.writeOutput to send CC messages to the midi controller. I'm looking here and here ... I'll probably take a few days to test, then report back if any issues arise. thx again giulio!

giuliomoro

odokian My next step is testing midi.writeOutput to send CC messages to the midi controller. I'm looking here and here ... I'll probably take a few days to test, then report back if any issues arise.

the hard part is to figure out how to get the data out of RNBO into C++, I guess?

odokian

Hi again- I implemented the below code and related stuff, and I'm successfully seeing my midi dial 0 alternate between value 0 and 127 every second.

Here's my generic RNBO patch. I'll send my stereo audio out the first two outputs (that's working), plus some CV signals out the next outputs (haven't tested extensively but seems to be working), then I guess I'll need to map what are currently numbered as outs 5,6,7 to midi_byte_t value, controller, and statusByte.

I've accomplished midiOutput in Pd before but I don't understand the paradigm in this case. Do I need to somehow map analog outs 5-7 to value, controller, and statusByte?

giuliomoro

I don't actually know how to get outputs from a rnbo patch into C++.

Here https://rnbo.cycling74.com/learn/sending-and-receiving-midi-cpp it suggests that you should create a class that inherits from RNBO::EventHandler and implements the handleMidEvent method. Then in that method you should insert code that converts the RNBO::MidiEvent argument into a message good to send out to midi.writeOutput(). It may be as simple as (untested)

class MidiHandler : EventHandler {
void handleMidiEvent(const MidiEvent& event) override {
    const uint8_t *data = event.getData();
    int length = event.getLength();
    rt_printf("Sending midi length %d\n:, length);
    midi.writeOutput(data, length);
}
};

(assumes midi is a global object declared above the class declaration).
Then create a global object of this type

MidiHandler midiHandler;

and in setup() after rnbo = new RNBO::CoreObject;, add:

rnbo->createParameterInterface(ParameterEventInterface::MultiProducer, (EventHandler *) &midiHandler);

That may be all, from what I understand from a quick read of that page.