The Dreaded HDMI & HDCP


The Dreaded HDMI & HDCP

HDMI & HDCP Versions

The dreaded HDMI and HDCP was originally introduced in 2002 to simplify the connectivity between media devices due to the ever-increasing number of connections. However, as this connection was uncompressed a digitally perfect replica of the source material could be made. So entered the even more dreaded HDCP1.0, (High-Bandwidth Digital Copy Protection). This encryption and handshaking system was designed to minimize or even try to prevent illegal copies of HD source material; with little success I might add. There have been many iterations of the HDMI/HDCP standard as shown in the table below. Each version adds additional features to the connection in order to meet the media industries latest desires/requirements. This connection is the ‘bane of my life’, and many other users. Not that I want to copy anything, it just wasn’t well thought out and is not suitable for multiple HDMI linked devices or long cable runs. And yes there is yet another HDMI version 2.1 on its way rumored to carry:

  • 48Gb/s data (that’s got to be a really short copper cable)
  • 32+ audio channels – why? Most people I know still have problems with setting up stereo properly let alone 5.1 – 12.1 surround sound and immersive audio.
  • Scene by scene dynamic picture metadata. (Dynamic HDR)
  • HFR up to 120 fps.
  • And more!!

The following tables summarize the current HDMI and HDCP versions:

The dreaded HDMI & HDCP

Image credit: HDMI Licensing’s HDMI 2.0 Overview document

Overview of current HDMI standards

 

The dreaded HDMI & HDCP

Based upon Wikipedia HDMI

Detailed overview of current HDMI version functionality

 

The dreaded HDMI & HDCP

Comparison of 4K HDMI Connectivity

(I have ignored RGB connectivity in the above table, as it does not seem to be very popular or used very often in HT.)

 

The dreaded HDMI & HDCP

HDCP Versions


HDMI Connections

There are several issues that you must be aware of in order to satisfactorily support a full 4K HD HDMI connection.

Up to and including HDMI/HDCP V2.0 connectivity and backward compatibility was always guaranteed; the major changes being functionality and increasing data throughput. The biggest change, as can be seen from the above tables, was that HDMI/HDCP V2.0 supports full 4K playback at P60 where as HDMI/HDCP V1.4 will only support 4K at P24/30.

HDCP V2.2 was specifically implemented to try to stop 4K copying and is NOT backward compatible with any other versions. So if your 4K sources, (UHD player etc.) are HDCP2.2 then your display(s) have to be HDCP V2.2 as well. Do not assume that if you have an HDMI 2.2 connection that it is also HDCP V2.2 compliant, most are not. Furthermore, most HDMI V2.2 cannot be upgraded by firmware to HDCP V2.2 so take care when you buy any 4K displays if you want them to support future 4K playback devices.

Note: Any current HDCP V1.4 to V2.1 Blu ray player that is only playing 1080P60 will work with an HDCP V2.2 display, projector or TV. However, any Bluray player that has HDCP2.2 will not work with anything other than a display or TV with HDCP V2.2.


HDMI Cables

HDMI cables carry extremely high data rates. In order for this data not to become corrupted or ‘lost’ the cables need to be made to certain standards. Also there are very real limits to how far you can send such a signal over a copper cable.

For most users the distances involved are not much greater than 6’-10’ and many of those original V1.4 high-speed HDMI cables should work. I say should because not all will; it just depends how well they were originally designed. If you intend to run 4K I would strongly advise replacing all your HDMI cables with a 4K Premium certified cable that show the following label:

The dreaded HDMI & HDCP

The New 4K Premium Certified Label

These Premium cables are not currently available over 25’. Using older cables, even short ones, can cause intermittent image and sound problems that users often put down to the disc or player when they are in fact cable issues.

HDMI cables come in two basic types:

  1. Passive – These cables are made from copper, gold and silver wires and do not require any power to make them work; they rely solely on the technical design of the cables to support the data rates. They are really limited to about 25 feet. Some reputable manufacturers do guarantee their 40-foot cables to support 4KP60 (18Gb/s).Ac2. These cables come as either copper or fiber optic.ActiveActiveActive.
  2. Active – These cables are either copper or fiber based:
  • Most active copper cables use the Redmere PRA1700 V2.0 chip that takes DC power from the DISPLAYS HDMI port to power this small chip that makes up for (equalizes) the cable losses. These cables are capable of supporting 4KP60 (18Gb/s) at distances up to about 50 feet.
  • Fiber optic cables convert to and from light that is passed down a hybrid fiber optic cable. The cable is hybrid as it also contains copper wires to send power to the player end optical converter and allow communications back to the player in order of support a number of HDMI features. Be careful with these cables, as many of the original optical converters did not support 18Gb/s. The latest optical cables will support data rates in excess of 18Gb/s (up to 21Gb/s) and as the fiber optical cable is virtually lossless they can be sold in lengths up to 1000 feet or more.

For more information on premium cables and the certification process visit:

  • HDMI.org – Premium Certified Cable
  • UL Lab – High Speed 4K Cable
  • DPL Labs – DPL Seal of Approval

There are several web sites that now sell Premium cables these include

The following web sites sell a range of passive and active HDMI cables:


HDMI Cable ‘Hops’

One type of connection HDMI does not support well is multiple cable ‘hops’ between many pieces of equipment; even two can cause issues. The handshaking process that authorizes one device to ‘talk’ to another is quite complex and if there is a chain of devices this ‘handshaking’ process can take a long time to occur. Furthermore, the entire chain has to be verified by the handshaking process before the keys are released to allow the encryption/decryption to occur. HDCP V2.2 also has another requirement called “locality check”. This means that each HDMI link needs to have a response within 20mS in order to establish the link. If it is longer than this the link is not established. In practice this should never be a problem, but never say never with HDCP and HDMI.

So if meeting all the 4K specifications is your aim use premium passive cables that are as short as possible or correctly rated active cables; and keep your number of connection hops to two or less.


HDMI Handshaking

Once the HDMI connection has established a valid link, the play device interrogates the TV/display/projector to find out what parameters that it can support, per the earlier tables. The most important of which, in my opinion, are:

  1. Supported display resolutions
  2. Supported frame rates
  3. Supported color spaces
  4. Supported OETF’s
  5. Supported audio formats

This apparently simply process turns out to be anything other than simple and depends upon how the displays manufacturer has configured its responses and how the player responds to them. The idea is that the two devices should ‘negotiate’ the optimal resolution and playback format to provide the best picture and audio that both devices can support. Well, as you guessed it, this process is not always optimal. It can result in the incorrect selection of color bit depth, color gamut and color space and even gamma curve (OETF). The good news is that many playback devices allow you to force the selection of other playback formats if the handshaking process is anything less than optimal.

The selection of the items 1, 2, 3 and 4 is often not as straightforward as you may think. Often a degree of experimentation is required on behalf of the user in order to obtain the best picture. This is because the ability of the display and the player to manipulate the disc/video format into the correct format to create the best picture is dependent upon the software and hardware in each device. For example some players do a better job at scaling than the display device, and may also do a better job of creating the correct color sub sampling. Also re-mapping of HDR to a non-HDR SDR display can be quite problematic.

There is no ‘golden panacea’ to solving this issue, and unfortunately at the moment the varying UHD standards that are becoming available are creating a significant number of headaches in trying to optimize your system to support them all WITHOUT continually “tweaking” the system when you change between them.


Certified 4K Displays and Projectors

HDMI cables connect sources, like Blu-Ray players, to AV receivers, TV’s and projectors. In order to ensure that the projectors and displays meet the required minimum technical requirements in order to display this pristine 4K signal a certification process was setup. Any device that carries the following label is supposed to meet those requirements.

The dreaded HDMI & HDCP

 

In order for a display or projector to sport the above label it must meet a number of criteria set down by the UHD Alliance. This alliance is a group of industry content producers, distributors and manufactures that created this logo so that buyers would know that they are purchasing a display that will support this new 4K standard.

In order to receive this label a display or projector must meet the following standards:

Home Displays

  • Native Image Resolution: 3840×2160
  • Color Bit Depth: 10-bit signal
  • Color Palette (Wide Color Gamut)
  • Signal Input: BT.2020 color representation
  • Display Reproduction: More than 90% of P3 colors
  • High Dynamic Range
  • SMPTE ST2084 EOTF
  • A combination of peak brightness and black level either:
    • More than 1000 nits peak brightness and less than 0.05 nits black level
      or
    • More than 540 nits peak brightness and less than 0.0005 nits black level

Professional Distribution

  • Native Image Resolution: 3840×2160
  • Color Bit Depth: Minimum 10-bit signal
  • Color: BT.2020 color representation
  • High Dynamic Range: SMPTE ST2084 EOTF

Content Mastering

  • Native Image Resolution: 3840×2160
  • Color Bit Depth: Minimum 10-bit signal
  • Color: BT.2020 color representation
  • High Dynamic Range: SMPTE ST2084 EOTF

Professional Mastering

  • Display Reproduction: Minimum 100% of P3 colors
  • Peak Brightness: More than 1000 nits
  • Black Level: Less than 0.03 nits

Unfortunately no home projector can currently meet these Home Display standards  or is likely to in the near future. So companies like Sony that sell native 4K projectors came up with their own 4K Premium label so that there would be continuity across all their 4K brands.


So where to now?

Unfortunately nowhere. We are stuck with this interconnect standard and I do not see any way of things improving except by the manufacturers improving their HDMI firmware. Modifying your devices, as I used to in order to support HDSDI for 1080P60, is not cost effective for 4K and I can never imagine anybody supporting or offering such an “upgrade”.

The third and final post of this series will review the various audio formats found on these shinny plastic discs. See post 1 High Definition Video Formats on DVD and Blu-Ray here.