equipped with analog and/or digital input interface and output a compressed signal in a serial bit stream that is a fraction of the original bandwidth. It is this signal that is most often handed off to a satellite or fiber network. If it is live or previously recorded, it can be streamed or run in real time across the network. The recorded or stored version can be transferred as one would any ordinary com- puter file using file transfer protocol (FTP). Program content is usually the product of multiple camera and microphone output signals mixed and switched to make continuous program material. In addition to these output signals, other material from videotape recorder/players-file servers, graphics systems, and remote, off-site feeds-can be used to contribute to any particular program segment. Figure 1-4 is a block diagram of a typical produc- tion system. If there is a possibility of converging program content with voice and data traffic in a common network, most of the action has to be at Production Mixing & Processing System AES EBU Audio Wired - Cable, Internet, ATSC/ Telecom Network Interface Encoder Wireless - SMPTE Cam 1 DTV, Satellite 259/292 SMPTE 259/292 Cam 2 E259/292 SMPTE Cam 3 259/292 Production Switcher Mixing SMPTE VTR 1 & Special VTR 1 SMPTE 259/292 Effects System (REC) 259/292 SMPTE VTR 2 VTR 2 SMPTE 259/292 (REC) 259/292 SMPTE Remote 259/292 FIGURE 1-4 Simple Production System Functional Block Diagram PRACTICAL IP AND TELECOM FOR BROADCAST ENGINEERING AND OPERATIONS physical and virtual channel interfaces, and within a common under- standing of bitrate and interface details. This is where good verbal and written communication skills and practices can achieve success, or a point where lack of understanding or misunderstanding leads to only partial success or outright failure. The idea is to define program content transport, in this case, audio and video signals, with coding, interface, and payload bitrates across common interfaces with consist- ent, standardized parameters. These details includ