Networked audio

Broadcasters increasingly are demanding more versatility and integration from their audio equipment. In the current fast-paced, technologically progressive era, TV companies want to ensure that their systems can produce programs efficiently and to the required specifications.

For their audio systems to be able to achieve this, greater consideration has to be given to their networks as a whole and how efficiently they can be controlled.

Multiplatform broadcaster BSkyB has pioneered technological innovations that are now commonplace around the world. It offered regular live HD sports coverage (including full 5.1 surround) in 2006, and it has laid down technological conventions and workflows for HD broadcast that are still guiding broadcasters making the transition to HD today. The broadcaster launched Europe's first 3-D channel in 2010, and in 2011 it completed work on its Sky Studios multi-studio complex.

In this article, Martin Black, senior sound supervisor and technical consultant at BSkyB, discusses some of the considerations and deliberations that were undertaken in designing and implementing the multi-studio complex, and the logic behind the decisions that were made when choosing the technology it uses.


The ultimate aim with Sky Studios was to create an environment in which the broadcaster's eight live studios and their corresponding galleries could be connected together, complete with multiple I/O formats. Other live areas within the building also had to be incorporated into the network, including the Sky Sports News Newsroom studio; 14 live commentary booths; an international commentary area (ICA) and enhanced control room, which manages all the interactive content; and the master control room. Within the network, it was necessary for all the audio resources to be shared among these areas for increased flexibility.


When planning a multi-studio complex, many aspects must be considered. The number of consoles and their location had to be determined in relation to the studios, ICA, sub-desks and mobile mixers in order to ensure total flexibility. BSkyB decided to use the Calrec Hydra2 network and Apollo and Artemis consoles to enable it to network consoles easily, to allow any console to utilize any I/O resource on the network, and to provide a solution for transmitting audio signals around the building.

The most common way of transmitting audio is by embedding it in SDI vision signals. The broadcaster employed the Hydra2 network system to transform incoming audio into SDI in order to transfer 16 audio channels in one vision circuit, which sufficed for its multichannel regime of two surround and two stereo audio. That way, as Black said, “We no longer have to rely on Dolby E to transmit the surround audio around the building.”

The main dilemma was how to carry the metadata that would have been present using Dolby E. Because BSkyB had always created the metadata at the source, i.e., from the OB or the studio making the program, a mechanism had to be devised that allowed control of the metadata.

According to Black, BSkyB adopted the SMPTE 2020 standard for use in the complex and uses the new audio network to decode the Dolby E down to 16 channels. Then the system is used to extract metadata from Dolby E signals and reformat the signal to SMPTE 2020 before it gets passed to the studio as SDI. The program is then made, and then the metadata is all embedded into the SDI signal ready for transmission.

Black further explained that the signal is routed throughout the facility using vision routers.

The system also includes stereo/5.1 mode switching for SDI studio outputs. SDI is used throughout the complex to transmit the audio and images.

Expandability is also a key concern. Even though Sky Studios is a large complex, there may be the need to add to its capability in the future. The audio system has the potential to expand the network to any size the broadcaster requires, thus ensuring the longevity of its operational life.


All of the audio hardware in the building is or can be connected to the network. So any microphone in any studio can be routed to any mixing console or recorder. With this infrastructure, it is possible to meet the studio production requirement of fully flexible control gallery/studio floor associations.

As Black said, “The gallery/floor association switching allows for more efficient use of resources and time.”

Currently, the complex has more floors than galleries. The networked audio system enables a set to be rigged on one floor while a gallery controls a production on a different floor. This is a more efficient usage of both areas. Otherwise, the gallery associated with a floor is effectively redundant while the studio is rigged and the set is lit.

The new audio network allows the use of mobile I/O resources. Stage boxes can be connected to the router via the broadcaster's fiber network so that a studio is no longer limited by its fixed resources. Larger productions can now be accommodated simply by plugging in more boxes. Each box is identified automatically, making the process quicker and ultimately more efficient than traditional router setups.

“With this flexibility [of mobile I/O] comes an added degree of complexity, however, and we've worked closely with Calrec to work through the issues we've experienced — as anyone would during any implementation process of this scale,” said Black.

Third-party controllers

To add greater functionality to the system, the station-wide Siemens BNCS control system allows certain operations to be implemented from third-party controllers. Many custom screens have been devised that make use of the EMBER protocol from L-S-B and SW-P-08 protocols from Snell to allow specific audio routing and configuration tasks to be undertaken. Alias files have been used to achieve simple floor-association switching for operators via EMBER. The files come complete with safety interlocks.

The complex uses the alias files to identify each studio's I/O resources by the gallery that is being used for a particular production. The alias files are used to point at the correct I/O ports, which makes a specific show's memories transportable among both the floors and the galleries.

“This allows us to produce a show on any floor using the same preconfigured show memory,” Black said. “The system is also interlocked, which acts as a safety mechanism. If someone has the alias loaded, then it is effectively ‘locked out’ and cannot be loaded up by another gallery.”

What's next?

BSkyB's adoption of audio and control networking has enabled it to create a fully scalable network that will provide it with a flexible infrastructure for many years. Increasingly, this model is being adopted globally; there are several large broadcast centers being designed for 2012 in the United States alone, and forward-thinking manufacturers should be considering integrating networking protocols into current product designs.

The requirement for better integration between video and audio systems is one of the fastest-growing challenges facing broadcasters today. In a fast-developing area like video and audio integration, broadcasters should not need to stick to using outdated or limited protocols. With a little collaboration and communication, manufacturers can do much more to ensure audio and video hardware are speaking the same language. After all, if integration is what broadcasters want — and at BSkyB this was central to its design philosophy — that is what more manufacturers will have to deliver.

Ian Cookson is marketing coordinator at Calrec Audio.