The Case for AoIP Interoperability and the Rise of AES67

By Martin Dyster on Feb 29, 2016 4:58:00 PM

Martin DysterThe global television broadcast community is poised at the brink of the next great revolution in technological advancement – audio and video over IP. The great leaps that we’ve witnessed over the last 50 years, from black and white to color, mono to stereo, analogue to digital, 4:3 to 16:9, SD to HD and from stereo to 5.1, have benefitted the viewer at home each step of the way, and has been embraced with the purchase of the latest TV or Home Cinema system. However, in the backrooms of TV stations, broadcast engineers around the world have toiled over system designs, white papers and equipment catalogues while manufacturers have raced to bring out the next best widget designed to do the job.

This latest revolution is markedly different because unlike the previous examples, it is arguably a case of the tail wagging the dog – audio and video over IP is about increased efficiency, streamlined systems ultimately designed to do the same job more simply and for less money using the enterprise network architectures that surround all our lives. The result will greatly help enable the transition from HD to UHD and from surround sound to immersive audio, but right now the result will be transparent to the viewer.  Unfortunately, the path to utopia is confused by competing protocols, diverse expert opinions and marketing spin that would embarrass even the most unscrupulous politician.

Thankfully, for those of us who inhabit the world of audio, thankfully the picture is a little clearer than that of our video-centric brethren. Network audio systems have been with us since the 1990’s and audio over IP (AoIP) since the introduction of Livewire in 2003, brought to us by Telos. Since then, over a dozen competing protocols have entered the market, each one serving a part of the pro -audio and broadcast community with their own needs, flourishing particularly in live sound, the install market and radio. TV has been surprisingly slow at embracing IP technology despite the fact that it is both proven and mature, broadcast. Broadcast television is taking baby steps and using IP connectivity as a point-to-point replacement for MADI whilst the true advantages of an IP based audio workflow seem to be hidden in plain sight.

Part of the problem undoubtedly lies in the confusion surrounding competing protocols and the fact that the customer is having to make a choice based upon the availability of compatible equipment rather than the ability to choose best-of-breed with complete impunity. This situation serves no one except for those companies who stand to profit from the license model that adopting a specific protocol fulfils. Fortunately, the will of the majority is bigger than the motive of any individual company and the. The case for interoperable AoIP standards has been gathering momentum and is now recognized in the form of the AES67 transport standard.

In a relatively short span of time, since the publication of AES67 in September 2013, an increasing number of companies have embraced the new standard with the majority of the organizations behind the competing protocols having now launched fully compliant solutions. Many product manufacturers have already proven their compliance at either of the two annual interoperability sessions called ‘Plugfest’, run in December 2014 and November 2015 respectively, on either side of the Atlantic. Now, with an ever increasing number of manufacturers recognizing the need for interoperability and the message behind the advantages of AoIP becoming clearer, the interoperability standard seems to have reached critical mass. It s not only gaining momentum on the audio side of the production chain; several key companies whose interest in IP is focused more on the video side are also recognizing it as the logical method of audio transport for use where audio and video signals are tied. The Alliance for Media Solutions (AIMS)—a not-for-profit trade organization founded by leading companies to foster the adoption of industry standards for the broadcast and media industry as it transitions from SDI to IP—sees the interoperability standard as the most technically viable and industry endorsed standard to be used to transport audio paired with video. This ringing endorsement from the video side of the TV broadcast workflow further shows why users should now invest in AES67 technologies.

The AES deliberately avoided mandating either a control or discovery mechanism when publishing the standard allowing manufacturers to develop their own bespoke methods whilst maintaining the ability to interconnect with any audio stream. The fact that the standard uses SIP for connection management however means that routing can be controlled without the need for discovery, providing the stream addresses are known. This means that a dynamically switched audio routing system can easily be constructed using AES67-compatible equipment with frame accurate switching achieved when using a system-wide PTP clock. In essence, everything that can be done now using an expensive baseband routing infrastructure can be replicated across a managed network, including the mapping of an IP router layer alongside an SDI video matrix. This capability can help to smooth the transition to a video and audio IP world by enabling the designer to adopt an AoIP system that will still be state-of-the-art when Video over IP catches up.  

AES67 helps to bring us one step closer to unleashing the power of an all-IP audio and video infrastructure. AoIP has the potential to bring converging subsystems that would otherwise have remained separate, together. By bringing together telecommunications, intercom, in-studio audio and external audio into one system, users dramatically decrease the number of physical interconnections, cabling, patching, routing, distribution and terminal hardware. The emergence of agnostic IP stream control and routing makes the management of IP audio simple and coherent. No longer are contribution and communication feeds tied up to their own matrix, nor does program audio need to be routed independently for both on-air and in-studio feeds. Access becomes open and devolved and the concepts of role-specific signal paths are flattened. Everything is just “audio”—low-latency, program-quality, 24-bit multi-channel sound.



Topics: AES67, Audio over IP, AoIP for Television

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