Hdmi Explained

lifestylestore · 08-16-2007, 08:26 PM

Hi everyone, as a specialist working inside the high end AV world i do come accross rather interesting material delivered stright from the manufacturers themselves, i found this this article about HDMI rather easy to understand, as well as displacing certain myths about the unfamiliar versions of HDMI, happy reading, and i will be definatley posting more interesting articles in the future.

Why HDMI and Where Did it Come From?
How Does HDMI Work?
What is HDCP and How
Does it Work?
HDMI Specifications
Future of HDMI

WHY HDMI AND WHERE DID IT COME FROM?
There are many reasons why HDMI has become the go-to cable for installers and consumers alike. This is a cable that carries compressed or uncompressed digital video and multichannel digital audio, and an intelligent control signal inside a single jacket. The fact that HDMI omits any analog to digital converters, and vice versa, to
create a lossless signal, immediately provides superior video over any analog transmission.
Beware of poorly made and non-HDMI compliant interconnects. These cables can cause image quality issues and system
failures.

HDMI LLC is a group made up of seven very well-known consumer

electronic companies: Sony, Panasonic, Hitachi, Philips, Silicon Image,
Thomson, and Toshiba. HDMI is found in almost every CE product available, and you will be seeing more computers with HDMI connectors.
In 2006, 60 million enabled HDMI products were shipped. It
is estimated that in 2009, 180 million CE products will be shipped with an HDMI connector built in.
HDMI is already able to support video resolutions beyond 1080p, up to 120MHz refresh rates, and 48 color bit resolutions. Although these specifications will not be available on CE products for some
time, the stage has been set.

There has always been a consumer need for a cable that carries many signals in one cable. We saw this first type of cable from Firewire. Although Firewire worked seamlessly, it was designed using
MPEG2 compression, making it recordable and also incorporated copy protection that was unacceptable to Hollywood. HDMI LLC saw this opportunity and introduced their solution.

HOW DOES HDMI WORK?

An HDMI connector is designed with 19 pins. And, as you know, HDMI is built to carry audio, video

and a control signal. Why so many pins? In the analog days, you could hook up these signals using 6 or 7 pins (connectors). Let's look at the HDMI connector and find out exactly what is going on inside an HDMI cable.

There are 5 shielded twisted pairs each with a drain. In addition, there are four more conductors inside this
cable:

• Three of the shielded twisted pairs are reserved for three high speed data A/V channels carrying TMDS.
Developed by Silicon Image, TMDS stands for Transition Minimized Differential Signaling. TMDS is a way to transmit huge amounts of data over a twisted pair, up to 3.4Gbps per pair. Because of the large
amount of information being sent, crosstalk can occur between the twisted pairs. TMDS uses an advanced coding algorithm that maximizes bandwidth by reducing crosstalk and data interference
between channels. Each twisted pair is color coded to carry the corresponding signal (red for red, green for green and blue for blue).
• The clock channel, another shielded twisted pair, enables reliable data processing. This basically means
that the clock ensures the TMDS signals arrive at exactly the same time.
• The last shielded twisted pair is for the Display Data Channel (DDC) which provides 2-way
communication system intelligence. This is also where the Extended Display Identification (EDID) channel is stored. The EDID is a genetics code for electronics. It holds the manufacturer's name, product type, video resolutions, audio type capabilities and other information. The EDID can be read through the DDC channel by all the components in the system. This function of HDMI allows the source to send the
best signal available for this display unit.

• The Consumer Electronic Control (CEC) uses only one conductor. The CEC is the control part of the cable. It is a bi-directional control that allows something called 1-touch play. This occurs when a trigger
sends a series of intelligent commands to multiple devices in a system. A few examples of 1-touch play are: system standby, one touch record, and tuner control. The CEC is found in all HDMI cables, but is optional on some devices.
• Another signal conductor inside HDMI is the Hot Plug Detect. This enables the components to detect
when an HDMI cable is attached, detached, or when an HDMI input is switched.
• The last conductor in the HDMI cable carries a 5 volt supply that provides low current power for the
purpose of reading the EDID ROM inside the display.

WHAT IS HDCP AND HOW DOES IT WORK?

Earlier it was mentioned that Hollywood needed some type of acceptable copyright protection for digital signals.
Hollywood insisted all set-top boxes capable of outputting HD signals over a digital cable, be protected from being copied. Intel developed a copyright protection called HDCP or High Definition Copyright Protection.
HDCP is a digital handshake for validation between source and display. The electronics use the DDC to perform the handshake. The source and display exchange a secret unique key value that is stored in each device. After the validation, the source encrypts and transmits to the receiver in the display a random algorithm that authenticates every 2 seconds.

Though it is mandatory for set-top boxes to have HDCP, it is not required for standard video or over the air hi-definition to use the HDCP validation. HDCP can support up to 128 displays of HD content. At the same time, up to 128 displays can display pictures up to seven layers of switching and/or distribution devices through one HDMI signal.

HDMI SPECIFICATIONS

HDMI specifications do not specify the maximum length of an HDMI cable. However, HDMI does set the minimum electrical acceptable level of signal quality at the end of every cable. All certified HDMI cables are capable of passing 1080i and 1080p up to 5 meters. It is difficult for 1080p to maintain a sufficient signal beyond 5 meters. The majority of HDMI cables will allow 1080i to pass up to 8m and some cables even further.
Depending on your equipment, Tributaries HDMI cables are able to pass 1080p up to 10 meters. We do, however, have an HDMI extender (HX-100) that will ensure a 1080p signal up to 25 meters.

FUTURE OF HDMI

The buzz word for video these days is HDMI 1.3. Within months, we will see consumer electronic companies
offering HDMI 1.3 in all of their products. With two different categories, HDMI 1.3 will be the standard for HDMI.
There will be no change in the connector; however, there will be an additional mini HDMI connector for handheld HD devices. The 1.3 cable itself will have tighter twists in the twisted pairs and tighter specifications for the TMDS lines and clock signal. The 1.3 certification can finally include HDCP testing, says HDMI LLC.

With these changes, Silicon Image says HDMI 1.2 cables will be able to pass an HDMI 1.3
signal. However, this will most likely hold true for HDMI 1.3 Category 1, which can handle the standard 2.2 Gbps. HDMI 1.3 Category 2 will require handling 10.2 Gbps or more. This category will not be available for some time. Tributaries cannot stress this enough: run flex conduit (2" if possible) to any display location that has or may use HDMI. You could avoid major headaches by future proofing your HDMI runs.

Another thing to note, HDMI has finally started talking about a locking connector that will be backwards compatible with current connectors, though we are not sure where or when we will see this connector.

A question that is often asked is will there be an in-the-field termination and can HDMI be spliced. The answer is... probably never and no. HDMI uses high speed digital signaling with precision timing tolerances. If the conductors are not the exact same lengths, within a few thousandths of an inch, the timing of the signals will be off, and the signal will not pass.

What we, as an industry, have found, is that many different manufacturers did not implement HDMI correctly in the beginning stages. This has made many people skeptical of this technology. HDMI 1.3 may not solve all of the issues that are frequently talked about, but it is a great stepping stone towards improving reliability.
Remember, HDMI Licensing LLC is our best ally, and they have developed a way to vastly improve our video and audio experiences

Loves2Watch · 08-18-2007, 04:34 PM

The problems with HDMI from it's inception are as follows. Weak connector and copy protection. Don't let anyone fool you into thinking any form of copy protection is of benefit to you. It is purely and simply another way for Hollywood to control you, where you can watch your legally purchased media and a way to make you pay for the same media over and over again. HDCP means screw the consumer at all costs and make them pay for it and brainwash them into thinking it is good for everyone.

Chris Gerhard · 08-18-2007, 08:08 PM

Nice post and welcome to the forum lifestylestore. Is your conclusion that HDMI will be fine or do you see some problems. There is an interesting, lengthy thread at AVSForums that discusses the possibilities with HDMI 1.1, 1.2a, and 1.3a and many of the products that use each version and what specific features of each verison. I have a number of HDMI sources now and I am trying to decide on an AV receiver, most likely with HDMI 1.3a, but I am still in the process of reading about all of the issues. Here is a link to the thread at that forum:

http://www./avs-vb/showthread.php?t=738511

Chris

Loves2Watch · 08-20-2007, 10:06 PM

I am certainly hoping that the connectors on equipment become more rigid and keep the wire from pulling out or loosening. Also HDMI 1.3 has great potential but as stated in my previous post HDCP is ruining it for the consumer and I don't see that getting better anytime soon. The digital DVI and HDMI were invented by manufacturers/Hollywood/the music industry (RIAA and MPAA) to restrict consumer access which in itself is problematic and causes a multitude of unnecessary, restrictive interconnection/codec/format issues.

08-16-2007, 08:26 PM	#1
lifestylestore Audio Visual Specialist Join Date: Aug 2007 Location: blacktown NSW Australia Posts: 1	Hdmi Explained Hi everyone, as a specialist working inside the high end AV world i do come accross rather interesting material delivered stright from the manufacturers themselves, i found this this article about HDMI rather easy to understand, as well as displacing certain myths about the unfamiliar versions of HDMI, happy reading, and i will be definatley posting more interesting articles in the future. Why HDMI and Where Did it Come From? How Does HDMI Work? What is HDCP and How Does it Work? HDMI Specifications Future of HDMI WHY HDMI AND WHERE DID IT COME FROM? There are many reasons why HDMI has become the go-to cable for installers and consumers alike. This is a cable that carries compressed or uncompressed digital video and multichannel digital audio, and an intelligent control signal inside a single jacket. The fact that HDMI omits any analog to digital converters, and vice versa, to create a lossless signal, immediately provides superior video over any analog transmission. Beware of poorly made and non-HDMI compliant interconnects. These cables can cause image quality issues and system failures. HDMI LLC is a group made up of seven very well-known consumer electronic companies: Sony, Panasonic, Hitachi, Philips, Silicon Image, Thomson, and Toshiba. HDMI is found in almost every CE product available, and you will be seeing more computers with HDMI connectors. In 2006, 60 million enabled HDMI products were shipped. It is estimated that in 2009, 180 million CE products will be shipped with an HDMI connector built in. HDMI is already able to support video resolutions beyond 1080p, up to 120MHz refresh rates, and 48 color bit resolutions. Although these specifications will not be available on CE products for some time, the stage has been set. There has always been a consumer need for a cable that carries many signals in one cable. We saw this first type of cable from Firewire. Although Firewire worked seamlessly, it was designed using MPEG2 compression, making it recordable and also incorporated copy protection that was unacceptable to Hollywood. HDMI LLC saw this opportunity and introduced their solution. HOW DOES HDMI WORK? An HDMI connector is designed with 19 pins. And, as you know, HDMI is built to carry audio, video and a control signal. Why so many pins? In the analog days, you could hook up these signals using 6 or 7 pins (connectors). Let's look at the HDMI connector and find out exactly what is going on inside an HDMI cable. There are 5 shielded twisted pairs each with a drain. In addition, there are four more conductors inside this cable: • Three of the shielded twisted pairs are reserved for three high speed data A/V channels carrying TMDS. Developed by Silicon Image, TMDS stands for Transition Minimized Differential Signaling. TMDS is a way to transmit huge amounts of data over a twisted pair, up to 3.4Gbps per pair. Because of the large amount of information being sent, crosstalk can occur between the twisted pairs. TMDS uses an advanced coding algorithm that maximizes bandwidth by reducing crosstalk and data interference between channels. Each twisted pair is color coded to carry the corresponding signal (red for red, green for green and blue for blue). • The clock channel, another shielded twisted pair, enables reliable data processing. This basically means that the clock ensures the TMDS signals arrive at exactly the same time. • The last shielded twisted pair is for the Display Data Channel (DDC) which provides 2-way communication system intelligence. This is also where the Extended Display Identification (EDID) channel is stored. The EDID is a genetics code for electronics. It holds the manufacturer's name, product type, video resolutions, audio type capabilities and other information. The EDID can be read through the DDC channel by all the components in the system. This function of HDMI allows the source to send the best signal available for this display unit. • The Consumer Electronic Control (CEC) uses only one conductor. The CEC is the control part of the cable. It is a bi-directional control that allows something called 1-touch play. This occurs when a trigger sends a series of intelligent commands to multiple devices in a system. A few examples of 1-touch play are: system standby, one touch record, and tuner control. The CEC is found in all HDMI cables, but is optional on some devices. • Another signal conductor inside HDMI is the Hot Plug Detect. This enables the components to detect when an HDMI cable is attached, detached, or when an HDMI input is switched. • The last conductor in the HDMI cable carries a 5 volt supply that provides low current power for the purpose of reading the EDID ROM inside the display. WHAT IS HDCP AND HOW DOES IT WORK? Earlier it was mentioned that Hollywood needed some type of acceptable copyright protection for digital signals. Hollywood insisted all set-top boxes capable of outputting HD signals over a digital cable, be protected from being copied. Intel developed a copyright protection called HDCP or High Definition Copyright Protection. HDCP is a digital handshake for validation between source and display. The electronics use the DDC to perform the handshake. The source and display exchange a secret unique key value that is stored in each device. After the validation, the source encrypts and transmits to the receiver in the display a random algorithm that authenticates every 2 seconds. Though it is mandatory for set-top boxes to have HDCP, it is not required for standard video or over the air hi-definition to use the HDCP validation. HDCP can support up to 128 displays of HD content. At the same time, up to 128 displays can display pictures up to seven layers of switching and/or distribution devices through one HDMI signal. HDMI SPECIFICATIONS HDMI specifications do not specify the maximum length of an HDMI cable. However, HDMI does set the minimum electrical acceptable level of signal quality at the end of every cable. All certified HDMI cables are capable of passing 1080i and 1080p up to 5 meters. It is difficult for 1080p to maintain a sufficient signal beyond 5 meters. The majority of HDMI cables will allow 1080i to pass up to 8m and some cables even further. Depending on your equipment, Tributaries HDMI cables are able to pass 1080p up to 10 meters. We do, however, have an HDMI extender (HX-100) that will ensure a 1080p signal up to 25 meters. FUTURE OF HDMI The buzz word for video these days is HDMI 1.3. Within months, we will see consumer electronic companies offering HDMI 1.3 in all of their products. With two different categories, HDMI 1.3 will be the standard for HDMI. There will be no change in the connector; however, there will be an additional mini HDMI connector for handheld HD devices. The 1.3 cable itself will have tighter twists in the twisted pairs and tighter specifications for the TMDS lines and clock signal. The 1.3 certification can finally include HDCP testing, says HDMI LLC. With these changes, Silicon Image says HDMI 1.2 cables will be able to pass an HDMI 1.3 signal. However, this will most likely hold true for HDMI 1.3 Category 1, which can handle the standard 2.2 Gbps. HDMI 1.3 Category 2 will require handling 10.2 Gbps or more. This category will not be available for some time. Tributaries cannot stress this enough: run flex conduit (2" if possible) to any display location that has or may use HDMI. You could avoid major headaches by future proofing your HDMI runs. Another thing to note, HDMI has finally started talking about a locking connector that will be backwards compatible with current connectors, though we are not sure where or when we will see this connector. A question that is often asked is will there be an in-the-field termination and can HDMI be spliced. The answer is... probably never and no. HDMI uses high speed digital signaling with precision timing tolerances. If the conductors are not the exact same lengths, within a few thousandths of an inch, the timing of the signals will be off, and the signal will not pass. What we, as an industry, have found, is that many different manufacturers did not implement HDMI correctly in the beginning stages. This has made many people skeptical of this technology. HDMI 1.3 may not solve all of the issues that are frequently talked about, but it is a great stepping stone towards improving reliability. Remember, HDMI Licensing LLC is our best ally, and they have developed a way to vastly improve our video and audio experiences

08-18-2007, 04:34 PM	#2
Loves2Watch SPAM Police Join Date: Aug 2007 Location: AZ, NM, TX, MX Posts: 13,928	The problems with HDMI from it's inception are as follows. Weak connector and copy protection. Don't let anyone fool you into thinking any form of copy protection is of benefit to you. It is purely and simply another way for Hollywood to control you, where you can watch your legally purchased media and a way to make you pay for the same media over and over again. HDCP means screw the consumer at all costs and make them pay for it and brainwash them into thinking it is good for everyone. __________________ Theater 1 - Panasonic TH-85PF12U Plasma TV, 6 Conrad Johnson LP275M Amps, Anthem Statement D-2 Pre/Pro, 6 Thiel SCS4 Speakers, 2 REL T-1 Subs, Infinity Interlude 120S Sub, Simaudio MOON Orbiter Universal Disc Player, ELP Laser Turntable, 2 Dish Network ViP 622 DVR's, Oppo BDP-83 Blu-ray Player, Onkyo DV-HD805 HD DVD Player. Friends don't let friends buy Korean brand TV's.

08-20-2007, 10:06 PM	#4
Loves2Watch SPAM Police Join Date: Aug 2007 Location: AZ, NM, TX, MX Posts: 13,928	I am certainly hoping that the connectors on equipment become more rigid and keep the wire from pulling out or loosening. Also HDMI 1.3 has great potential but as stated in my previous post HDCP is ruining it for the consumer and I don't see that getting better anytime soon. The digital DVI and HDMI were invented by manufacturers/Hollywood/the music industry (RIAA and MPAA) to restrict consumer access which in itself is problematic and causes a multitude of unnecessary, restrictive interconnection/codec/format issues. __________________ Theater 1 - Panasonic TH-85PF12U Plasma TV, 6 Conrad Johnson LP275M Amps, Anthem Statement D-2 Pre/Pro, 6 Thiel SCS4 Speakers, 2 REL T-1 Subs, Infinity Interlude 120S Sub, Simaudio MOON Orbiter Universal Disc Player, ELP Laser Turntable, 2 Dish Network ViP 622 DVR's, Oppo BDP-83 Blu-ray Player, Onkyo DV-HD805 HD DVD Player. Friends don't let friends buy Korean brand TV's.

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08-18-2007, 08:08 PM	#3
Chris Gerhard High Definition is the definition of life. Join Date: Nov 2005 Posts: 8,206	Nice post and welcome to the forum lifestylestore. Is your conclusion that HDMI will be fine or do you see some problems. There is an interesting, lengthy thread at AVSForums that discusses the possibilities with HDMI 1.1, 1.2a, and 1.3a and many of the products that use each version and what specific features of each verison. I have a number of HDMI sources now and I am trying to decide on an AV receiver, most likely with HDMI 1.3a, but I am still in the process of reading about all of the issues. Here is a link to the thread at that forum: http://www./avs-vb/showthread.php?t=738511 Chris