It's no exaggeration to call the switcher the "heart" or "nerve center" of a modern video production facility. More than any other piece of equipment, the switcher is central to the creation of video programs of all types, and it is literally the connecting point for most other pieces of video equipment in a studio. Although switchers are also used in postproduction editing facilities, as you will see in Chapter 11, this chapter concentrates on the operation of the switcher in a studio production environment. The general operation of the switcher is the same in either situation.

The video switcher serves a number of different functions. First and foremost, it is an editing device that facilitates the time-ordered sequencing of inputs within a live or live-to-tape video production. To do this, the switcher serves a channeling or routing function as it selects a video source from all the available inputs, such as cameras, videotape machines, remote feeds, graphics generators, and computer- generated graphics. The switcher also functions as a selecting and altering component that can combine two or more visual sources in a number of different ways. Through the use of digital video effects (DVE), a switcher can become a special effects generator (SEG) with the capability of altering the appearance of video inputs.

The continuing conversion of television signals and equipment to digital is affecting switchers as well. Increasingly, switchers function fully in the digital domain, inputting and outputting digital bitstreams, performing digital effects, and even "talking to" other digital equipment such as video servers, videotape recorders, and computers. For the most part, however, this chapter does not differentiate between analog and digital switchers. Operationally, they are essentially the same, at least when it comes to the basic techniques described in this chapter. For the most part, it makes no difference to the switcher operator whether the signals coming into and going out of the switcher are analog or digital.

Despite the wide range of switcher types and levels of complexity, a few basic principles of design, function, and operation are common to all units. Once you understand these essential principles, you can more confidently approach the operation of the advanced switcher units found in professional production environments. This chapter is designed to help you understand these essential principles and the basic operation of video switchers.

The disciplines of switchers include understanding how they are connected to other equipment and the basic concepts of their design. This understanding will make the techniques of achieving various effects using a switcher much easier to grasp. This chapter covers the following topics:

• The basic configuration and design concepts of switchers (9.1)
• The types of buses found on switchers (9.2)
• The function of various buses found on switchers (9.2)
• Basic operating concepts of a typical switcher, including performing cuts, dissolves, wipes, and other effects (9.2-9.3)
• Advanced functions of switchers, including digital effects and the control of external equipment (9.4)
• Commands given by the director to the technical director operating the switcher (9.5)