2.8.1 Layered Approach to Broadcast Media Interfaces

It is common to talk of a 'stack' when referring to interfaces and protocols for transfer of IT data across a computer network. This is a reference to layers of processing within software and perhaps associated hardware, necessary to provide a reliable information link between computer applications. Some communications engineers refer to an idealised 'OSI seven-layer model'.

Transmission of data on the broadcast industry standard interfaces described here is in many ways simpler than transfer of data over IT style packet networks. These broadcast interfaces carry digital video, audio and related data in one direction, usually over a dedicated point-to-point or point-to-multi-point circuit. Such data interconnections offer very high reliability, freedom from errors, stable reference clocks and consistently low latency. The use of dedicated physical media data pathways is suited to operational practices that make it straightforward to distribute, route and monitor video and audio. The physical routes are robust and reliable, but if they do fail it is usually quick to isolate a fault. Standards for these broadcast interfaces are well known, stable and widely supported by equipment manufacturers.

Having sung the praises of specialist broadcast interfaces over dedicated links there is an increasing trend towards use of IT networks to carry broadcast data. The attraction of less specialist, and therefore lower cost, fast Ethernet network infrastructure carrying broadcast media essence (sound and vision) as well...