THE CHALLENGES OF INTERFACING HDMI
IN THE WORLD OF PROFESSIONAL AV

By Brian Morris – CTS, Chris Kopin – CTS, ISF-C,
Tom Kopin – CTS, ISF-C, Matt Kopin – CTSFEBRUARY 2015

KRAMER WHITE PAPER
WWW.KRAMERELECTRONICS.COM

TABLE OF CONTENTS

THE CHALLENGES OF INTERFACING HDMI IN THE WORLD OF PROFESSIONAL AV ....1
HOW DID WE GET HERE?.....................................................................................1
HDMI TODAY .......................................................................................................2
WHERE THE TROUBLE STARTS............................................................................3
HDMI ISSUES: EDID . . ...........................................................................................4
HDMI ISSUES: HDCP. . ..........................................................................................6
HDMI ISSUES: APPLE PRODUCTS........................................................................7
HDMI ISSUES: DEEP COLOR................................................................................8
CONCLUSION......................................................................................................9

THE CHALLENGES OF INTERFACING HDMI IN THE WORLD OF PROFESSIONAL AV

The High Definition Multimedia Interface (HDMI), ubiquitouson everything from consumer televisions and Blu-ray and DVD
players to set-top boxes, game consoles, and digital cameras andcamcorders, has become just as commonplace in the world ofKramer C-HM/HM
Figure 1.
A typical HDMI interconnecting cableprofessional video production and display equipment.
You’ll find this display interface on digital cameras, camcorders,and media players; videoconferencing equipment, projectors,
and display monitors. HDMI distribution amplifiers and matrix
switchers are widely available to support all of these connections,as are HDMI presentation switchers and signal format conversion
products.
At first glance, using HDMI as a professional AV display interface
would appear to be ill-advised, as its copy protection overlay wasnever designed with multi-point video and audio signal distribution
in mind. Yet, these are different times: the world of consumer
electronics drives most of the new product innovation anddemand for the pro AV channel, so customers routinely expect
to use HDMI-equipped products in commercial installations andapplications.
HDMI can create major problems when switched among
multiple displays, particularly if the displays have different native
pixel resolutions. Several approaches have been engineered
to overcome these issues while preserving the essential
characteristics of HDMI – secure copy protection and automatic
display clock detection and optimization – and allow it to be ported
reliably to more than one monitor, TV or projector.

HOW DID WE GET HERE?

HDMI evolved from an earlier attempt at an intelligent,
100%-digital display connection known as DVI, or Digital Visual(Video) Interface. DVI was first developed by the Digital Display
Working Group (DDWG) and released as a standard in 1999
to replace the 15-pin Video Graphics Array (VGA) analog display
connector, commonly found on desktop and notebook computers
Kramer AD-DM/HF
Figure 2.
A DVI-HDMI adapter

and still in widespread use today.
DVI allowed video sources to communicate with connected displaysby using Extended Display Interface Data (EDID), first seen on VGA
connectors in 1994. The intent was to deliver uncompressed
digital video to the display at optimal resolution and refresh rates
by using transition-minimized differential signaling (TMDS) to

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1

support a maximum resolution of 1920x1080 pixels, refreshed @ 60Hz, in a single-link implementation(165 MHz pixel clock), or 2048x1536 pixels, refreshed @ 60Hz, in a dual-link implementation (330 MHz
pixel clock).
The first implementation of DVI supported both ‘pure’ digital connections to computer monitors (DVI-D)
and hybrid analog/digital connections (DVI-I). However, the DVI-I connector soon spread beyond computer
monitors to consumer electronics devices, such as terrestrial, cable, and satellite set-top receivers, DVDplayers, and HDTVs.
As a result, concerns were expressed that digital content transmitted through DVI-D connections could becopied and distributed illegally, leading to the formation of the HDMI Consortium (Hitachi, Matsushita ElectricIndustrial [Panasonic], Philips, Silicon Image, Sony, Thomson [RCA] and Toshiba).
This group developed the HDMI interface in 2002 as a more robust version of DVI; one that could also carryembedded digital audio and metadata, and at faster data rates.
As originally conceived, HDMI would be a “plug-and-play” video/audio interface between media players and
HDTVs; one that resembles an ad-hoc “peer-to-peer” network connection. In addition to supporting EDID,HDMI would also feature High-bandwidth Digital Copy protection (HDCP), developed by Intel. The HDMI
connector would be smaller than its DVI counterpart, and would also be compatible with both RGB andweighted component video (YCbCr) color.

HDMI TODAY

Most of the development work and extensions to the HDMI standard have been the responsibility of Silicon
Image of Sunnyvale, CA. In the years since the HDMI standard was first announced in 2002, it has undergone
numerous revisions and updates, with the latest implementation being version 2.0 (September 2013). V2.0
increases the maximum interface data rate to 18 gigabits per second (Gb/s) and includes support for 32
discrete channels of audio with a maximum sampling rate of 1536 kHz.
HDMI 2.0 can also transport two 1920x1080p/60 signals simultaneously through one connector. With
this boost in speed, the interface can now transport an Ultra HD (3840x2160) display signal encodedas 8-bit RGB color with a maximum refresh rate of 60 Hz. Ultra HD images with deeper color can beaccommodated at slower refresh rates or encoded in the YCbCr format (4:2:2, 4:2:0).
There are five different versions of the HDMI connector, with Type A being the most widely implemented (19pins, slide-on) across televisions and Blu-ray players. Type C is used on some mobile devices as a stand-aloneinterface, although it isn’t as popular as the Mobile High-definition Link (MHL) iteration that carries HDMI and
USB through the same 5-pin connector.
With HDMI now widely adopted, support for the DVI standard has been discontinued, even though theconnector remains popular. Manufacturers of motherboards and video cards are largely moving to HDMI
to replace VGA, although some have also adopted DisplayPort as a digital display connection, primarily forcomputer monitors.

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WHERE THE TROUBLE STARTS

In HDMI language, there are two parts to a connection – the ‘source’(DVD/BD player, set-top box, game console, and computer) andthe ‘sink’ (TV, monitor, projector). Allowances were made in the
HDMI standard for additional AV equipment that might need to beconnected between sources and sinks, such as audio receivers.

VM-4HC
Figure 3.
A four output HDMI Distribution Amplifier
with “Intelligent” EDID Handling.

These devices are equipped with “repeaters” to retransmit the
HDCP Keys. The HDCP connection requires a complex exchange
of keys between sources and sinks. Each HDCP-capable device has
a pool of forty different 56-bit keys, which are exchanged randomly

and asymmetrically between each source and sink when an HDMI connection is made. Compromised keys
will disable the connection, i.e. Blu-ray and DVD discs will not play if the players are presented with acompromised key or keys.
In a peer-to-peer HDMI connection, only one display would be connected as a sink, but multiple sources could
be connected to that sink either directly or through repeater-equipped devices. This architecture worked
very well, as the exchange of EDID information and HDCP “keys” was straightforward. The connected display
would send its EDID information to the source, which in turn would configure the pixel clock accordingly. The
HDCP overlay would then establish that a secure connection existed and begin streaming content.
This approach ensures that copy-protected content remains encrypted from the source to the sink. While
this system may work well for the multi-source, single-sink world of consumers, it is not at all manageable inprofessional and industrial AV channels where the reverse condition is usually found – a single source driving
multiple sinks, or displays.
Designing a professional video display distribution system around a secure, all-digital connection like HDMI isgenerally not ideal, particularly when SDI and HD SDI interfaces can already do the job. Yet it is being doneby numerous companies not only to support formats such as Blu-ray players and HDTV set-top receivers,
but also to take advantage of the high-density connector and eliminate discrete connections for video, audio,
and data.
For AV systems integrators, the challenge is to connect two or more displays with different resolutions to asingle HDMI source and maintain reliable connection. Which EDID is to be supported? Are all displays HDCPenabled? What if multiple sources are being connected to one or more displays? How can any computersconnected through a HDMI matrix switcher stay active when no active sink is detected?
All of these are real problems faced by anyone designing a multipoint HDMI distribution system. Let’s take acloser look at each of the HDMI interfacing issues.

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3

HDMI ISSUES: EDID

It can easily be seen that simply connecting and disconnecting different displays to an HDMI matrix switcher
or distribution amplifier could possibly result in (a) dropped connections, (b) long intervals waiting for EDID
to be exchanged and updated, and (c) in some cases, no images at all. The typical peer-to-peer HDMI
connection found in the home does not work for two or more connected displays, particularly if they havedifferent native resolutions.

highest common display resolution. For example, a 6x6 matrix switcher

Figure 4a.

The HDMI
switcheranalyzes all
EDID720p
information
providestwomatrix
1080p
displays,one
and that
one still480p
display
A might
more havesensible,‘smart’approachfortheprodisplay,
AVandmarkettakes
full advantage ofByEDID
is “intelligent”
to store EDID
using anthe source with a new EDID which is the highest common resolution

connected, as seen in figure 4a.

polling and storage system, the1080P EDIDof alldisplay
displays. settings
In this case,inthe
highest common
resolution
betweenthe chosen
memory.
These
settings
canallremain active in non-volatile memory,emulatingsystem can be optimized to thefour displays is 480P, so that is what the HDMI source will output.

a virtual display to ensure a connected PC or media player does not go into “sleep” mode highest
when common
it is notresolution.
theThis ensures that all displays will have a picture.

selected source.

480P
EDID

Display EDID

Display EDID

NativeThe HDMI matrix switcher analyzes all EDID information and provides
NativeResolution:
Resolution:
the source with a new EDID which is the highest common resolution
1080P
480P
1080P EDID
A distributionof amplifier
with
EDID
canresolution
also analyze
connected
all displays. In
this “intelligent”
case, the highest
commonbetweenall
all of the EDID information for each
480P
fourEDID
displays is 480P, so that is what the HDMI source will output.

display and automatically choose the highest common display resolution. An example of the use of this “autoThis ensures that all displays will have a picture.

480P

Display EDID

ay EDID
Displ
ay
EDID
Nativ
mix” mode operation would be if a 1x4 distribution amplifier were to have two
displays, Displ
one
720p
e ay EDID
Displ
EDID 1080p

display, and one 480p display connected, as seen in figure (4a.)
Received EDID

Resolution:
720P Native
Resolution:
480P

720P
EDID

NativeNative:
Resolution
Resolution:
1080P1080P

Kramer VS-66H 6x6 HDMI switcher in“Intelligent” EDID Mode
480P EDID
OutputResolution:
The HDMI
Distribution Amplifier analyzes all the EDID information and provides the source with a new
EDID
which is the highest
Display
EDID1080P
EDID
Display EDID
Nativ
common480P
resolution of all the connected displays. In this case, the highest common resolution between
alle four displays is 480P,
Resolution:
Nativeso that is what the HDMi source will output.
720P
Resolution:
720P
1080P
Received EDID
Kramer VS-66H 6x6 HDMI switcher in
EDID
1080P EDID
This ensures all displays will have a picture. “Intelligent” EDID Mode
OutputResolution:

When all four
displays are active, the source is prompted to output
480P 480p,
480P
Display EDID
as that is the maximum resolution common to all four displays.EDID
A picture
Native Resolution:is seen on all displays. Should the 480p display be disconnected from the480P
480P
matrix, the EDIDEDID
analyzer within the matrix switch automatically reportsback 720p as the highest common display resolution to the connectedWhenfour displays
source,asallshownin figureare
4b.active, the source is prompted to output 480p,
Display EDID
Received
as thatEDID
is the maximum
resolutioncommontoAmplifier
all four
Kramer VM-4Hxl
1:4 HDMI
Distribution
in displays. A picture
Output Resolution:
Native Resolution:“Intelligent”
EDID Modeis seenonalldisplays.
Shouldthe480p
displaybedisconnected
from
the
480P
720P
720P
EDID reports
matrix, the EDID analyzer within the matrix switch automaticallyback 720p as the highest common display resolution to the connectedsource, as shown in figure 4b.

1080P EDID
Display EDID
Native Resolution:
1080P

Figure 4b.
When the display with thelowest native resolution is
disconnected,
the matrix
Display EDID
switcher automatically defaults
Native Resolution:
to the next-highest resolution
1080P
supported
all displays.
Figureby
4b.
When the display with thelowest native resolution is
1080P
EDID
1080P
EDID
disconnected,
the matrix
switcher automatically defaults
to the next-highest resolution
ay EDID
Displbysupported
all displays.
Display EDID

Now, the 480P monitor has been unplugged.

thisusingcase, anthe“Intelligent”
highest common
betweenall threedisplays
Figure 4a.In By
EDIDresolution
polling andstoragesystem,the installation can be optimized to the highestNativcommoneNativeis 720P, so that is what the source will output.
Resolution:
resolution.
Resolution:
1080P
480P

1080P EDID

720P EDID

When all four
displaysareactive,the sourceNow,
the 480P
monitorhas been
unplugged.is prompted to output 480p as that is the maximum resolution
Display EDID

EDID
lay
common to all four displays. A picture is seen on all displays. Should the 480p display
be disconnectedfrom
Display
Disp
EDID
Nativ
e lay EDID
Disp

In this case, the highest common resolution between all three displays
Resolution:
NativeNativeis 720P,
so that isthe
whatEDID
the source
will output.
720P Native reports backlution:the distribution
amplifier,analyzer
within the distribution amplifier automatically
720p
Reso
Resolution

Received EDID

Kramer VS-66H 6x6 HDMI switcher in“Intelligent” EDID Mode:
1080P1080P

Resolution:
480P

720P

EDID in figure (4b.)
as the highest common display resolution to the connected source, as shown
720P EDID

OutputResolution:
720P

Display EDID

1080P EDID

Received EDID

Kramer VM-4Hxl 1:4 HDMI Distribution Amplifierin “Intelligent” EDID Mode

720P
EDID

If the 720pOutput
display is then switched out, the matrix switcher reflects back
1080p toResolution:
the source. This design ensures that all connected displays will
always have720P
a picture, and it will be the highest resolution image supportedby all connected displays.

NativeResolution:
720P

Display EDID
NativeResolution:
1080P

1080P EDID

If the 720p display is then switched out, the matrix switcher reflects back
1080p to the source. This design ensures that all connected displays will
always have a picture, and it will be the highest resolution image supported
4
KRAMER ELECTRONICS, Ltd
THE CHALLENGES OF INTERFACING HDMI IN THE WORLD OF PROFESSIONAL AV
1080P EDID
by all connected displays.

5 • WHITE PAPER

720P

Display EDID

Display EDID

Native Resolution:

Native Resolution:

480P

1080P

Received EDID

in “Intelligent” EDID Mode

If the 720pOutput
display is then switched out, the matrix switcher reflects back
1080p toResolution:
the source. This design ensures that all connected displays will
always have720P
a picture, and it will be the highest resolution image supportedby all connected displays.

1080P EDID

If the 720p display is then switched out, the matrix switcher reflects backNow,
the 480p
monitorhasp been
In this case,theallhighest
commondisplays
resolutionwill
between all three displays is 720p.
1080p
to thesource.
Thisunplugged.
design ensuresthatconnected
So alwaysthat is whatthesourcewill
output.
have a picture, and it will be the highest resolution image supportedby all connected displays.

1080P EDID

5 • WHITE PAPER

720P

5 • WHITE PAPER
EDID
Received EDID
Output Resolution:
720P

Kramer VM-4Hxl 1:4 HDMI Distribution Amplifier in“Intelligent” EDID Mode

720P
EDID

Display EDID

Display EDID

Native Resolution:

Native Resolution:

480P

1080P

Display EDID

Display EDID

Native Resolution:

Native Resolution:

720P

1080P

1080P EDID

Figure 4b. When the display with the lowest native resolution is disconnected, the distribution amplifier automatically defaults tothe next highest resolution supported by all the remaining displays.

This design ensures that all connected displays will always have a picture, and it will be the highest resolution
image supported by all connected displays.
For matrix switchers, the system designer should design the system with EDID in mind. The best system
uses all the same monitors so that the resolutions and EDID are all the same. If that is not possible, thenthe switcher should be set to the highest common resolution possible.
Storing EDID in memory also speeds up the HDMI connection “handshake,” which can take several seconds
to execute. This approach to handling EDID ensures that all connected sources remain active at all times
and that every connected display will show an image, although the resolution may change to accommodate
all displays. The adoption of Silicon Image’s InstaPort technology has sped up the process of reading EDID
considerably, allowing much faster connection times after hot plug detection.

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HDMI ISSUES: HDCPThe next step is to verify and establish an HDCP connection to all sinks. Using the conventional approach,a repeater within a distribution amplifier or matrix switcher would pass all HDCP keys back to the source.
This means the source needs to decipher a different set of keys for each connected display, and if any key iscorrupted, no signal will pass to any connected display, even if the remaining displays are transmitting valid keys.
(1) Repeaters pass HDCP keys back to the source for handshake(2) Source needs to decipher 4 HDCP keys instead of 1 to output an image(3) If one display is not HDCP-compliant, or if one HDCP key is corrupted, then source will not output content to any display
Problem: Many AV sources do not support repeater devices!

HDCP Sink Key
HDCP
Repeater Key
HDCP Sink Key

HDCP Sink Key
4HDCP
Sink KeysHDCP Sink Key
HDMI Source
1:4 HDMI DA

SourceSink

HDMI Displays

Repeater

HDCP Keys

Figure 5. An HDMI distribution amplifier that depends on repeater keys is not reliable.

It’s clear that the distribution amplifier cannot simply repeat the connection to each display, as it would witha single, peer-to-peer HDMI connection. What happens when a non-compliant display is connected? What if
a non-compliant source is switched in place of a compliant source? For a conventional distribution amplifier
or matrix switcher using a repeater design, this approach became a nightmare.
Once again, a more practical approach was needed; one that maintains and respects the HDCP overlaywhile
also ensuring the reliable HDMI connection of a matrix of displays. The solution? Make the matrix switcher
or distribution amplifier a sink unto itself, thereby ensuring a constant and secure connection to every
connected source.

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THE CHALLENGES OF INTERFACING HDMI IN THE WORLD OF PROFESSIONAL AV

SOURCESINK

HDCP Keys

HDMI ISSUES: APPLE PRODUCTS
repeaterkeys needed
asMacBook
each display
now hascomputers,
its own ‘sink-source’
Most NoApple
products,
includingnotebook
Mac Minihandshake with DA
computers,TVits
set-topboxes, and handshakeiPads, canwith
enablecopy
Source Apple
now hasown ‘sink-source’
inputorofdisable
DA
protection automatically. This setting is determined by (a) the presence ofprotected
content
and (b) the detectionof either
If onevideo
display
is not HDCP-compatible
or if one
HDCP ankeyHDCP-compliant
is corrupted, then only that display will be affected!
or non-compliant display. If any of these Apple products first sense a nonHDMI Displays
A reliable
and securesolution!
compliantswitchingor signal
distribution product in the signal path, copy
protection will be disabled. This allows non-compliant video and audio topass, but blocks HDCP-compliant content from being viewed.
HDCP Sink Key

HDCP Sink Key

7 • WHITE PAPER

HDCP Sink Key

1 HDCP
Sink KeyHDMI Source

Source1:4 HDMI DAHDCP Sink Key
VM-4HXL

Sink

HDCP Keys

Figure 6. By using separate source keys on each output of the HDMI distribution amplifier, HDCP connections are maintained
reliably while outputs to non-compliant displays are disabled.

Now, each HDMI output of the distribution amplifier becomes a second source, looking for its own HDCP
handshake with a connected display in a peer-to-peer arrangement. Once the secure connection is verified
and keys exchanged, video from the actual source is passed through to the display.
If any connected display is non-compliant with HDCP, the matrix switcher or DA will not pass video to that
display only – all other connected, compliant displays will continue to see video normally without interruption.
As new displays are connected to each port on the matrix switcher or DA, the secure connection is simply reestablished during the HDCP key exchange. The copy protection is maintained at all times, on all ports. The
issue with repeaters is eliminated, and multiple sources can now be connected as easily as multiple displays.

HDMI ISSUES: APPLE PRODUCTS

Most Apple products, including MacBook notebook computers, Apple TV set-top boxes, and iPads enable
or disable copy protection automatically. This setting is determined by (a) the presence of protected video
content and (b) the detection of either an HDCP-compliant or non-compliant destination, or “sink.” If any ofthese Apple products first sense a non-compliant switching or signal distribution product in the signal path,copy protection will be disabled. This allows non-compliant video and audio to pass, but blocks HDCP-compliant
content from being viewed.
However, if an HDCP-compliant device is first detected in the video path, the Apple product will encrypt all
video and audio content through the display connection continuously, even if the original content was neverprotected. The idea was to allow for easy switching from non-protected to protected video on an Apple
product, but this operating mode can create major problems for AV professionals.
An example would be if a MacBook is connected to the input of an HDCP-compliant scaler/switcher and

KRAMER ELECTRONICS, Ltd

THE CHALLENGES OF INTERFACING HDMI IN THE WORLD OF PROFESSIONAL AV

7nge begins
rified with scaler/switcher
shake is madeaterial is output, it will still

DVI - Non HDCP Compliant

picture is displayedRa non-compliant video monitor or video conferencing codec is connected to the output. Since the scaler/switcher is HDCP-compliant, the MacBook detects that and accordingly encrypts all content that it plays
back. The result is that the scaler/switcher’s analog outputs (component video, VGA, etc.) are disabled,even when they do not need to be.
When configuring an AV system with Apple products and connecting one or more displays that are not
HDCP-compliant, this unique problem can be solved with the addition of an EDID emulator (such as Kramer’s
PT-1C) right after the Apple product in the signal path. The Apple product will detect the emulator, turn off

d added support for three so-called
its encryption, in addition to thebasic 24-bitmode,(8 bitsand
per pass non-protected video and audio content through the system.
ay discs, and set-top boxes. These added
er pixel), 36-bit color (12 bits per pixel),that has been authored in these Deep
video monitor does support Deep Color,
player may detect that support and switch
ut mode. Again, this operating mode canmmercial AV installation.• HDMI cable is inserted
•
•
•
•
•

VP-730

DVI - Non HDCP Compiant

The EDID exchange begins
HDCP key is verified with scaler/switcher
Compliant handshake is madeIf non HDCP material is output, it will still be encrypted
The result is no picture is displayed

Figure 7. Issues with HDCP using Apple products, compliant switchers, and non-compliant displays.

HDMI ISSUES: DEEP COLOR

Version 1.3 of the HDMI standard added support for three so-called “extended color” operating modes, inaddition to the basic 24-bit (8 bits per color) mode used by DVDs, Blu-ray discs, and set-top boxes. These
added modes are 30-bit color (10 bits per pixel), 36-bit color (12 bits per pixel), and 48-bit (16 bits per pixel).
Presently, no broadcast, disc, or streaming content is available that has been authored in these Deep Colormodes. However, since newer televisions and monitors do support Deep Color, then a newer, connected Blu-ray
player will detect that support and switch into a simulated Deep Color output mode. Again, this operating modecan create a serious problem in a commercial AV installation.
Here’s why: Many HDMI twisted-pair distribution products were designed to handle a maximum data rate of
1.65 gigabits per second (Gb/s) per color channel (1920x1080 pixels, 60Hz refresh rate, with 24-bit color).
But increasing bit depth pushes the data rates up to 2.08 Gb/s for 36-bit color, and 2.67Gb/s for 48-bit
color, well beyond the extender’s bandwidth.
One work-around is to set the Blu-ray player’s output frame rate to 24Hz (if available) when playing backmovies. This is the native resolution of most Blu-ray discs and it is an original film rate, not a display resolution.
By dropping the frame rate to 24Hz from 60Hz, the bit rate and bandwidth are also reduced to a range
supported by professional AV switching and distribution devices, regardless of the color depth. (It’s importantto check all Blu-ray players to verify that, if Deep Color modes are supported during playback, they can be easily
disabled or reset from the menu.)
It should also be noted that notebook computers that support deep color modes are also widely available. If
support for deep color is detected in EDID, that mode will be turned on in the computer’s video card and it
may not be possible to disable this mode without a lot of work. An EDID emulator, such as the PT-1C, may berequired in the signal chain to force 8-bit color output.

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Deep Color capable Blu-ray

36-bit Color Signal can notpass through transmitter.

To resolve this problem, change therefresh rate of the output 36-bit Color
Signal from the Blu-ray player to 24 Hz.

To resolve this problem, change the refresh rate of the output 36-bit Color Signal from the Blu-ray player to 24 Hz.

9 • WHITE PAPER
EDID

PT-571PT-572+

PT-571PT-572+8-bit
Color Signal

Deep Color capable Blu-ray

EDID

36-bitColor Signal
at 60Hz

Deep Color capable Blu-ray

Figure 8. The switcher and source are compatible with 36-bit color, but the UTP/STP transmitter and receiver are not.

CONCLUSION

High-bitrate, multifunction digital consumer display interfaces based on a peer-to-peer architecture (HDMI,
DisplayPort) are here to stay. In order to distribute video from these connections to two or more displays in acommercial or education AV installation, the exchange and storage of EDID must be managed in a sensible,
repeatable, and reliable way.
Similarly, exchanging and verification of HDCP keys when viewing protected content must also work within
the requirements of commercial and educational AV installations and their need to support multiple displays
from one HDMI source, even if there is only one HDCP-compliant device in the entire system.
An ounce of prevention is definitely worth a pound of cure when it comes to installing HDMI switchers,
distribution amplifiers, and STP transmitters and receivers in a commercial or educational AV system.
The smart approach is to start in the design phase and identify every HDMI source/sink connection in a
distributed video/audio system.
Third-party software programs like Entech’s Monitor Asset Manager (www.entechtaiwan.com) are invaluable
aids when reading and configuring EDID and ensuring that EDID is exchanged correctly and maintained evenwhen connected sources or displays are “sleeping.”
HDCP issues are best resolved during the build and testing phases. HDCP exchanges should be verified atevery source-sink connection to ensure video and audio are presented without interruption, that all HDMI
switching and transmission components are compatible with the latest version of HDMI, and that any
connected sources can be configured manually if there are compatibility issues.
The Kramer white paper library covers many important topics. Several of the topics covered in this white paper
are also covered in greater depth in other papers. Please be sure to check out our full white paper library.

KRAMER ELECTRONICS, Ltd.

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