HDCP attempts to solve a serious problem that?s plagued the studios and other content producers for years and is something that is good for everyone.

HDCP: For Better or for Worse?

| DVIGear Technology Connection

HDCP: For Better or for Worse?
DVIGear Technology Connection

HDCP attempts to solve a serious problem that's plagued the studios and other content producers for years and is something that is good for everyone.


HDCP (High-bandwidth Digital Content Protection) is considered to be either the best or worst feature of digital display technology, depending on who you are. Created by chip giant Intel, HDCP is an encryption technology designed to protect digitally transmitted picture content from illegal copying and distribution (piracy). As such, HDCP is relevant to both DVI and HDMI signal connectivity; with the important footnote that it may or may not be used with DVI signals, but is a mandatory requirement for all HDMI signals.

Backed by content producers (studios) who strongly desire to protect their investments, HDCP's underlying charter is to protect and maintain control of copyrighted materials. Let's look at the piracy issue more closely. Consider today's analog video system. In use for over 50 years, our NTSC video system was developed in an age where vacuum tubes were the norm and solid state devices were unknown. In these early days, piracy was not a concern as video tape recorders were not yet invented. Today, by their own reports, Hollywood studios lose billions of dollars per year on illegal copying and distribution of movies and other forms of program material. As we make the transition from low resolution NTSC video to high definition television (HDTV), the concern over piracy is heightened as the picture quality now more closely approximates the cinematic quality of first-run motion picture films. With its vastly superior picture quality, HDTV represents a clear and present danger to the studios. At the same time, it also represents a major opportunity to stem the flow of illegally pirated content. With HDTV signals encrypted in the digital domain, HDCP ensures that they are far better protected than with the conventional analog signals in use today. The hope is that, as HDTV rises in popularity, HDCP will also become increasingly more effective in thwarting piracy.

Lesson #1: HDCP is backed by the studios as it helps protect their product (movies) from theft.

But how exactly does HDCP work ? HDCP encryption was developed to protect and maintain the integrity of content traveling between two or more digital sources. Therefore, to make HDCP work, all equipment in the system must be fully HDCP compliant, that is, it must conform to all aspects of the HDCP standard. An essential aspect of this compliance is maintaining the integrity of the HDCP encrypted content, which can only be decrypted using special cipher keys. With these keys in use, display devices (TVs, flat screens, projectors, etc.) are able to display the encrypted video content. Without these keys, the HDCP signal cannot be decrypted and hence cannot be displayed. However, it is important to note that HDCP encryption does not protect against illegally copying the information after the receiving device has received and decrypted it. Not surprisingly, the HDCP specification places great emphasis on degree that manufactures must go to ensure HDCP cannot be defeated by "hot wiring" their products.

If a company wishes to implement HDCP in their products (most major manufacturers have), they must obtain a license from the Digital Content Protection, LLC. These licenses are expensive, as they cover the cost of the entire encryption process and are designed to prevent "fly-by-night" suppliers from using HDCP unless they are licensed.

In order to encrypt the information, HDCP compatible units contain a set of forty 56-bit keys that make up the unit's device private keys. Each set of these keys is associated with the device's key selection vector (KSV), which is entirely unique to that device. Therefore, each HDCP-compatible transmitter and receiver has a KSV all to itself. This KSV allows for transmitters and receivers to communicate their encryption to one another in order to ensure the validity of their content protection. Only after a two-part encryption process takes place will the transmitter begin to send information to the receiver via its digital output (i.e. DVI or HDMI display port). If the set of device keys is found to be invalid or corrupt, the digital picture information will not be sent from the transmitter. This process takes a fraction of a second to complete. Of course, all the standard analog ports will still operate with or without HDCP; however, in the future, these analog ports will only carry low resolution signals not exceeding 480p. If you want to enjoy the superior picture quality of full HDTV resolution, you must use the digital (DVI or HDMI) signal ports where HDCP is a key factor.

Lesson #2: HDCP compliant devices are a must for any forward-looking system.

This all sounds simple enough, right? Well, not really. Keep in mind that all devices in the signal chain must be HDCP compliant. Even if the devices on either end of the application are compliant, all devices in the middle must be as well (repeaters, converters, switchers, etc.). Fortunately most cables and adapters simply pass through the HDCP information and hence are not a major concern. For example, if we are using a DVD player with an HDCP encrypted DVI output and sending the signal to a projector, the projector must be equipped with HDCP. If we want to show this same content on two projectors simultaneously, the DVI distribution amplifier that we are using must also be equipped with HDCP. As the application becomes more complex it becomes less likely that all the devices will be HDCP compliant. Remember - if one device is not HDCP compliant - then no signal is passed and your screen goes black.

So, if your system is working non-HDCP now, why should you care? Well, many of us are still viewing prime time TV, DirecTV HD movies and HDTV via cable networks using analog connectivity (Y, Pr, Pb) and it looks just fine. But remember that the FCC has mandated that by 2007, everything will be digital. So for HDTV, you will be obliged to use digital connections (DVI or HDMI) sooner or later. After viewing a side-by-side comparison of digital versus analog connectivity, you may not want to wait. This is even more relevant when you keep in mind that HDCP not only concerns playback of pre-recorded HDTV movies, but also live HDTV broadcasts such as TV shows and sporting events.

Regrettably, there is a down side to HDCP - it's called obsolescence. First, since HDCP is a digital standard, all our legacy analog video equipment cannot participate in what it has to offer. Second, not all manufacturers have adopted the HDCP standards as quickly as one might think. This has resulted in many complaints from end users that have purchased non-HDCP compliant systems. A typical example of this problem happens when an end user purchases a DVD player with a DVI+HDCP output and doesn't understand why his projector's DVI input is "dead".

So what happens if your display devices aren't HDCP compliant and you have sources providing HDCP content? Will your plasma screen or projector just blow up? Not exactly, but you may very well wish it did. In such cases, you'll be obliged to fall back on old analog connectivity which, in the future, will be limited to 480p resolution - not exactly true HD. Your digital inputs will either run with a black screen or perhaps display a convenient message informing you of your HDCP incompatibility.

Ok, now you realize you're stuck with a non-HDCP display with an HDCP compliant source. What are your options? The best option is to return your display and exchange it for one that is HDCP compliant. Otherwise, unfortunately, your choices will be limited. Of course, you could go HD component video (analog HD), which will still produce a far superior image to NTSC, but it's not HD digital which means your possibilities for source material may become increasingly limited as we approach the all-digital cut-over year in 2007.

As we converge on the future, eventually everything will probably use HDCP. For example, if you plan on using your new DVI equipped projector for display of PC or Mac-based computer signals, you may still want to go the route of buying an HDCP compliant model. Computer graphics card manufacturers will likely be pushed to enable HDCP of their products as well to protect digital content. In fact, the Radeon 9700 Profrom ATI already incorporates HDCP. Currently, you could use a PC's DVD player to output a DVI signal to your non-HDCP display without problems, but everyone in the PC industry thinks that will be short-lived as well. Today HDTV PC cards exist that allow for off-air HDTV broadcasts to be routed into a tuner in your PC that could then send signal to a non-HDCP DVI Display. Two popular cards are the MyHD MDP-120 (available with DVI output "Daughter Card") and the Telemann HiPix DTV-200. Although watching TV via a PC receiver isn't the simplest form of TV connectivity to explain to the babysitter, it does work, for now…

HDCP attempts to solve a serious problem that's plagued the studios and other content producers for years and is something that is good for everyone. In fact, piracy is cited as the main reason why audio CD's never got to that price point was promised when they debuted in the early 1980's. While there is still much confusion in the marketplace today due to a lack of understanding, it is clear that HDCP is the wave of the future and that smart buyers will look for HDCP compliance as future-proof protection. Over time, consumer awareness will improve as HDCP enabled devices become more readily available; thus helping fuel the widespread adoption of digital HDTV.

If you are interested in learning more about digital connectivity or have a special application request, please contact DVIGear for more information.


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