ShuttlePRO

Copyright 2013 Eric Messick (FixedImagePhoto.com/Contact)
Copyright 2018 Albert Graef <aggraef@gmail.com>

This is a user program for interpreting key, shuttle, and jog events from a Contour Design Shuttle device, like the ShuttlePRO v2 or the Shuttle Xpress. It was originally written in 2013 by Eric Messick. The latest work on it was done by Albert Graef, offering various useful improvements, such as additional command line options, automatic detection of Shuttle devices, the ability to detect applications using their WM_CLASS property (in addition to window titles), and support for Jack MIDI output. The latter lets you use the Shuttle as a fully configurable MIDI controller.

NOTE: Eric's original README file along with some accompanying (now largely obsolete) files can be found in the attic subdirectory. You might want to consult these in order to get the program to work on older Linux systems. But for newer Linux systems you should be able to find all necessary information to get up and running in this file.

Description

The shuttlepro program translates input events (button presses, jog and shuttle wheel movements) of the Shuttle device into X keystrokes, mouse button presses, scroll wheel events, or, as an option, MIDI output. It enables you to use the device conveniently on Linux to operate various kinds of multimedia programs, typically audio and video editors, digital audio workstation (DAW) programs and the like. It does this by checking the (name and class of the) window which has keyboard focus and picking a suitable set of translations from its configuration (shuttlerc) file. Default translations for programs not explicitly specified in the configuration file can be given as well.

Shuttle events can generate sequences of multiple keystrokes, including the pressing and releasing of modifier keys. In addition, MIDI messages can be generated and output using Jack MIDI.

The shuttlerc file is just an ordinary text file which you can edit to your heart's content, in order to configure the program for use with any kind of application taking keyboard, mouse or MIDI input. A sample shuttlerc file containing configurations for various popular applications is included, see example.shuttlerc in the sources.

Installation

First, make sure that you have the required dependencies installed. The program needs a few X11 libraries and Jack (the latter is only required if you plan to utilize the MIDI support). And of course you need GNU make and gcc (the GNU C compiler). On Ubuntu and other Debian-based systems you should be able to get everything that's needed by running this command:

sudo apt install build-essential libx11-dev libxtst-dev libjack-dev

Then just run make and sudo make install. This installs the example.shuttlerc file as /etc/shuttlerc, and the shuttlepro program in the default install location. Usually this will be /usr/local/bin, but the installation prefix can be changed with the prefix variable in the Makefile. Also, package maintainers can use the DESTDIR variable as usual to install into a staging directory for packaging purposes.

Configuration File

After installation the system-wide default configuration file will be in /etc/shuttlerc, where the program will be able to find it. We recommend copying this file to your home directory, renaming it to .shuttlerc:

cp /etc/shuttlerc ~/.shuttlerc

The ~/.shuttlerc file, if it exists, takes priority over /etc/shuttlerc, so it becomes your personal shuttlepro configuration. You can edit this file as you see fit, in order to customize existing or adding your own application configurations. (If you create any new entries which might be useful to other users of this program, please consider submitting them so that they can be included in future releases.)

NOTE: The program re-reads the shuttlerc file whenever it notices that the file has been changed, but in the current implementation it only checks when a shuttle event is sent with a different window focused from the previous shuttle event. Thus you can edit the file while the program keeps running, but you'll have to switch windows and operate the device to have the changes take effect.

Usage

The shuttlepro program is a command line application, so you typically run it from the terminal, but of course it is also possible to invoke it from your desktop environment's startup files once you've set up everything to your liking.

Before you can use the program, you have to make sure that you can access the device. On modern Linux systems, becoming a member of the input group should be all that is needed:

sudo useradd -G input username

Log out and in again, and you should be set. Now make sure that your Shuttle device is connected, and try running shuttlepro from the command line (without any arguments). The program should hopefully detect your device and print something like:

shuttlepro: found shuttle device:
/dev/input/by-id/usb-Contour_Design_ShuttleXpress-event-if00

(The precise name of the device will differ, depending on the type of device that you have. E.g., the output above indicates that a Shuttle Xpress was found.)

If the program fails to find your device, you'll have to locate it yourself and specify the absolute pathname to it on the command line. Usually there should be an entry under /dev/input/by-id for it, which is simply a symbolic link to some device node under /dev/input. Naming the device on the command line will also be necessary if you have multiple Shuttle devices. In this case you may want to run a separate instance of shuttlepro for each of them (possibly with different configurations, using the -r option, see below).

If your device was found, you should be able to operate it now and have, e.g., the terminal window in which you launched the program scroll and execute mouse clicks if you move the jog wheel and press the three center buttons on the device. When you're finished, terminate the program by typing Ctrl+C in the terminal window where you launched it.

This default "mouse emulation mode" is actually configured in the [Default] section near the end of the distributed shuttlerc file, which reads as follows:

[Default]
 K6 XK_Button_1
 K7 XK_Button_2
 K8 XK_Button_3
 JL XK_Scroll_Up
 JR XK_Scroll_Down

As you can see, the buttons denoted K6, K7 and K8 (which are the three buttons right above the jog wheel, see the comments at the beginning of the shuttlerc file for a description of the button layout) are mapped to the corresponding mouse buttons, and rotating the jog wheel to the left (JL) and right (JR) emulates the scroll wheel, scrolling up and down, respectively. (Besides these mouse actions, you can also bind input events to arbitrary sequences of key strokes, so operating the functions of any application that is well-equipped with keyboard shortcuts should in most cases be a piece of cake. Have a look at the other configuration entries to see how this is done.)

One useful feature is that you can invoke the program with various debugging options to get more verbose output as the program recognizes events from the device and translates them to corresponding mouse actions or key presses. E.g., try running shuttlepro -drk to have the program print the recognized configuration sections and translations as they are executed. For instance, here is what the program may print in the terminal if you move the jog wheel one tick to the right (JR), then left (JL), and finally press the leftmost of the three buttons (K6):

$ shuttlepro -drk
shuttlepro: found shuttle device:
/dev/input/by-id/usb-Contour_Design_ShuttleXpress-event-if00
Loading configuration: /home/foo/.shuttlerc
translation: Default for ShuttlePRO : bash (class konsole)
JR[]: XK_Scroll_Down/D XK_Scroll_Down/U 
JL[]: XK_Scroll_Up/D XK_Scroll_Up/U 
K5[D]: XK_Button_1/D 
K5[U]: XK_Button_1/U 

It goes without saying that these debugging options will be very helpful when you start developing your own bindings.

It's also possible to use alternative configuration files, by specifying the shuttlerc file to be used with the -r option. Also, try shuttlepro -h which prints a help message with the available options and a brief description.

More information about the available configurations and on how to actually create your own configurations can be found in the example.shuttlerc file. You may also want to look at the comments at the top of readconfig.c for further technical details.

MIDI Support

The shuttlepro program can also be used to translate input from the Shuttle device to corresponding MIDI messages rather than key presses, using Jack MIDI for output. This is useful if you want to hook up the device to any kind of MIDI-capable program, such as software synthesizers or a DAW program like Ardour.

The program will automatically be built with Jack MIDI support if the Jack development files are available at compile time. (However, if you do have Jack installed, but you still want to build a Jack-less version of the program, you can do that by running make JACK= instead of just make.)

If the program was built with Jack MIDI support, you still need to run it as shuttlepro -j to enable the MIDI support at run time. This will start up Jack (if it is not already running) and create a Jack client named shuttlepro with a single MIDI output port which can then be connected to the MIDI inputs of other programs.

We recommend using a Jack front-end and patchbay program like QjackCtl to manage Jack and to set up the MIDI connections. Non-Jack ALSA MIDI applications can be accommodated using the a2jmidid program, an ALSA-Jack MIDI bridge which exposes ALSA sequencer ports as Jack MIDI ports, so that they can easily be connected using QjackCtl. (Starting up a2jmidid can be handled automatically by QJackCtl as well; in QJackCtl's Setup dialog, on the Options tab, simply place the command a2jmidid -e & in the "Execute script after Startup" field. This will work no matter which Jack version you use, but it should be mentioned that the latest versions of Jack1 have the a2jmidid functionality already built into it.)

The example.shuttlerc file comes with a sample configuration in the [MIDI] section for illustration purposes. You can try it and test that it works by running shuttlepro -j, firing up a MIDI synthesizer such as FluidSynth or its graphical front-end Qsynth, and connecting the two. In the sample configuration, the buttons K5 .. K9 have been set up so that they play some MIDI notes, and the jog wheel can be used as a MIDI volume controller (CC7). The configuration entry looks as follows:

[MIDI]

 K5 CH10 B2
 K6 CH10 C3
 K7 CH10 C#3
 K8 CH10 D3
 K9 CH10 D#3

 JL CH10 CC7
 JR CH10 CC7

NOTE: The special [MIDI] default section being used here will only be active if the program is run with the -j option. This allows MIDI output to be sent to any connected applications, no matter which window currently has the keyboard focus. This is probably the most common way to use this feature, but of course it is also possible to have application-specific MIDI translations, in the same way as with X11 key bindings. In fact, you can freely mix mouse actions, key presses and MIDI messages in all translations.

The CH10 tokens in the entry above merely specify that output should go to MIDI channel 10 (the drum channel), they do not output any MIDI messages by themselves. The actual MIDI notes to be played follow. E.g., C3, which is bound to button K6, is the note C in the third MIDI octave, which on channel 10 will produce the sound of a bass drum, at least on GM (General MIDI) compatible synthesizers like Fluidsynth. The bindings for the jog wheel at the end of the entry send control changes for controller 7 (CC7), which is the MIDI volume controller, so by turning the jog wheel you can dial in the volume that you want in this example -- turning the jog wheel to the right increases the volume, while turning it to the left decreases it.

The program keeps track of both the jog wheel position and the current controller values on all MIDI channels internally, so all that happens automagically. The shuttle (the rubber wheel surrounding the jog wheel) can be handled in a similar manner, using IL and IR in lieu of JL and JR. This can be put to good use, for instance, with MIDI pitch bends (PB), because the shuttle will automatically snap back to the center position, and thus works exactly like the pitch wheel available on most MIDI keyboards.

Besides MIDI notes, pitch bends and control change messages, the shuttlepro program also supports sending program change (PC) messages in response to button presses, which may be useful to change scenes or presets in some applications. Other messages (in particular, aftertouch and system messages) are not supported right now, but may be added in the future. Again, please refer to the example.shuttlerc file and the beginning of readconfig.c for further details.