WacOsc

Wacom to Open Sound Control

This project was made for the 19th GBE (Gara delle Batterie Elettroniche)

Requirements

1. Linux

2. Carla

3. LV2 plugins

4. Python 3.10

5. liblo

6. lilv

Brief Description

evdev is used to get the event devices for the pen, pad and finger events

Using select we poll events on those files, unpack and handle them

Carla hosts the plugins and allows the parameters to be controlled.

But, we need to map them using pain python code.

So this project isn't indended to be used by "non-technical people"

And it is pretty limited in compatibility, at least currently.

The code itself is probably naive and hacked together

Project Structure

confusing? diagram!

getting the devices mapping

xinput.py

it has a function named find_ids that allows you to get a dictionary that maps like this:

{
    "10": "Wacom Intuos Pro S Pad",
    "11": "Wacom Intuos Pro S Finger",
    "17": "Wacom Intuos Pro S Pen Pen (0x74800073)",
    "9": "Wacom Intuos Pro S Pen"
}

this module can also be called with $ python -m wacosc.xinput for detection debugging purposes.

my initial assumption about xinput ID == kernel event ID was totally wrong.

use evdev or eviocgname modules instead is the right way to gather information through the kernel.

you can disable the mouse movements

just run $ python -m wacosc.xinput --grep Wacom --action disable

and you can also enable them again

evdev.py

use this only if you encouter issues with eviocgname.py

pyton-evdev dependency is needed to use this module.

{
    "/dev/input/event19": "Wacom Intuos Pro S Finger",
    "/dev/input/event18": "Wacom Intuos Pro S Pad",
    "/dev/input/event17": "Wacom Intuos Pro S Pen"
}

$ python -m wacosc.evdev

eviocgname.py

we list /dev/input devices and use ioctl to request the name directly from the hardware.

You can optionally install the ioctl_opt package to get actual input.h equivalents, for other informations, read the source code.

It is optional because I defined a constant value for eviocgname(1024)

$ python -m wacosc.eviocgname

wacom.py

code to poll the files in a separate thread.

this is the core of this project.

the actual core is the function handle_wacom that uses select to multiplex the events by their file descriptors and calls the other handle_* functions defined in this module itself.

the handle_* functions are just setting the stylus, pad and touch objects's items they are reactive objects and automagically call the carla osc methods...........

reactive.py

a ReactiveDict is defined here

tui.py

code to show/debug the inputs using curses

carla.py

code to control carla lv2 plugins

we also use lilv to get all the lv2 plugins installed on the system, because carla currently doesn't expose the parameters list and the relative names and ranges so for each plugin we get the parameters name, default, minimum and maxium value.

carla notifies through osc when plugins are added on the patchbay.

carla allow the parameter value to be set through osc, but I wasn't able to find the mappings between parameter id and parameter name in carla, maybe here but i'm not sure.

here's instead the carla code that listens to our osc calls

to get that mapping

I open the plugin "edit" interface of carla and start couning them by 1 and I annotate them in plugins.py file

plugins.py

code that uses lilv and dictionaries made as explained above (in carla.py explaination)

this module exposes ranges dictionary.

you can query by plugin name running like $ python -m wacosc.plugins "Noize Mak3r"

Special People

I acknoledge Rico, Magenta, Tab and a few others for supporting the idea and for giving or taking back motivation

Installation

Install python, carla, lilv.

$ git clone https://framagit.org/castix/wacosc.git
$ cd wacosc
$ python -m venv --system-site-packages venv
$ . venv/bin/activate
$ pip install Cython
$ pip install -e ".[all]"
# echo 'KERNEL=="event*", SUBSYSTEM=="input", ATTRS{idVendor}=="056a", MODE:="0644"' > /etc/udev/rules.d/10-wacosc.rules

about system site packages

--system-site-packages is required in order to match the system-wide lilv bindings.

if you don't want to use that option or is broken/unavailable, you can also copy lilv binding to site, for example:

cp /usr/lib/python3.10/site-packages/lilv.py ~/virtualenvs/wacosc/lib/python3.10/site-packages/lilv.py

about the udev rule

setting the udev rule is to avoid the need of running wacosc with root permissions, and you need to reconnect you wacom device then. 056a is genuine wacom, you you have a different manufacturer, get the idVendor with lsusb

limitations

touch event while stylus in proximity

TODO: what happens by changing this? https://github.com/torvalds/linux/blob/9b57f458985742bd1c585f4c7f36d04634ce1143/drivers/hid/wacom_wac.c#L836

moultitouch count fingers unreliable

see https://github.com/torvalds/linux/blob/9b57f458985742bd1c585f4c7f36d04634ce1143/drivers/hid/wacom_wac.c#L1235 by quoting https://www.kernel.org/doc/html/v4.14/input/event-codes.html

Note: In multitouch drivers, the input_mt_report_finger_count() function should be used to emit these codes. Please see multi-touch-protocol.txt for details. I didn't found count in that file, but seems still documented https://www.kernel.org/doc/html/latest/driver-api/input.html#c.input_mt_report_finger_count

currently our counting mechanism is just wrong, probably it is better to remove it completely

my experiment environment

I run archlinux, with pipewire on a thinkpad x230.

I am using a wacom intuos pro S (PTH-451) that Valentina Bianca sold to me for 75€ (in mint condition) in a online marketplace

The wireless kit is not working so well, because the battery doesn't hold charge. after a drop the charging connector bent 🤦

see it in action

2022-05-22 GBE

https://peratubo.chmod.cyou/videos/watch/78b1f0b8-1a15-4f99-b530-0568e33ac6c7