Controlling the AR programatically? [MIDI] Linux

dRAT3 · 2022-11-19T13:05:32.366Z

Hi there I run linux and I would like to control the AR with midi controllers from my DAW. So I would like to have a go at making a vst plugin like overbridge that can control and automate the AR, my first idea was to use the midi mode, but I’m not sure if it outputs midi when you change kit or when you twist knobs so my faders can reposition. I’m new to elektron gear, but read about overwitch, does anybody know if the same can be done for controlling the parameters or if the AR sends back midi when you change stuff?

I’d like to ask first before diving in and wasting time

Thanks

DG2 · 2022-11-19T14:28:24.286Z

Owerwitch developer here.

AFAIK, there are 3 possible approaches here.

Use your AR in MIDI mode and use the standard MIDI infrastructure, drivers and libs. This will be limited to the MIDI messages sent and received by the device. You can search for the recognized messages and create a small interface to send and receive data. This could be useful for everyone using the AR in MIDI or Overbridge mode. So far, pretty obvious. Keep reading.
Use your AR in Overbridge mode and use the Overwitch library to get the MIDI messages, audio and the Overbridge protocol data. I won’t suggest using the Overwitch library as you’ll need to write a lot of code to synchronize everything and you’ll probably are already using JACK or PipeWire (same protocol).
Maybe, we can work together. It wouldn’t be complicated for me to add another MIDI port to the JACK plugin for you to access the Overbridge protocol data. If this is done, you’ll have the MIDI data, and the Overbridge data, and the audio data will be available too. If we go this route, you can develop whatever you want using the standard libs and tools and your code will be totally independent from Overwitch.

If you think the 3rd approach is good for you, create an issue in GitHub and we’ll discuss the technical stuff there.

dRAT3 · 2022-11-20T10:05:07.205Z

Sorry for replying here, but I didn’t want to clutter the gh issue.

I would like to go route 3, but I have an mk1, on the latest firmware. So we’d first have to get overwitch working on it. If you help me I can do testing etc. My C skills are barely existent. I was planning on making the vst with nih-plug in rust. Do you know if the overbridge protocol data is the same on the mki? I read the issue on github so I know abt the isochronous issue.

DG2 · 2022-11-20T11:29:16.347Z

dRAT3:

Sorry for replying here, but I didn’t want to clutter the gh issue.

It’s perfect because there are other things to consider first.

ATM, together with another @personnealienee , we’re adding limited Overbridge support to AR MKI.
For some reason I understood that we were talking about the MKII. Sorry for being misleading here.

dRAT3:

So we’d first have to get overwitch working on it.

Absolutely. If you want to give it a try, checkout the mki branch. I’m on the #elektron channel on irc.esper.net (IRC) if you need some help.

Regarding the data, these are the Overbridge packet details known so far. There are 28 unknown bytes in each and this is what is believed to be the internal protocol. This is what I was thinking to provide via another MIDI ports for you or anyone to access it in the way you like.

github.com/dagargo/overwitch

src/engine.h

24fb1333c


      
          ----------------------------------------------------------------
          
          Raw data of the transfer consists of 24 blocks, each block holding
          - a fixed header
          - a sample counter (uint16 BE), increased by 7 per block (because
          each block contains 7 samples)
          - 7 samples (int32 BE) * 2 channels (interleaved)
          
          (total 168 samples, 2112 Bytes). Structure of a single block:
          
          0                   1                   2                   3
          0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
          | fixed header: 0x07FF          | sample counter (uint16_t)     |
          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
          |                                                               |
          +                            unknown                            +
          ...
          +                           (28 Bytes)                          +
          |                                                               |
          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

github.com/dagargo/overwitch

src/engine.h

24fb1333c


      
          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
          
          
          
          Data format FROM Digitakt (USB interrupt transfer, EP 0x83)
          ----------------------------------------------------------------
          
          Raw data of 24 blocks (total 8832 Bytes). Structure of a
          single block:
          
          0                   1                   2                   3
          0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
          | fixed header: 0x0700          | sample counter (uint16_t)     |
          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
          |                                                               |
          +                            unknown                            +
          ...
          +                           (28 Bytes)                          +
          |                                                               |
          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

We don’t even know exactly what data is going on there but some messages look like MIDI and I’ll bet that the protocol is the same for MKI devices.

I’ll post some detailed packet data later.

DG2 · 2022-12-07T14:22:20.981Z

In case anyone is interested, I took a look at the unknown bytes and noticed that can be easily arranged in blocks of 128 bytes. This is a block from my Digitakt.

e0 00 23 aa ea 00 00 00  00 00 00 00 00 00 00 00
00 00 00 00 00 01 00 00  00 00 00 00 00 00 00 32
00 00 32 00 00 32 00 00  32 00 00 32 00 00 32 00
00 32 00 00 32 00 00 32  00 00 32 00 00 32 00 00
32 00 00 32 00 00 00 00  00 00 00 00 00 00 00 ef
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00

I’ve created an issue to keep track of the findings.