Digital Design Guide
Digital Video for Professional A / V Systems

© 2009 Extron Electronics. All rights reserved. All trademarks mentioned are the property of their respective owners. 09-06, 68-1787-01, Rev. A

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Extron Digital Design Guide

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The A/V industry is in the midst of a major transition, from analog to digital presentation technologies. As a
leading manufacturer of products engineered for the commercial A/V market, Extron has a long history with the
development of digital solutions, going back nearly a decade with the release of many of the industry’s first DVI
distribution and extension products. Over the past five years, our product line has grown considerably and now
includes the A/V industry’s most complete portfolio of digital switchers, cables and adapters, and twisted pair
and fiber optic extenders. Most importantly, Extron manufactures the interfaces and signal conversion products
necessary to make possible the transition from analog to the many available digital formats, including DVI, HDMI,
DisplayPort, and HD-SDI.

This Digital Design Guide addresses the A/V industry’s primary challenge as it transitions from analog to digital how these new signal types and system topologies are integrated into A/V presentation systems that serve the
communication needs of our customers. It provides a reference for A/V system designers seeking to understand

these emerging technologies and the options available, with a practical approach to integration in new and
legacy presentation systems.

In this Guide you will find overviews of each of the digital video formats most commonly used in commercial
A/V applications. Next, you will find sample A/V system designs, ranging from a simple classroom to a network
operations center, that describe the practical aspects of these transitional A/V systems, the type of equipment
needed, and signal flow from one device to another. Following the system design section is a condensed
catalog of Extron products designed for the integration of these digital technologies. At the end of the Guide,
you’ll find a comprehensive Glossary of terms related to digital video for professional A/V applications.

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TABLE OF CONTENTS

Digital Video for Professional A/V Systems
The Digital Connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Digital Video Signal Formats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Anatomy of a Digital Video Signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Understanding EDID - Extended Display Identification Data . . . . . . . . . . . . . . . . . . . . . . . . . . 14
DRM for the A/V Professional . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Digital System Designs
HD Video Conference & Presentation Room . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Digital Upgrade to Existing Analog System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
College/University Classroom System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Network Operations Center System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Corporate Training Room System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Municipal Courtroom System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Lecture Hall System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

26
28
30
32
34
36
38

Extron Digital Video Product Solutions
Extenders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Distribution Amplifiers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Switchers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Matrix Switchers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Signal Conversion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Test & Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cables & Adapters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

42
47
49
53
58
63
64

Glossary
Digital A/V Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

www.extron.com

1


The Digital Connection
The prevalence
of various digital
signal formats in
the professional A/V
industry presents
opportunities as well
as challenges for
integration.

The A/V industry is currently in the midst of


now. In the medical, visualization, and computer

a significant transition, from analog video to

graphics segments, DVI has been an established

digital video technologies and applications.

format since 1999. Continual evolution within

Every day, system designers face the challenge

the computer, broadcast, and now consumer

of integrating digital and analog video signals

electronics industries has brought digital signal

into new and previously-installed A/V systems.

connectivity to the forefront with the introduction

As digital video is associated with the cutting

of two, newer digital video standards – HDMI

edge in A/V technology, there is an increasing

for consumer products and DisplayPort for


desire by integrators and their customers to

computers and related technologies.

incorporate digital video into their systems. A
wide array of digital video ports, including DVI,

The prevalence of these various digital signal

HDMI, DisplayPort, and HD-SDI, are present in

formats presents opportunities as well as

some form on virtually every new component

challenges for integration of professional A/V

found in the market today. In addition, there is a

systems. DVI and DisplayPort are common to

very large installed base of analog hardware, as

PCs and laptops, and are standard on many

well as content, which must be kept viable even

professional displays and high-end projectors.


within new system designs. For the foreseeable

HDMI is primarily found on HDTV-capable

future, then, most presentation environments will

products such as Blu-ray Disc players, game

require mix of analog and digital video products

consoles, and satellite and cable DVRs and

and technologies.

receivers. While designed for consumer and
residential applications, some HDMI-equipped

Digital Video – It’s More Than Just HDMI

products are now being utilized in commercial

Although the digital transition is currently headline

applications as well.

news, digital video is not new to the professional
A/V industry. The broadcast, teleproduction, and

High definition digital video has also found its way


rental/staging segments adopted serial digital

into many applications beyond the broadcast

video, SDI, more than 20 years ago, and HD-

studio as a means to capture, distribute, and

SDI has been in use for more than a decade

display high definition content, extending

Figure 1-1.

Digital Transmission Can Achieve Perfect Signal Reconstruction
Digital Source Device
Internal
Digital
Functions

Serialize

Digital Display Device

Deserialize

Original
digital
video
pixels


Perfectly
reconstructed
digital video
pixels

1 0 1 0
Digital video at
serializer output

2

Extron Digital Design Guide

Internal
Digital
Functions

1 0 1 0
At deserializer input,
distortions caused by
cabling, etc can readily be
corrected by practical means


into house of worship and rental and staging

Complicating the decision is the knowledge that,

environments. Just about every display available


while new A/V technologies and signal types are

today has some type of digital video capability.

continually introduced, not all of them survive

Whether it’s a desktop PC display, ceiling-

and the ones that do generally don't immediately

mounted projector, or a large flat-panel LCD on a

replace the legacy formats. For example, many

wall, chances are that a DVI, HDMI, or DisplayPort

new digital source devices incorporate an

connector is available to accept incoming signals

assortment of analog video outputs, including

from digital source devices.

composite video, S-video, and component video.
Correspondingly, most new digital displays are

Why Digital?


still equipped with analog inputs. You might ask

The implementation of digital A/V technologies

“why do manufacturers go to the extra effort,

brings the promise of several distinct advantages

and additional expense, to provide a variety

over analog technologies. First, for the

of connectors on their products?” In a word,

manufacturers of computers and displays, there is

compatibility.

the potential of removing a considerable amount
of processing circuitry from a device. Since

Most manufacturers realize that sources and

signals are already digital within the electronics

displays are rarely replaced at the same time. New

of virtually all A/V products, most if not all analog-

sources, such as Blu-ray Disc players and higher-


to-digital and/or digital-to-analog conversion can

end laptop PCs, need to maintain compatibility

be eliminated, resulting in lower manufacturing

with older displays. New, high-resolution flat panel

costs and allowing for more competitive pricing.

displays and projectors, on the other hand, need

Second, in comparison to analog-based devices

to remain compatible with older sources, such as

and systems, digital signals are by nature,

VHS recorders and DVD players that are retained

lossless, enabling the distribution of pixel-perfect

for use with legacy content.

Digital signals by
nature are lossless,
enabling distribution
of pixel-perfect and
consistent, pristine

quality images while
reducing the time
and effort required for
system and display
set-up.

and consistent, pristine quality images while
reducing the time and effort required for system

System designs for typical training and

and display set-up (see Figure 1-1). Finally, a digital

presentation facilities, therefore, very often

infrastructure can be designed to accommodate

accommodate a hybrid mix of analog and digital

the high resolutions commonly found today, such

capabilities, providing support for legacy analog

as 1920x1200 and HDTV 1080p, and provide

video formats while incorporating newer signal

support for the higher rates on the horizon.

types such as DVI, HDMI, DisplayPort and, in

some cases, HD-SDI.

Making the Choice – Analog, Digital, or
Both?
Part and parcel of any transition are uncertainty,

Extron SW4 DVI A Plus
Switcher with selectable
cable equalization

the fear of the unknown and desire to look for
expert help and assistance in making decisions.
In your role as an A/V IT manager, consultant
or A/V system integrator, your customers are
depending on you to help them make the best
choices. In the face of a wide array of products
and disparate technologies, customers want
advice during the design and implementation
phases to ensure that A/V systems meet their
requirements for functionality and performance,
stay within budget and, ideally, provide for future
growth and further changes in technology.
www.extron.com

3


The Digital Connection
Basic questions you
need to ask before

designing a system:
•

•

•

Will the system need
to accommodate both
Analog and Digital
formats?
Is this an upgrade to an
existing analog based
system?
Is the system expected
to span a technology life
of many years?

The first question to be answered, then, is the

around an all-digital switcher or matrix switcher,

most difficult, as it goes right to the core of the

with any legacy analog sources accommodated

transition. Should you:

through the use of an analog-to-digital


• Stick with a tried-and-true analog design for the
time being?

converter.

• Build an digital / analog hybrid system that
incorporates a mix of technologies?

The bottom line is that, just as video replaced

• Or, build tomorrow’s system today with an alldigital design and some provision for legacy analog
products?

cassettes, digital technology in one or more forms

The answer, as with so many decisions and

presentation systems will move to a fully digital

choices to be made, is “It depends.”

design in the future; for the time being, however,

motion picture film and DVDs replaced VHS
will replace analog in the majority of applications
over time. Typical corporate and educational

a hybrid system design that supports both analog
Some systems are likely to remain predominantly


and digital signals takes into account a wide

analog for some time, with signal converters

range of presentation needs and technologies

added as needed to accommodate new digital

and, in the long run, is the most prudent and

displays or source devices. For example,

cost-effective approach.

technology budgets for K-12 classrooms
typically do not allow the wholesale upgrade of

Later in this Guide, you’ll find examples of real-

a media system simply to accommodate a new

world applications and the system designs used

technology. Integrating a new, HDMI-equipped

to address the particular needs of the customer

playback source, however, may require nothing

or presentation environment.


more than the appropriate digital extender and
a direct connection to the digital input on the

Matching Technology to Need

projector.

Before undertaking a system design, full
knowledge of the customer’s needs and

Others, such as in university lecture halls

expectations are necessary. Once the primary

and corporate boardrooms, are beginning to

question – analog, digital, or both? – has been

incorporate digital video technologies on a

answered, many more questions remain to be

broader, more systematic scale to accommodate

asked.

the continuously evolving needs for digital media
presentations while maintaining compatibility with


• Is there a requirement for interoperability

existing stores of analog content and playback

between digital and analog components?

equipment. Digital input capability can be added

Depending on the source content, this may not

by changing out the central switcher or scaler

be feasible due to digital rights management

to one that accepts analog and digital signals;

such as HDCP.

conversely, digital displays can be accommodated
through the use of a switcher or scaler that
outputs digital signals.

• Is this an upgrade to an existing system? If so,
is there a need to support legacy devices while
providing the flexibility to address future growth

Finally, specialized applications such as

capability? System longevity is also a key


visualization, simulation, military and medical

consideration in determining the appropriate

imaging, and command and control, are

product solutions.

adopting a fully digital approach that can deliver

4

Extron Digital Design Guide

uncompromised, very high quality, very high

• Is the system expected to span a technology

resolution images – one of the major benefits of

life of many years? If so, perhaps an all-digital

digital video. These system designs are based

infrastructure should be considered to support


the continued evolution of video resolutions.

to destination. In order to compensate for this


System scope and size also determine

limitation, signal conditioning products such as

operational practicality.

equalizers can be used to recover and restore a
signal to distances up to 200 feet (60 meters).

Understanding the true operational requirements

For even longer cable runs, or to accommodate

of any system during the design phase will help

the need to run cable through conduit, digital

control potential cost overruns later. For example,

signals can be converted and distributed using

if there are HDCP requirements, does protected

standard, shielded Category cable, or with fiber

content have to be viewable on all displays within

optic technologies.


The effects of cablerelated losses for digital
signals are far more
noticeable and abrupt,
with sparkles, flashing
images, or complete
image loss all together.

the system, or only in a few, select locations?
Having an operational understanding of a system

Second, there are very specific performance

will go a long way in meeting the needs as well as

and timing parameter requirements that

the budget of the customer.

need to be maintained throughout the entire
signal path. For example, in HDMI, the RGB

Going the Distance

video lines, or channels, must be accurately

A/V professionals face three primary challenges

synchronized in order to be accurately handled

in the handling of digital signals and the


and reproduced throughout the system. Terms

management of their distribution to ensure

such as equalization, jitter, and reclocking in

robust, reliable operation. The first is to maintain

the digital world replace the familiar level and

full signal integrity from source to destination.

peaking terminology of the analog world. Signal

Digital video signals are considerably different in

conditioning requirements for digital signals are

comparison to analog. Digital video signals do

also different and must be understood accordingly

not degrade linearly as with analog video. For

before designing a system.

analog signals, the effects of cable-related losses
worsen gradually with cable length, but for digital


The third challenge in the successful integration

signals the impact is usually far more noticeable

of digital A/V systems is to be able to reliably

and abrupt, with sparkles, flashing images, or

switch, distribute, and route signals. Some digital

complete image loss altogether, as cable length

video connections, including DVI, HDMI, and

increases beyond a “digital cliff” threshold.

DisplayPort, require two-way communication
between a source and a display. If this

Technologies such as DVI, HDMI, and DisplayPort

communication is interrupted, such as following

are primarily designed for short, point-to-point

a disconnection, source switch, or signal split,

connections, for example from a computer to a

image display can be delayed, or even lost


desktop monitor, or from a Blu-ray Disc player

completely. In many cases, the content being

to a flat panel television. Distances in these

used has a direct effect on this communication

applications are relatively short and, in light of

as well. For example, some early scaling DVD

the very high data rates involved and a desire

players with HDMI output did not allow the use of

to reduce cost and power consumption, digital

a repeater, and so the signal ended at the input

source devices can rarely drive a signal more than

of the switcher and was not passed through to

a few feet. Use of high quality, high performance

the display.

cables can help to a degree and, in some cases,

can provide for reliable signal transmission up to

Later in this Guide, you’ll learn in detail about the

75 feet (25 meters) or so. While suitable for most

two primary forms of two-way communication:

consumer applications, this distance limitation

EDID - Extended Display Identification Data, where

can have a serious effect on professional A/V

applicable, DRM - Digital Rights Management.

installations where signals must be routed

Both are extremely important aspects of digital

many tens if not hundreds of feet, from source

signal formats that can significantly impact
www.extron.com

5


The Digital Connection
For reliable

presentation of
protected content
within a system, all
relevant signal paths
must be fully HDCP
compliant.

system reliability if not properly accommodated

player is connected directly to a flat panel display,

and implemented.

but both commercial and residential A/V systems
usually present the necessity of sending signals

In brief, EDID relates to the communication of a

from multiple sources to multiple destinations

display’s performance capabilities, such as its

(see Figure 1-2.) The primary difference, though,

native and supported resolutions, to the source

between residential and professional A/V systems,

connected to it. EDID simplifies system setup,


is the type of content that is being distributed and

in that the display “tells” the source what pixel

displayed on a regular basis.

rate and resolution it prefers, and the source then
outputs the optimum rate and resolution for the

In a home environment, virtually all content is

display, generally resulting in perfect images that

derived from commercial, copyrighted sources:

are accurate on a pixel-for-pixel basis.

movies on Blu-ray, satellite broadcast, or
streamed across the Internet; games on Blu-ray,

DRM is the protection of intellectual property, of

DVD, or solid-state memory; and sports or other

which HDCP - High-bandwidth Digital Content

live entertainment from pay-per-view satellite or

Protection is the most widely implemented.


cable TV sources. In order to protect the rights of

HDCP encryption is found on commercially-

the legitimate owners of this content, digital rights

recorded Blu-ray Discs, high-definition digital

management in general, and HDCP in particular,

satellite and cable television, downloadable

will become common.

content, and more. DRM is a primary concern
in residential applications, where content piracy

Content regularly used in professional A/V

is of great concern to copyright holders, such as

applications, on the other hand, is almost always

motion picture studios, who stand to lose millions

locally generated. This mostly includes the display

of dollars if content is made available through

of Microsoft® applications such as PowerPoint®


unauthorized replication. For reliable presentation

or Excel ®; institutionally-produced video for

of protected content within a residential

training, demonstration, or sales presentations;

entertainment system, all relevant signal paths

and custom or proprietary software applications

must be fully HDCP compliant and conforming

designed specifically for institutional operations

to specific rules. This is relatively simple in the

or command-and-control needs. Very rarely is

typical one-to-one scenario where a Blu-ray Disc

the content used in professional applications

Figure 1-2.

Professional Digital A/V System with HDCP

Blu-ray


Projector

Flat Panel
Display

DVR

Projector

Flat Panel
Display

Projector

Flat Panel
Display

1x4
DA

Flat Panel
Display

4x4
Matrix
Switcher
PC

PC


HDCP Source
HDCP Repeater
HDCP Sink

6

Extron Digital Design Guide


encrypted with HDCP. Typically, rights-managed

is the goal of all system designers. The

content is limited to the occasional use of

implementation of digital signals does not change

commercially-recorded materials, for example

the fact that projectors are mounted on ceilings

when a sales manager wishes to “rally the troops”

with cables routed over long distances or run

by playing a scene from his or her favorite movie.

through conduit. Not every system involves
matrix switching capabilities, but almost every


The key is to select digital products based on

A/V system is designed to accommodate the

the day-to-day requirements of the application

need to split or switch signals, or provide the

for which the system is being designed. In all

signal conversion necessary to introduce analog

applications, proper management of EDID

signals into a digital system, or vice versa.

communications is a must. For residential
applications, compliance with a DRM scheme

Extron offers a wide variety of product solutions

such as HDCP is also mandatory for all system

that address the digital video needs of all market

components. And for commercial applications,

segments. The diversity of product lines brings


DRM must also be considered within the

flexibility and choice, giving designers the means

system design to allow the occasional use of

to address systems at all levels. Augmenting a

commercially-generated content, but may not be

legacy system with digital inputs and distribution

necessary for all system components or for every

capability can help keep upgrade costs down,

signal path within the overall system design.

while still addressing customer needs. Mixed
format systems are easily achievable and can be

Extron Digital Solutions

accommodated in small to large systems with

Professional A/V systems are highly customized,

short to extremely long distance requirements.

each one designed to meet a particular set of


An all-digital system can be designed with various

presentation requirements. Overcoming the

levels of functionality, by utilizing products with

challenges presented by various technologies,

performance features that address the exact

customer needs, or environmental parameters

needs required by the integrator. ■

Extron offers a wide
variety of product
solutions that address
the digital video needs
of all market segments.

www.extron.com

7


Digital Video Signal Formats
HDMI is not the only
digital video standard
found in commercial

A/V environments.
Frequently encountered
digital video formats
include:
DVI
• HDMI
• DisplayPort
• SDI
• HD-SDI
• 3G-SDI
•

The video marketplace is currently dominated

Some, such as SDI, have been in use for

by high resolution plasma and LCD flat panel

many years while others, such as HDMI and

displays, and LCD and DLP projectors. These

DisplayPort, are relatively new and are being

displays are natively digital in their design,

updated continuously through the standards

construction, and operation. Similarly, the vast


revision process. At this point, it is premature

majority of sources that drive these displays,

to predict whether any one of these formats

including computers, DVD and Blu-ray Disc

will ultimately dominate professional A/V. Each

players, high definition digital video recorders or

format has its own technical advantages as well

DVRs, and A/V receivers, are inherently digital

as unique capabilities to meet specific integration

devices. These products stand in contrast

requirements within the A/V industry. Let’s take a

to the traditional, analog video sources and

look at each one in some detail.

displays such as VHS recorders and CRT-based
televisions or data monitors that utilized signal

DVI - Digital Visual Interface


interfaces such as composite video or RGBHV.

DVI and HDMI are based on a common signaling
scheme for video known as TMDS - Transition-

For a digital video source to initiate analog signal

Minimized Differential Signaling. A DVI TMDS link

transmission, its digital output signals must be

consists of three serial data channels, one for

converted to analog video, a process known

each color – red, blue, and green – plus a fourth

as digital-to-analog conversion or DAC. At the

channel carrying a pixel rate clock which provides

receiving end, a digital display must convert these

the timing reference that keeps the three color

analog signals back to digital, a process known

channels synchronized. All TMDS data and clock


as analog-to-digital conversion or ADC. Each

lines are differential, or balanced, and are carried

DAC and ADC conversion introduces errors and

on twisted pairs within DVI cable assemblies.

distortion into the video signal. By employing all-

DVI connector

digital transmission, these unnecessary errors,

To support different resolution requirements, the

as well as the extra expense of ADC and DAC

DVI specification provides for one or two video

circuitry, can be eliminated. See Figure 2-1.

links per connector, commonly known as single
link or dual link, respectively. The maximum pixel

There are several standard signal formats in use

rate for single link DVI is 165 MHz, corresponding

for digital video transmission between sources


to 4.95 Gbps, which is more than sufficient for

and displays. These include:

WUXGA 1920x1200 and HDTV 1080p/60, with a

•DVI - Digital Visual Interface
• HDMI - High Definition Multimedia Interface
• DisplayPort
• SDI - Serial Digital Interface

HDMI connector

color depth of 8 bits per color. Higher resolutions
and greater color depths can be supported by
use of dual link DVI, which handles pixel rates
up to 330 MHz and resolutions as high as
3840x2400.

Figure 2-1.

DAC/ADC Conversions Can Degrade Transmitted Signals
Digital Source Device
Internal
Digital
Functions

Digital Display Device


Unnecessary if source and destination
are both natively digital
ADC

DAC

The DVI specification also provides for two
additional lines of communication, both of

Internal
Digital
Functions

which are essential in achieving successful DVI
transmission between devices (see Table 2-1).
The DDC - Display Data Channel is a serial
connection for EDID and HDCP communication.
The HPD - Hot Plug Detect pin allows for
implementation of hot plug detection, which

Original digital
video pixels

8

Extron Digital Design Guide

Transmitted analog
video with errors
due to DAC non-linearities


Reconstructed digital
video pixels with
additional distortion
caused by ADC
quantization errors

allows a computer, for example, to detect the
presence of a display without user intervention.


VGA - VESA

E-DDC host assignment

HDMI
type A

Table 2-3.

The DVI specification provides for two types of

HDMI 1.3 Basic
Performance Parameters

connectors: DVI-D, the standard connector, and
DVI-I, which can carry analog RGBHV as well as
digital signals.
DVI is a royalty-free standard originated by the


Table 2-2. HDMI pin configurations
PIN

FUNCTION

PIN

FUNCTION

✔ Performance:
- DVI compatible
- 25-340 MHz
- Upward of 10 .2 Gbps data speed
- Color depth: 24-bit, plus 30, 36,
and 48-bit Deep Color
- Color space: ITU-R BT709-5,
xvYCC

1 DisplayPort
TMDSData2+
source-side

11

TMDSClockShield

2

TMDSData2Shield


12

TMDSClock-

1.0 of the DVI specification was released in

3

TMDSData2-

13

CEC

April 1999, and there have been no subsequent

4

TMDSData1+

14

N/C

revisions since then.

5

TMDSData1Shield


15

SCL

6

TMDSData1-

16

SDA

✔ Integratedvideo,audio,and
contentprotection

7

TMDSData0

17

DDC/CECGround

✔ Highlevelconsumercontrol

8

TMDSData0Shield

18


+5VPower

9

TMDSData0-

19

HotPlugDetect

10

TMDSClock+

DDWG - Digital Display Working Group. Version

HDMI - High Definition Multimedia
Interface
The HDMI format incorporates the TMDS video

✔ Simple,plugandplay
connection
✔ Onlyonecablerequired

✔ Autolipsync

Table 2-4.

functionality of DVI and extends TMDS to

carry digital audio and control information. By

June 2002. The current version is HDMI 1.3,

consolidating high definition video, audio, and

released in August 2006. Compared to previous

control into a single, compact connector, HDMI

versions, HDMI 1.3 specifies a twofold increase

has been very successful in the consumer audio/

in the maximum TMDS single link clock rate to

video market (see Table 2-2).

340 MHz, corresponding to 10.2 Gbps (Table
2-3). The increased bandwidth of HDMI 1.3

The most common HDMI connector is the 19-pin

enables up to 16 bits per color – also known as

Type A, which contains a single TMDS link plus

Deep Color, an extended color space, the latest

DDC and HPD lines. A 5 volt power supply line


high resolution surround sound audio formats

is also provided. In addition, HDMI connectors

for Blu-ray Disc, and video resolutions up to

incorporate the CEC - Consumer Electronics

WQXGA 2560x1600. Version 1.3 also mandates

Control line, which is used for integrated control

the inclusion of High-bandwidth Digital Content

of multiple devices within an A/V system. At

Protection or HDCP, a digital rights management

this time, CEC control protocols are proprietary

scheme that prevents the copying of digital video

to each equipment manufacturer, and there is

and audio content. The next version, HDMI 1.4

no CEC compatibility between manufacturers.

(Table 2-4) was recently announced and the


However, there are implementation guidelines for
CEC and manufacturers are beginning to work

DVI-I Dual Link
analog and digital

DVI-D Dual Link

HDMI 1.4
Enhanced Functionality
✔ HDMIEthernetChannel:
- Bi-directional data channel
supporting 100 Mbps Ethernet
connectivity
- Allows multiple devices to share
one network connection
✔ AudioReturnChannel:
- Returns upstream audio from
a display's internal tuner to a
receiver
✔ Supportshighermaximum
resolutions:
- 3840x2160 at 24 Hz, 25 Hz, and
30 Hz
- 4096x2160 at 24 Hz
✔ 3DSupportupto1080p
✔ Additionalcolorspacesupport:
- Provides enhanced color
accuracy with digital still cameras

✔ NewHDMIMicroConnector:
- Approximately 50% smaller than
current HDMI mini connector

DVI-I Single Link

digital only

analog and digital

DVI-D Single Link
digital only

together to develop standardized control.
Other HDMI connector variations include Type
B, a connector intended to support dual link

Table 2-1. DVI pin configurations
PIN #

SIGNAL NAME

PIN #

SIGNAL NAME

PIN #

SIGNAL NAME


HDMI applications but one that has not yet

1

TMDSData2-

9

TMDSData1-

17

TMDSData0-

been implemented; and Type C, a miniaturized

2

TMDSData2+

10

TMDSData1+

18

TMDSData0+

connector designed for portable equipment such
as consumer camcorders.


3

TMDSData2/4Shield

11

TMDSData1/3Shield

19

TMDSData0/5Shield

4

TMDSData4-

12

TMDSData3-

20

TMDSData5-

5

TMDSData4+

13


TMDSData3+

21

TMDSData5+

6

DDCClock[SCL]

14

+5VPower

22

TMDSClockShield

The HDMI specification and licensing is

7

DDCData[SDA]

15

Ground(for+5V)

23


TMDSClock+

administered by HDMI Licensing, LLC. In contrast

8

Analogverticalsync

16

HotPlugDetect
VGA - VESA

24

TMDSClock-

to DVI, the HDMI specification has evolved

C1

AnalogRed

C5

AnalogGNDReturn:
(analogR,G,B)

C3


AnalogBlue

C2

AnalogGreen

--

--

C4

AnalogHorizontalSync

through several standards revisions. Version
1.0 of the HDMI specification was released in

E-DDC host assignment

www.extron.com
HDMI
type A

9


HDMI
type A


Digital Video Signal Formats
DisplayPort is capable
of supporting Deep
Color, multi-channel
high resolution audio,
and video resolutions
well beyond WUXGA
1920x1200 and
HDTV 1080p/60.

specification is expected to be published by

DisplayPort
source-side

June 30, 2009.

DisplayPort

Table 2-5. DisplayPort pin configuration (Source-side)

DisplayPort is a royalty-free digital interface

PIN

between sources and displays that is being

1

ML_Lane0(p)


11

GND

positioned as a low-cost alternative to HDMI for

2

GND

12

ML_Lane3(n)

PC equipment manufacturers. DisplayPort uses a

3

ML_Lane0(n)

13

GND

digital video transmission scheme that differs from

4

ML_Lane1(p)


14

GND

5

GND

15

AUXCH(p)

6

ML_Lane1(n)

16

GND

7

ML_Lane2(p)

17

AUXCH(n)

8


GND

18

HotPlugDetect

Type A and Type C connectors, can be used to

9

ML_Lane(n)

19

Return

pass HDMI signals, provided that the device

10

ML_Lane3(p)

20

DP_Power

TMDS and is therefore not directly compatible with
HDMI and DVI. However, the 20-pin DisplayPort
connector, with characteristics similar to the HDMI


FUNCTION

PIN

FUNCTION

supports HDMI (see Table 2-5). For example, if
a video source only has a DisplayPort connector,

In addition to zero licensing fees, DisplayPort

but also has HDMI signaling capability, then it is

is intended to provide further cost savings by

possible to use a DisplayPort-to-HDMI adapter

unifying the interface signals for both internal and

to connect the source to an HDMI-equipped

external connections within a device, such as the

display. Such DisplayPort connections, referred to

connection between the motherboard and display

as “dual-mode” or “multi-mode,”


on a laptop PC. The VESA - Video Electronics

are symbolized by a special logo

Standards Association released the initial version of

to indicate this capability:

the DisplayPort standard in 2006. The most recent
revision, 1.1a, was released in January 2008.

DisplayPort video and audio signals are carried

DisplayPort connector

on four lanes of differential wires, with each

SDI - Serial Digital Interface

lane running at either 1.62 Gbps or 2.7 Gbps

SDI is a set of video standards, defined by the

for a maximum data rate of 10.8 Gbps. As with

Society of Motion Picture and Television Engineers

HDMI 1.3, DisplayPort is capable of supporting

or SMPTE, for serial transmission of video and


Deep Color, multi-channel high resolution audio,

audio over standard RG59 or RG6 coaxial cable

and video resolutions well beyond WUXGA

(see Table 2-6). SDI standards encompass a

1920x1200 and HDTV 1080p/60. Analogous

variety of data rates from 270 Mbps to 2.97 Gbps

to the DDC channel for HDMI, DisplayPort

per link and are primarily utilized on professional

connectors provide for a differential AUX channel

broadcast and video production equipment,

for EDID communication. In addition, DisplayPort

with secondary use in live events, rental and

incorporates digital rights management similar

staging, medical imaging, digital cinema, and

to HDCP - DisplayPort Content Protection


telepresence cameras and recording devices.

or DPCP.

An SDI-based video infrastructure is becoming
increasingly popular for A/V signal distribution,

Table 2-6. SMPTE - Society of Motion Picture and Television Engineers SDI Standards

due to the benefits of inexpensive or existing
cabling, ease of termination, and transmission

STANDARD

NAME

DATA
RATE

VIDEO
FORMAT

COLOR
ENCODING

COAX
DISTANCES

SMPTE 259M-C


SDI

270Mb/s

480i,576i

4:2:2YCbCr

300meters

for HD-SDI and 3G-SDI signals. SDI is strictly a

1.485Gb/s 720p,1080i,1080p/30 4:2:2YCbCr

100meters

serial, one-way protocol for video, audio, and

distance capabilities up to 330 feet (100 meters)

SMPTE 292M

HD-SDI

SMPTE 372M

DualLinkHD-SDI

2.97Gb/s


1080p/60,2K

various

100meters

metadata such as time and date stamps or GPS

SMPTE 424M

3G-SDI

2.97Gb/s

1080p/60,2K

various

100meters

coordinates, with no provisions for other auxiliary
communications. ■

10

Extron Digital Design Guide


Anatomy of a Digital Video Signal

Digital video signals are considerably different
in comparison to traditional analog video
signals, with specific performance and timing

Clock Period

requirements that must be maintained throughout

Signal
Swing

the entire signal path. Terms such as equalization,
jitter, and reclocking in the digital domain replace
the familiar level and peaking terminology for

Low
Level

analog signals. Signal conditioning requirements
for digital signals are also different, and must

Clock Period

High
Level

Fall
Time

Rise

Time

Figure 3-1. Digital Data Parameters

be understood accordingly before designing a
digital-based A/V system.
All standard digital video signal formats, including

disappears, otherwise known as cliff effect. This

SDI, DVI, HDMI, and DisplayPort are synchronous,

is in contrast to analog transmission, whereby the

that is, the value of a synchronous digital signal

receiver’s output gradually degrades as the signal

may change only at specific intervals determined

worsens, but still remains viewable long into its

by a reference signal known as the clock. Digital

degraded state.

video signals are binary in nature - the signal can
be either a high or a low level, with rapid transitions

One of the key contributors to timing errors is


in between (see Figure 3-1). The amount of time

jitter. Jitter is defined as the variation of the clock

it takes for a digital signal to transition from low

period in relation to the reference clock signal.

to high is known as the rise time, and the time it

Jitter can occur over long lengths of low quality

takes for the signal to transition from high to low

cable, or through the cumulative effect caused

is known as the fall time. The difference between

Period
by cascading several
digital devices Clock
between
the
High

the high and the low values of the signal level is

source and the destination.


Level

called the signal swing. The minimum allowable

Jitter can occur over
long lengths of low
quality cable, or
through the cumulative
effect caused by
cascading several
digital devices or
cables between
the source and the
Clock Period
destination.

Signal

time interval between transitions is known as the

Swingin quantifying digital
Eye diagrams are useful

clock period.

signal integrity. They can be produced on an
Low

oscilloscope by sampling
a series of digital pulses

Level
Because it is binary, a digital signal is fundamentally
robust, since a receiver only needs to distinguish

Clock Period

in
succession,
and overlaying theRise
samples on the
Fall
Signal
Level
Time

Uncertainty

oscilloscope display (see Figure 3-2).

Time

between “high” and “low” levels for each clock
period in order to completely reconstruct the
original transmission. However, this becomes
increasingly difficult as the signal swing is
decreased and as timing becomes less accurate.
Rise and fall times, signal swing, and timing
accuracy are all subject to degradation in digital

Usable

Signal
Swing

Minimum
Eye Opening
Mask

Figure 3-2. An eye diagram is
formed by repeated sampling
of a digital signal.

Signal Level
Uncertainty

Timing Jitter/Uncertainty

Timing Jitter/Uncertainty

signal transmission caused by cable attenuation,
cable capacitance, impedance mismatch, noise
coupling, crosstalk, and so forth. It is important
to quantify the amount of signal degradation
so that standards for signal integrity can be
defined. If the signal is degraded beyond the
receiver’s ability to distinguish high and low signal
values with correct timing, the receiver’s output
abruptly becomes meaningless, and the signal
www.extron.com

11



Anatomy of a Digital Video Signal
cable capacitance and attenuation will degrade
Clock Period
Signal Level
Uncertainty

signal rise time and amplitude as cable length
increases. Since DVI, HDMI, and DisplayPort
signals are transmitted over twisted pair-type

Minimum
Eye Opening
Mask

Usable
Signal
Swing

cables, skew is introduced at long cable lengths
due to the variations in twist rates of individual
wire pairs in the cabling, which in turn impacts the

Signal Level
Uncertainty

relative timing between the video data lines. The
Timing Jitter/Uncertainty


Timing Jitter/Uncertainty

Figure 3-3. Eye Diagram Parameters

compromised “eye” pattern in Figure 3-4 shows
the resulting distortion caused by attenuation
losses and skew-related timing errors from long

The resulting diagram displays the aggregated

cable lengths. The resulting waveform encroaches

levels and timing characteristics of the signal

on the limit mask, which potentially leads to erratic

being transmitted (see Figure 3-3). The open, eye-

images, or no image displayed at all.

shaped regions between the waveforms give the

The direct signal
output for the source
device is often
assumed to be good,
but just one adapter
or low quality cable
may degrade the
signal to the extent

that no image is
displayed.

“eye” diagram its name. To determine whether

Signal conditioning can be applied within digital

the value of the signal is “high” or “low,” the signal

video equipment via features such as inputsignal

should be captured at intervals corresponding

equalization and output signal reclocking.

to the midpoints within these regions. These

These advanced features provide compensation

intervals are also the midpoints in time between

for losses experienced throughout the signal

signal transitions. The smaller the opening of the

chain. It is important to note that such losses

eye, the more difficult it is to accurately determine

are not limited to the signal path, but may also


the signal value. Digital video format specifications

be related to the source device itself. The direct

include required values for eye openings as

signal output from the source device is often

minimum standards for signal integrity. These

assumed to be good, but this is not always the

values can be overlaid onto eye diagrams as a

case. Awareness of this is key to managing the

reference or limit “mask” when making signal

integrity of the overall system. In situations where

quality measurements.

long cable lengths are unavoidable, active cable
equalizers can be deployed to restore signal

Maintaining Digital Signal Integrity

integrity and extend drive distances. Active


A clean digital signal path is crucial for signal

equalizers are designed to compensate for the

integrity. Cable lengths should not exceed the

effects of long cable runs. Special amplifiers and

driving capability of digital signal sources, as

filters matched to cable losses restore signal
swing as well as rise and fall times. Clock and data
recovery circuitry can remove jitter and restore
clock timing, resulting in a measurable opening

Assessing signal integrity using a standardized minimum eye opening mask

of the signal eye pattern. Figure 3-5 shows the
result of signal conditioning applied by the Extron
DVI 201xi Twisted Pair Extender to the distorted
“eye” pattern in Figure 3-4. Signal conditioning
features including input equalization and output
reclocking are common to many Extron digital
product solutions.
As video resolutions and associated signal

Figure 3-4. Fail

Figure 3-5. Pass


frequencies increase, the signal becomes more
and more susceptible to discontinuities along

12

Extron Digital Design Guide


the cable. Such discontinuities cause reflections
which will degrade the signal. Therefore, the

Substantial signal degradation caused by simply inserting a DVI gender changer

bend radii of cables should be kept as large as

DVI
Female to Female
Adapter

possible, and cable splices, joiners, or gender

6 ft. (1.8 m) DVI Cable

changers should be avoided. Figure 3-6 depicts
the substantial degradation that can be caused by
simply inserting a gender changer between two

6 ft. (1.8 m)
DVI Cable


6 ft. (1.8 m)
DVI Cable

cables. In this example, the eye diagram shows
the result of a 1920x1200 source signal passing
through a 6 foot (1.8 m) DVI cable, then through
a DVI female-to-female coupler, and finally an

Figure 3-6.

additional 6 foot DVI cable. This emphasizes
the importance of proper design considerations

or fiber optic cable. This approach provides a

for management of all high resolution digital

means to conveniently route cabling through

signals. System interconnects should be kept

walls and within furniture, the convenience of field

to a minimum, and signal distribution equipment

terminating connectors, and the ability to send

should always feature signal conditioning

signals extended distances.


capabilities to best accommodate specific design
challenges that may compromise digital video

Category 5-type twisted pair cable offers a cost-

signal integrity.

effective, easily installed and terminated option
for digital signal transmission distances up to 200

Solutions for Extending Digital
Video Signals

feet (60 meters). For longer distance transmission

The customized nature of professional A/V

applications where security or outside electrical

systems usually presents many digital video

interference are of concern, fiber optic products

distribution challenges to the integrator, including

may be selected for a variety of reasons:

the need to send signals over significant
distances. Extron offers a variety of products

for specific digital video formats to help meet
infrastructure-related requirements. For example,
most installations call for cable runs of 35 feet
(11 m) or beyond, and also require that cables be
managed within walls and up into ceiling spaces.
This can be a problem with standard digital cable
assemblies, since the connectors are often too
large to conveniently run through conduits and

requirements, up to several miles, and for

System interconnects
should be kept to a
minimum, and signal
distribution equipment
should always feature
signal conditioning
capabilities.

• High image quality – Pixel-for-pixel performance up
to 1920x1200 resolution
• Long distance transmission – Image quality can be
maintained at distances up to 30 km
• Immunity to outside interference – Can be utilized
in environments that can’t be served by copperbased cabling. such as elevator shafts or near
HVAC and other electric machinery
• Ideal for secure environments – Well-suited for
government, military, and judicial environments ■

raceways, and terminating HDMI and DVI cables

1" Conduit
OD = 1.16" (29.5 mm)
ID = 1.05" (26.6 mm)

in the field is difficult with very few tools available
(see Figure 3-7). Even when this is possible,
most standard cable assemblies offer insufficient

Type A (Female) HDMI
Width = .547" (13.9 mm)
Height = .175" (4.45 mm)

performance to send signals over significant
distances. Fortunately, products and solutions
are available that offer the flexibility to address

0.53"
(13.46 mm)

specific system needs. A popular alternative to
standard cable assemblies is to use an active
transmitter and receiver pair to send digital
signals over standard, shielded Category 5-type

0.80"
(20.32 mm)

Figure 3-7. Running a preterminated HDMI cable
through conduit can be inconvenient


Formoreinformation,seeExtron’swhite
paperatwww.extron.com/digitalvideopaper

www.extron.com

13


Understanding EDID - Extended Display Identification Data
EDID is used
by a display to
communicate
information to a
source device about
the range of signals
it can support as
well as additional
information such as
native resolution and
preferred timing.

What is EDID?

with data formatting defined by the EDID

EDID data exchange is a standardized means for a

specification.

display to communicate its capabilities to a source

device. The premise of this communications is for

As display types and capabilities increased, 128

the display to relay its operational characteristics,

bytes became insufficient, and both EDID and

such as its native resolution, to the attached

DDC were extended so that multiple 128-byte

source, and then allow the source to generate

data blocks could be exchanged. This is known

the necessary video characteristics to match

as E-EDID and has been implemented in many

the needs of the display. This maximizes the

consumer devices. In fact, the CEA - Consumer

functional compatibility between devices without

Electronics Association has defined its own EDID

requiring a user to configure them manually, thus


extensions to cover additional video formats

reducing the potential for incorrect settings and

and to support advanced multi-channel audio

adjustments that could compromise the quality

capabilities.

of the displayed images and overall reliability of
the system.

What EDID information is exchanged
between display and source?

Where is EDID utilized?

The base EDID information of a display is

Generally, the source device will be a computer

conveyed within a 128-byte data structure (see

graphics card on a desktop or laptop PC, but

Table 4-2) that contains pertinent manufacturer

provisions are in place for many other devices,


and operation-related data. The current EDID

including HDTV receivers and DVRs, DVD and

version defines the structure as follows:

Blu-ray Disc players, and even gaming consoles,

Table 4-1.

EDID Development History
EDID

Defines the data
structures sent from a
video display to a source
over E-DDC lines to
describe its capabilities

to read EDID and output video accordingly.

Vendor/ProductIdentificationBlock – The first

Originally developed for use between analog

18 bytes identify the display manufacturer and

computer-video devices with VGA ports, EDID is

product, including serial number and date of


now implemented for DVI, HDMI, and DisplayPort.

manufacture.

History

EDIDStructureVersion&Revision – The next

EDID was developed by VESA - the Video

two bytes identify the version and revision of the

EDID 1.0

Defined original
128-byte data structure
(Deprecated)

Electronics Standards Association, with version

EDID data within the structure.

EDID 1.1

Defined some
alternative uses for
space in data structure
(Deprecated)


DDC standard. See Table 4-1.

1.0 introduced in 1994 within version 1.0 of the
five bytes define characteristics such as whether
Prior to the development of EDID, pins 4, 11, 12,

the display accepts analog or digital inputs, sync

and 15 on the VGA connector were sometimes

types, maximum horizontal and vertical size of the

used to define monitor capabilities. These ID bit

display, gamma transfer characteristics, power

pins carried either high or low values to define

management capabilities, color space, and

different screen resolutions. VESA extended

default video timing.

EDID 1.2

Defined some
alternative uses for
space in data structure
(Deprecated)


EDID 1.3

Current definitions for
128-byte EDID data
fields

EDID 2.0

Introduced new
256-byte data structure

this scheme by redefining VGA connector pins

E-EDID

Defined optional
additional 128-byte
extension blocks for
EDID 1 .3, incorporated
EDID 2 .0 as optional
extensions

DisplayID

14

Introduced variable
length data structure


Extron Digital Design Guide

Basic Display Parameters/Features – The next

9, 12, and 15 as a serial bus in the form of the

ColorCharacteristics – The next 10 bytes define

DDC - Display Data Channel. This allowed for

the RGB color space conversion technique to be

much more information to be exchanged, so that

used by the display.

EDID and other forms of communication were
possible between the source and the display.

Established Timings – The next three bytes
define the VESA-established video resolutions/

The original DDC protocol defined 128 bytes

timings that are supported by the display. Each

to be sent from the display to the video source,

bit represents an established timing such as



640x480/60. The last of the three bytes defines

EDID information is typically exchanged when the

the manufacturer’s reserved timing, if any.

video source starts up. The DDC specifications
define a +5V supply connection for the source to

StandardTimingIdentification – The next 16

provide power to a display’s EDID circuitry so that

bytes define eight additional video resolutions

communication can be enabled, even if the display

supported by the display. These resolutions must

is powered off. At startup, the video source will

adhere to standard VESA defined timings.

send a request for EDID over the DDC. The EDID/
DDC specifications support hot plug detection,

DetailedTimingDescriptions – The next 72

so that EDID information can also be exchanged


bytes are organized into four 18-byte blocks that

whenever a display is re-connected to a video

describe additional video resolutions in detail,

source. Hot plug detection is not supported

so that custom video timings/resolutions can be

for VGA, but is supported in digital interfaces

supported. The first of the four blocks is intended

including DVI, HDMI, and DisplayPort. For these

to describe the display’s preferred video timing.

interfaces, the display device will supply a voltage

The timing data can be structured according to

on an HPD - Hot Plug Detect pin, to signal to

the VESA GTF - Generalized Timing Formula or

the video source device that it is connected. The

CVT - Coordinated Video Timings standards.


absence of a voltage on the HPD pin indicates

Consumer displays
are prevalent
in commercial
environments. Before
EDID 1.3, EDID data
was not properly
communicated
between the consumer
displays and PC’s.

disconnection. The video source device monitors
ExtensionFlag – EDID versions 1.3 and higher

the voltage on the HPD pin and initiates EDID

allow for additional 128-byte blocks of data

requests as it senses incoming voltage.

to describe increased capabilities. This byte
indicates the number of additional extension
blocks available. Various structures for these
extension blocks have been defined, including
DI-EXT - Display Information Extension,
VTB-EXT - Video Timing Block Extension, and
LS-EXT - Localized String Extension. But the


Table 4-2. EDID File Structure

Address
(Decimal)

Data

0-7

Header

most prevalent extension is CEA-861, which

8-9

Manufacturer ID

was defined to support advanced capabilities

10-11

Product ID Code

of consumer devices incorporating HDMI. The

12-15

Serial Number

significance of the CEA-861 extension is that it


16-17

Manufacture Date

aims to address previous operational disparities

18

EDID Version #

19

EDID Revision #

20

Video Input Type

21

Horizontal Size (cm)

22

Vertical Size (cm)

23

Display Gamma


experienced with integrating consumer-based
display devices into computer-based commercial
A/V systems, allowing for proper conveyance of
EDID information between devices.

24

Supported Features

EDID/DDC Protocols

25-34

Color Characteristics

The DDC uses a standard serial signaling scheme

35-36

Established Timings Supported

known as the I2C bus. I2C is used extensively

37

Manufacturer's Reserved Timing

where electronic devices and components need


38-53

EDID Standard Timings Supported

54-71

Detailed Timing Descriptor Block 1

to exchange information, due to its simplicity,

72-89

Detailed Timing Descriptor Block 2

I2C bus consists of three wires: SDA (data), SCL

90-107

Detailed Timing Descriptor Block 3

108-125

Detailed Timing Descriptor Block 4

(clock), and a logic “high” DC pull-up voltage.

126

Extension Flag


127

Checksum

low pin count, and bi-directional capability. An

For the DDC, the logic “high” voltage is specified
to be +5V.

General Description
Constant Fixed Pattern

Display Product Identification

EDID Version Information

Basic Display Parameters: Video input
type (analog or digital), display size, power
management, sync, color space, and
timing capabilities and preferences are
reported here .
Color Space Definition

Timing information for all resolutions
supported by the display are reported here

Number of (Optional) 128-byte Extension
Blocks to Follow

www.extron.com


15


Understanding EDID - Extended Display Identification Data
EDID management
is most important
when multiple
displays with varying
native resolutions
are integrated into
multi-source A/V
environments.
Inconsistent video
output can be avoided
by utilizing products
that properly manage
EDID.

EDID Issues
Display devices can have various levels of
EDID implementation and, in some cases, they
may lack EDID information altogether. Such
inconsistencies can cause operational issues
ranging from overscan and resolution problems,
to the display device not displaying the source
content at all.
The following are examples of some potential
issues with EDID communications, along with the


reducing the likelihood of no image being displayed. If
this does not match the native resolution the display,
fonts will likely appear to be abnormally large, small,
or fuzzy.
• The PC is connected to multiple displays with
different native resolutions. Since it can only read
EDID from one display, the output will be mismatched
in resolution with all other displays, resulting in less
than optimal image quality, or no image displayed at
all. This issue is a common occurrence in professional
systems when digital video signals need to be
distributed or routed to multiple displays.

possible causes:
Problem
Noimageisshownonthedisplay.
PossibleCause
• The source device, such as a PC graphics card, or
laptop, cannot read the EDID information from the
display. As a result, in some cases the PC will not
output any video signal.

EDID Tools
Third-party software can be used to help
troubleshoot possible compatibility issues
between the display device and the source. A
Google search using “EDID viewer” will result
in many usable tools, such as those offered by
ViewSonic including EDID Editor or EnTech Monitor Asset Manager. These tools allow you to


Problem

read the display’s EDID and determine whether

The display loses the image when a new
sourcehasbeenselected.

a graphic card and the display device may be
experiencing EDID handshake problems.

PossibleCause
• This is a common occurrence with VGA sources, due
to the lack of hot plug detection.
• While hot plug detection is supported for DVI, HDMI,
and DisplayPort, EDID communication problems
can arise from inconsistencies in the implementation
of HPD signaling between devices from different
manufacturers. This frequently becomes an issue
for professional integration, since the ability to switch
digital video signals is a necessity.

located displays and often include multiple
source devices. It is important to realize this can
potentially contribute to EDID-related issues. The
necessity to switch, distribute, and route signals
from sources to displays presents a considerable
challenge in terms of ensuring proper EDID
communications and therefore reliable system
operation.


nimageisshown,butthesourceresolution
A
doesnotmatchthatofthedisplay.

While there is not always a solution to every

PossibleCause

EDID-related problem, Extron products include

• The PC is able to read the EDID information, but
the graphics card limits the output resolution to
XGA 1024x768, a resolution most displays can
accommodate, ensuring a usable image and
Extron Digital Design Guide

A/V systems typically comprise several remotely

Problem

• A PC cannot read the EDID information, so it defaults
to a standard resolution, such as 640x480. If the user
subsequently attempts to manually set the resolution
to match the display, some graphics card drivers
may enforce the lower default resolution and create a
scrolling/panning desktop without actually changing
the video resolution.

16


EDID Solutions

features to help prevent or solve many of them
by properly managing EDID communications
between sources and displays in A/V systems.
These features provide automatic and continuous
EDID management with attached source devices,
ensuring proper power-up and reliable output of
content.
EDID Emulation is a feature of many Extron
DVI and HDMI products, including switchers,


distribution amplifiers, and matrix switchers. It

algorithm to determine a common resolution,

maintains constant EDID communication with

refresh rate and color space, and then uses

source devices by providing pre-stored EDID

the EDID protocol to set up the input sources.

information for various signal resolutions. A user

This powerful convenience feature simplifies

can select the desired signal resolution, and then


system setup for the integrator, helps ensure

the corresponding EDID block is conveyed to all

consistent and reliable image display, and makes

attached source devices. This EDID information

system operation virtually transparent to the

is constantly available to the sources, even in a

end user. ■

switching application where inputs are regularly
selected and de-selected. The output of the
sources should match the native resolution of the
intended display device.
EDID Minder ™ is an advanced, Extronexclusive technology for EDID management.
It encompasses EDID Emulation, but also
incorporates an additional level of “intelligence.”
Extron products with EDID Minder can

Extron EDID Minder
captures, stores,
and conveys EDID to
connected sources to
ensure proper, optimal
video format output.


communicate with the display device, and
automatically capture and store EDID information
from the display (see Figure 5-1). This captured
information can then be used as the reference
EDID for the sources. EDID Minder is a standard
feature in most Extron DVI and HDMI extenders,
switchers, distribution amplifiers, and matrix
switchers, as well as products that incorporate
DVI or HDMI switching.

Extron EDID 101 D Emulator for DVI
with EDID Minder
Formoreinformation,seeExtron’swhite
paperatwww.extron.com/edidpaper

The functional role of a given product as a
distribution amplifier, switcher, or matrix switcher
determines the complexity of EDID Minder
implementation. Matrix switching environments
represent the most difficult EDID management

Figure 5-1. EDID Minder Communications

situation, with simultaneous EDID communications
required for multiple inputs and outputs. The
displays connected to the outputs are very likely

EDID


OK, sending
video to fit
your format.

Output

Video

to be of different models and native resolutions.
The EDID information between them is different
and needs to be conveyed to the source devices.
Proper EDID management within the system is
crucial to consistent and reliable operation.
Extron HDMI and DVI matrix switchers with
EDID Minder achieve this by managing EDID
communications for each input/output tie. EDID
Minder first analyzes the EDID for all displays

Video
EDID Minder

Input

Video
EDID Minder

OK, here is my
native resolution
and vertical
refresh rate.


Input

Video
EDID Minder

Input

connected to the system, applies a complex
www.extron.com

17


DRM for the A / V Professional
What is DRM?

familiar adage of “Just because one can, doesn’t

DRM - Digital Rights Management is used by

mean one should” is fully appropriate in this case.

owners and holders of IP - Intellectual Property to

HDCP-compliant systems are increasingly being

enforce restrictions on the use of their copyrighted

requested by customers and integrators alike. This


content.

type of system could be used to show protected
content in public spaces. Therefore, users should

In the A/V industry, DRM is used to secure digital

be made aware of the potential issues that may

music and video content to prevent unauthorized

arise from inadvertent public display of private-

playback or copying. For digital video content

use, content-protected materials. During system

protection, the most prevalent DRM systems

commissioning and training, the integrator should

are HDCP - High-bandwidth Digital Content

consider educating system operators, and even

Protection and AACS - Advanced Access Content

include discussion of DRM and content protection


System. HDCP is an encryption protocol applied

within system documentation. Of course, this is

to digital interfaces including HDMI, DVI, and

not as much of an issue for residential installations,

DisplayPort. AACS is a standard for encrypting

where the entire system is generally intended for

high definition optical discs that also works in

personal use.

conjunction with HDCP.

Users should be made
aware of the potential
issues that may arise
from inadvertent
public display of
private-use, contentprotected materials.
Multiple display system in a public space
environment.

DRM exists to protect the rights of content

DRM for Video - Separate Protocols

That Work Together

creators and owners to receive compensation

HDCP is designed to prevent unauthorized

for their initial ideas and subsequently bringing

access of protected video content and to enforce

them to market. Movies and music are the

restrictions on authorized playback. HDCP-

most recognized source content within the A/V

enabled video sources, such as Blu-ray Disc

industry that is impacted by DRM enforcement.

players, PCs, and other digital media devices

An individual who purchased a copy-protected

always undergo through a three-step process to

Blu-ray Disc, for example, is entitled to utilize

protect the video from unauthorized access:


that disc only within a personal-use environment,
which extends to the home or other private

1.Authentication: The video source determines

viewing locale. For that movie to be played in a

that all devices connected to its outputs are

public space, additional licensing requirements

authorized and able to receive encrypted video. This

must first be met. If that licensing has not been

is accomplished by means of an initial authorization

obtained, significant fines can be levied against

handshake protocol, where cryptographic public

the offender. These fines may very well extend to

keys, KSV - Key Selection Vector, and encrypted

the owner of the installed system.

messages are exchanged between the source and
the downstream devices connected to its outputs.


18

Extron Digital Design Guide

A/V systems in public spaces are the center of our

The HDCP 1.3 specification calls for a maximum of

industry, with installations taking place on a daily

127 simultaneous devices connected downstream

basis. It is for this reason that DRM considerations

from the source, and up to seven allowable levels

must be made and addressed at the earliest point

of repeater devices between the source and the

of system design. The time when needs are being

display - also known as the sink. The source uses

assessed for an A/V integration project is also the

the initial handshake protocol to determine that

time to determine the functional requirements of


these system size restrictions are not violated.

a given system. This is when the sales engineer

HDCP version 1.3 is the currently implemented

should ask the right questions and inform the

specification. As will soon be discussed, the latest

prospective customer on the legalities involved

version, HDCP 2.0, further restricts the allowable

with personal-use devices and/or material being

maximum number of simultaneous devices and

used in public and commercial spaces. The old,

repeater levels.


2. Content Encryption: After the source

With the release of version 2.0 in October 2008,

authenticates that all downstream devices are

HDCP became interface-independent, and can


HDCP compliant and in good standing, and

be applied to any two-way digital transmission

that no system size restrictions are violated, the

between sources and displays, wired or wireless,

source sends encrypted video downstream. The

compressed or uncompressed. See Table 5-1.

source periodically revises the encryption key for
the video as an additional security measure.

HDCP 2.0 calls for many other important changes.
For wireless connections, HDCP 2.0 adds a

3.Renewability: Since HDCP relies on digital

locality check to the authentication protocol, to

encryption using secret keys, the system can

ensure that only devices nearby will be able to

be circumvented if the secret keys residing in

receive protected content. Furthermore, HDCP


HDCP-licensed products fall into the wrong

2.0 replaces the specialized 56-bit HDCP 1.x

hands. Therefore, a means has to be established

encryption scheme with two standard algorithms

to revoke any compromised keys. The HDCP

from the data security industry: for authentication,

administration authority, Digital Content

an RSA system with 1024 and 3072-bit keys; and

Protection, LLP can add a list of public keys of

for content encryption, a 128-bit AES - Advanced

compromised products to video content such as

Encryption System. In addition, the maximum

Blu-ray Disc. Video sources will read this data,

number of connected devices is reduced to 32,

store it in non-volatile memory, and compare the


and the maximum level of repeaters is reduced to

public keys of any downstream devices against

four. As of result of all these changes, HDCP 2.0

this revocation list. If any key matches, no video

is not directly backward compatible with HDCP

will be transmitted.

1.x. The new specification provides for converters

When switching
between sources, HDCP
authentication needs
to be re-established
between the new source
and display. Depending
on the number of
devices within the
system, this can cause
the displayed image to
be delayed.

between HDCP 1.x and HDCP 2.0 devices to
Figures 5-1 and 5-2 on the next page provide a


support mixed A/V systems with devices that

step-by-step illustration of the communications

comply with both versions. These converters are

that occur between source and sink devices

important, because the HDCP license agreement

within an HDCP-based system.

requires that licensees support any new
specification within eighteen months of release.

The multi-step process of HDCP authentication
can take several seconds to complete. This is a
primary reason for the perceived sluggishness
of some digital video systems, especially during
startup and when video signals are switched

HDCP 1.x

or re-routed, requiring HDCP re-authentication.
The best switching performance can be realized
in HDCP-compatible video equipment built

Encryption Method

Applicable Interfaces


DVI, HDMI, DisplayPort

Any two-way digital interface

Maximum Downstream
Receivers for Each Transmitter

< 128

< 32

Maximum Repeater Levels for
Each Transmitter

<7

<4

Backward Compatibility

Yes, no electronic
components required

Yes, using specialized electronic
HDCP-1 .x-to-2 .0 and HDCP-2 .0-to-1 .x
converters

Wireless Support


Not specified

Explicitly specified with new locality
check requirement

internal design and proper deployment of HDCP

Until the introduction of HDCP 2.0, the basic
protocol of HDCP had not changed substantially.
The only major differences between HDCP
versions 1.0 through 1.3 is in the types of physical
A/V connections. HDCP version 1.0 applied to the
DVI interface. Version 1.1 incorporated HDMI, and
support for DisplayPort was added for version 1.3.

Authentication:
Data security industry standard RSA
1024 and 3072-bit asymmetric system

Specialized 56-bit
symmetric system used
for both authentication
and video encryption

to minimize re-authentication through careful
processing components.

HDCP 2.0

Video encryption:

Data security industry standard
AES 128-bit symmetric system

Table 5-1. Major changes in HDCP 2.0

www.extron.com

19


DRM for the A / V Professional
HDCP specifications
define total
supported device
counts, maximum
repeater levels, and
timing expectations
for system-wide
communications
exchange

Communication process that occurs between source and sink devices within an HDCP-based system.

Phase 1

Figure 5-1. Phase 1
Initial Key Exchange

Phas
Initial Key Exchange


You have 100ms
to get thru this
Here’s my public key
Aksv: 101101...
Remember this number
An: 010011...

Here’s my public
key Bksv:
001100...
I’m NOT a repeater

REPEATER!?
You have 5 seconds
to tell me who’s
downstream

Here’s my p
key Aksv:
101101...

Data
Transmitting

Calculate Shared Secret Keys
Your public key
checks out. Now I can
compute the secret
key Km from our

public keys*:
1110100...

Repeater Performs Initial Aut
- Downstream Device Keys a

Phase 1
Authentication
Procedure
(Described
Before)

Now I can
compute the secret
key Km’ from our
public keys*:
1110100...
* Km and Km’ are computed using each device’s private key along with the public keys of both
devices. This is a special calculation that results in matching Km=Km’ IF all the keys are valid.

Encrypt a Message Using Secret Key
Now I can use MY
secret key Km to
encrypt An to form a
message RO:
0000110...

Repeater Reports Key List an
Now I can use My
secret key Km’ to


encrypt An to form a
message RO’:
0000110...
Data
Transmitting

Receiver Demonstrates Secret Key Knowledge
Here is an encrypted
message RO’:
0000110...

Transmitter Validates Connec

√ You we
downs
than 5

Data
Transmitting

√ The do
keys ha

Initial Authentication

√ There a
total do

Your encrypted

message matches
mine, and you gave it
to me in less than
100ms

√ There a
of repe
downs

Repeater Authentication Com

OK, here is your
encrypted video:
1111111100
0011001101
1011100010
1000000001...

Transmit Video

HDCP
Rx

OK, here is your encrypted video:
1111111100 0011001101
1011100010 100000001
0001111000 000100000
1111000100 0011000100
0111110110 1011000010...


H
Data
Transmitting

Data
Transmitting

20

Extron Digital Design Guide

H


e’s my public
Bksv:
100...
NOT a repeater

Phase 2

Figure 5-2. Phase 2
Initial Key Exchange
REPEATER!?
You have 5 seconds
to tell me who’s
downstream

HDCP
Tx


Here’s my public
key Bksv:
001100...
I’m a REPEATER

Here’s my public
key Aksv:
101101...

HDCP
Rx
Data
Transmitting

ing

•
•
•
•
•
HDCP
Tx

Repeater Performs Initial Authentication with Connected Devices
- Downstream Device Keys are Collected

HDCP
Tx


Phase 1
Authentication
Procedure
(Described
Before)

can
te the secret
m’ from our
keys*:
0...

•
•
•
•
•

HDCP
Rx

ey along with the public keys of both
hing Km=Km’ IF all the keys are valid.

Phase 1
Authentication
Procedure
(Described
Before)


HDCP
Tx

•
•
•
•

An A/V device with
digital video inputs
must support HDCP,
if a user expects to
connect a PC to it
and play commercial
Blu-ray Discs.

Repeater Reports Key List and Topology

can use My
t key Km’ to

pt An to form a
age RO’:
10...
Data
Transmitting

owledge


Here are the keys of
downstream devices:
0010011...
.
.
.
0001100...
Here is how they are
connected:

HDCP
Tx

HDCP
Rx

Sink

Repeater

ncrypted
O’:

Sink
Sink

•
•
•
•

•
HDCP
Tx

Sink

Transmitter Validates Connections
HDCP
Tx

√ You were ready to give me
downstream info in less
than 5 seconds.

ing

√ The downstream device
keys haven’t been revoked.
√ There are less than 128
total downstream devices.

HDCP
Rx

√ There are less than 7 levels
of repeaters connected
downstream.

•
•

•
•
•
HDCP
Tx

Repeater Authentication Complete

OK, here is your
encrypted video:
1111111100
0011001101
1011100010
1000000001...

HDCP
Tx

HDCP
Rx

pted video:
1
1
0
00
0...
Data
Transmitting


•
•
•
•
•
HDCP
Tx

OK, here is your
encrypted video:
0110001100
0011011110
1110000010
0001101110...

Separately Encrypted
Data Transmitting

OK, here is your
encrypted video:
1111111100
1011100010
0001111000
1111000100...

•
•
•
•


ing

www.extron.com

21


DRM for the A / V Professional
The HDCP licensing
agreement does not
allow for analog video
outputs on repeater or
display devices.

Therefore, this implies that HDCP 2.0-compliant

The final AACS specification will include a

devices will soon emerge on the market. An

provision for making authorized copies of Blu-ray

existing A/V system incorporating HDCP 1.3 will

Discs, whereby a recording device can connect to

require converters if newly acquired HDCP 2.0

Internet servers at the AACS LA - AACS Licensing


devices are to be incorporated into the system.

Administrator to obtain electronic permission to
make a legitimate copy of protected content.

AACS is the DRM standard adopted for Blu-ray
Disc. AACS is designed to protect Blu-ray Disc

Analog Outputs

content similar to the way that the CSS - Content

The HDCP licensing agreement does not allow

Scramble System protects commercial DVDs,

for analog video outputs on repeater or display

but with additional features. Both AACS and

devices, but does not restrict analog outputs for

CSS encrypt the video data on-disc, so that only

sources. Nonetheless, this does not preclude

authorized players can read the content (see Table

separate agreements that would prevent analog


5-2). Both AACS and CSS prevent unauthorized

outputs on source devices. Such agreements

copying of commercial Blu-ray Disc and DVD,

could be negotiated on an ad hoc basis between

and both systems have mechanisms for revoking

content providers and hardware makers.

compromised players. AACS offers greater

However, the AACS licensing agreement is very

protection than CSS in the following areas:

specific about analog outputs and provides
for several measures to control them. Blu-ray

• AACS employs AES 128-bit encryption, while CSS
implements 40-bit encryption

Disc titles that support AACS have usage rules

• AACS allows for the revocation of individual Blu-ray
Disc players, whereas CSS can only revoke entire
models of DVD players


producer to limit the analog output resolution by

• AACS encrypts the digital outputs of Blu-ray Disc
players with HDCP
• AACS provides for the eventual elimination of
analog video outputs on Blu-ray Disc players

data embedded in them that allow the content
invoking the ICT - Image Constraint Token, or
even to disable the analog outputs entirely by
invoking the DOT - Digital Only Token. As of the
first quarter of 2009, no Blu-ray Disc titles have
included these restriction tokens, but this may
change with future releases. The AACS license
agreement also provides for an “analog sunset”
for newly manufactured Blu-ray Disc players,
such that models manufactured after 2010 can

DVDs (CSS)

Blu-ray Discs (AACS)

only include standard definition analog outputs,
and after 2013, no Blu-ray Disc players may be

Encryption Method

Specialized 40-bit stream
cipher


Data security industry standard AES
128-bit symmetric system

manufactured with any analog outputs.

Player Revocation

All players in a model
range are revoked

Individual players can be revoked

Computers

Disc Copy Prevention

Hidden disc lead-in area
prevents bit-for-bit disc
copy

Encrypted volume ID prevents bit-for-bit
disc copy

Output Signal Scrambling

Macrovision applied at
analog outputs

Managed Disc Copying


Analog Sunset

No provisions

No provisions

Extron Digital Design Guide

computers. The computer industry is a major

HDCP applied at digital outputs

source of innovation for content creation as

Macrovision applied at analog outputs

well as for unauthorized reproduction of that

Authorized copies are possible by
connecting to AACSLA server and
obtaining permission (details to be
finalized)

content. Computer DRM methods have been

Players manufactured after 2010 may not
have high definition analog outputs
Players manufactured after 2013 may not
have any analog outputs


Table 5-2. Differences between CSS and AACS encryption

22

There are numerous DRM schemes for

devised to protect software, digital music, digital
video, digital books, games, etc. The present
discussion will be limited to video content
played on a computer and the associated DRM
schemes therein. These DRM schemes are
mainly for preventing unauthorized access to


protected commercial video such as Blu-ray Disc

Conclusion

or downloaded content including movies or TV

Any A/V system that is intended to support

shows. But non-commercial video files can also

playback of protected video content, such as

be protected with DRM, if the content creator has

Blu-ray Disc and consumer-purchased HD


access to DRM technology. The DVI, HDMI, and

video downloads, must be compliant with the

DisplayPort outputs of computers should have no

associated DRM. Since DRM implementations

DRM restrictions when the content being played

such as HDCP and AACS are meant to restrict

is not protected.

what the end user can do with protected content,
it makes sense for the A/V professional to inform

As of the first quarter of 2009, for Blu-ray

the end user of these restrictions at the outset.

Disc playback, only PCs running Windows

®

Such restrictions include limiting the number of

operating systems have software authorized to

simultaneous displays for content-protected video


play Blu-ray Discs. The same AACS and HDCP

playback, disallowing recording or copying, and

restrictions apply for PC Blu-ray Disc playback

disabling analog outputs. For example, an A/V

as for standalone players. Thus, a PC must be

system may have the capability to distribute HDMI

equipped with a video card that is capable of

video to 16 displays and provide analog video

HDCP encryption. An A/V device with digital video

recording. These functions will always be available

inputs must support HDCP, if a user expects to

when a PC with HDMI output is connected

connect such a PC to it and play commercial

for PowerPoint presentations and other non-

Blu-ray Discs.


protected material. But once a protected Blu-ray
Disc is inserted into the PC for playback, HDCP

The market for authorized downloads of

and AACS restrictions may disable output to

commercial video content is crowded with

several displays and to the recorder.

companies and products, with frequent
turnover of market entries and exits. Current

Since many large-scale A/V systems can display

market players include Amazon, Apple iTunes,

unencrypted video on a large number of displays,

Blockbuster, Netflix, and Vudu, to name just a

freely distribute analog signals, and provide

few. These companies offer a plethora of options

video recording capabilities, end users of such

for the end user. Movies or TV shows can be


systems must be made aware that some system

rented or purchased, some in high definition, but

functions may not be available when playing

most in standard definition. The video may be

DRM-protected content. ■

Since DRM
implementations such
as HDCP and AACS
are meant to restrict
what the end user
can do with protected
content, it makes
sense for the A/V
professional to inform
the end user of these
restrictions at the
outset.

either streamed or stored locally to a computer, a
networked set-top receiver, Blu-ray Disc player, a
video game console equipped with a hard drive, or
even a display with Internet access capability. The
one constant among all these different options
is the existence of DRM for protected content,

which is used to restrict the allowable viewing
duration of “rented” video content and the ability
to transfer the video to different computers. In the
case of protected HD video downloads, HDCP
support is required on any device that is playing
the video. Therefore, a display with digital video
inputs must support HDCP, if a user expects to
connect a computer to it and play downloaded
commercial HD content.

FormoreinformationonHDCP,
seeExtron’swhitepaperat
www.extron.com/hdcppaper

www.extron.com

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