Most server, and especially most digital on-screen graphic and character generator (CG) manufacturers will have a specific device driver for their device, with increasing degrees of complexity, and different automation companies will include these drivers to enhance their product or to fit a customers need. This is the "traditional" method of playout automation, where there are multiple devices. Some modern automation systems use a unified playout method, where the broadcast server fulfills the functions of multiple devices as a self-contained system, like the PlayBox Technology channel-in-a-box. Playout devices Playout will usually involve an airchain of devices which begin with content, typically stored on video servers, and ultimately an output, either as an (Asynchronous serial interface) (ASI) / IP or (Serial Digital Interface) (SDI) for on pass to a distribution company. The devices in the chain depend on the service required under the contract with the Channel. Typically a standard television channel would require a Master Control, Video switcher, and/or a Video router to allow switching of live sources. This video switcher may include other functions such as keying (graphics) (also known as Down Stream Keyers), Audio Overs for mixing in voice overs (VO) or announcements, and facilitate transitions between events, such as a fade through black or crossfade (also known as mix). Other devices include: Graphics inserters – At least one Graphics inserter, or one with several layers. This allows for Station identification/Logo/Digital on-screen graphic (Dog or Bug) insertion, and can also be used for end credits sequences, coming next graphics or programme information straps Subtitling inserters – This can be either closed or open – i.e. in vision as a graphic for all to see, or closed either as an MPEG stream item, Closed Captioning or World System Teletext. Audio servers – An audio playout system would provide scheduled voiceovers Aspect Ratio Converters – These alter the picture shape or send an embedded signal to allow the material format to be displayed correctly on a particular feed (e.g. Widescreen on a standard non-widescreen Analogue terrestrial feed) Some of these more advanced devices require information from the playlist, and so do not tend to use an RS422/232 driver, but a complex XML based system which allows for more complex metadata to be passed, e.g. a "Now" or "Next" Graphic can be created from a template using text information from the playlist. Channel-in-a-box concept With the "softwarization" of the various functions