BROADCAST ENGINEERING CONCEPTS

In broadcast engineering signals are used in the form of AUDIO and VIDEO 
video signals can be Digital (SDI or ASI) or analog (component,composite,s-video).
similarly audio signals can be analog or digital (AES).


SDI SIGNAL  


Serial digital interface (SDI) refers to a family of video interfaces standardized by SMPTE. For example, ITU-R BT.656 and SMPTE 259Mdefine digital video interfaces used for broadcast-grade video.
the bit rate of standard definition SDI signal (SD-SDI) is 270MBps and the bit rate of high definition SDI signal (HD-SDI) is 1.485 GBps .


An emerging interface, commonly known in the industry as dual link HD-SDI and consisting essentially of a pair of SMPTE 292M links, is standardized in SMPTE 372M; this provides a nominal 2.970 Gbit/s interface used in applications (such as digital cinema or HDTV 1080P) that require greater fidelity and resolution than standard HDTV can provide. A more recent interface, 3G-SDI, consisting of a single 2.970 Gbit/s serial link, is standardized in SMPTE 424M that will replace the dual link HD-SDI.


These standards are used for transmission of uncompressed, unencrypted digital video signals (optionally including embedded Audio and/or Time Code) within television facilities; they can also be used for packetized data. They are designed for operation over short distances (less than 300m. with coaxial cable); due to their high bitrates they are inappropriate for long-distance transmission. SDI and HD-SDI are currently only available in professional video equipment; various licensing agreements, restricting the use of unencrypted digital interfaces to professional equipment, prohibit their use in consumer equipment^{[citation needed]}. There are various mod kits for existing DVD players and other devices, which allow a user to add a serial digital interface to these devices.