Editing Amiga Original Chip Set (section)

===External video timing===
Under normal circumstances, the Amiga generates its own video timings, but Agnus also supports synchronising the system to an external signal so as to achieve [[genlock]]ing with external video hardware. There is also a 1-bit output on this connector that indicates whether the Amiga is outputting background color or not, permitting easy overlaying of Amiga video onto external video. This made the Amiga particularly attractive as a character generator for titling videos and broadcast work, as it avoided the use and expense of [[B-roll|A/B roll]] and [[chroma key]] units that would be required without the genlock support. The support of overscan, interlacing and genlocking capabilities, and the fact that the display timing was very close to broadcast standards (NTSC or PAL), made the Amiga the first ideal computer for video purposes, and indeed, it was used in many studios for digitizing video data (sometimes called frame-grabbing), subtitling and interactive video news.