digital video transmission the it-friendly...

March 2017

Digital Video Transmission the IT-Friendly Way

Real world options for sending video over CATx cables or IP networks

© 2017 Wainhouse Research

Migration from Analog to Digital Video Traditional audio visual (AV) systems were designed to support analog video signals. While well-known

and understood by AV professionals, analog video brought with it many disadvantages including:

- Signal Degradation – even when high quality cables were used, analog signals would degrade

over distance, especially when higher resolutions (e.g. XGA and above) were used.

- Susceptibility to Interference – even with properly shielded cables, analog signals were

susceptible to interference from other signals (e.g. network cables, audio cables, power lines).

In addition, there are many disadvantages to the cabling required by analog video including:

- Weight – a 500 foot spool of RGBHV cable (see image below middle) might weigh 40 pounds or

more. This impacted shipping cost, ability for people to carry high volumes of cable, etc.

- Bulkiness – an RGBHV cable might have an outer diameter of 0.5 inches (12.7 mm) or more

which limits the number of cables that could pass through standard cable conduits (see image

below right) and makes it hard to hide cables (e.g. under a carpet).

- Cost – high quality coaxial cables (see image below left), especially multi-conductor cables, can

be very expensive. A professional VGA cable, for example, might cost several dollars per foot.

- Connectors – analog video connectors tend to be expensive, bulky, and difficult to install onto

the ends of the cable. Some (e.g. BNC connectors) require a special crimping tool and an

experienced AV technician to install. Others (e.g. VGA connectors) are too bulky for most

conduits and are almost impossible to connect (terminate) in the field. This impacts installation

time, cost, and limits flexibility.

The takeaway is that analog video, and specifically analog video cabling, introduced many AV system

challenges. And the magnitude of these challenges has grown exponentially due to the increased use of

high resolution sources (e.g. computers, HD cameras, etc.) requiring multiple coax cables.

But that was then, and this is now. Today, driven largely by consumer products, the video world has

gone digital. Basically all of our video sources (e.g. cable TV, satellite, DVD players, media players, PCs,

etc.) have gone digital and now support HDMI and/or Display Port connections instead of composite,

component or VGA outputs. And while some still carry analog inputs for backward compatibility,

basically all current generation display technologies (e.g. LCD, DLP, etc.) are inherently digital and

designed for use with digital signals.


Given that our sources and destinations are now digital, it makes no sense to convert signals to analog

for transmission and then back to digital as this would impact quality and cost, and add complexity.

Fortunately, the electronics manufacturers understood this issue and in 2002 created the HDMI (High-

Definition Multimedia Interface) standard which allows for the transmission of uncompressed HD video

signals, multi-channel audio, and control signals over a single cable.

And while HDMI works well for most consumer / residential

applications, it doesn’t work as well for professional AV applications

for many reasons including:

- Cable Fabrication / Installation Issues – you can’t terminate an HDMI cable in the field.

- Cost Factors – HDMI cabling is expensive per foot, especially for high quality shielded cables.

- Distance Limitations – the maximum acceptable length of an HDMI cable depends on the quality

of the cable, which gives rise to two issues:

o The fact that there is a limit at all (e.g. if you need to transmit a digital video signal 150

feet to a comms room, this would not be possible with HDMI cables). Most AV

professionals would not recommend HDMI cable runs beyond 50 feet (~ 15 meters).

o The fact that the real limit depends on many factors such as cable quality, bandwidth

(meaning signal resolution, color depth, etc.), the devices in use, interference, etc.,

means that one cannot safely predict whether a specific distance will work in the field.

- Reliability – HDMI cables are well suited for the consumer environment, but the inability to lock

HDMI connectors into devices is a reliability problem.

So converting digital signals to analog for transmission doesn’t make sense, and standard digital video

signal transmission methods using HDMI cabling has its own set of challenges. So the AV world needed

other options.

This white paper, sponsored by the HDBaseT Alliance, provides information and insight into real world

options for transmitting digital video signals in an enterprise and IT-friendly way.


Today’s Options for Digital Video Video over CATx Cabling (HDBaseT)

Several years ago, a number of manufacturers released solutions for the transmission of digital video

signals over CATx cables. These solutions, however, did not interoperate, and in some cases required

multiple CATx cables which increased cost and installation time. And then came HDBaseT.

HDBaseT is a standard 1 for the transmission of digital signals between two or more locations over CATx

cabling. 2 Using HDBaseT, a single CAT6 cable can carry the following types of signals over a distance of

up to 100 meters / 328 feet:

- One or more (bandwidth permitting) 3 digital uncompressed video signals at up to 4K resolution

- Multiple channels of audio

- Various control signals (CEC, RS-232, IR etc.)

- One USB channel (connects one USB host to one or more USB devices)

- 100 Mbps Ethernet

- Power (up to 100W)

The ability to transmit multiple signal types, including uncompressed video, over relatively long

distances on a single, standard CATx cable makes HDBaseT well suited for audio visual systems.

HDBaseT applications range from simple to complex. For example, the image above shows a typical

meeting room environment in which a single transmitter box is sending signals to a single receiver.

The image below shows a more complex HDBaseT deployment involving multiple transmitters sending

signals to an HDBaseT switch that, (1) receives the HDBaseT signals, (2) mixes / processes the signals,

(3) provides signal outputs (e.g. HDMI, audio, etc.) at the switch, and (4) transmits HDBaseT signals to

remote receiver(s).

1 HDBaseT is a global standard ratified by the HDBaseT Alliance, an organization with more than 180 members around the world

including Valens, LG, Samsung, Sony Pictures, and others.

2 In February 2017, the HDBaseT Alliance announced its intention to expand the HDBaseT offering to include HDBaseT over IP

which will enable the encapsulation of HDBaseT signals over IP for transmission over standard IP networks. Valens, the

inventor of HDBaseT, has provided the Alliance with an initial draft for consideration, and the Alliance expects an initial Alliance

draft to be released by the summer of 2017.

3 The ability to transmit multiple video streams on a single CATx cable was released as a part of HDBaseT version 2.0 and is

available within solutions from certain vendors.


Version 2.0 of the HDBaseT standard supports multiple channels of video on a single CATx cable, and

daisy-chaining of HDBaseT devices. In some applications (e.g. the transmission of a small number of

signals to numerous digital signage displays), these capabilities enable the creation of large scale

HDBaseT environments without the need for a central HDBaseT switch.

Advantages of HDBaseT Disadvantages of HDBaseT Longstanding and field-proven technology in use by the majority of leading AV signal distribution vendors

Comfortable approach for AV integrators

Leverages standard CATx cabling (or optionally fiber)

Use of dedicated (but standard) CATx cabling results in a closed and controlled environment with predictable performance

Supports transmission of video, audio, USB, control, Ethernet and power on a single cable

Signals stay digital – end to end

Supports sending more than one video signal (depends on available bandwidth and HDBaseT device in use)

Transmits uncompressed video

Offers low transmission latency (delay)

Relatively inexpensive for small to medium deployments

Certified HDBaseT products from different vendors can work together (interoperability)

Available in chip and System-on-Module form (makes it easier for vendors to adopt HDBaseT)

HDBaseT signals cannot pass through standard network switches and routers (see footnote on prior page for information re: pending HDBaseT over IP capabilities)

Fully routed applications (allowing any input to be sent to any output) require the use of one or more dedicated HDBaseT “switches,” which can be very expensive

Typical deployment involves a star architecture which may add complexity, cost, and need for additional cabling

Relatively expensive for large deployments

Vendors seeking to implement HDBaseT within their solutions have two basic options: buy HDBaseT

chips, or buy “System-on-Module” boards. Both are available for purchase from Valens, the inventor of

HDBaseT, and both take much of the development cost, complexity, and time out of developing

HDBaseT transmitters, receivers, and switches.


For example, the Valens Colligo VS2310 supports the transmission of HD video, audio, control signals,

Ethernet, and USB 2.0 signals over a distance of 100 meters using a single CAT6 cable. The VS2310

offering includes two chips – a transmitter chip for use in HD source equipment, and a receiver chip for

use in projectors and other types of AV equipment such as displays, extenders, switchers, receivers etc..

HDBaseT has been implemented in products by the vast majority of leading AV signal distribution

vendors including (in alphabetical order) AMX, Atlona, Crestron, Extron, Kramer, and TV-One.

Video over IP Data Networks

This approach involves the transmission of digital AV signals on an IP data network. The source signals

can be native digital signals (e.g. signals from a computer or other digital device) or analog signals

connected to an interface (transmitter) box that converts the signals to digital.

Author’s Note: Unlike traditional streaming solutions, these video-over-IP solutions are designed

to transmit video signals with very low latency (typically less than 1 frame) at high quality levels.

Video over IP solutions can use standard IP network switches that meet the proper specifications for

speed and protocol awareness. For example …

- AVB (described below) requires an AVB-aware switch or a totally separate network (the AVB

protocols can deal with network contention, but only if an AVB-ready switch is used).

- AptoVision (a new entrant to the space) requires a 10 GB switch

These network switches then switch / route the AV traffic to the appropriate receiver interface that

converts the signal back to the required format.

One challenge related to sending video over IP is delay / latency. In order to transmit the AV signals

over IP, the signals must be packetized – which adds some latency. In many cases, the signals are also

compressed as they are digitized, which adds more latency and may decrease quality. In addition, the

signals are subject to IP overhead and the associated IP latency (transmission from source to

destination, traversing routers and switches, etc.).

A second challenge with sending video over IP is network contention. Digital video not only has a big

footprint on a network, but must traverse the network quickly. This can wreak havoc on networks not

designed to support such traffic.

The Video over IP approach is in use by numerous vendors including (in alphabetical order) AMX

(Harmon / SVSi), Atlona, Biamp, ClearOne and Kramer.4 Unfortunately, each of these solutions are

unique and thus do not typically interoperate with each other.

4 One vendor, AptoVision, also sells video over IP chipsets for use by other vendors seeking to implement AptoVision’s

technology into their devices.


For the most part, vendors seeking to use video over IP must develop their own solution. AptoVision,

however, offers ready-to-use chips and kits to simplify the development of 4K uncompressed video

transmission solutions using their video over IP protocol. 5

Audio Video Bridging (AVB) is a set of standards for the transmission of AV signals over IP networks.

AVB also includes the ability for AVB devices to work together to synchronize the timing of all AV signals

traversing the network. And the AVNU Alliance ensures that AVB devices follow the AVB standard and

can interoperate (to some degree).

However, video transmission over AVB is not commonplace today. In fact, WR is aware of only one

vendor currently using this approach.

Essentially, video over IP makes video transmission a standard network function, with the exception of the need for AV transmitter and receiver boxes.

Advantages of Video over IP Disadvantages of Video over IP Leverages standard CATx cabling (or optionally fiber)

Leverages standard, relatively low cost IP data networks (routers, switches, etc.)

Can run on a company’s production network (assuming bandwidth and QoS are in place)

Can be monitored (to some degree) using standard network monitoring and management tools

Comfortable approach for IT professionals

Supports transmission of video, audio, USB, and control signals (depending on solution)

Supports use of video compression (reduces bandwidth but impacts latency and quality)

Supports transmission of multiple channels on a single network link (depending on bandwidth available)

Follows a distributed architecture which offers various advantages (e.g. less physical cabling, possible cost savings, etc.)

Standardized (and in some cases interoperable) solutions are available including:

- AVB solutions verified by AVNU Alliance

- AptoVision-powered solutions verified by the SDVoE Alliance

Video signals on network may interfere with production network traffic – especially if high resolution, uncompressed video signals are in use. In some cases, network upgrades or even the use of a dedicated network may be required.

Input and output interfaces (transmitters and receivers) are relatively expensive compared to HDBaseT solutions

Requires the designer / integrator / customer to have some IP-knowledge (IP addresses, QoS, network capacity, etc.)

Limited interoperability between video over IP solutions today

Video over IP solutions are relatively new and …

- Several technology stacks are in use - The range of products available is limited

Video over IP solutions require technology from more than one vendor (video vendor and the network switch vendor), which:

- May impact reliability - Multiple management tools must be used

Essentially, video over IP allows the transmission of AV signals over standard IP networks, but network

congestion must be considered and interoperability between vendors remains an issue.

5 Founded in January 2017, the SDVoE (Software Defined Video over Ethernet) Alliance is a consortium of vendors working

together to define and promote standardized hardware and software platforms for video over IP. Founding SDVoE Alliance

members are AptoVision, Aquantia, Christie, Netgear, Sony, and ZeeVee.


Comparison of Approaches The table below compares the key areas of the two key approaches to transmitting digital video:

Area of Comparison Video over CATx Cabling

(e.g. HDBaseT) Video over IP

(e.g. AVB, AptoVision)

Standard in Use HDBaseT standard AVB or AptoVision (SDVoE) standards Also numerous proprietary offerings

Market penetration Strong – in use by many vendors across many products

Limited

Interoperability between vendors

Strong - HDBaseT Alliance tests and certifies solutions

Limited … - AVNU tests AVB solutions, but AVB is used

mostly for audio applications only today.

- SDVoE Alliance has announced plans to verify interoperability.

Comfort level for AV integrators

Strong Limited

Comfort level for IT professionals

Limited Strong

Ability to Monitor Good - Requires dedicated tools developed by the solution vendor, but signals can be monitored in great detail.

Good – Standard network monitoring tools can be used to monitor signals to some degree. However, video specific insight is limited.

Cabling CATx or Fiber Cabling CATx or Fiber Cabling

Architecture Point-to-Point Star Architecture Daisy-Chaining

Distributed Architecture

Signals Types Supported Video, Audio, Control, USB, Ethernet and Power (depending on product)

Video, Audio, Control, USB and Ethernet (depending on solution and product)

# of AV Signals Per Cable 1 or More Video Signals (up to UHD) Multi-Channel Audio

1 or More Video Signals (up to UHD) Multi-Channel Audio

Compression / Signal Loss None (video sent uncompressed) Depends on solution and configuration

Cost of Interface Boxes (transmitters, receivers)

Relatively low Relatively high

Cost of Central Switch Relatively high (special HDBaseT switch needed)

Relatively low (standard network switches can be used – protocol awareness helpful)

Impact on Production Data Network

None – runs on separate CATx cabling plant Depends on situation – QoS or other tools may be needed to protect network.

Suitability for Long Runs Good - Requires HDBaseT switch or repeater ~ every 100 meters. Can use fiber for longer runs.

Good – Uses standard network switches ~ every 100 meters. Can use fiber for longer runs.

Ease of Implementation for vendors

Strong - Valens sells HDBaseT chips and SoM boards

Weak - Most vendors develop their own code. AptoVision offers chips and boards.


Making the Right Digital Video Choices When choosing between the two approaches, end-users should consider various items including:

- Project Scope – How many video signals will be transmitted? Where will the signals be sent

(across the room, across a campus, between campuses)?

- Video Quality – What level of compression will be used (none, standard, or heavy)? How much

latency is acceptable? Some applications can tolerate latency, while others cannot.

- Standardization – How likely is it that devices from multiple vendors will be used (likelihood

increases as scale increases or multiple entities are involved)? How important is interoperability

between vendors? Will this change in the future?

- Existing Investments – Is digital video transmission already in use within the environment? How

important is backwards compatibility with those existing systems?

- Total Cost – Total cost is impacted by network requirements, scale (# of signals to be

transmitted), footprint (location of the sources and destinations), and existing deployments.

Key questions include:

o Can the existing data network support digital video (some solutions require 10 Gig)?

o If a change is to be made, how expensive will it be to replace existing solutions?

o What is more cost effective for the specific application – a solution with lower cost

interfaces but higher cost switches, or vice versa?

The takeaway here is that which approach makes the most sense depends on the situation, and this

requires a proper understanding of the overall requirements – both today and in the future.


Conclusion Organizations seeking to transmit digital video signals without sacrificing quality and with very low

latency have two basic options:

- Video over CATx Cabling (e.g. HDBaseT)

- Video over IP Data Networks (e.g. AVB, AptoVision, or other proprietary solutions)

Each of these approaches has its pros and cons. For example …

- Video over CATx solutions are field-proven, well understood by AV professionals, available from

many vendors, offer strong interop between vendors, and do not impact a company’s

production network.

- Video over IP solutions are well understood by IT folks, leverage standard network switches, and

can (if desired and proper network QoS is in place) run over the production IP network.

WR is often asked by end-user customers which approach makes more sense. The reality is that the

answer to this question depends on a range of items including the project scope, video quality required,

the importance of interoperability and standardization, whether existing investments have been made

(e.g. in a previous HDBaseT deployment), and more.

In some cases the best solution involves a combination of both options.


About the Authors

Ira M. Weinstein is a Senior Analyst & Partner at Wainhouse Research and a

25-year veteran of the conferencing, collaboration and audio-visual industries.

Ira has authored and contributed to dozens of articles, white papers, studies,

reports, and evaluations on rich media communications, video conferencing,

streaming and webcasting, audio-visual design and integration, business

strategy, and general business practices. Ira specializes in providing strategic

advisory services to vendors, resellers, and end-users within the collaboration

space. Ira can be reached at [email protected].

Saar Litman is a Senior Researcher & Consultant at Wainhouse Research and

has 17 years’ of experience in the audio-visual and video conferencing

industry. Saar’s primary focus is the products, services, and companies within

the audio-visual space. In addition, Saar provides AV design services, helps

enterprise organizations define and implement global AV standard systems

and designs, and manages the WR test lab in Coral Springs, Florida. Saar can

be reached at [email protected].

About Wainhouse Research Wainhouse Research, www.wainhouse.com, is an independent

analyst firm that focuses on critical issues in the Unified

Communications and Collaboration (UC&C). The company conducts

multi-client and custom research studies, consults with end users on key implementation issues,

publishes white papers and market statistics, and delivers public and private seminars as well as

speaker presentations at industry group meetings.

mailto:[email protected]

mailto:[email protected]

http://www.wainhouse.com/

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