Time Base Corrector (TBC)
A Time Base Corrector is a device which takes a video input and does any or all of the following before outputting the signal:
- Make adjustments to the technical parameters of the signal, e.g. voltage level, horizontal and chroma phase, etc.
- Synchronize video parameters with other equipment.
- Correct defects in a video signal, e.g. replace a weak synch pulse with a more stable one.
Frame Store (Frame Buffer / Synchronizer)
Professional TBCs use a frame store or synchronizer system. This stores either a full field or (preferably) a full frame of video in a buffer and releases it at a very precise moment. Synchronisation is important when mixing different vision sources together, to avoid picture disturbances caused by out-of-synch transitions.
Some TBCs provide digital effects such as mosaic, posterization, multi-picture, etc.
Although time base correctors are usually associated with professional equipment, many consumer video players and cameras have a built-in TBC. In most cases this is a simple on-off switch with no other controls (as pictured right).
Cheap stand-alone TBCs are also available for home use. Naturally these don't have the full range of features and quality as the professional models but the basic principles are the same.
Some TBCs are available as cards which slot into your computer. This type of TBC may be recognized by the operating system or it may be a pseudo-standalone device, only using the PC as a convenient source of power.