Aug/090
HDCP in detail
High Definition digital video allows users to experience high resolution, near perfect video content. Asmore content is delivered digitally, the content creators are increasingly concerned with content piracy because digital content can be perfectly duplicated. Therefore anti-piracy safeguards such, as High Bandwidth Content Protection (HDCP) is necessary in order for original content creators to protect their assets. In this article we will touch on the key points of HDCP.
What is HDCP
High-Bandwidth Digital Content Protection,HDCP, is an encryption scheme developed to defend against uncontrolled copying of digital content over high bandwidth digital interconnects such as DVI and the HDMI. The FCC approved HDCP as a “Digital Output Protection Technology” on August 4th,2004. A HDCP protected system consists of: 1) HDCP transmitter(DVD player for example), 2) the digital interface (DVI orHDMI), and 3) the HDCP receiver (your display monitor). Inbrief, the content is encrypted at the transmitter and the signal is passed to the HDCP receiver (display) via the DDC lines (in essence an I2C bus) where it is decrypted before viewing. HDCP requires that both the transmitter and the receiver comply with standards. If either one does not comply,the video will not be displayed properly. Incidentally, HDCP does not apply to analog interface such as component video although component video can be used to display high definition video.
Why should the consumer care about HDCP
It is highly recommended that consumers be aware of HDCP and purchase sets that are HDCP compliant. Here is why. It has been speculated that the two competing high definition DVD standards HD DVD, and BLUE RAY, due out in 2006 will only deliver full resolution on HDCP protected outputs such as HDMI or DVI. If true, then usersmust have a HDCP monitor in order to experience full resolution HD DVD technology. Therefore it is prudent for the consumer to select HDCP compliant displays so the display can be used with future applications.
What is involved during a HDCP session
HDCP is a complicated process but can be broken down to 3 key functions: Authentication, Encryption, and Renewability
Authentication:
The first step before video is actually sent is for the HDCP transmitter to determine if the receiver is “authorized” to accept HDCP protected content. Stored in the PROM of each transmitter and receiver is an array of 40, 56-bit secret keys and a 40-bit entity called Key Selection Vector. Authentication requires that the transmitter and receiver pair exchange “secret keys” and key selection vectors. The keys are scrambled and never revealed. The mathbehind the encryption allows each half to calculate a resultant number, call it Rs, based on the key exchanges. The Rs value is then shared and compared. If the Rs value matches, the receiver is accepted as an authorized HDCP receiver and video transmission can start.
Encryption/Transmission:
Once authentication is completed, transmission of the video content can commence. To prevent an unauthorized receiver from receiving the content, the video data must be encrypted prior to transmission. At the transmitter end, the video data bits are exclusive-ored with ashared calculated number lets call it Rt ( Rt is similar to howRs was calculated) and sent to the receiver. At the receiver end the encrypted data is again exclusive-ored with Rt. Since the XOR function is invertible, XORing with the same Rt at the receiver end will reveal the true unscrambled video bits. Incidentally, a new Rt value is calculated about every 2 secondto prevent corruption due to hacking.
Conclusion
HDTV technology is changing rapidly. Content providers need to protect against piracy by implementing HDCP. HDCP and digital connection standards such as HDMI will become the de facto standard for digital video connections. We have outlined the important features of HDCP, so the consumer can make intelligent purchasing decisions.
Aug/090
Is HDMI the ultimate digital source or just souped up DVI
High Definition Multimedia Interface (HDMI) has been largely hailed as the ultimate interface to enjoy supreme quality high definition audio and video but is it really that good, after all, surely DVI is just as good. Do we really need HDMI?
HDMI was developed with the specific intention of replacing DVI. DVI was primarily used to convert analogue signals to digital for computer monitors. There are actually three different types of DVI, which are DVI-A, DVI-D and DVD-I.
DVI-A uses analogue signals the same as VGA. DVI-D uses a digital signal (as with modern home cinema systems and consumer products). DVI-I is a combination of both DVI-A and DVI-D. Modern electronics use the single link standard for performance but DVI-I can handle this as well as dual link to make it adaptable for future advancements. DVI-I supports a fully digital protocol, which means video up to 1080p can be viewed.
HDMI on the other hand offers an uncompressed digital audio and video interface that has the full support of manufacturers including Panasonic, Sony, and Toshiba to name but a few. Major movie companies too have backed HDMI including Warner Brothers and Universal Pictures. HDMI offers an interface that can connect any audio or video source together. It can do this through a single HDMI cable.
HDMI supports high definition video, normal video as well as digital audio and also have bandwidth to spare in order to make it ready for future advancements in HDMI technology. It must be remembered though that HDMI and DVI are a lot similar and are actually based on a set of specifications that were extremely alike, in fact, HDMI was derived from the DVI requirements.
So, is HDMI any different to DVI? Well yes it is. HDMI actually incorporates a form of content security known as High Definition Content Protection (HDCP). HDMI also can support both audio and video signals through one cable at the same time whereas DVI is limited to only video.
The number of cables needed to set up with DVI is at least two. One is for the audio and one is for the video. HDMI requires only a single HDMI cable therefore leaving fewer cables to be tangled up behind the electronic equipment. This means that anyone using HDMI is going to end up with a cleaner less cluttered space around their equipment.
The important thing to remember is that quality wise; HDMI and DVI are the same. This is because as mentioned earlier they are both derived from the same specifications but HDMI’s ability to support digital audio gives it the edge over DVI. Combine this with the fact that HDMI can do this through a single HDMI cable and it is easy to see why HDMI and HDMI cables have proved to be so popular.
Jul/090
Mini DisplayPort to HDMI adapter available, HDCP compliant
If you’ve been waiting for a way to connect your Mini DisplayPort-equipped Mac to an HDTV via HDMI, Knoxed has got you covered. The company has begun taking orders for its 12.99GBP Mini Display Port to HDMI Adapter, which are expected to begin shipping this Friday.
The adapter is most significant in that it finally allows protected HD content, like that available from the iTunes Store, to be displayed on an HDTV. DisplayPort, mini or otherwise, supports the HDCP encryption scheme designed to “prevent pirating” of HD content. Unfortunately for users of new Macs, most monitors don’t support the standard—but luckily HDTVs do. Gizmodo got a unit to test and they say it works as advertised.
The adapter will transmit audio data along with video if a device’s Mini-DP supports it, however Apple’s implementation on all current Macs does not. It should especially be useful to folks using a Mac mini as an HTPC, but also for folks hooking up a MacBook or MacBook Pro to watch occasional content as well (hello, Hulu). Knoxed is also known for its other display adapters that are usually far cheaper than Apple’s own options.