Audio Co Existence In The AoIP World
Spending a bit of time with sound installation people, I’m used to the acceptance of Dante as a ‘good thing’ for connecting and interfacing multiple channels of audio and exchanging control and reporting between quite disparate audio components.
Dante is a commercial realisation of audio over IP (AoIP) and it is the advantages of AoIP that is driving this positive vibe.
With traditional analogue, the install requires multiple channels of copper wiring between the stage, the control and the speaker systems. In wiring terms this is relatively costly to install, there is the potential for connections failing – how many hire companies have gone into an older venue to find duff tie lines and patch boxes? The cabling is all point-to-point and can’t be re-routed or expanded – and it doesn’t carry data.
AoIP in many forms
Roll up AoIP, here in the form of Dante, but also AVB, CobraNet, Ravenna and EtherSound. Instead of analogue audio over single cables, the audio is digitised, multiplexed and sent down Cat 5e (or above) network cables. Instead of only going where those dedicated analogue cables go and being limited to the number of wiring channels installed, AoIP can be routed anywhere and everywhere where there is an IP connection and it is no longer point-to-point.
Data – which can be control, identification and reporting information – goes down the same cable, and this opens up a whole new world of interaction between the component parts of an installation. Mic systems talk to mixing desks, which talk to processors, which talk to amplifiers which in turn talk to speaker processors – all of which can be controlled and interrogated remotely. This later facility also means that it’s possible to analyse, adjust and troubleshoot installs without necessarily needing to get on site, a potential for real savings in time and money.
Of course AoIP is not all upside. Although early technical limitations such as reliability, latency, audio quality and synchronisation have largely been resolved, overall it does carry the added cost of the networking cards, switches and controllers. Designers, installers and to a degree, owners, do need an understanding of IP, networking and some level of network fault-finding – new technologies for some, but not too tough for experienced engineers.
Audio people have gravitated to Dante as it is supported by many of the equipment manufacturers that they like to use regularly, so they are not too limited on their choice of hardware. But it is still early days and some have reservations about the industry throwing its lot in with a proprietary system controlled by a single entity – in Dante’s case, Audinate.
The arguments against a proprietary system include the cost and process of licensing or what happens if the parent company stops trading or is taken over, but also that an open standard is more likely to attract more manufacturers to implement it on more hardware.
An alternative to Dante, that has traction in the AV market, is IEEE AVB/TSN (Audio Video Bridging and Time Synchronised Networking). More commonly called AVB, this is the open standard of a range of IEEE 802 protocols to deliver audio, video and data over Ethernet. As well as the pro AV and broadcast industries, AVB is also targeting the consumer markets with multi-room systems.
Whilst the consumer world is somewhat different, take-up there will help cut hardware and implementation costs and it’s a small jump from systems that drive domestic multi-room video/audio to ones useable for commercial AV.
Interoperability issues
AVB/TSN is promoted by the AVnu Alliance, a consortium of the manufacturers who include AVB support in their systems. One of the functions of the Alliance is to certify implementations of IEEE AVB/TSN to ensure interoperability between hardware. No matter how a standard is written, different manufacturers will implement the standards in different ways, which can lead on to some incompatibilities, and the AVnu certification ensures that the AVB/TSN is properly implemented.
This does for AVB what Audinate’s licensing/approval process does for Dante – ensuring that when the systems are plugged together that they will work fully. So although this is ostensibly about audio, we are talking about the AV world. When the delivery channel doesn’t care if it’s carrying audio, data or video, the opportunity is there to combine everything down the one cable.
The broadcast world is buzzing with developments for video streams over IP and it’s being done live at 4K quality levels and with multiple streams – but at a substantial price. Developments for video is happening in both AVB and Dante, but it may take a year or two to get to the same level of performance and functionality with video as we currently have for audio.
So the future looks like it will have at least a couple of formats co-existing. There is the possibility that other protocols, such as AES67, could form a partial bridge across them, and some manufacturers will opt to be agnostic standards supporting which they see is most popular in their market or offering both options. But at least the Cat cabling infrastructure will continue to be useable whatever happens at either end.
