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Last week, I attended a webinar hosted by CEDIA (Custom Electronics Design and Installation Association) called "HDMI 2.0: A Look Into the Standard." The presenters were Steve Venuti, President of HDMI LLC; Jeff Park, Technical Specification Manager of HDMI, LLC; and Michael Heiss, CE industry consultant and jolly-good CEDIA Fellow as well as chair of the CEDIA Technology Council.

 

I didn't learn much that I don't already know, but it was a good reminder that the version number doesn't mean much other than a list of possible features that manufacturers might or might not implement. That's why HDMI Licensing wants companies to indicate what HDMI features they have included in their products rather than simply touting "HDMI 2.0." That number refers only to the specification that defines what features are supported, not what must be implemented.

 

HDMI 2.0 ups the maximum bandwidth from 10.2 gigabits per second to 18 Gbps, which can be carried on existing high-speed HDMI-certified cables. However, extenders, boosters, and any other electronics in the HDMI signal chain—including Redmere booster chips and HDBaseT—probably can't support that bitrate without a hardware upgrade.

 

The increase in bandwidth is made possible by a new, more efficient signaling method. Even better, the interface uses the previous signaling method for traffic below 10.2 Gbps, then kicks in the new signaling above that, which means it's completely backward compatible with HDMI 1.4 devices.

 

New features supported by HDMI 2.0 include the ability to transmit 4K video at 50 and 60 frames per second (with some limitations, which I'll get to in a moment) and up to 32 channels of audio with a sample rate up to 1536 kHz. Also, new commands have been added to CEC (Consumer Electronics Control, the ability to control multiple connected devices from one remote), and all commands must be implemented rather than being optional as in previous versions—a welcome requirement even if it flies in the face of HDMI's otherwise feature-optional paradigm. Other features include support for the Rec.2020 color space, dual viewing (two programs displayed on the same TV and isolated for each viewer with glasses, much like 3D), multi-stream audio, dynamic auto lip-sync, and the 21:9 aspect ratio.



HDMI 2.0 adds many new features to the HDMI spec. (Graphic from HDMI Licensing, LLC)

 

As I said earlier, HDMI 2.0 can handle 4K/UHD at 50 and 60 frames per second, but there are some limitations—in particular, in the bit depth and level of color subsampling it can convey. For those who are unfamiliar with color subsampling, it's a type of data compression in which some color pixels are discarded from a component-video signal and reconstructed by the display. It's specified as a series of three numbers—the most common schemes are 4:4:4, 4:2:2, and 4:2:0. Because color subsampling applies to component-video signals, the first number refers to the black-and-white pixels, while the second and third numbers refer to the color-difference pixels.

 

With 4:4:4, no color pixels are discarded, while 4:2:2 discards half the color pixels, and 4:2:0 discards 75% of the color pixels, which reduces storage and transmission-bandwidth requirements. However, the less color subsampling that is used, the better the image quality, especially in terms of clean transitions between colors. Amazingly, Blu-ray uses 4:2:0 and still manages to achieve great picture quality.

 

Using 4:2:0 color subsampling, HDMI 2.0 can convey 4K/UHD at 50/60 fps with up to 16 bits of resolution per color. This provides tremendous dynamic range—far more than the current HD system, which uses 8-bit resolution. If the color subsampling is 4:2:2, HDMI 2.0 can accommodate up to 12 bits of resolution for 4K/UHD at 50/60 fps. And at 4:4:4, HDMI 2.0 is limited to 8 bits for 4K/UHD at 50/60 fps. This presents a conundrum for video-content creators and consumers, who want the best possible specs all around.

 



As more data is transmitted, the bandwidth requirements increase. Notice how much bandwidth is required for 8K (4320/60p) at 4:4:4 with 12-bit resolution—far more than HDMI 2.0 can support! (Graphic from HDMI Licensing, LLC)

 

I suspect—hope, actually—that the UHD system will settle on 4:2:2 at 12-bit resolution, but that is far from certain at this point. A resolution greater than 8 bits is critical to support a higher dynamic range without visible banding, which is even more important than the increased number of pixels in my opinion. And less-aggressive color subsampling will yield sharper transitions between colors.

 

HDMI 2.0 also supports the Rec.2020 specification, which includes a much wider color gamut than the current Rec.709. This allows content and displays to accurately reproduce many more colors than today's Blu-rays and HDTVs.

 



Rec.2020 specifies a much larger color gamut than the current standard of Rec.709. (Graphic from HDMI Licensing, LLC)

 

Many people ask me about alternatives to HDMI—in particular, DisplayPort. As you can see in the following table, DisplayPort 1.2 does offer a somewhat higher overall bandwidth than HDMI 2.0, and much higher Ethernet bandwidth. It also transmits some power and USB communications. DisplayPort is common in the world of computers, but HDMI is so entrenched in the consumer-electronics industry that I doubt it will ever be replaced by DisplayPort. HDBaseT also carries power and USB along with HDMI signals, but its overall bandwidth is the same as HDMI 1.4 until its hardware is upgraded.

 



DisplayPort 1.2 offers a bit more overall bandwidth, but HDMI is too entrenched in the CE industry to be supplanted. (Graphic from HDMI Licensing, LLC)

 

The bottom line is that the term "HDMI 2.0" means next to nothing when trying to figure out the specific capabilities of a particular piece of gear. It's up to consumers to discover which features a manufacturer has included in its products, which can be added in a firmware update, and which will never be implemented. Hopefully, manufacturers will start explicitly listing the features they include in each product, making it easier for consumers to select the gear that's right for them.

 

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some of that sounds better than expected, for once.


but I'm curious, when you're saying the features are optional, are you talking in regards to the displays and sources, not the cables right?


I mean, I'm a little confused with what is actually changing. sounds like for the shorter cable lengths, the cables don't actually need to be changed, but I'm sure they will be relabelled as '2,0' now that there is a standard for it. so for cables, they would be able to support ALL those features listed, correct?


and then, the displays, like has always been, would need to specify what features they support. just like current displays may have hdmi1.4 inputs, but not be 3d capable. and the same thing for sources, just because it has an hdmi 2,0 output, that only means it will pass 18gbps, but the features will still be independently listed. has this not always been the case? or are you saying a display/source may list hdmi2.0 but not support 18gbps? and they can claim that simply because an hdmi 2.0 cable can be plugged into it?


the other thing that interested me was the support for 21:9. After seeing the possibilities of a CIH system with a projector, I find it hard to find a downside to using a wider display and doing the same thing. well, the downside being how difficult is it to get content that's not broadcast in 4:3 around here, but hopefully that would 'have' to change
 

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Discussion Starter · #4 ·

Quote:
Originally Posted by fierce_gt  /t/1523994/hdmi-2-0-cedia-webinar#post_24521175


some of that sounds better than expected, for once.


but I'm curious, when you're saying the features are optional, are you talking in regards to the displays and sources, not the cables right?


I mean, I'm a little confused with what is actually changing. sounds like for the shorter cable lengths, the cables don't actually need to be changed, but I'm sure they will be relabelled as '2,0' now that there is a standard for it. so for cables, they would be able to support ALL those features listed, correct?


and then, the displays, like has always been, would need to specify what features they support. just like current displays may have hdmi1.4 inputs, but not be 3d capable. and the same thing for sources, just because it has an hdmi 2,0 output, that only means it will pass 18gbps, but the features will still be independently listed. has this not always been the case? or are you saying a display/source may list hdmi2.0 but not support 18gbps? and they can claim that simply because an hdmi 2.0 cable can be plugged into it?


the other thing that interested me was the support for 21:9. After seeing the possibilities of a CIH system with a projector, I find it hard to find a downside to using a wider display and doing the same thing. well, the downside being how difficult is it to get content that's not broadcast in 4:3 around here, but hopefully that would 'have' to change
The cables only convey data; they don't care what those data are. HDMI-certified high-speed cables can convey 18 Gbps, no matter what specific features are included in that datastream.

 

Some manufacturers claim that certain 2013 products have "HDMI 2.0" with a bandwidth of 10.2 Gbps, and that's technically true in that they could handle 2160p/60 at 4:2:0 with 8-bit resolution, which requires a bandwidth of 8.91 Gbps. That's technically HDMI 2.0, but those products can't handle higher specs, so calling it HDMI 2.0 is a bit misleading in my book. Upping the bandwidth to 18 Gbps requires new hardware, which wasn't even available last year.
 

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Quote:
Originally Posted by dew42  /t/1523994/hdmi-2-0-cedia-webinar#post_24521435


Was there any talk of 3D? 1080p 3D with 48/60 fps or 2160p 3D with 24/30 fps? I think I'd prefer HFR over 4K for 3D.

I'd rather have 12 bit 4:2:2 and a wider color gamut and object audio than 3D.
 

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Quote:
Originally Posted by Dan Hitchman  /t/1523994/hdmi-2-0-cedia-webinar#post_24521491


I'd rather have 12 bit 4:2:2 and a wider color gamut and object audio than 3D.

I'd hope the bandwidth 3D adds would have no impact on 2D in the HDMI spec. I'd like 12 bit 4:2:2 for 2D and 3D. The compromise I suggested to give up 4K to get HFR would be for 3D only.


Looking at the numbers above; 1080/60p 4:4:4 16 bit uses 8.91 Gbps. Times two for 3D would be just under the 18 Gbps limit.
 

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Pity about DisplayPort. Perhaps Apple will enter into the foray with the option for DisplayPort given its new dealings with Comcast and also potential entrance into 'media displays' (TVs as it were). Apple is perhaps the only company that could bend the trend to move forward with HDMI 2.0. Then again, I don't want to be victim to Apple's Henry Ford mentality.
 

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So anyone who wasted $20K on Sony's 4K projector, or LG's 84" UHD TV now has an expensive paperweight given HDMI2.0 standards didnt exist when these were released... hands up who saw that coming...
 

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Quote:
Originally Posted by KidHorn  /t/1523994/hdmi-2-0-cedia-webinar#post_24522101


I'm confused about the 3D comments. Why would 3D require more bandwidth than 2D? Don't 3D and 2D use the same number of pixels?

Twice as many, seeing as it processed two video streams at once.
 

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Granted this is in an HDMI 2.0 discussion, you never specified 4K. 4K 3D if/when it becomes available would render two 2160p images at a time. 1080p 3D renders two full 1080p images at once. It still increases the required bandwidth regardless if the 3D is 1080 or 2160. There are two simultaneous video feeds being supplied with 3D Blu-Ray.


It doesn't increase the pixel count, it is only the amount of bandwidth it has to process at once.
 

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"The bottom line is that the term "HDMI 2.0" means next to nothing when trying to figure out the specific capabilities of a particular piece of gear. It's up to consumers to discover which features a manufacturer has included in its products, which can be added in a firmware update, and which will never be implemented. Hopefully, manufacturers will start explicitly listing the features they include in each product, making it easier for consumers to select the gear that's right for them."


Thanks again Scott, as always, a great report.


Now, let me just start by saying that I COMPLETELY DISAGREE with the HDMI Organization, letting the product manufactures provide the consumer with which parts of the HDMI 2.0 spec they will be offering in their product. I believe that ALL HDMI 2.0 products should adhere to the COMPLETE SPEC, with ALL FEATURES IMPLEMENTED, PERIOD!


This entire HDMI cabling 1.0 - 2.0 (mess as I call it), can be confusing to even some AVS enthusiast, let alone the common Joe consumer out there, imagine the confusion they will run into.

Another issue I have is that, the HDMI Org should NOT ALLOW manufactures to implement specs OVER FW up-grades..... you could be waiting months or even a year for a FW. (Pioneer BDP-51 - DTSMA FW anyone- almost 1 year wait for FW)

Personally the HDMI association is putting way too much faith in the manufactures. Either that, or they are trying to please them given the mess the HDMI Org has put this entire industry in.


To the HDMI ORGANIZATION - DO IT RIGHT OR DON"T DO IT AT ALL!!!


Paul
 
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