Frame synchronization (video)
In video, frame synchronization is the process of synchronizing display pixel scanning to a synchronization source. When several systems are connected, a synchronization signal is fed from a master system to the other systems in the network, and the displays are synchronized with each other.
A Frame Synchronizer is used in television/video production to synchronize the timing of a video source signal to coincide with a central timing reference (usually a color black signal aka "black burst" that is distributed throughout a facility). The synchronizer accomplishes this by (first digitizing in an analog scenario and) writing the incoming digital video into a frame buffer memory using the timing of the sync information contained in that video signal. Simultaneously the digital video is being read back out of the buffer by an independent timing system that is "genlocked" to the house timing reference. As a result, the timing or alignment of the video frame can be adjusted so that the start of the upper left corner scan line of the image occurs simultaneously on all video equipment in the work flow. This is an absolute requirement for both analog and digital systems in order to perform video effects or glitch-free source switching. Note that frame synchronization can only be performed within a given television line standard. A synchronizer will not convert an NTSC signal to a PAL signal or vice versa; it takes a Video Standards Converter to do that.