Black Burst

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A Composite video signal, with a black picture used to synchronize (Genlock) certain video equipment together, thereby aligning the output. The signal is made up of vertical and horizontal sync. and Chroma burst information (1 wire).

Also sometimes called video sync or house sync, black burst is a blank video signal. In other words it is a video signal with no picture data. It is just black. In video editing situations it has always been important for all video decks and cameras to be "gen locked," which means that their video clocks are all synchronized. They don't always have to be at the same location (which would be addressed by SMPTE Time Code), but they do have to be frame locked which means that they are moving from one frame to the next in precise synchronization. This is critical for combining (editing) video data.

An easy way to achieve this is to have a master time base that all of the other equipment slaves to for synchronization. In video the relevant time base is the frame rate of the video, and thus black burst is used. As audio people began to do work for video it also became important for them to be synchronized to the exact frames of video (especially for digital audio work) so they also became acquainted with and now use black burst generators.

A black burst generator is often a simple little box with one or more video outputs. The outputs simply supply an accurate, and more importantly common, source for the timing of all equipment in the studio. Thus they also are named house sync generators.


  1. Sweetwater Expert Center Black Burst [1]

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