Pioneer Cdj 850
This is a CD and USB media player that can control Mixxx via USB with MIDI or HID. It can also control Mixxx by playing timecode from a CD or USB drive and running that signal into Mixxx through a sound card.
This is the Mixxx Wiki - 
Mixxx is a free and open-source DJ software.
Manual
Hardware Compatibility
Reporting Bugs
Getting Involved
Contribution Guidelines
Coding Guidelines
Using Git
Developer Guide
Contributing Mappings
Mixxx Controls
MIDI Scripting
Components JS