Audio Everywhere provides Wi-Fi Audio in sports bars and similar locations. Recently, we surveyed the techniques of the companion challenge of video distribution, and were surprised by the diversity of techniques and equipment available. Here’s a discussion of some of the pros and cons of each method.
There are some basics. While there are exceptions to everything, generally there are one or two RF (radio frequency) signals coming into the establishment from a satellite antenna or cable. These media bring in hundreds of channels on a coaxial cable. Inside the venue there are from one to more than 100 TVs, all of which need to be within the sight lines of customers.
TV technology today is dominated by LCD displays, though OLED TVs, with their generally better black levels, are coming down in price. They are stunning.
The challenge is getting the signal from wherever it enters the venue to the correct TV. There are myriad technologies to help you do this.
We will break down the material below into two sections. In the first we illustrate five “typical” cases to get a sense of the approaches available. In the second section we attempt to generalize what we saw in the examples to fill out the structure of possibilities and examine the pros and cons of various approaches.
Here are our five canonical examples. In the diagrams we use the convention of blue for video, red for audio, and green for control.
For all of these cases we will, naturally, assume that the audio goes to an Audio Everywhere stream-audio-to-smart-phones-over-WiFi system. Audio over the PA (public address) system is typically sourced just from one main TV tuned to the channel one wants to put over the PA—for example, the home team game.
We will discuss possible vendors just to get you started. We have not vetted them and, besides, offerings change all the time. Caveat emptor.
Starting simple: A receiver behind each TV
Figure 1 illustrates running the RF (radio frequency) cable to each TV location.
For this example we assume one source, e.g., a satellite receiver, though it could clearly be generalized to multiple sources, e.g., COMCAST and DirecTV. Splitters (formally, “directional couplers”) pull the signal off the cable. The splitters can be in series, as shown, or formed in some sort of tree topology that branches from the trunk (input) to the TVs (leaves)—it doesn’t matter as long as minimum RF signal levels are preserved.
Rather than go directly into the TV or video display, the signals go into specialized receivers. The reason: the content that one generally wants to show in a sports bar is copy protected and requires a decoder, which is part of the receiver.
Since the receivers are close to the TV in this example, it is easy to run a short HDMI cable to the TV, which allows the highest quality image. Channels are changed on the receiver, not on the TV, which is tuned to an input such as “HDMI-1” and not changed.
It is common in sports bars with multiple rooms to see two TVs mounted nearly back-to-back and driven from one receiver. This requires an HDMI splitter, which, unfortunately, introduces the topic of HDCP, High resolution Digital Content Protection. HDCP is designed to “protect” the higher resolution content going over HDMI and prevent its use in ways which conflict with the license. HDCP issues plagues many installations. If your splitters and HDMI baluns or extenders do not seem to work, HDCP is your most likely problem. For this reason make sure to test any system that uses HDMI carefully at all resolutions you will use.
Since there is no central point where all the audio sources are easily accessible, the audio must be brought back from the TVs to the venue audio server. The best place to gather the audio is from the receivers, which usually have those red and white RCA analog line-out connectors. If the length back from the TV to the Audio Everywhere venue server is less than about 10 meters, it is easy just to use shielded audio wire to bring the sound back to the location with the Audio Everywhere appliance. For longer runs, it is better to use audio baluns to create balanced signals. Baluns are transformers that convert a signal in which one wire voltage goes up and down into a balanced signal on a pair of wires where when one voltage goes up the other voltage goes down by the same amount. This has the huge advantage that it has much higher immunity to noise sources such as motors, fluorescent lights, and so forth because those sources tend to affect both wires equally and can be cancelled out by a differential receiver in or near the Audio Everywhere system that subtracts the plus and minus signal voltages. Since mono is fine for sports bar content, a summing balun at the TV end does the trick. This is discussed in detail in our blog. This will work in even a mammoth establishment.
The key advantage of this system is simplicity and the robustness that comes with simplicity. One disadvantage is the requirement to have wait staff running around trying to point the remote control at (only) the correct receiver, which can be somewhat hidden behind the TV and also finding the right channel. In some cases the channel-changer must be part contortionist. The other disadvantage is that 25 TVs running 8 different channels generally requires 25 receivers, each of which has a monthly charge.
Using a multi-input receiver
In the last example, we needed to have a receiver at each TV in order to decode the protected cable or satellite signals. Several vendors provide systems that will decode the signals, and then output them on a coaxial cable in a way that can be received by a basic TV. Essentially this special device allows you to have your own simple, private cable network in your establishment. For instance, to see eight stations at a time the converter would take the hundreds of protected channels off the cable input and output eight channels as selected by the bar. These become, for instance, new channels 1, 2, 3, 4, 5, 6, 7, 8. Tune the TV to one of those channels and you see one of eight that were selected from the hundreds that were available. Here is a diagram to make it clearer. There are special sports-bar oriented TV guides to make this process easier, e.g., SBMX
Control is split into two places. First, one selects which eight of the hundreds of input channels one wants to transmit on your private local cable network and second, for each TV, you select which one of the eight to watch on that specific TV. Both are changeable.
Both ZeeVee and TechniColor offer such systems. The multi-input receivers have slots for the decoder cards for, for instance, DirecTV so that they are decrypted at the head end. Audio is done in the same way as in the last example.
A very common physical architecture consists of satellite or cable or both feeds coming into a common area where they are fanned out to a rack of receivers. Below we show this for both a COMCAST feed and a DirecTV feed fanning out to four receivers (one COMCAST and three DirecTV). The HDMI signal must be converted to a different electrical format that will carry the signal a long distance with a device sometimes called HDMI “baluns” or “extenders.” Unfortunately, this “balun” is a transformer in a very different sense than the audio baluns mentioned above, but goes by the same name.
The challenge with this physical architecture is that one cannot successfully run HDMI very far. Thus one has to convert it to something else. There are many options here from composite video (please don’t) to component video to video over IP to lossless HDbaseT to even SVD (serial digital video) as used by the broadcast industry. Note that SVD is run over coax, e.g., RG6, while DHbaseT is typically run over CAT6. Component video over CAT6 is a cost-effective solution for sports bars that don’t need the very highest resolution. Analog solutions tend to be pretty robust. A key question for the venue is, how much resolution do you really need?
Here we show converting from HDMI to Video on CAT6 and then back again. There still seems to be a lot of black art in this as some HDMI baluns are robust while others occasionally lock up and need to be reset—not something anyone wants to deal with. Most practitioners test several parts and vendors and select one or two to use in all their installations. Even the run from the HDMI balun to the TV over HDMI can be quite sensitive to cable brand and length. But digital is now the highest quality transport mechanism and always must be considered. It gets better and cheaper every year.
By the way, don’t forget that one must get power to the baluns near the TVs and this is an example of a place where POE, Power Over Ethernet, is super useful. HDbaseT also has a remote power feature.
One of the advantages of this approach is that one only needs one receiver for each channel one wants to show. A typical US sports bar needs at least eight receivers (one for each simultaneous NFL football game broadcast in the Fall). Most sports bars run between eight and 16 receivers, though we have seen cases of many more. Though not everyone will agree, there are other things other than NFL football. A casino we work with has up to 32 different channels running simultaneously.
This architecture is particularly easy for Audio Everywhere since one can put the Audio Everywhere venue server in the same rack as the receivers. The runs are short, so no need for audio baluns on the audio wires. Note that the latency through the video system is very brand dependent, from 15 ms to 500 ms. Generally it is stable, whatever it is, so the adjustable delay function in the Audio Everywhere system can used to null it out.
For control, one can use any number of controllers from Control4 to AMX and Crestron. At the very least, an RF controller such as those offered by Home Theater should be used. There are also specialized controllers, e.g., DirecTV has one that runs on an iPad and will control and DirecTV box on the local area network. Some people offer IR (infrared signal) receivers for control in the HDMI balun near the TVs that can be used to control the receivers at the head-end.
Generalizing the previous case, we can put a video matrix (matrixes up to about 16x16 are practical) or gigabit Ethernet switch between the receivers and the TVs for ultimate flexibility. The Ethernet switching method is a relatively new thing, but definitely seems aligned with the future.
Here we represent how advanced functions such as tiling TVs together to form larger images can be accomplished. See, for instance, products from Just Add Power. Key Digital is a big proponent of HDbaseT vs video over IP solutions and they make their arguments here.
Of course these systems, and the ones in the previous example, can be used to allow one receiver to drive multiple TVs. The challenge here is HDCP, which limits the number of displays which can be connected to a given source. HDCP relies on cryptography, with all that involves, including users breaking the codes. The Wikipedia entry for HDCP dwells on these aspects. For us, what matters is that, in the real world, HDCP splitters often have problems and when one HDMI device extends the signal to others, it must generate crypto keys. When it all works well it is more or less invisible.
Basic question: are there physical numbers on the TVs? The usual answer is “yes” but the matrix or switch can scramble things quite a bit. The ZeeVee units have a nice feature where they can be programmed to put a ghost image or watermark on a corner of the TV screen that lets the viewer know what source is being used. We have seen other systems with LED signs driven from the controller.
SportsbarTV has a cute system where their controller can throw any program onto any TV. Thus a patron sitting near TV4 can say, “Hey, can we have the game playing over there on TV17 also playing over here on TV4?” and a couple of taps on an iPad and the deed is done.
Video over IP
Video over IP is the new new thing in video distribution and it is aligned with the future. See the article by Zee Vee. Video over IP can be a proprietary format or a standard. As is usual in the evolution of technology, the proprietary formats come first and are eventually supplanted by standards-based solutions. The two standards fighting it out these days are HDbaseT over IP and Software Defined Video over Ethernet. The key enabling technology is 10 Gbit Ethernet, which allows even 4K video (the highest resolution TVs commercially available today) to be carried without compression. Video over IP works even for 1000baseT (Gigabit) Ethernet, but one must compress High Definition video to make it fit.
Video over IP’s attraction is that it uses standard networking components for much of the heavy lifting and, as we know, these prices push inexorably lower. Video over IP uses standard, but high quality, Ethernet switches to move the signals around. Special devices are only used at the edges of the network for transmitters (conversion from HDMI to Ethernet) and receivers (Ethernet to HDMI). HDCP is handled by the transmitters and receivers and multiple receivers can be dynamically paired with each transmitter. The usual controller companies have systems for managing the Ethernet switches. For example, JustAddPower doesn’t sell their own switches but rather recommends those from companies in the networking business.
Centralized vs Distributed Receivers
To separate out the various channels from the RF cable require a collection of receivers, at least one per channel, and the most basic question is, are these receivers distributed so that they are all near the TVs, or are they centralized in one location so that they are near each other. Note that TVs have their own built-in receivers, but these are not generally useful to receive the copy-protected and encrypted program content that a sports bar would want to show, so we are generally talking about locating the receivers that are external to the TVs.
Underlying this challenge is the fact of life that HDMI signals, the way most TVs consume video today, do not like to run a long distance.
Another general point is that there are often a lot more TVs than channels being consumed thus, if you were to optimize for the number of receivers, a moderately large sports bar might have 8 to 16 receivers and 25 to more than 100 TVs.
Physical distribution architecture
One obvious option is to put the receivers close to TVs, usually attached to the mounting brackets in the back. Here are some pros and cons to this geometry:
|It is a short distance from the receiver to the TV so a short HDMI cable can be used to provide the highest resolution image possible.||Difficult to get audio back to a central location.|
|Minimizes central points of failure. Yes, the satellite receiver can break, but then you are hosed in any scenario.||Pay for extra receivers because one needs one receiver for every one or two TVs.|
|While extra receivers add to cost, this architecture generally has a pretty low cost/high-resolution solution.||A common solution for control is having the wait-staff go around with a remote control and point it at the receiver behind the TV. Not a very value added use of their time when things are busy, and can get chaotic.|
The advantages and disadvantages of centrally located receivers are:
|Control is more uniform, centralized, and even programmable.||Single point of failure|
|There are solutions to put any channel on any TV even if they come from different providers, e.g., DirecTV and Comcast.||Harder to distribute high-resolution video because HDMI does not support long distance runs.|
|If you want to tile four or 16 TVs into one image for a big game, this type of solution can do that.|
|There are easy solutions to problems such as “put the game on that TV over there on this TV over here”|
There are three signals that need to be moved around the facility. The first is, of course, the video. The second is the audio. And the third is control.
In Table 3 we see many of the transportation mechanisms for video
|RF signal from the cable or satellite receiver. Can be used to carry many stations, or as few as one.||This is the basic signaling mechanism used by cable TV and similar systems. Typically runs on 75-Ohm RG6 coaxial cable.||Inexpensive and widely available.||Needs a receiver at the end point with a way to pick the channel.|
|Composite Video. The yellow wire.||Carries all the video information for one channel.||Low cost.||Low quality. Will not do high-resolution.|
|Component Video. Three cables per channel.||Reasonably high quality video. Generally the highest single-channel analog method.||Good enough for most sports bars. Lower cost than HDMI and other digital techniques. Runs long distances well.||Cannot do the very highest resolution images. Uses three cables per channel.|
|HDMI||Highest quality.||Highest quality.||Only runs short distances. Splitters and extenders often have issues with the copyright protection mechanisms (HDCP).|
|HDbaseT||A format mostly for streaming uncompressed video over CAT6||Highest quality. Is a standard, which lowers costs and improves compatibility.||Ethernet switches are somewhat expensive.|
|HDbaseT over IP (competitor is SDVoE)||Combination of HDbaseT and video over IP.||High quality. Is a standard, which lowers costs and improves compatibility.||Very new. Best with 10 Gbit Ethernet.|
|CAT 5E, CAT 6||This is computer networking cable. Can run long distances. Used in conjunction with HDMI modulator/demodulator pairs, whether they are component video, video over IP, or HDbaseT.||Inexpensive and easy to find people who know how to run it. Can use without loss of quality because they are digital.||The devices to convert to and from HDMI are expensive.|
|SDV||Broadcast quality||Lossless, i.e., no compression||Expensive|
There are generally two places one wants the audio to go (1) the (possibly multi-zone) PA system or (2) a Wi-Fi Audio to smart phones system such as the ones offered by Audio Everywhere. The location of the receivers makes a huge difference on how difficult this is. It’s generally easy if the receivers are all co-located (e.g., in a rack in the back) but difficult if the receivers are located near the TVs. In the later case, the line level audio signals generally need to be sent back from the TVs in balanced mode. A summing balun is typically used to transform the single-ended analog left and right stereo signals from the (red and white) audio connectors to a single summed balanced signal suitable for running long distances, e.g., more than 10 meters.
One complication is that modern TVs often have no analog audio output ports but rather use TOSLINK optical outputs, which can be simple S/PDIF digital format or more complex, e.g., Dolby. LG-brand TVs won’t even output stereo S/PDIF signals on their optical outputs, which is kind of a pain. After all, locations such as sports bars don’t need anything more than mono and no one wants to pay for expensive converters. S/PDIF (also called PCM) outputs in stereo are available on Samsung and most other TVs, but still one needs a device to transform from TOSLINK to electrical analog because, generally, the multimode plastic fibers used for TOSLINK are only good for about 10 meters of travel.
In most cases, if the receivers are centrally located, the problem is easier because the audio can be grabbed right there, but note that some centralized receiver systems, such as those in our second example, do not have a local audio output, necessitating using the aforementioned techniques to bring the audio back from the TVs anyhow. For example, ZeeVee has this challenge.
Controlling the whole system is dependent as much on philosophy as on technology. Are you a “let a 100 TVs bloom” type, confident that a distributed system without a master controller will get the right programs on the right TVs? Or are you a “I have a plan and want to control the chaos” type?
Table 4 shows some of the methods and their pros and cons
|Staff running around with IR remote controls||Cheap||Wait staff on remote control duty are not serving food or liquor.|
Requires line-of-sight to the receiver and keeping the signal away from the other receivers you do not want to change. Can even require some contortions.
|RF remote controls, e.g., those from Home Theater.||Does not require line of sight.||A lot to set up. How do you get the IR signals to the receivers?|
|RF remotes with IR transmitters on modulators. This is applicable when one, for instance, converts from HDMI to CAT 6 and then back, the remote converter might have a IR transmitter or receiver built in.||Does not require line of sight.||Converting to IR to control the receiver at the TV end is taken care of.|
|Brand-specific controllers. Matrix switches have these, but so do receivers such as those from DirecTV.||Complete solution||You are limited to using that brand only.|
|General purpose controllers, such as Control4, Crestron, AMX.||Very general purpose, programmable, and powerful solution||Expensive to very expensive.|
This is not a “how-to distribute video in your bar” article but rather a “how-to ask good questions about distributing video in your bar” piece. I hope that you learned a couple of things that might help you get the system you want without stepping on too many land mines. Good luck.
I would like to thank the following people for their advice and teachings, Richie Normand of RichieAudio, Rick Marks of Homesmart Central, Jeff Graham of Alaska DTS, and Jeff Mayes of Sportsbar-TV. The insights are theirs and the mistakes are mine.