Article reproduced with kind permission from LINE UP Issue 103, Nov/Dec 2005
Networking Broadcast Audio
It is a well known fact that when we all talk to each other life is better: less complicated and less likely to go wrong. Fortunately for us all, this was realised by computer boffins thirty years ago and they took steps to ensure computers could do likewise.
It was in the1970’s that networking was first introduced into computing as an aid to improve productivity and cut costs. Exploited initially by using simple LAN networks, by the mid 1990’s cheap network switchers were available in your local PC shop on the high street.
Despite initially being fairly rudimentary these systems have developed over time, and now represent a very stable, very cheap and very straightforward method of sharing information across a number of technologies.
In fact, it’s all rather liberating.
As a broadcast console manufacturer, audio networking in studio facilities is something that Calrec is asked about more and more. Increasingly, manufacturers are offering a variety of networking systems which all promise greater connectivity and interactivity with digital consoles, and can all help increase your all important Return On Investment.
This is a fact not lost on those who design and operate production facilities with multiple studios and control rooms. Networking is more than just a technical solution to sharing incoming and outgoing sources – it is about giving operators and studio managers greater creativity and scope to do their jobs.
Sound sources have been shared between mixing consoles for many years, using distribution amplifiers and cable – in some cases miles and miles of cable. While this offers reliable and simple connectivity, the widespread use of digital audio routers has enabled much more elegant audio networking, with greater capacity and potential for control.
Today’s networked facilities mean that sharing inputs and outputs across any number of mixing consoles is an easy and natural process, no more complicated than plugging a mic into a stand-alone console and just as reliable.
Most networks are cheap, easy to install and very simple to understand. Some, such as Calrec’s Hydra System, use Ethernet technology and use off-the-shelf network routers and Cat 5e or Cat 6 cable.
Calrec’s solution differs from most in that we use Gigabit Ethernet fabric to provide high bandwidth, low cost, excellent resilience and enormous scalability through development of 10 gigabit technology.
It is important to resist the tendency to panic at the suggestion that broadcast audio should be subjected to the fragility of IT networking. Those familiar with the origins of Ethernet will understand that its performance is anything but deterministic - disastrous for a real-time audio system! But this is relatively simple to get around by establishing three key design principles.
The first is that audio sample delivery operates strictly at the data link layer. This means that no TCP/IP overhead is imposed. Secondly, bandwidth is entirely predictable as the network is kept private. Finally, the network is constructed in a star topology. These three principals combine to eliminate collisions and guarantee deterministic behaviour.
Put simply, that means no network hang-ups and the audio always gets to where it needs to be.
As technology evolves, your facility is under increasing financial pressure to keep pace, and effective network planning is one way in which you are able to safeguard against this.
We have been amazed by how our customers have adapted Calrec’s Hydra network to meet their needs, from simplifying installation projects to creating multi-console/multi-studio systems which can cater for any eventuality.
In fact every single one of our customers who has adopted networking has utilised it in a different way to solve different problems. The following examples illustrate several interpretations of networking by broadcasters of differing size.
1. Global Broadcast Centre, NJ, USA
Three studios, three control rooms, three digital consoles, 10 wall boxes
Calrec’s first foray into networked systems was for a custom designed global headquarters for a major US broadcaster, and we learned a lot from it.
The facility houses three studio floors: Studios A, B and C. Studio A is divided into two production areas, each of which is capable of hosting its own show. There are three Audio Control Rooms (ACR’s) each with a digital console, and seven studio wall boxes spread out amongst the studios (three in Studio A and two each in Studios B and C) which enable all three desks to access every source.
Once set up these wall boxes remain untouched so all sources are wired to the network at all times. Any desk can access any input freely, thus removing the need for set up before every broadcast.
This arrangement gives the broadcaster total flexibility. The most conventional set up is to use ACR 1 with Studio A, ACR 2 with Studio B and ACR 3 with Studio C.
However, they may want to switch from one area of Studio A to another part of Studio A (it’s a VERY big studio!) for the next programme, and for ease of setup they may decide to use a different desk. Whilst the first programme is going out to air through ACR 1, ACR 2 can use the network to work with sources from the other part of Studio A and test output levels. When the switch occurs, ACR 2 can “grab” ownership of any appropriate sources from Studio A and continue the broadcast seamlessly.
Suppose again that a special guest is common to both programmes, and is required to go into more depth in an auxiliary programme due to air on a different channel or at a later time. Wired with a radio mic he can appear on programme one through ACR 1, and then ACR 2 can grab ownership of his mic for programme 2. Then he can go straight to an audio booth to record his extended interview, as ACR 3 grabs control of his mic to record to tape….the talent does not need any further mic set-up for each location.
Furthermore, the foldback to the talent’s earpiece can be switched to follow him between ACR’s.
This kind of comprehensive network also allows for changes to existing daily routines.
For example, Studio C hosts a daily chat show using the console situated in ACR 3. However, on occasion this studio is utilised for special event programming, and this can spill over into other studios. The console in ACR 3 can easily grab all relevant sources from the network and oversee the entire production across all studios with no additional set up time.
Assuming a maximum number of 88 Mic inputs per wall-box, to install or wire in a conventional way would need 7 x 88 = 616 individual cables, or 1232 cores, or a combination of both. Networked, the same can be done with seven Cat5e cables. To make this fully redundant with a secondary cable would require two cables for each wall box…a total of 14 cables. In other words, considerably fewer cables and a lot less time putting them in!
That’s seven of 10 wall boxes accounted for. This facility has a further three wall boxes populated with AES inputs. These are located in a central machine area and allow all desks to access central sources directly without the need to use the station router.
2. Public Television Studio, MD, USA
Three studios, two control rooms, two digital consoles, three wall boxes
This station uses networking to maximise the efficiency of the station facilities. Their careful application of the technology ensures that absolutely no time, effort or equipment usage is wasted.
The system was installed in a three studio facility with two control rooms, each containing a large digital console. Each of their three studios contains a wall box. Unlike our first example, these studios are not pre-wired for all eventualities as all three studios are used in rotation for different projects. And as there is never an occasion when all three studios are in use simultaneously, the facility has no need for a third console.
However, there are frequently two studios in use at the same time. Therefore, while two of the studios are in use, the third is either being set up or taken down. When this studio is ready to go to air, either of the two audio consoles can take control of its audio sources via the network….and while this is being broadcast the unused studio is set up for its next broadcast. Equally, during election time, two studios can be opened up to form a much larger, audience friendly space that can be controlled by either of the two control rooms associated with them.
This allows for extremely efficient use of time, space and equipment.
3. Owned and Operated Local Television Station, TX, USA
One studio, one control room, one console, one wall box
This is the most straightforward system where the broadcaster simply wanted to minimise cabling whilst using a central machine room for location of all processing equipment. This area is some distance from the audio control room. The wall box in the studio runs a Cat 5e cable to the equipment room where the desk processing is located. Simple to install and easy to maintain, this is considerably cheaper and easier to install than a conventionally wired solution. It also allows for a potential second studio to be created in future that would share the central apparatus area and be easily and cheaply connected to the same audio control room.
4. Multi Studio News Network, NY, USA
Six studios, six control rooms, six consoles, six wall boxes
This installation provides the ultimate in redundancy. This facility has six control rooms assigned to their studios with their own mic boxes. The network is fully redundant – each Cat 5e cable has a secondary cable, and not one but two switches are used for belt and braces resilience!
Given this level of planning you would expect some sharing of sources, but there is barely any as each control room serves its own studio. Each console is on the network purely as a backup for everything else. As the majority of broadcasts are live, the facility’s core business is at stake, and should a problem develop in any of the control rooms production management is unwilling to waste time moving sets or talent from one studio to another. In the event of a problem, any console can grab ownership of another studio’s sources in a matter of seconds.
This example is a good illustration of how it is possible to use networking to incorporate the ultimate in redundancy. It’s like having tie-lines to multiple locations with remote gain control on inputs….giving every control room the ability to be a backup without the expense of actually having to build a spare!
5. A proposed use of network for OB use
Three trucks, three digital consoles, six mic boxes
Trucks have been using Remote Mic Boxes for years, but there are real benefits to be gleaned from using networked sources, not least purely in terms of ease of installation.
One of our US customers intends to use networks to enable flexible sharing of sources between multiple control vehicles on location using six remote mic boxes; two per unit across three trucks. They would use remote boxes for locations in the field as normal. From each Remote Mic Box up to 88 mono inputs or return sends can be sent down one length of Cat 5e cable over 90 meters. Using optical fibre, this stretches up to 10 kilometres. However, when more than one vehicle needs to access sources, any or all of the three vehicles could use any of the inputs spread across the venue site without special allocation by the host vehicle’s engineers. This removes the need for significant amounts of cable and additional hardware that currently provides inter-vehicle connectivity.
This can be very useful when covering, for example, a golf tournament, where the action-centers can be kilometres apart and there may be a number of vehicles working for different broadcasters. The system gives enormous flexibility and the network can be configured to recognise as many or as few remote source boxes as it needs.
This has obvious benefits in an OB environment when anything which streamlines set up and saves weight saves you money.
- Please note that names of individual broadcasters have been withheld as several have very specific internal rules about publicity and press coverage. Should you require more information about any of the above installations, please do not hesitate to contact me directly at kevin.emmott@calrec.com.
Article reproduced with kind permission from LINE UP Issue 103, Nov/Dec 2005