HDMI Forum Releases Part 1 of the HDMI 2.1 CTS

[Glenwing]

Since the release of the HDMI 2.1 master specification in November 2017, I have seen many people who expect HDMI 2.1 monitors to start coming out at this point, but this is actually impossible at the current time. This is because the testing procedures for determining HDMI 2.1 compliance have not been written yet. The HDMI Forum is still at work drafting version 2.1 of the HDMI Compliance Test Specification, or HDMI CTS, which is a separate document from the HDMI Specification. The HDMI CTS is the document used to certify products as "HDMI 2.1 compliant", not the HDMI specification, which mainly describes how all the features operate at the bit level so engineers can start working on hardware that will do those things.

 

The release of the master specification is when engineers begin designing products, it typically takes at least a year (usually more) after the release of the specification before products implementing it are released (with exceptions for companies like Sony, who are one of the principle designers of HDMI and thus have a special advantage when it comes to developing hardware for new versions).

 

Up to this point there has been no HDMI 2.1 CTS at all; the HDMI Forum had stated that it will be released in parts, beginning in late 2018. They appear to be on schedule with that claim, as the HDMI.org FAQ has been recently updated this month with the release of the first part of the HDMI 2.1 CTS:

 

https://www.hdmi.org/manufacturer/hdmi_2_1/  (archive)

Quote

Testing and Certification FAQs

Q: What is the testing policy for HDMI 2.1 products? 
A: All products must comply with Version 2.1 of the HDMI Specification and the HDMI 2.1 Compliance Test Specification (CTS); and until the CTS is available and a product has passed compliance testing a product cannot claim to be 2.1 compliant or market that it supports 2.1 features.

 

Q: When will the HDMI 2.1 Compliance Test Specification be available? 
A: The HDMI 2.1 Compliance Test Specification (CTS) is being published in stages and the first release was in August 2018 including support for Enhanced Audio Return Channel (eARC). Additional features will be added in the coming months.

[...]
 

Q: Can I use “HDMI 2.1” in my marketing
A: You can only use version numbers when clearly associating the version number with a feature or function as defined in that version of the HDMI Specification. You cannot use version numbers by themselves to define your product or component capabilities or the functionality of the HDMI interface. And please note that NO use of version numbers is allowed in the labeling, packaging, or promotion of any cable product. Please check the Adopted Trademark and Logo Usage Guideline for a complete explanation of the policy, available on the Adopter extranet and here.

 

I should also note that you should watch out (in general) for "HDMI 2.1" devices that will inevitably appear on the market. "HDMI 2.1" is not a feature that you support or don't support. It is the version of the document that is used to design HDMI devices.

 

The HDMI 2.1 specification supersedes the HDMI 2.0 specification and therefore the HDMI 2.1 will be referenced for all new designs. Even if you are designing a 4K 60 Hz TV and don't plan on using any new features from the new specification, you don't dig into your file cabinet and pull out an old version of the specification to design from. You would always use the newest one available. All designs that are valid under the HDMI 2.0 specification will also be valid designs under the HDMI 2.1 specification, you don't select which version of the document to use based on what features you want, you always refer to the newest version of the document.

 

Beyond that, the HDMI "version" has no official meaning. When a product claims to have an "HDMI 2.1 port", maybe they just mean they used the HDMI 2.1 specification when designing the product, which doesn't necessarily mean they implemented any of the new features described; they could also mean to say that their product is compliant with the HDMI 2.1 CTS, to which the same applies; you don't have to implement any new features to be compliant with the CTS.

 

There have in fact already been AV receivers released months ago with "HDMI 2.1" ports despite that fact that the compliance test wasn't even written yet. The "HDMI 2.1" claim has no meaning, since it does not actually imply anything (even though people will assume things from it things like 48 Gbit/s bandwidth and such). They seem to have implemented eARC, but they don't claim anything else of substance.

 

https://www.avsforum.com/yamaha-rx-v385-av-receiver-implements-hdmi-2-1/

Quote

Perhaps the biggest news is that the RX-V385 implements HDMI 2.1 in its four inputs and one output, making it one of the first products I know of to use the latest HDMI spec. The maximum bit rate is not specified, but the AVR is said to support 4K/60p 4:4:4 video, high dynamic range (HDR10, Dolby Vision, and HLG), and BT.2020 color. So, I assume the bitrate is 18 Gbps—the same as HDMI 2.0's top rate—which I will confirm as soon as possible. In addition, the RX-V385 will add eARC (Enhanced Audio Return Channel) in a firmware update.

 

We actually had this same problem when HDMI 2.0 was released, AV receivers quickly started claiming "HDMI 2.0" support, but in fact some were still limited to HDMI 1.4 bandwidth and features (it was harder to tell in this case, because they could still claim to support "4K 60 Hz"—just only with YC_BC_R 4:2:0 subsampling, which falls within HDMI 1.4-level bandwidth). These new "HDMI 2.1" receivers I expect are the same old story.

 

https://www.audioholics.com/hdtv-formats/hdmi-2.0-hdcp-2.2

Quote

On the flip side, new Onkyo receivers are listed with HDCP 2.2. What they aren't telling you is that the HDMI 2.0 implementation is limited to 10.2Gbps (just like HDMI 1.4).

 

So, be very careful when you see "HDMI 2.1" products. A version number does not imply anything at all about its feature support.

 

This is precisely why the HDMI licensing authority banned the use of HDMI version numbers in product labeling and promotion back in 2012 (or 2009 for cables). HDMI devices are properly described by listing their actual capabilities (i.e. HDMI port with ARC, VRR, 48 Gbit/s bandwidth, or for cables a "High Speed HDMI cable" or "Standard Speed HDMI cable", etc.), not with a version number which doesn't actually imply anything. Of course, this is somewhat cumbersome notation which not everyone is happy with (people like version numbers), and the policy is not enforced very strongly, but there it is.

Quote

Effective January 1, 2012, when marketing an HDMI Product, any references to HDMI version numbers is prohibited.

HDMI Cables

Using HDMI version numbers in the labeling, packaging, or promotion of any cable product is prohibited. This includes releases of the HDMI Specification (for example, HDMI 1.4, 1.3, etc.), interim version numbers (for example, HDMI 1.4a, 1.3a, etc.) and CTS (Compliance Test Specification) version numbers (for example, 1.4a, 1.3c, etc.).

Cable products that refer to version numbers are considered non-compliant and subject to trademark enforcement actions.

Non-cable products

Effective January 1, 2012, you may not use version numbers when marketing your HDMI Products.

 

In any case, the HDMI Forum has released only Part 1 of the HDMI 2.1 CTS. The remainder of the HDMI 2.1 CTS is not yet complete, and it is therefore at this time still impossible for an "HDMI 2.1 compliant" product or cable to exist, since there is nothing for them to comply with yet.

 

Any product claiming to be "HDMI 2.1 compliant" right now, or any HDMI cables that claim to have an Ultra High Speed certification, are fake. (For clarity, it is the claim of certification that is fake; a new product could very well support all the new HDMI 2.1 features (it's just unlikely, in this amount of time); technically if someone had magic super fast engineers they could design hardware capable of performing the tasks described in the master specification from day 1 of release, there is nothing stopping them from doing that. But they cannot possibly have certified compliant products until the HDMI 2.1 CTS is complete.)

 

http://www.bluejeanscable.com/articles/what-about-hdmi-2.1.htm

Quote

 In fact, at the moment even if someone were to come up with a new device implementing 2.1, there'd be no way to certify it, because HDMI has published only the master specification document. In order for products to be evaluated for conformity to 2.1, there will need to be Compliance Testing Specifications, and these are not likely to be out until deep into 2018. The upshot is that it's fairly likely that you won't see products until 2019, so don't fret about not having 2.1 devices in your system today, or in the coming year or so. After that, we'll see how long it takes for 2.1-specific features, protocols and resolutions to be implemented.

 

Anyway, the takeaway is that we are now 1 step closer to implementation of HDMI 2.1 into the market, which is cool. Personally, I expect that it will still be another year or so before products which implement meaningful 2.1-specific capabilities actually become available for purchase, likely with the next wave of 4K 144 Hz displays (in fact I expect that the availability of HDMI 2.1 silicon will actually dictate when that particular wave of products will occur, but we'll see ).

[WereCat]

I find this all very confusing. 

Its like a USB type C.

 

When device has it, you have to check the reviews or find some data sheets to find out which features it has on the particular product.

[Stefan Payne]

5 hours ago, Glenwing said:

 

Anyway, the takeaway is that we are now 1 step closer to implementation of HDMI 2.1 into the market, which is cool. Personally, I expect that it will still be another year or so before products which implement meaningful 2.1-specific capabilities actually become available for purchase, likely with the next wave of 4K 144 Hz displays (in fact I expect that the availability of HDMI 2.1 silicon will actually dictate when that particular wave of products will occur, but we'll see

You know anything about variable refreshrate?
Is that still optional or mandatory for HDMI 2.1??

[Glenwing]

40 minutes ago, Stefan Payne said:

You know anything about variable refreshrate?
Is that still optional or mandatory for HDMI 2.1??

Nothing in HDMI is mandatory other than baseline requirements for interoperability. Features like VRR are optional.

[EnergyEclipse]

I still cannot find were to even purchase a HDMI 2.1 cable here in the UK, and its not easy to get a real HDMI 2.0b anywho

[mynameisjuan]

8 hours ago, WereCat said:

Its like a USB type C.

No even close to how fragmented type-c is. But I get your point. 

[Jito463]

9 hours ago, EnergyEclipse said:

I still cannot find were to even purchase a HDMI 2.1 cable

Probably because of this quoted section from the OP:

19 hours ago, Glenwing said:

You cannot use version numbers by themselves to define your product or component capabilities or the functionality of the HDMI interface. And please note that NO use of version numbers is allowed in the labeling, packaging, or promotion of any cable product.

 

[Glenwing]

11 hours ago, EnergyEclipse said:

I still cannot find were to even purchase a HDMI 2.1 cable here in the UK, and its not easy to get a real HDMI 2.0b anywho

There are no "HDMI 2.1 cables", that's the point No products can receive HDMI 2.1 certification because the certification tests have not been finished yet. All "HDMI 2.1 compliant" products currently are fake.

[inumoto]

Quote

On ‎14‎.‎08‎.‎2018 at 4:15 AM, Glenwing said:

All "HDMI 2.1 compliant" products currently are fake.

 

It's a fake or not but the chip vendors already has started selling the hardware components for 2.1. E.g. Lattice offers the eARC chipset. It's a complete solution, both Rx and Tx parts. I'm not sure about the certification label but Lattice is a major sponsor for the HDMI commettee so it seems they knows what they're doing.

 

Anyway from the engineering perspective it's interesting to watch the evolution of the HDMI specification. A lot of new facilities came with recent versions. The version 2.0 introduced scrambling and SCDC while version 2.1 introduced eARC. According to the marketing materials the eARC is able to carry a loseless HD audio (such as Dolby True HD). Sounds very good. But what exactly is done to make it possible? For commoners, the version 2.1 is a hard to find thing at the moment so I can't look into it but I see the point of concern.

 

The analysis of the 1.x versions shows that there is nothing that prevents transmission of loseless audio over conventional ARC. It allows an IEC 61937 frames over the 60958 stream (optionally) so from the protocol perspective, any format that has the respective 61937 definition is automatically supported. Moreover, since the version 1.4, a twisted pair (HEAC+ and HEAC-) with defined characteristics is used for ARC so the bandwidth is not likely an issue (at least for usual True HD, without Atmos) even in the Single or Common mode signaling. Anyway technically it's perfectly possible with 1.x spec. But I'm not aware of any implementation. I think the problem is not lack of bandwidth but the DRM issue. It's not common to transmit a valuable commercial content over the wire in clear. In the forward channel the DHCP mechanism is used so the content can be encrypted. But the 1.x spec defines no DRM mechanism for the return channel (ARC) and this is why loseless surround formats can't be transferred over ARC. So I wonder if such mechanism is defined for eARC? Because if not it's another dead feature. Again, I don't have access to the spec but it seems a well-informed people are here. So the question.

 

PS I'm new here and this is my first post so the good conduct rules requires to introduce myself. But doing so will make the post even larger so maybe next time...

[Glenwing]

17 minutes ago, inumoto said:

It's a fake or not but the chip vendors already has started selling the hardware components for 2.1. E.g. Lattice offers the eARC chipset. It's a complete solution, both Rx and Tx parts. I'm not sure about the certification label but Lattice is a major sponsor for the HDMI commettee so it seems they knows what they're doing.

Well, as I said in the original post...

 

On 8/12/2018 at 8:27 PM, Glenwing said:

Any product claiming to be "HDMI 2.1 compliant" right now, or any HDMI cables that claim to have an Ultra High Speed certification, are fake. (For clarity, it is the claim of certification that is fake; a new product could very well support all the new HDMI 2.1 features (it's just unlikely, in this amount of time); technically if someone had magic super fast engineers they could design hardware capable of performing the tasks described in the master specification from day 1 of release, there is nothing stopping them from doing that. But they cannot possibly have certified compliant products until the HDMI 2.1 CTS is complete.)

 

[inumoto]

15 minutes ago, Glenwing said:

But they cannot possibly have certified compliant products until the HDMI 2.1 CTS is complete.)

That's true. On the other hand, it's reasonable to don't over-estimate importance of such labels. The service of registered certification labs costs a lot so according to the HDMI rules only the first product of given vendor needs to be submitted to an independent lab for official testing. All subsequent products can be self-tested. Afaik for an HDMI 1.x products