Information systems-video, audio, automation, networking, Internet-have an unquenchable thirst for higher and higher rates of data. This is usually referred to as the need for higher and higher bandwidth, but the bottom-line goal is to be able to increase the throughput, which is the number of bits per second (bps). Maximum data rates place an upper limit on the speed that information can travel. For certain types of data delivered to and from your computer, high speed is nice but not crucial. Low throughput will increase the number of seconds it takes for your question to reach Google or for your email to reach your friend across the country, but usually not by that much. However, if you want to watch streaming video from the Internet in real time, the data rate you can handle makes a huge difference. There is nothing so frustrating as having long pauses while you wait for your system to catch up.
The availability of high-end digital video media systems for both home and commercial applications is highlighting the need for upgrading the quality of local area networks (LANs). High definition video is one of the biggest drivers for improving the wired infrastructure. Homeowners want to be able to move that video from a central source, such as a cable company set-top box or a Blu-Ray player, to monitors in different rooms. Commercial users are looking to improve video displays in places like transportation hubs, big-box stores, auditoriums and conference centers, and for digital signage. There is also an increasing need for high definition video in healthcare, where the ability to diagnose, consult and observe remotely, over the Internet, is a rapidly growing application. A detailed and exact video image can make a big difference in diagnosing and analyzing a medical condition. University classrooms are also increasing their use of sophisticated audio/visual equipment, high-speed LANs and Internet connections.
The ability of a LAN to deliver high throughput is limited by the physical media over which the data is carried. The upgrading of LAN media is following a few different tracks. One is the continual improvement of twisted pair cable, at the same time that the Ethernet standards are being upgraded. The throughput rating of the cable and the Ethernet standards tend to track each other. The standard is continually upgraded to make maximum use of the available cable, and the standards developers are always looking to push up the envelope to nudge the cable manufacturers forward. Currently, wise users who are upgrading their LANs by installing twisted pair cable should not consider anything less than category 6. This will give them a guaranteed throughput of 1 Gb/s at 100 meters and probably even 10 Gb/s at 50 meters. (It's important to remember that the category rating doesn't specify the actual performance - only the minimum - so a cable from a particular manufacturer might exceed the minimum performance.) Category 6a, which according to the standard must deliver 10 Gb/s at 100 meters, is now available, although at this time (early 2012) it is more expensive, and is mostly being used for professional applications such as data centers. However, it is gradually becoming the choice for users who are looking to have their infrastructure capable of handling the high data rates that will be normal in the near future. As with most technology, rising demand lowers the cost of manufacturing, so the price for 6A will fall. The next step being considered for twisted pair cable is for a 40Gb/s throughput.
In recent years, the development and adoption of new technology has been driven by the consumer market, with commercial, healthcare, education, and industrial applications catching up afterwards. This is very much the case with video. The driver there is high definition television (HDTV), which is based on digital transmission and requires very high throughput. By the end of 2013, all HD video sources, such as Satellite and CATV, Blu-Ray discs, servers (video on demand), and video conferencing CODECs, will only provide digital outputs. This will impinge on commercial applications, such as projectors and signage. A major driving force for this is the strong push by content-providers for digital rights management (DRM) in order to control access to their products. A number of companies have formed an alliance to develop a content-protection standard, which they call the Advanced Access Content System (AACS). These include The Walt Disney Company, Warner Brothers Studios, Microsoft, IBM, Intel, Sony, Panasonic and Toshiba. Their goal is to make sure that they can control the right to access all digital HD content. Video produced by these suppliers employs an encryption scheme called HDCP (High Bandwidth Digital Content Protection). At present, HDMI is the most commonly used cabling system for transporting uncompressed video containing HDCP encryption. Residential and commercial HDTV devices will have to be able to handle this encrypted digital information, as well as legacy digital and analog signals.
High quality video must be delivered in an uncompressed format. There are two main reasons for this. The most important is that the picture quality is better - it has very low latency. If you're transmitting compressed signals, there must be two electronic devices in the line: one to do the compression and another at the receiver to uncompress the signal before it can be viewed. Each time you add a device in series with the signal you are introducing some delay and distortion. Also, video compression systems involve deleting data based on statistical methods, and then reintroducing the lost bits, which can be a source of incorrect details in the image. Another major problem with compressed video is that since there are different standards for compressing the signals, in order to be able to watch video from different compressed sources, the receiver has to be capable of dealing with the variety of different proprietary compression schemes that exist now and that may come into existence in the future.
To deliver high definition digital video, you need a network that is able to transport the signal. HDMI is designed to deliver uncompressed video containing HDCP content protection. There are, however a number of serious problems with HDMI as a transport medium. The most important is that the maximum length of a single run of HDMI cable is very limited - 15 meters, tops. Although there is no formal specification for the length of HDMI cables, in order to be certified as compliant, they have to meet various video performance specs such as maximum signal attenuation. Depending upon how the cables are constructed, this dictates a length of somewhere between 12 and 15 meters. So to send uncompressed video more than about 50 feet, you need to use a powered signal booster. HDMI is okay for a single room in a home, but for whole-house or for commercial applications, it's a real problem. Another issue with it is that the connectors have a special arrangement of 19 conductors, which besides being different from all other existing cables, makes it very difficult to work with. This presents a significant problem for the near future when content-protected digital video becomes the norm for all new equipment.
The HDBaseT Innovation
It is obvious that a better means of connecting uncompressed HD digital video is needed. In June of 2010 the HDBaseT Alliance was formally incorporated, with LG Electronics, Samsung Electronics, Sony Pictures Entertainment, and Valens Semiconductor as the founding members. The Alliance was formed to create a new standard for high definition digital media distribution, based on a chipset developed by Valens. It enables HDMI video to be sent over a single standard twisted pair category 6 cable and to attach by means of standard RJ 45 Ethernet connectors. Category 6 cable is widely available, can be run in 100-meter (330-foot) lengths without a booster, is robust and is quite inexpensive. This is in stark contrast to HDMI cable, which is expensive, and has a difficult-to-attach, and not very reliable, connector. HDBaseT combines the advantages of two different worlds: the physical infrastructure of standard Ethernet and the signal-carrying ability of HDMI. Furthermore the signals use the same basic format as traditional Ethernet, which makes troubleshooting and analysis straightforward. If there is already an Ethernet-based LAN installed in a location, it can be used for HDBaseT instead. Rather than requiring separate cables for video, audio, and control signals, as well as Ethernet and DC power, these functions are all incorporated over that single piece of category 6. The HDBaseT Alliance calls this 5Play™ convergence.
Power Over HDBaseT (POH)
The method of providing DC power is an important HDBaseT innovation. Power over Ethernet (PoE), which allows 15.4 watts of DC power to be distributed on an Ethernet LAN, has been around for a while. In 2009, the IEEE standard was amended to allow 25.5 watts (PoE plus). This sets the limit for the power that can be carried on one of the four pairs in the 5e/6 cable. HDBaseT, however, delivers DC power on all four pairs, thereby enabling them to source 100 watts, which they term Power Over HDBaseT (POH).
How It Works
The key to how this is achieved is by changing the way that the signals are handled. The HDBaseT chipset enables all four pairs that make up the category 6 to be used for transmitting video. The return channel is only used for Ethernet and control signals like CEC, USB/RS232, and IR. According to the HDBaseT 1.0 specification: "HDBaseT uses an asymmetric method, sending video, audio, Ethernet and controls from source to sink, but only 100 Mb are transferred back (Ethernet and controls)." It uses a special encoding in which video, audio, and control signals are all coded into a single HDBaseT digital packet. The uncompressed video can be sent, along with audio, Ethernet and controls from a network of sources such as digital video recorders (DVRs), Blu-Ray disc players, game consoles, PCs and mobile devices, to receivers, such as TVs, monitors or projectors in multiple locations.
According to the Valens website, the HDBaseT technology is embedded in a set of two chips they call VS100:
- "VS100TX (Transmitter): for use inside DVDs, STBs and other HD source equipment.
- VS100SRX (Receiver): for use inside HDTVs, projectors and other display equipment."
The transmitter chip encodes the signals into packets and the receiver chip separates them for use by the display devices. These chips have been embedded in commercial products by various companies, including Crestron, Extron, Gefen and AMX. In fact, according to Justin Kennington, product line manager for DigitalMedia™ at Crestron, their engineers had started work on a product line to solve the problems with HDMI at about the same time Valens was developing their chips. Crestron was approached by Valens at a trade show and invited to see a demonstration of their chipset. They were impressed enough to start working in partnership with Valens and eventually incorporated HDBaseT into their line of high definition HDMI-based distribution and switching products. Kennington gave a few examples from the Crestron product line, of how they use HDBaseT. The core of their system is a video switch unit that can accommodate 8 to 32 inputs from various video sources and 8 to 32 HDBaseT outputs for connecting to displays. They also have room controllers, which accept HDBaseT inputs from the switch units (which can be as far away as 330 feet) and HDMI outputs, which can feed a display up to about 45 feet away. They have transmitter units, which can accept inputs from a PC, for example, and transmit the signals via HDMI or HDBaseT to the switch unit. The room controllers and transmitters can be powered by POH, so there is no need to have a separate power source for each device.
According to Micha Risling, marketing committee chair for the HDBaseT Alliance, their immediate next step is getting manufacturers to imbed the HDBaseT chips into all video equipment so that users can plug their RJ45 connectors carrying HDBaseT directly into a jack on the back of a TV set, or monitor, or projector, or set-top box, or PC. This would eliminate the need for room controllers and local transmitters. Risling said the Alliance is also demonstrating the advantages of HDBaseT technology for the high-end video surveillance industry.
The bottom line is that the members of the HDBaseT Alliance are betting that HDBaseT will sooner rather than later, become the standard for HD digital video.
Q & A
- What are sources of uncompressed video? For residential applications? For commercial applications?
All traditional outputs send uncompressed video (HDMI, DVI, DisplayPort and etc.). Sources including set-top-boxes and Blu-ray players distribute uncompressed video. Devices for both residential and commercial applications that generate interactive HD-audio AV, such as game boxes, PCs, electronic program guides (EPG) and rich custom GUI overlays, require uncompressed technologies.
HDBaseT delivers full HD/3D and 2K/3K uncompressed video to a network of devices or as a point-to-point connection. Uncompressed content supports all video sources, including legacy products, accurately renders gaming graphics and features such as EPGs, and does not degrade video quality or add latency. An uncompressed interface is the only way to provide a universal video interface which can support all video sources-legacy, new and future. Whereas a compressed video interface has very limited applications since compressed video is rarely provided at the output of video sources.
- Can all video displays, such as TV sets and monitors display uncompressed video if they have the proper connectors?
Most video displays can ONLY display uncompressed video and only few displays can deal with compressed content. Built-in encoders are required to show compressed content. These encoders convert the content back to its origin uncompressed format before it can be displayed.
- Can HDBaseT controllers and cables carry uncompressed digital audio?
Yes, HDBaseT technology sends uncompressed, digital video and audio up to 10.2 Gbps.
- What are the sources and receivers?
Any audio device will work. As of today the majority of devices will use HDMI for both Audio and Video and others will use other types of digital audio outputs (SPDIF).
- Would all uncompressed audio require digital to analog conversion in order to be played back?
No, most of the devices can deal with digital audio directly.
- What are the sources and receivers?