Editing Genlock (section)

== Possible problems ==

Video signals generated and output by generator-locked instruments are said to be [[wikt:syntonize|syntonized]]. Syntonized video signals will be precisely frequency-locked, but because of delays caused by the unequal transmission path lengths, the synchronized signals will exhibit differing phases at various points in the television system. Modern video equipment such as production switchers that have multiple video inputs often include a variable delay on each input to compensate for the phase differences and time all the input signals to precise phase coincidence.

Where two or more video signals are combined or being switched between, the horizontal and vertical timing of the picture sources should be coincident with each other. If they are not, the picture will appear to jump when switching between the sources whilst the display device re-adjusts the horizontal and/or vertical [[Raster scan|scan]] to correctly reframe the image.

Where composite video is in use, the [[phase (waves)|phase]] of the [[chrominance]] [[subcarrier]] of each source being combined or switched should also be coincident.  This is to avoid changes in colour hue and/or saturation during a [[Film transition|transition]] between sources.