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Frequently Asked Questions About IP-Audio Networks

With more than 600 installed studios (and more in the works), there’s a lot of talk about Axia these days — a lot of it from our competitors!

You know how it goes... when there's something new on the scene that challenges the old order, there is a lot of labored huffing and puffing as some people dependent on the old way get desperate to hold back the advancing tide. Telos' founder, Steve Church, said it 20 years ago in the Telos 10 manual: The first reaction to a fresh idea from the guys who are threatened is some variation of “it won't work.” The next phases are grudging acceptance in the face of the evidence, and finally, copying the innovation as they see it succeed in the marketplace. It seems like Axia is just now in the late first phase, with some quite creative variations on “it won't work” being thrown around. We thought you’d appreciate some straight talk to clear the air about some of the things being tossed around.

Topics:

“I’ve been told that with Axia, latency increases whenever you add inputs. The more sources you add, the higher the delay.”

No, Livewire's latency remains fixed at the same low value regardless of the channel count. You can run a system with a thousand channels and the latency will be the same as for a single stereo stream. Indeed, the delay is so consistent that channel-to-channel phase shift is less than 1/4 sample.

The total latency of an analog input to analog output using the Axia Livestream format is about 2.75 milliseconds:

  • The time through the A/D and D/A converters is about 1.5 ms.

  • The network transit time is 1.25 ms.

To put this into perspective, the analog input to output latency on a self-contained BMX-Digital is about 1.75 milliseconds.

The backplane of a modern Ethernet switch can handle full duplex traffic on all ports simultaneously without any packet loss. And since Axia component links are designed so that they never exceed any port's capacity, we never exceed the switch capacity. The way we prevent port overload is simple: we “own” each port. Every Axia audio node is plugged into an unshared 100Base-T port on the switch. Even when all of a node’s inputs and outputs are active, we are still well under the bandwidth of the ports, and the switch is completely under control. Because the switch has the backplane capacity to handle all ports fully loaded, the system performance doesn’t change from one to thousands of audio channels.

Let's explore the issue of switch capacity a little further. We know how much capacity is required per port for each node, and we know that a node will never produce or consume more than 16 stereo streams total. But what about the mix engine? To support a large console with a lot of buses, inputs, mix-minus outputs, etc., you may have 40 or 50 simultaneous signals (or more). Because this could exceed the port capacity of a 100Base-T port, the mix engine is connected via Gigabit Ethernet only. Using Gigabit for the engine, we could support a 200 fader console with 200 outputs and still have room to spare! Each console's mixing engine gets its own Gigabit port.

“The other guys say Axia consoles don’t have all the features they have. Like voice processing.”

Sure we do. Voice dynamics is a standard feature on all Axia consoles — and it was developed by Omnia's Frank Foti, who knows a little something about audio dynamics processing. Other standard features include per-source EQ and panning, headphone EQ and a one-touch off-air recording function, all of which can be set and saved to instantly recall each jock’s favorite settings. The Element console features four stereo program buses, and four stereo aux sends with two stereo aux returns for off-air production.

Element also does things that no other console can do. For example, you can connect the latest Telos broadcast phone systems with one RJ-45 — all audio I/O for four hybrids plus line-selection control from a tightly integrated drop-in panel enter the system using one skinny Ethernet cable. It has optional dynamics processing on the headphones. It has a one-touch record-mode button for recording phone bits. It has a powerful system that lets you set, save and recall events and personal preferences for each jock. A clock that can be synched to NTP network time. A motor fader option. Add our Pathfinder routing control package, and you get extensive user-programmable event handling, built-in silence-sense that automatically switches to a backup audio feed, interactive on-screen virtual control panels for studio PCs, and much more.

“One of your competitors says that you'll have to replace the Ethernet switches every 3 – 4 years. And when you do, you'll have to load all new software to work with it (if you can even make your stuff work with it).”

Ethernet is a standard, IEEE 802.3. Axia gear works with any switch or router that supports the standard. We do generally need higher-end switches because Livewire uses advanced multicast and Quality-of-Service features that are not included in low-end switches.

You might want to upgrade to a larger or more powerful switch for some reason in the future; for example, if you were to add more studios to a cluster. Or maybe you would like to change from copper to fiber for some kind of remote uplink connection. Or you might want to replace an older switch at some point. Thanks to IEEE 802.3, the replacement switch would simply plug into the network and function, with no software changes needed on any equipment. But there is certainly no requirement to do this at any particular time interval. Ethernet's open and evolving nature gives you choices that closed systems don't. That's an advantage.

“I’ve heard that switch standards are pushed by Microsoft and the PC industry, and they change all the time. Won't I have the risk of my Axia equipment becoming obsolete?”

Not to belabor this point, but Ethernet standards are supervised by the IEEE (Institute of Electrical and Electronics Engineers), a non-profit group that takes input from a quite large number of interested parties. Ethernet switches are always getting faster and having new features to make networks more capable, robust, reliable and flexible. But these new features don’t obsolete other equipment. Think about it: if you buy a new switch for your computer network, do you have to throw out your old PCs? Of course not.

“They also say that Axia networks only work with one switch, and if they stop making that switch, I won't be able to expand or modify my network.”

Axia has qualified several different switches from well-known manufacturers such as Cisco, Allied Telesyn, and Hewlett-Packard, to suit the needs of different-sized installations. We are not tied to a particular switch or manufacturer. Indeed, as time goes on, we find more switches that include the features we need.

Ethernet has been around for more than 30 years. It is supported by hundreds of vendors. It continues to evolve to be faster and more powerful, to use different connection media, etc., but backward compatibility is always maintained.

“Your competition says that you have to be an IT expert to run an Axia system.”

We’re engineers, and we like to talk tech. Sometimes, we talk about the tech more than we need to! But in this respect, an IP-Audio network is like a car: you don't have to understand how the engine works in order to drive it. Just connect two pieces of gear together with CAT-5e and they will talk to each other — like plugging a mic into a mixer. The Livewire protocol takes care of routing the audio without any need for intervention from you. And the equipment interface is all web-based with GUI control. It works intuitively, and you don't have to know anything about the tech inside to make it work.

That having been said, another of the advantages of Ethernet and IP is that bookshop shelves are full of well-written books that can explain any aspect of standards-based networking at any level of detail you might want.

“What about network collisions? Isn't Ethernet going to drop audio packets?”

Years ago, Ethernet used a shared coax cable. In rare cases two devices would grab the bus simultaneously. When this happened, one would back-off and send a few milliseconds later. These were the famous collisions. But With today's switched Ethernet, there is no shared bus – each device completely owns its own full-duplex link. There are never collisions or lost packets as a result of network congestion; it’s physically impossible.

“How do I know that Audio over IP will be reliable? It's new, unproven technology.”

Axia uses the same technology that underlies VoIP telephony. Did you know that over half of the Fortune 100 companies now use VoIP? Or that VoIP PBX systems now outsell the old kind by a wide margin? With these systems, telephones plug into a standard Ethernet/IP network. Contrast this with traditional PBX phone gear — proprietary devices which required you to purchase phone sets and parts exclusively from the company that built the mainframe. You were locked into a single vendor, because the technology that ran the mainframe was owned by the company that made the gear. (Kind of like the TDM router companies.)

IP is growing as a universal transport for almost any kind of signal. You see it now in television studios, business teleconferencing, government communications, banking, etc. And it's hardly unproven, even for applications specific to radio studio infrastructure. There are plenty of people successfully using it – now.

“What about Program Associated Data? Is your system compatible?”

Yes. Devices that generate PAD plug into the Axia network; the information they supply is sent along with its associated audio, and any devices that need it can also plug into the network and retrieve it. This means that you can send audio and PAD together, without incurring extra costs for separate audio and data networks.

“Does your system route logic with audio, too?”

Of course. IP is great for data, no? Logic commands from external devices like CD players, DAT machines, etc., enter the network using GPIO Nodes. The logic data is then “bound” to the audio stream, and is routed with it to whatever console the source is loaded on.

Devices equipped with Livewire interfaces (like the latest Telos Zephyrs and phone hybrids, Omnia audio processors and IDC satellite receivers, for example) supply audio and control logic directly from the device to the Ethernet switch over a single CAT-5e connection, further simplifying in-studio wiring and making Livewire’s audio+logic routing even more convenient.

“I wouldn’t use IP-Audio, because I don’t want compressed audio in my studios.”

Livewire is not compressed. Axia networks carry linear, 48 kHz, 24-bit studio-grade audio, and there are switches that have enough bandwidth to carry 10,000+ channels of uncompressed, real-time stereo audio simultaneously.

“If IP-Audio is uncompressed, I guess I can't use it for STL, because that's always compressed.”

Sure you can, using Ethernet radios like BE’s Big Pipe. These line-of-sight radios (and others like them) are capable of data rates of 45 Mbps — enough for several channels of uncompressed audio in each direction. On the other hand, if you want a compressed link, the latest generation Telos Zephyr can do that for you. It takes Livewire audio in, generates a compressed IP stream, then delivers it back again to another Livewire network or to traditional analog or AES devices.

“So what is the best audio format to use with Axia systems?”

Axia networks don't care what format your music files are stored in. During the playout process, your playout software will uncompress any compressed-format files (MP3, MP2, apt-x, etc.) and present them to the Axia IP-Audio Driver. What this means is that all audio that moves within the Axia system is the same - uncompressed.

So, the question really becomes, what audio format is best for your storage needs, your convenience, and the desired audio quality you want to have on-air. Our feeling, since large capacity hard drives are very cheap nowadays, is that it's better to store all audio in a linear fashion, as the resultant audio quality will be higher, especially after any audio processing.

“I know Axia a new division of Telos. It looks interesting, but I'll wait until you've got some stuff in the field.”

Actually, as of this writing (October, 2007), there are already 600 installed studios worth of Axia equipment. The adoption curve is turning sharply upward, so by the time you read this, there are likely to be many more. There are many other people using Axia gear for non-studio applications like fiber or microwave links. Some have built routing switchers.

“Are those customers happy?”

Very! Axia systems are faster to install than traditional routing setups, work reliably and are easy to reconfigure. Why not talk to the people actually using it and see what they have to say? We’ll be happy to provide you with a list of references upon request.

“I wouldn’t buy Axia consoles; I want modular boards.”

Our Element console is modular. Element modules contain groups of four faders, which are easily accessed for service by removing just two screws and a cable or two. They’re hot-swappable, too – since all the mixing is done away from the board, in the StudioEngine, you can even take out a module while it’s on the air without affecting the audio in any way. Indeed, you can hot-swap the entire console without disrupting audio.

“What happens if I need to replace an on/off switch? Do I have to send the whole module back to the factory?”

Element components are made to stand up to even the most heavy-handed jocks. For instance, we use switches designed for avionics, and rated for long life. We even designed our our own buttons and protective bezels specifically to prevent switch element damage from abuse.

Of course, we realize that all equipment requires maintenance eventually, so Element modules are made to be serviced easily in the field. On/off switches, for instance, can be individually replaced, as can individual faders. And since actual audio mixing is done outside the console, in the Axia StudioEngine, you can actually pull a module while it's on-air without disrupting any audio streams controlled by its faders.

“What does Telos know about console design, anyway?”

Quite a lot, actually. Axia President Mike Dosch, the man who designed PR&E’s Radiomixer console, also designed Element. We’ve got the biggest R&D department in the broadcast industry, and it’s filled with folks who’ve spent years around consoles, figuring out what works and what doesn’t. We have over a dozen ex-broadcasters on our staff, by the way. It's fair to say we know our way around faders and buses.

“I've heard that your consoles are good at mix-minus. What's so different about the way you do it?”

We’re part of Telos, so as you might imagine, we’ve studied mix-minus for a long time. And we’ve always been amazed at how complicated and confusing it is to set up correctly. With today’s radio shows relying heavily on phones and remotes, something needed to be done.

Our Element consoles generate mix-minuses automatically, on-the-fly, without any intervention needed from talent. The way it works is simple: when a caller is on the air, he hears the main Program feed, minus himself. When off the air, he hears a special “off-line” phone mix that can contain audio sources: pre-fader audio from the host mic, other phone callers, etc.

Best of all, mix-minus settings for audio sources such as phone hybrids and remote codecs are assigned to the source itself, not the console fader — so when a source that needs a mix-minus is loaded onto any fader, on any console, the mix-minus settings are automatically loaded too.
At the physical level, mix-minus is easy, too. Livewire carries audio in both directions, so one RJ-45 covers everything.

“How many mix-minuses can your consoles have?”

One for every fader! There’s a lot of processing power in our StudioEngines, enough that Axia consoles can provide automatic mix-minuses simultaneously for every fader on the console. You’ll probably never need to have 40 mix-minuses running at once, but isn’t it nice to know that you could?

“I just need a router — I don't need consoles.”

No problem. Axia networks can work with your existing consoles. Just plug the inputs and outputs into our audio nodes — and use Router Selector nodes to control X-Y switching functions. For sophisticated systems, use our Pathfinder router control software package. You can do everything any other router can do – and much more.

“A friend in the PA business told me about Cobranet. That's something like Livewire, right?”

Cobranet was not developed for broadcast use, which demands very low latency in the DJ-to-headphones path. Cobranet is much higher latency than Livewire, making trouble for live listening. It also will not allow non-audio traffic on the links — an important consideration for broadcasters who wish to have machine control, PAD, RDS, etc. integrated within their facility.

There are also limits to the number of audio sources Cobranet can handle. Cobranet groups audio channels into “bundles” (which are packets), 8 mono audio channels per bundle. According to the Cobranet website, there is a systemwide network limit of 8 bundles. 8 bundles x 8 channels = a 64-channel limit, whereas IP-Audio networks using the Livewire protocol can handle upwards of 10,000 stereo streams.

Cobranet is not IP Audio, since it works only at the Ethernet level. Axia networks use state-of-the-art IGMP (Internet Group Management Protocol) to manage the transmission of Multicast audio streams, which allow multiple subscribers to receive and use audio from the same origination point. IGMP also makes it possible to dynamically add and subtract subscribers from a stream. Cobranet does not use IGMP; users must map out individual point-to¬-point connections with Unicast IP addressing. If more than one destination wants to listen to a given source, the source has to send multiple copies of the stream, which then hits Cobranet’s limit of 8 streams coming from any given source. You could choose to send audio as Multicast IP data to all points on the network, but with 8 bundles of channels active, all 100Base-T links everywhere in the system would be at full capacity. These limitations make Cobranet unsuitable for broadcast audio networks.

“I've heard that Axia costs half as much as the other guys. What did you leave out?”

Nothing. Our cost savings compared to traditional routers are achieved by using standard, off-the-shelf switching hardware rather than custom-built solutions. It’s a lot less expensive to use a mass-produced Ethernet switch available from any network vendor than it is to construct a customized cross-point routing switcher, with its cards, frame and peripherals. This is the same principle that has driven almost all stations to use PCs for audio playout and editing – they are a lot cheaper and more powerful than any broadcast-industry specific machine could be.

Another way Axia saves money lies in the way PC audio is handled. With a traditional router, PC audio must be brought in through a router input card or console module; bringing multiple channels of audio into the system in this manner (from workstations or digital delivery systems) can significantly increase the overall cost of the system.

Instead, we wrote an IP-Audio Driver for Windows PCs that looks just like a sound card to the OS, but streams audio in and out of the computer’s network card instead. Or, if you need the realtime MPEG compression or time compression features of a high-end sound card, our partner Audioscience makes an audio card with a Livewire output that plugs directly into the Axia network. Either of these approaches eliminates the cost of the I/O needed to get audio into the switching network. So Axia clients usually realize several thousand dollars worth of savings over and above the cost of the sound cards themselves.

“Those other guys say they’re just the same as you. After all, you all do audio over CAT-5.”

We all use Category cable, but that’s where the similarity stops. Axia IP-Audio networks are standards-based, adhering to Internationally-recognized Ethernet standards. Using a standard is much different than using a proprietary protocol with CAT-5. This standard makes it possible for any broadcast equipment or software vendor to interface directly with Axia networks.

Here’s a list of companies that make products using the Livewire standard to connect directly with IP-Audio networks. (Ask the other guys what products connect to them directly, without using a proprietary interface or breakout box.)

  • 25/Seven Systems

  • Audioscience, Inc.

  • Broadcast Electronics

  • BSI

  • D.A.V.I.D. Systems

  • Digispot

  • dMarc / Google / Scott Studios

  • ENCO Systems

  • Fraunhofer IIS

  • International Datacasting (IDC)

  • Netia

  • Omnia Audio

  • OMT Technologies / iMediaTouch

  • Pristine Systems

  • Prophet Systems Innovations

  • Radio Systems

  • Synadyn

  • Telos Systems

  • Zenon Media

“If my favorite delivery system isn’t on your list of partners, can I still use my system with Axia?”

Yes, the same way you do it now: just plug the delivery system’s outputs into our inputs, and send the contact closures into our GPIO nodes. (Then ask your delivery system provider when they’re going to become an Axia partner!)

“Another router/switcher company says their system is better than the Axia standard, since they're more efficient with their bandwidth.”

Why is this at all relevant? Sure, Ethernet/IP packets have overhead from the required headers. But the capacity of the Ethernet links and switches is plenty high enough to handle all that is needed. So this makes no difference in practical use and is never seen by the user.

“I’ve heard that I have to use CAT-6 to connect everything. That could get pricey.”

CAT-6 is used for only two heavy-traffic network segments: connecting Axia mixing engines to Ethernet switches, and connecting switches to each other. All other equipment is connected with common, inexpensive CAT-5e cable.

“What happens if someone accidentally unplugs a cable? What then?”

Axia audio nodes “advertise” the presence of their audio streams to the entire Livewire network. So if someone unplugs a node, the sources attached to it will be offline. But all you have to do is plug that node back in, and the node will “advertise” that the audio streams are available again. Within 10 seconds, all destinations that need those sources will be back up and running.

Additionally, among the many features of Pathfinder is a silence detect function that can be programmed to switch to another feed should one stop working for any reason.

“I’ve heard that there's a PC inside your nodes. I don't want to trust all my audio to a PC.”

No, Axia audio nodes do not have a PC inside them. They are "embedded" designs.

Our mixing engine, on the other hand, does. These days, Intel processors and motherboards are the best way to get tremendous power at low cost. But we are using these as if they were embedded DSP processors. There are none of the components that cause problems in PCs, like hard drives or general purpose operating systems. The software core is a special high-reliability real-time Linux variant that is dedicated only to the mixing application. Our engineers designed the engine for bulletproof, 24/7 reliability.

“Your competitors say that your networks can catch viruses. Is this true?”

There are no general purpose operating systems in Axia devices, so the answer is “No.” You can keep computers attached to your Livewire audio network safe by keeping it isolated from data networks.

“Do Axia networks have any single points of failure? Is there a central ‘brain’ I can lose that will take the system down?”

Axia networks are distributed, with no central box. Ethernet networks can be designed any number of ways, including those that are fully-redundant and self-healing. Normally, our clients build larger facilities with “edge switches” serving each studio, connected to a redundant core. Each studio is able to operate stand-alone.

“Is Axia more expensive to install than traditional routing systems?”

In fact, Axia costs lots less to install, because everything in an Axia network connects using off-the-shelf Ethernet cables, which carry multiple uncompressed channels of stereo audio. 100Base-T links can carry 25 audio channels simultaneously; Gigabit links can handle 250. The money saved just from the elimination of expensive multi-pair cable for studio interconnects can be significant.

Even our audio connectors are designed to promote fast, inexpensive installation. All of our Audio Nodes use the Radio Systems StudioHub+ RJ-45 standard for I/O jacks (except for mics, which use standard XLR connectors); a huge variety of adapters are available from Radio Systems for all kinds of devices. Tally up the savings in labor realized from not having to purchase and hand-solder hundreds of XLR and RCA connectors, and the money saved becomes even more impressive.

There’s considerable time saved during Axia installations as well. Due to the reduction of cabling and the quick connection of devices, our clients tell us that installation of Axia networks goes 30% to 50% quicker than wiring studios the traditional way.

“Most companies recommend that I bring them on-site to help install and configure their systems. Do I need your help to install an Axia system?”

With those other guys, you'd better hire their systems engineers. With us, it's much easier! While we’re happy to come and help commission your new Axia network, it’s not necessary. If you know how to use a Web browser and plug a telephone into the wall, you’ve got all the skills needed to install and configure your new Axia network. And Axia Technical Support is there to help if you need it, too.

If you do decide you’d like on-site installation services, let us know . We’ll be happy to talk with you about it.

 
 

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