OB Truck

An OB truck (outside broadcast truck) is a mobile production facility, essentially a control room on wheels, used to capture, mix, and transmit audio and video from the site of a live event such as a sports match or concert. It is where the live program mix is committed in real time, blending commentary, crowd, effects, and music. Because those elements are combined here, recovering them later from the finished mix is a job for source separation.