gateway devices to span engineered WANs.” This project is expected to take approximately 24-36 months. If a desire for greater interoperability
is a given, there is still considerable debate regarding implementation. For example, much of the current debate revolves around the viability of employing existing IP networks. This is the approach taken by Ravenna, the audio transportation technology developed by Lawo group company ALC NetworX. As a pure Layer 3 solution routed via IP, Ravenna – which counts Genelec, Merging Technologies, Innovason and Neumann among its partners – can be added to most existing network infrastructures. Significantly, the Layer 2-revolving
AVB requires the specification of dedicated switches – not the case with Ravenna, which can potentially operate on any manageable network infrastructure supporting multicast and Layer 3 protocols. The extent to which the two approaches will compete is debatable: for now, Ravenna is focused towards broadcast applications, while AVB has greater resonance with live touring and other areas of fixed install. ALC NetworX senior product
manager Andreas Hildebrand confirms that a pure IP/Layer 3-based approach requires more administrative and management support of the network infrastructure – a necessity that is likely
to be particularly problematic for live sound. Accordingly, it could be that – as Hildebrand suggests – “AVB will have its natural place in applications where insertion of a new network infrastructure is feasible and content distribution can be limited to a LAN segment, while Ravenna will be the preferred technology for larger, already installed corporate-type networks spreading across several subnets”.
Rallying for Ravenna Merging Technologies is among those for whom Ravenna currently “ticks all the right boxes to serve our customers’ requirements, be they in broadcast, recording, live or fixed installations”, says Merging’s Claude Cellier. “We will, of course, continue to support existing protocols, and the best testimony to that is that our first hardware-based product with Ravenna support, Horus, is actually able to serve as a ‘bridge’ between these two worlds.” Meanwhile, the overall audio-over-IP
‘movement’ is being complemented by an Audio Engineering Society project, X-192, which – in the words of its mission statement – seeks the creation of ‘a high-performance streaming audio-over-IP interoperability’ standard. X-192’s supporters include QSC, which backs interoperability of products over Layer 3 networks and is the company behind the Q-Sys integrated system
Questions of control
The control landscape has historically been dominated by manufacturer- specific innovations. But here, too, there is now enhanced focus on standardisation, exemplified by the activities of the Open Control Architecture (OCA) Alliance. Established by nine pro-audio
manufacturers, the alliance is pursuing the elevation of OCA to the status of an open public communications standard for the control and monitoring of devices in professional media networks. In itself, OCA does not provide signal transport, but is designed to co-operate with current and future transport standards, including the AVB suite. The starting point for OCA was AES-
24, a system control protocol developed by the AES in the 1990s. But according to Ethan Wetzell – platform strategist at OCA Alliance member Bosch Communications Systems – this foundation has been transcended thanks to “extensive modifications, enhancements and extensions... OCA has come into its own and really is a unique architecture.” OCA is already informing some major
product developments – not least Bosch’s own OMNEO architecture. Combining a transport suite employing
Dante with an OCA-based control component, OMNEO encompasses both primary concerns of a media network. According to Wetzell: “Interest in, and enthusiasm for, OMNEO has been very high from all areas of the industry.”