Also known as Black Burst or House Sync. It is a reference video signal generated by a very stable source (commonly known as a House Sync or Black Burst generator). The signal is used to precisely synchronize equipment to a specific video frame rate. This ensures that multiple machines in a studio are all referenced to one common speed, which is critical for all video editing and production. Some audio equipment is capable of synchronizing to video sync for the purposes of having a common time base in a system and for having the time base be compatible with projects being done for video or film.