Video

4K: Get Ready

The format today and where it will take us.

It’s that magical time of the year again: early summer, when we trek out to Las Vegas and see the latest and greatest in AV gadgets. (And try not to swelter in the process.)
And this year, we’re undoubtedly going to see several ultra high definition (UHD) displays (mostly direct view, with some projection), along with media players and a pile of interfaces that are all “4K ready” or “4K certified.” In other words, a new 4K “train” is boarding at the station. Should you get on it?

At first glance, much of the interest in 4K seems to be hype generated by marketing and PR departments. And it’s perfectly understandable to figure that, after 3D fell flat on its face and other TV add-ons like “smart” operating systems met with a tepid response, this new emphasis on 4K is just another crass attempt to sell more televisions and displays.

But there’s more to the story than you may think. And much of it has to do with supply-chain issues in Asia, and not with the desire to sell more televisions to consumers. Add in economies of scale and Moore’s Law, and what we really have coming is a whole new television system: one that will definitely impact our industry in short order.

Display Economics 101
Right now, the television industry isn’t a fun place to play in for most manufacturers. According to NPD DisplaySearch, worldwide shipments and sales of televisions have declined for two years in a row, dropping 6% in 2012 from 2011 and falling by another 3% in 2013. Plasma and CRT display technologies are on a death watch, with both of them accounting for only 7% of all TVs shipped last year.

To make matters worse, everybody and their brothers are in the LCD panel manufacturing business. That has resulted in an oversupply of panels on multiple occasions and falling prices across the board. For Japanese manufacturers, display panel fabs have proven to be a money-losing venture, leading some major brands to exit the TV business altogether (Hitachi, Mitsubishi) and phase out plasma (Panasonic).

In Korea, both Samsung and LG are strong players in panel manufacturing. Yet, both company’s market shares remained about the same in 2013 from the previous year, while their net margins on wholesale LCD panels have dropped into the low single digits. LG Display announced at the end of April that it had incurred a net operating loss of about $79M, and that shipments of LCD glass for all display applications had decreased by 13% over Q4 2013.

Meanwhile, LCD panel manufacturing is ramping up in Taiwan and China, and profitability is much better: as much as 8% to 10% of the wholesale panel price. And manufacturers are getting better at making big panels (larger than 55 inches). In fact, many Chinese companies decided to concentrate on larger 2K and 4K panels in 2013, instead of trying to get into the sexy but lower-yield organic light-emitting diode (OLED) display business.

Smaller Is Better?
More panel production is moving to tablets and other portable gadgets, and in fact, 2014 LCD panel shipments for Bring Your Own Device (BYOD) applications are expected to surpass those going into televisions, the first time that’s ever happened. What this all adds up to is plenty of LCD manufacturing capacity, diminishing demand, and a move to higher resolution to recover profitability. Truth be told, it doesn’t cost that much more to build a large 4K (3840×2160) LCD panel for a television than a 2K panel, and the latter isn’t very profitable.

Indeed; Vizio announced at CES earlier this year that it would bring out a line of aggressively priced 4K TVs this fall. How aggressive? Consider that a typical 55-inch 4K LCD TV with LED backlight currently sells for about $2700 from Japanese and Korean nameplates. In contrast, Vizio will sell a 55-inch 4K LED TV for just $1300 and a 65-inch version for $2200. TCL has already come out with a $999 50-inch 4K set, and others will follow.

What all this points to is an accelerating shift away from 2K glass in large LCD TVs and monitors (above 55 inches). It won’t be long before all large LCD displays come with 4K resolution, whether you want it or not. (We went through this before, about eight years ago, transitioning from 720p and 760p resolutions to 1080p. Remember?)
So, there you have it: 4K is inevitable, but not for the reasons you may have thought. Now, let’s address the problems that scenario creates.

Gozinta, Gozoutta
Setting aside the question about image scaling from 2K to 4K in these new products (yes, image scaling chips are built-in, and they work better than you think), how the heck will we interface these displays? Right now, the dominant digital display interface for displays and monitors is still good ol’ HDMI, with DVI and VGA still found here and there.

Guess what? You can kiss VGA goodbye with 4K because it simply isn’t fast enough. And support for DVI has essentially ended; it is expected that DisplayPort will replace it over time. So, where do we stand with both interfaces?

Last September, Silicon Image released the latest specs for HDMI 2.0. The maximum clock rate was kicked up to 18 gigabits per second (Gb/s), almost double that of the current HDMI 1.4 standard (10.2Gb/s). That’s encouraging, because HDMI runs out of gas pretty quickly when dealing with high frame rate (50Hz and higher) display signals, especially if expanded color bit depths are used (think desktop and notebook computers).

As usual, there is a catch: Only 80% of the total data rate is actually used for the display and audio signals. That’s because the format for transmitting HDMI’s transition-minimized differential signal (TMDS) is mapped using an 8-bit/10-bit format; just the same as HD-SDI, DisplayPort and FireWire.

So even though we now have 18Gb/s as a target, our display interface can only use 14.4Gb/s of that to make a display connection. And with 60Hz refresh, a Quad HD (3840×2160 pixels) signal in the RGB format has a pixel clock of at least 556.7MHz and requires a data rate of 13.36Gb/s (less the extra 2-bit overhead).
Now, change the color resolution to 10 bits per pixel, and you’ve blown by the 14.4Gb/s speed barrier. This is a real problem because more and more computer video cards will operate in expanded color modes with high frame rates over digital interfaces.

Right now, there is a dearth of HDMI 2.0 interfaces on AV gear and that’s not going to improve for several more months. So, when you see manufacturers advertising that their interfacing gear is “4K Ready” or “4K Certified,” they’re likely still using the older HDMI 1.4 interface standard.

That may be OK, as long as you aren’t trying to connect a Quad HD signal with anything other than 24 and 30Hz refresh rates. (HDMI 1.4 can only handle a Quad HD signal with a maximum refresh rate of 30Hz and 8-bit color, or 24Hz refresh with 12-bit color.) But if you want to set up a high-powered workstation with faster refresh rates and deeper color, you’ll need multiple HDMI 2.0 connections and a way to break up and re-stitch each frame of video.

DisplayPort Is ‘Pure’
I mentioned DisplayPort earlier. The current iteration of this interface (1.2) is already faster than HDMI 2.0. Unlike HDMI, DisplayPort is a pure digital interface, streaming data, audio and control packers over four scalable “lanes” from source to display. The maximum data rate per lane is 5.4Gb/s and for all four lanes, 21.6Gb/s.
Applying the 80% rule leaves us 17.28Gb/s for a Quad HD or “cine” 4K signal (4096×2160). And that’s fast enough to connect Quad HD with a 60Hz refresh and 10-bit color (16.7Gb/s without the 2-bit overhead). Note that the DP interface is fast enough to support older blanking intervals (4400×2250), as well as a new, smaller interval (4176×2222 pixels) recently standardized by VESA.
DisplayPort 1.3

Later this year, DisplayPort 1.3 will be officially released as a standard. Although most of the details are still in the works, version 1.3 will allow for light compression of the display signal and kick the maximum data rate well over 30Gb/s. Applying the 80% rule means we’ll still have 25Gb/s to play with, and that will support Quad HD @ 60Hz with 12-bit color.

Still, the transmitter and receiver chips for DP 1.3 will still take some time to get to the market. But for now, using DP 1.2 as an interface is a pretty good idea and provides some degree of future-proofing for your soon-to-be-designed UHDTV monitor system. (Some 4K consumer TVs already have a DisplayPort connection, as do an increasing number of computer video cards.)

Skeptical about everything I’ve just told you? Guess what! In mid-April, Toshiba started selling the Satellite P55t, a Quad HD notebook computer. Yes, it has a native 4K display screen (3840×2160 LCD, 15.6″) and the HDMI 1.4 connector can port a Quad HD signal @ 30Hz to the appropriate monitor. And it costs only $1500!

Nothing To See Here?
So, where’s the 4K content? It’s coming. Several TV manufacturers are already selling custom 4K media players, loaded with movies, as an add-on to their TV products. (As I’m writing this, Samsung is offering customers who buy its top-of-the-line curved 4K LCD TV a free 4K movie/media pack that contains five feature films.)
The real challenge here is bandwidth. It’s pretty obvious that 4K streaming will be here faster than an updated 4K Blu-ray format. In any event, the average consumers have indicated they’re more interested in streaming movies and TV shows from a “cloud” server than buying or renting optical discs.

So, to complete our 4K ecosystem, we need to develop a new video codec: one that is much more powerful than the MPEG4 H.264 Advanced Video Codec we currently use.

Guess what? That codec is here. It’s called High Efficiency Video Coding (HEVC), and its designation is MPEG-H H.265. Although the vast majority of H.265 demos conducted to date use software encoding and decoding, there are dedicated H.265 chipsets coming from Broadcom, with Qualcomm developing ASICs for tablets and smartphones.

How efficient is H.265? How about streaming Quad HD content at 15Mb/s, about the same average bit rate as a Blu-ray disc playing out a 2K movie file. Speaking of 2K, video at that resolution can be streamed at just 2Mb/s to 3Mb/s using H.265, while standard-definition video for small BYOD screens requires less than 1Mb/s.

Coming To A TV Near You…
This isn’t “pie in the sky” stuff. At NAB 2014, LG and Gates Air (the old Harris Broadcast operation) partnered to show an ATSC 3.0 next-generation digital TV demo that combined a Quad HD signal, a 2K broadcast, and a standard definition program, all in one 6MHz TV channel, using H.265 encoding and decoding.

With the current (and practically obsolete) MPEG2 standard used for digital TV broadcasts, we’re limited to one HD and one or two SD programs in the same channel if we want to maintain a high-quality image for each program. So, H.265 now can encode 2K HD video at bit rates lower than MPEG2 SD video…quite an advance in 20 years!

There’s another reason why we need a new codec (and faster display interfaces). A new generation of cameras is coming to market, and these wonder boxes can capture images with very high dynamic range: as much as 13 to 14 stops of light in the same scene. Not only that, they will do this using high frame rates (48Hz and up to 120Hz).
If you do the math, that is a ton of pixels to refresh. Add in expanded color bit depth (a must with 4K; 8-bit color doesn’t cut it) and you can see where we have real challenges looming in encoding, decoding and displaying 4K video, let alone 2K video.
Like A Rainbow

Keep in mind that a new color space (ITU BT.2020) has been defined for ultra high definition video. And it’s much, MUCH wider than the BT.709 space currently used for HDTV. In fact, it may not be possible to create some of the colors in this space unless high-power lasers are used!

High dynamic range (HDR), high frame rate (HFR) video and expanded color bit depths aren’t going to show up on your doorstep tomorrow. But they will arrive faster than you think! At NAB, several compact 4K cameras were shown at surprisingly affordable prices.

GoPro already has a 4K camera (sort of) with the $399 Hero 3: It can shoot Quad HD at 15fps. And Blackmagic Design has a $3000 4K studio camera to go with the new Ursa 4K shoulder camcorder (about $6000) seen at NAB 2014. In the JVC booth, they unveiled two new 4K camera designs: the GY-LSX1 (shoulder mount) and GY-LSX2 (handheld). Prices weren’t announced, but JVC has been aggressive in the past.
Ready Or Not…

We’ve just scratched the surface with 4K. Not all of the puzzle pieces are in place yet, but 4K direct-view and projection displays are already available, even if their interfaces aren’t fast enough. Of course, anyone who sells HDMI 1.4-compatible switchers, scalers and distribution amplifiers can claim they are “4K ready” and be partially truthful.

On the content end, we’ll see hardware encoders roll out this year, once dedicated H.265 chipsets are widely available. And some companies are already playing around with 4K streaming, most notably Netflix. 4K media players that support the older HDMI 1.4 standard are yours for just $299, believe it or not. And SMPTE is currently finalizing standards for multi-link HD-SDI, allowing streaming rates to 12, 24 and even 48Gb/s for UHD-1 and UHD-2 format signals.

As you can see, there really is “more than meets the eye” with 4K. Better get on board before the train pulls out…

Contributing Editor Pete Putman, President of ROAM Consulting LLC, is a Senior Academy Instructor for InfoComm and was named Educator of the Year for 2008. Pete authors the monthly “AVent Horizon.” He is a member of both SMPTE and SID, and holds CTS and ISF industry certifications.

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