NEWS ANALYSIS
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The Missing Link?
As the new AES67 standard for interoperability of networked/streaming audio over IP is published, Kevin Hilton looks at how the broadcast market is responding.
SOMETIMES THE market decides the viability of a technology before standardisation organisations get round to agreeing on conformity and guidelines. So the publication in September of the new AES67 standard for interoperability of networked/streaming audio over IP can be seen as just further institutional recognition for a technology that was already becoming established in broadcasting for distributing material. Audio over IP (AoIP) first made itself felt in radio for contribs, distribution, and then transmission, while, in parallel about 10 years ago, intercom developers were looking at it for inter-studio and location communications. As with anything derived from a non-broadcast technology there was resistance from some quarters of the engineering community to both developments, with concern over sound quality and latency. This last point is perhaps the more
critical; any delay on a link could adversely affect the smooth running of a production, particularly for intercom messages between the director of a show and the crew. In the announcement of its new AoIP interoperability standard, the AES recognises that latencies lower than 10 milliseconds can be attained on modern high-performance media networks, which also have the capacity to carry professional quality audio at 16 bit/44.1kHz and higher. AES67 is not designed to establish
a new format for AoIP but instead provide “an interoperable subset of existing technologies”. The specification for AES67 contains “comprehensive interoperability
recommendations in the areas of synchronization, media clock identification, network transport, encoding and streaming, session description, and connection management”. While IP is now a major
consideration in studio routing, intercom, and distribution applications, audio contribution over IP (ACIP) for radio has been the sector most willing to embrace the new ways. It is now fertile ground for the development of systems and techniques that allow journalists to report live from the scene of a story or file a report for later broadcast; and for contributors and commentators to link to the studio. Dutch software developer Technica
Del Arte was an early advocate of AoIP for contributions. The company developed the Luci Live app for PCs and smartphones that has been adopted by many European broadcasters, including the BBC’s speech and news networks. A defining moment for Luci Live – and by extension AoIP – was when BBC Radio 5 Live reporter Nick Garnett used it to broadcast on location during the 2011 riots in Salford. The local radio car had been attacked and was out of action but, to any casual observer, Garnett was just a man talking into his iPhone, not a journalist reporting from the scene. AoIP is succeeding ISDN and
hardware codecs as the contributions and links technology of choice for radio broadcasters. ISDN, which itself took over from expensive booked lines and permanent circuits, is now being phased out in many countries, further pushing the uptake of AoIP. Luci Live uses network standards such as RTP (Real-time Transport Protocol), which Technica Del Arte founder and chief executive Joost Bloemen calls a “very available” worldwide standard. Bloemen’s vision of the future is a network of servers supporting AoIP connections with no need for cabled lines. During IBC2013 UK codec and
Glensound Electronics’ GS-GC5 USB incorporating Luci Live was launched at IBC2013
18 November 2013
commentary system manufacturer Glensound Electronics introduced a new product that incorporates Luci Live. The GS-GC5 USB is a four-
Technica Del Arte developed the Luci Live app for PCs and smartphones
“Few people would say that AoIP as it is today delivers the highest possible audio quality; the thinking is that in high- pressure live news situations listeners will accept it as part of the immediacy.” Kevin Hilton
channel commentary mixer that adds IP connectivity to the now expected choice of MP2, AAC, AAC-HE, G711, and G722. Glensound had been considering the move into IP for some time but eventually decided not to develop its own codec for the technology but instead design a hardware interface that would be familiar to commentators for setting up AoIP connections. Also at IBC Luci Live was
demonstrated with video capability and this dual medium approach now seems to be the way forward. Another take on AoIP/IP video contributions is the Remote Contribution Terminal (RCT), developed by UK company IN:Quality Media. This uses IP DTL (down the line), based on a vLine connection, which in turn is hosted using WebRTC (web real-time communication), the Google- developed open source communications technology. Google Chrome browsers are used by both the radio or TV studio and the contributor
for control and user interfacing, with the overall combination creating what the developer says is a low-cost and easy-to-use system. IN:Quality director Kevin Leach, who is also a broadcaster and software designer, comments that there is a growth in demand for getting live guests on air for radio and TV when people are not able to get to studios and when other connections – satellite or ISDN – would stretch the production budget. RCT is already being used by the
BBC, Sky, and Al Jazeera for both audio-only and video contribs. It was recognised at last month’s Radio Academy Festival TechCon where it won the Technical Innovation Award. Accepting the prize, Leach said many people insisted on referring to the AoIP system as ISDN but said that was “fine”. Few people would say that AoIP as it is today delivers the highest possible audio quality; the thinking is that in high-pressure live news situations listeners will accept it as part of the immediacy. In other circumstances they can be less forgiving. During TechCon a delegate remarked that BBC Radio 4 listeners were often complaining about connections dropping out in the middle of an interview or contribution. That is something which needs
addressing before AoIP can be fully accepted but it is worth bearing in mind that in its early days ISDN was seen as lower quality and prone to cutting out at inopportune moments. Acceptance is hard won but it does come.
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