A few days ago I bought a Logitech F310 gamepad at my local
thrift store. FreeBSD detected it immediately and created the appropriate
uhid entry in /dev. SDL2 also saw the gamepad, which I was able
to verify with Joytran. The Mednafen game console emulator
did not see the device, however. Here's why:
Mednafen 1.22.2 supports three different joystick backends:
Linux event devices (evdev), SDL2, and MS Windows
DirectInput / XInput devices. The backend is selected when the autoconf
./configure script is run, and then that backend selection is compiled
into the Mednafen binary (see the ifdef statement at line 178 in
src/drivers/Joystick.cpp).
Mednafen's autoconf script selects the evdev backend if it finds the file
linux/joystick.h in the header search path. The FreeBSD port
devel/evdev-proto installs that joystick.h header file. So, if you
have evdev-proto installed (it's required by x11-toolkits/qt5-gui)
and then compile emulators/mednafen it will use evdev and not
SDL2 for its joystick support.
I worked around this by commenting out parts of src/drivers/Joystick.cpp
(again around line 178) to force Mednafen to use SDL2 for joysticks. I should
probably post on FreeBSD's bug tracker; could submit a patch too, it's simple
enough.
This whole situation is definitely a corner case. The joystick backend
selection in Mednafen could be better, but I'm also doing something
a little unusual here.
Posting because this took me hours to figure out, and so I'll remember next
time I encounter this problem.
The SCS.4DJ
is a "Digital DJ Mixstation" made by Stanton Magnetics.
It's a little standalone workstation unit with a "Coldfire" ARM (ARM10TDMI?)
board in it that runs Linux (2.6.14?) and a custom set of DJ software. The
unit seems to have been engineered, both hardware and software, by a company
called IVL Audio. The current equivalent
product, functionality-wise, would be something like the Pioneer XDJ-RX.
I purchased one of these at clearance prices in 2015. It is both one
of the worst and best pieces of DJ equipment I've ever used.
Worst because it's incredibly cheaply made. The control surface itself - the
buttons, knobs & sliders - require a very light touch to keep from breaking.
The mixer section of mine lasted a year before it started to bleed sound. The
computer in the device is underpowered. Even the jacks seem flimsy.
Which is a shame, because the SCS.4DJ does something truly great:
it plays two mp3 files simultaneously, through seperate outputs, with pitch
and transport control, in a small and lightweight package. I run one "deck" on
the SCS.4DJ out the headphone output and the other out the main, with both
plugged into my DJ mixer. And there it becomes one of the best: feed it good
data, use fast USB drives, handle it carefully and it'll run all night no problem.
The dj software the device runs seems to be called, appropriately, "djapp".
It uses GTK2 for its UI and runs Xfbdev(1)
to display graphics. It keeps its database in SQLite 3.x format. For it to
operate smoothly, feed it good data. I've tried both FLAC and MP3 files, and
FLAC has always caused problems. (I suspect because my USB media devices don't
have the throughput to stream that much data). I've never had any issues
with MP3 files I've encoded myself with LAME.
Maybe I'm being a little unfair with respect to the hardware. As
DJWorx noted in their
review, the jogwheels are very good. They easily make up for the lack of
resolution available with the pitch slider. And while the device always feels
like it wants to break, it has not done so yet. Just... don't press anything
too hard.
I plan to write a companion to this post about Quickgrid - what it is, how it
works, and how to re-implement it using bourne shell, WINE, and parts of the
Quickgrid package. That post will come once I clean up my script.
Some of the information in this post is based on the blog post Stanton SCS.4DJ - Under The Hood
by Kris Sum at Switch Systems. The rest I gleaned myself from running strings(1)
against binaries packed in the SCS.4DJ software update. If my SCS4 ever
becomes unusable for DJing, or if I pick up a second one, I'll try to continue
Kris' line of exploration (network connectivity, SSH).
So yeah. Apologies if that rambled a bit. I don't recommend this thing to other
DJs, as it's too cheaply made and a bit too particular about its data. But if
you're a Linux/Unix person this thing is fascinating.
