If you're using rekordbox lighting and looking for the easiest way to to automate which deck is selected when using an External Mixer device, this is the guide for you! I'll walk you through assigning the crossfader to keyboard shortcuts so each end of the crossfader will trigger the appropriate manual lighting channel selection.
The first thing you'll need is midiStroke; a tiny 52kb application that will convert MIDI input into a keyboard command. I've chosen this option as Bome's MIDI Translator Pro is a fantastic application and is super-powerful, but it's much more complicated than what you need for this task.
Unzip the download and stick the app it in your Applications folder, then launch it. You'll see this simple window:
Click the + icon at the left and some numbers will appear in the left set of columns. You'll have to enter the MIDI codes for your device as outlined at the end of this article. We'll use the DDJ-RZ as our example:
Here I've entered 31 / 7 / 0 as the number / channel / value.
Next, click the + at the right, and enter a keyboard shortcut you don't have assigned anywhere else, be it a system shortcut or within rekordbox.
I've selected 1, and clicked the boxes for SHIFT (the arrow) and OPTION (the split line).
Finally, select the source at the bottom as your device:
Repeat the process for the other side of the crossfader, again, assigning a keystroke to that MIDI input. Here I've used the same number and channel, but a value of 127, and I've assigned the 2 + SHIFT + OPTION as the shortcut:
Next, we need to add these keyboard shortcuts within rekordbox, so open the Preferences > Keyboard and toggle open the Lighting section. Find the Deck Select/Deck1 and Deck Select/Deck2 items and assign the appropriate keyboard shortcuts:
Close the preferences and toggle the LIGHTING panel open, if it's not already, and now you can see your lighting deck selection toggle as you move the crossfader to each end. Note that this animation shows the mixer onscreen to illustrate the crossfader position, but you can still operate it with the mixer hidden:
The first time you try using midiStroke to actually send a signal, you may receive a pop-up warning from the Mac OS (depending on the version) asking you to allow it to use the Accessibility features. Unlock the panel with your user password, then tick the box beside midiStroke to allow it to send the keyboard shortcuts:
The only caveat to the midiStroke application is rekordbox must be in the foreground as whichever application is in the foreground will receive the keystrokes sent by midiStroke.
Same thing as above (effectively), but you're using midikey2key instead.
Each Pioneer DJ hardware device may send a different signal, and if you have changed the output MIDI channel, it may not match those listed below. In that case, you may need to grab MIDI Monitor (Mac) or MIDIOX (PC). This application isn't necessary for the translation / execution part, but it will help you find the proper codes for your device.
*Sorry, I haven't listed out every device, these are just the ones I've personally tested. If you have one I've missed, please post it to the forums and we'll add it.