Trusting manuals and specification sheets can be a let-down. Jerry Murray of AV Pro Alliance outlines recent findings.

When it came to HDMI 2.0 installations, we expected everything to work as described in the manuals.

Many of us relied on those manuals and became terribly frustrated. It was like troubleshooting in the dark – replacing potentially defective components with versions known to be OK.

In a similar vein, this article shares AV Pro Alliance findings on the state of UHD/4K from a practical standpoint (what we do in the field) as well as a technical one (what is it, what are the numbers and what do they mean?).

Field testing issues

We have had many 4K UHD TVs and monitors in our lab since the launch of 4K, and about 90% of brands on the market are represented by our samples.

We don’t have every model, but we do have most of the mid and high-end models, and that really does make a difference.

The high-end models tend to have the features we seek. They are mostly all ‘smart’, but beyond that the terminology and features vary widely.

We used Quantum Data 780C generators (HDMI 1.4x) and DVDO TPGs (HDMI 2.0) as reference sources. We also used players – FMP-X10, Nvidia Shield, Smart TVs, Android-equipped USB players, etc – and we had EDID readers.

For cabling we used 0.5m to 5m lengths from various manufacturers – some rated 10.2Gbps, some more than 20Gbps. We also had extenders that use HDBaseT technology and H.264 (HD over IP) technology (encode/decode).

So, in no particular order, here are some findings from when we began ‘testing’ and before we wrote a process for testing and documentation:

The displays don’t always perform as claimed: what it says in the manual, what you are told on the phone by the manufacturer and, in some cases, what is printed on the HDMI port are often incorrect.

We did a web search by model number to determine whether others were experiencing the same thing, and sure enough there were many reports. There are more frustrated early adopters working on this than we thought.

Some online case studies had work-arounds: forcing the TV into a 2.0 mode, or sometimes UHD 2160P60 4:4:4 mode; renaming the HDMI port type to PC; or selecting the menu option for UHD expanded colour.

In other cases only one port was set-up for UHD, and the rest limited connections to 1080P. Even when we employed all the tricks, some displays didn’t lock on to anything above 30fps – certainly not a 2.0 input.

HDCP is also something that is hard to find reliable information on. Some ports do HDCP 2.2 and others fail.

We saw HDCP 2.2 work at 2160P60 4:2:0, and not at 2160P60 4:4:4 (in the same port).

Cables

Cable length matters … and it doesn’t matter.

At first we were not paying much attention to cables and cable length, probably because they all worked out initially to the 5m we were using.

The thing is, at first we were only testing to the limits of our sources – which meant 2160P60 4:2:0 and 2160P30/24 4:4:4 – and everything worked well.

The Nvidia Shield that we picked up only a few weeks ago does do 2160P60 @ 4:4:4. However, it is not a setting you can force: it reads the EDID and sends a 4K signal that will lock on.

We were tricked into thinking everything was OK. When we got to the point of being able to force a 2160P60 4:4:4 signal (>17Gbps TMDS throughput), cable length began to matter.

In our testing, we could not pass 2160P60 4:4:4 signal more than about 2m. Admittedly, we didn’t test lots of different cables, but the results were consistent across five major brands.

We also did not test powered cables or cable booster boxes. When the cables got longer than 2m the picture started to blink – sometimes every five seconds and sometimes every 60 seconds. Cable length seems to matter a lot at high bandwidth.
Extenders

Extenders work and don’t work – something that is well documented, so no surprises there.

2160P60 4:4:4 8-bit was a no go, 2160P60 4:2:0 8-bit was a go. HDBaseT is limited by bandwidth to 10.2Gbps and works perfectly well up to that point and also handles HDCP 2.2.

HDIP is also limited to 4:2:0 8-bit, but HDCP 2.2 also works well there.

Sources

Sources are tricky, and HDMI 2.0 reminds me of 5-Play when HDBaseT came out.

The spec is there, but some items are optional and not required for the 4K UHD 2.0 nomenclature.

Depending on who you are (or rather, who your customer is and what they want to watch) the devil is in the details. Most consumer devices, for good reason, lock on to the preferred format from the TV’s EDID to make sure there is always a picture. They also handle passing HDCP 2.2 keys for encrypted content.

Generators are the trick for forcing signals through systems. The problem is, there isn’t a low-cost option to do everything we wanted to do.

Resolutions

The current flavour for 4K is H.265, which is twice as efficient as H.264 (uses half the bandwidth).

H.265 is what Netflix uses. A full resolution 4K image on Netflix may be softer, and often is softer than an image produced from a 1080P Blu-ray player.

Why? Bandwidth – the Blu-ray is running about 36Mbps, which is much more than most domestic internet services.

MPEG compresses files enough to get through the pipeline to your TV, thus higher speeds (bandwidth) result in a better picture quality and experience. Another way to prove this is via an off-air UHF antenna.

The new Blu-ray player is said to be upwards of 100Mbps and is likely to be 2160P24 4:4:4 10-bit to match a film’s frame rate, although there is a camp that believes it will be 2160P60 4:2:2 10-bit.

In some commercial applications, and for obvious reasons, no compression is a must – engineering, simulation, graphics/CGI, etc.
Conclusion

Our testing might not have been truly scientific, as we initially expected everything to work as described.

Unfortunately, the cards are stacked against you as an integrator at this stage. However, there’s a great opportunity to get ahead of the curve and become a trusted adviser to customers.

What every integrator needs is knowledge and a tool to provide good signals up to 2160P60 4:4:4 with HDCP 2.2 for validation that installations will work and comply with the customer’s application and requirements.