Embracing the AES67 standard to create AoIP-based networks

Professional audio is an umbrella term covering disparate areas of expertise that are connected, sometimes loosely, because they all involve sound. There are ostensible similarities between broadcasting, live performance, installation and music recording but enough specialist techniques and idiosyncratic peculiarities to make them very different from each other. Which is why audio over IP (AoIP) for distribution, networking and interconnectivity would appear to be universal to all three but also have to adapt to suit the specific requirements of each.

These sectors are still coming to terms with the implementation and potential of AoIP, if not the basic concept. While there is the core, almost generic Layer 3 format for carrying audio over IP-based IT connections, different manufacturers have produced their own takes on the technology to match their products and core markets. Early systems such as CobraNet and LiveWire have been joined in the last ten years by RAVENNA, which, with its connections to Lawo, was initially regarded as more a broadcast format; and Audient’s Dante, originally seen as a live sound and installation protocol.

Despite this demarcation the two systems have always been seen as competitors, increasingly so as each has crossed over into the other’s ‘territory’. With users adopting one or the other, it was probably too late for anyone to develop a fully open AoIP system. Which is why the AES (Audio Engineering Society) decided to develop a means to enable interoperability between all existing systems.

From its introduction in 2013, all three arms of pro audio have been recognising and assessing the potential of AES67 to create AoIP-based networks. As consultant Roland Hemming observes, this has created almost different forms of AES67, each adapted to the protocol it is being used in conjunction with.

This is illustrated by the Telos Alliance now marketing its AoIP offering as LiveWire+AES67. Martin Dyster, vice president of business development with the company’s TV Solutions Group, describes the various AoIP systems as “almost IP surrogates for MADI”. With LiveWire+AES67, he explains, the aim is to get away from traditional, involved infrastructures that pulled back to a TDM matrix or router. “The idea is to use IP as a transport stream that creates an entire backbone, with DSP engines running on computers as opposed to a crate full of cards and an FPGA doing the grunt work,” he says.

Early adopter

Telos subsidiary Axia was among the first manufacturers to produce AoIP mixing consoles. These have been predominantly for radio but the year-old TV Solutions Group was formed to push both the mixers and AoIP into television production. One of the first results of this is a TV centre installation at a US sports and education facility, which, frustratingly, was still under a non-disclosure agreement at the time of writing.

This involves Axia desks and other Telos products, including xNode IP interfaces and Pathfinder routing software, on the audio side connecting through AES67 to Evertz video routers and switchers and a Riedel intercom system. The network is the basis of a large campus with two control rooms and a multipurpose media centre, among other facilities. Dyster comments that the idea behind this is to create a distributed IP network. “People are looking at installations that are made up of any devices that are able to connect to any other device,” he explains. “In this way they can build large infrastructures with existing base band systems but replace crate-based card style routers.”

Dante is being used for both fixed installations and broadcast. During last year’s US presidential elections BBC Radio sent live reports back to the UK using the technology but it does appear to be lending itself more readily to situations combining PA sound and recording or in-house TV. A recent example is the Fellowship Alliance Chapel in New Jersey, USA. This now features a multichannel audio system with routing, distribution and management features based on a Dante network incorporating Dante Via, which is designed to emulate low-cost computer-to-computer networks.

Earlier this year Audinate announced the Dante Domain Manager server-based software for enhanced management of networking. Joshua Rush, vice president of marketing at Audinate, explains the concept was to create an audio system that looked and behaved more like “a traditional IT network”. To achieve this, Domain Manager includes features for authentication, domain creation and reporting of changes.

“This means you can set up admins, different types of users and give them access to specific devices and not other devices,” Rush explains. “Now you can set up networks as big or as small as you want and cross sub-nets. Broadcast facilities tend to be pretty large, with different studios and LANs. But if you want to pass audio across those networks you can do it because they’re contained within anything plugged into the main switch. It gives the flexibility of having the device groupings however you want them, for a room, a building or over a campus.”

That last word – campus – is being used increasingly when networking is discussed today. RAVENNA – in conjunction with Lawo mixing consoles and, in several instances, its IP video matrices – has been part of a number of large installations in the last year. Among these is the new International TV Centre for Chinese broadcaster ZRTG (Zhejiang Radio and TV Group). This includes six TV studios, which are connected to audio control rooms over AoIP. Mixing desks are linked to DALLIS stage boxes in the studios using RAVENNA, with audio distributed by Nova routers. The whole process is controlled by VSM management software.
While there is no definite number of how many AoIP networks have been built so far – certainly there appears to be anecdotal evidence of only approximately ten percent of new installations featuring AES67 – the last year has seen not just more practical implementation of the technology but a greater awareness and understanding of it and what it can do.

Industry awareness

AES67 has been the focus of industry seminars organised this year by Roland Hemming involving Genelec and ALC NetworX, which oversees development of RAVENNA. As with LiveWire+AES67, RAVENNA is now being promoted as fully interoperable with “AES67 built in”. Genelec’s 8430A IP SAM studio monitor has featured in demonstrations involving not just its integrated RAVENNA capability but also the ability to connect to Dante units through AES67. While best known for its music studio, broadcast control room and post house monitors, Genelec does not see its AoIP offering as exclusively in those areas. The company is involved in live venue installations of its IP loudspeakers, with the intention of bringing more high fidelity to the club market.

The AES itself has continued to promote interoperability and AoIP connectivity through its Plug Fests. After successful events in the US and on mainland Europe involving many different manufacturers, Plug Fest came to the UK earlier this year. Held at BBC Broadcasting House in London, the event featured tests of equipment from Audio-Technica US, Digigram, Prism Sound, Neumann, Shure, Sonifex and Thum+Mahr.

Bruce Olson, chair of the AES standards committee and founder of technical systems consultancy Olson Sound Design, attended the Plug Fest, which he feels shows the growth of AES67. “It’s not early days for it any more,” he says. “We’re seeing a steady take-up and organisations like the BBC have been showing some future developments using the technology.”

Another significant development is the introduction of ANEMAN (Audio Network Manager), produced by RAVENNA and Merging Technologies. This is designed to provide fast, efficient configuration of networks and monitor network movement. This is now included on Pyramix systems as the standard discovery and management device.

“I think everybody knows that all AoIP schemes work and we have done enough Plug Fests to know AES67 is very useful as an interchange format,” comments Chris Hollebone, sales and marketing manager with Merging Technologies. “However, the bar has been raised now that we are looking at serious over-IP systems as featured in the IP Showcases that have been at NAB and will be at IBC. There is still an issue of management to be solved, but ANEMAN could be part of that solution in the future.”

AES67 has also moved AoIP beyond sound-only installations or self-contained systems by being included in the SMPTE 2110 standard for video – and general media – transport over IP. Patrick Warrington, technical director at Calrec Audio, sees the almost wholesale integration of AES67 into this scheme – where it is known as ST2110-30 – as giving the interoperability standard “a further fillip”.

Calrec currently offers an AoIP Gateway including AES67 and supports industry groups including the MNA (Media Networking Alliance) and AIMS (Alliance for IP Media Solutions), both of which advocate AES67 and its ST2110-30 counterpart. As for the continuing development of AES67, Warrington says, “We expect future revisions of the standard to refine issues around the practical implementation of AES67 and, equally crucially, to offer guidance on conformance. Experience shows that interoperability is enhanced when suppliers are able to measure their implementations against a set of performance criteria.”

The real hope for digital/IT-based technologies in broadcast and live sound has been greater – and easier – integration of all systems and devices, including audio, video and data. AES67 has laid some foundations for this, which will be built on if ST2110 and the discovery and connection management protocol NMOS (Networked Open Specifications) are widely adopted. An area of audio and general production that has readily accepted IP and other new media techniques is communications. All the main intercom manufacturers now produce systems with some form of AoIP capability and continue to expand capabilities. RTS’ Omneo uses Dante for audio transport controlled by OCA (Open Control Architecture). It is also compatible with the AVB (Audio Video Bridge) open IP format.

Riedel Communications continues to develop its MediorNet system, which is designed to route and distribute programme feeds as well as intercom signals. This is now able to communicate on a broader AoIP basis through the adoption of RAVENNA/AES67.

Elsewhere in the market

Clear-Com states that it is able to work with a variety of AoIP networks. Its Intercom over IP range is based on the LQ series, which is intended to form part of a larger IP network through LANs, WANs or internet connectivity. It is also tailoring its approach for specific sectors with products such as the Agent-IC virtual IP intercom app. Simon Browne, vice president of product management at Clear-Com, says Agent-IC has potential for live events in expanding conventional two-wire party line intercoms, with wider wireless connectivity. “Recording studios could benefit from streaming bi-directional audio over the internet at 20kHz bandwidth using LQ or just linking up high quality voice bandwidth intercom between production centres,” he adds.

Something like that would probably be best suited to recording, TV or post studios within a large broadcast centre or on a media campus. The recording world in general, while recognising the need for sharing material and moving equipment such as processors and effects between different suites, is still considering its options. Studio producer and front-of-house mixer Matteo Cifelli, who works with Tom Jones and Il Divo among many others, says he has not had happy experiences with Dante. Instead he relies on custom rigs inc orporating DiGiGrid units with their own protocol.

Live sound and recording console manufacturer DiGiCo uses the SoundGrid network to connect to either DiGiGrid recording systems or SoundGrid plug-ins. All of which is based on what Austin Freshwater, general manager of DiGiCo, describes as solid connections to either PCs, Macs or SG servers. But this does not mean the company is ignoring AoIP.

“With Dante there are two implementations,” Freshwater says. “The first is an eight- channel I/O card used in the standard SD-Rack running at 96k for connection to third party equipment. This is ideal to get signals on and off the network to be managed by the console. The second is a 32-channel I/O at 96k, DMI card, which is used for larger connectivity to the network for RF mic connection or larger channel count networking. We don’t tend to use this for recording due to the channel limitation on our larger systems.” DiGiCo also has a group project looking at AES67. The first result of this is now available, which Freshwater hopes will be expanded into DMI cards in the near future.

Another recording-oriented company, Focusrite, launched the Red 8Pre last year with Dante network capability. It has also added AES67 support to its RedNet product range, with further capability for snapshot recall from MIDI programme change messages.

AoIP may not be fully established in the three branches of pro audio just yet but it is something to be considered in broadcast, live sound and recording for the future.