The Next-Generation HDTV

Television manufacturers are moving toward ultra high definition -- also known as "4K" -- which offers four times the resolution of HD. It also offers greater depth of color and faster frame rate. That means more information must travel through the cable-wire from the video source to the TV.

The current de facto cable, HDMI (high-definition multimedia interface), solves some of the old problems of multiple cables, incompatible interfaces and bandwidth issues, but it could it be approaching the end of the line.

"There are currently two schools of thought," Susan Schreiner, analyst at C4 Trends, told the media in an interview with our reporters. "Those that say that you don't need a new HDMI cable for Ultra HD 4K -- and those for whom it is a concern."

The Same Pipe Before

Cable technology -- as in the wired cables that deliver a signal to a TV -- have evolved, but that evolution has been slow. It wasn't really an issue until the arrival of the VCR and, later, video game consoles, which needed a connection to the TV. Remember when there were three cables that delivered the picture from the source to the TV?

That was the composite video era. Sound was sent on two analog stereo cables that were red and white, while video was sent over a yellow cable. Composite technology is still around, even in today's HD sets, as it allows for older devices to be connected.

"Composite video is basically the lowest common denominator for video cables," Michael Heiss, consumer industry consultant, explains. "It is a legacy cable that will still likely stick around, as people might need to watch an old VHS tape."

While composite never went away, it did start facing competition from S-Video, which separates the black-and-white and color signals, thus providing better image quality than composite video. It became a "step up" video cable in the late 1990s, offering an improvement in picture quality over composite.

S-Video does not carry an audio signal, and that has to be delivered separately -- either via an analog solution such as the red/white cables, or via a digital option such as optical. As a result, S-Video actually doesn't streamline the process much. Moreover, it is not able to carry an HD signal.

For HD, the industry adopted component video cables, which transmit video as three separate signals. Again, there were issues -- notably, that audio is not carried in these cables, but also the fact that component cables provide no copyright protection for HD content.

HDMI 2.0

The industry's solution to these problems came in the form of HDMI, which was adopted in 2003. It carries a digital video signal along with a digital audio signal over a single -- albeit it big -- cable. By its 10th anniversary, there were more than 3 billion HDMI devices in use worldwide, according to the HDMI Licensing Group. It had become the true industry standard.

With the arrival of 4K, are the days of HDMI already waning? Not exactly.

HDMI 2.0 -- also referred to as "HDMI UHD" -- which was released last year, allows for great throughput of data, which meant that it can carry 4K resolution at 60 frames per second (fps). It also includes the options of the Rec. 2020 color space, provides Dual View, 4:2:0 chroma subsampling, and supports 25 fps with 3D formats. It supports the 21:9 aspect ratio and offers improved 3D capability.

On the audio front, it carries up to 32 channels of audio, up to 1536 kHz audio, and four audio streams. It offers dynamic auto lip-sync support. In other words, HDMI 2.0 should be more than enough for the next generation of displays -- but some aren't convinced.

1.4 or 2.0 - That Is the Question

The problem is that the industry has tried to stick with HDMI 1.4, which can't do all the magic of HDMI 2.0. The first 4K sets supported HDMI 1.4, and that has created problems.

"The current HDMI 1.4 spec works with the initial wave of 4K sets," noted C4's Schreiner. "It can pass the maximum resolution with the current generation of Ultra HD 4K TVs, which means it needs to pass 3840 x 2160 pixels at up to 30 frames per second, and 4096 x 2160 at 24 frames per second.

"That's the maximum sending and receiving ... available in this initial wave of 4K sets," she added.

"We're just at the beginning of a new product cycle, so we expect that this will become of greater concern in the next generation of TVs -- and newer 4K sets are already starting to sport HDMI 2.0 ports," Schreiner said.

"HDMI 1.4b, which is supported by systems now, provides UHD at 30 frames per second and 24 bits color," noted Craig Wiley, chair of the VESA (Video Electronics Standards Association) marketing task group.

"Released in September 2013, HDMI 2.0 extends this capability to 60 frames per second, but the difficulty has been in delivering HDMI 2.0, since it extends the data rate on a legacy signal format that is difficult to support," he told the press.

All Argument for Display-Port

Because the move to HDMI 2.0 could require a radical shift, interest has arisen in adopting DisplayPort 1.3 as the next-generation cable interface for TV displays.

"VESA published the DisplayPort v1.2 standard in January 2010, which provided support for 4K up to 60 frames per second and 30 bit color, and there have been systems available now for a few years," Wiley pointed out.

"DisplayPort uses the common high-speed signal technology shared by USB, PCI Express, and other high-speed interface standards," he said.

"DisplayPort 1.3, the latest version of the DisplayPort standard, delivers a higher data rate, which is sufficient to support 4K video at 120 Hz, multiple 4K video streams, or 5K video. [It] is used by the latest computer monitors in the marketplace," continued Wiley.

"The emergence of 4K video resolutions and beyond may spark a reassessment of video interconnect technologies," he suggested. "DisplayPort is based on a more modern packetized data structure that uses all four lanes for data transmission with an embedded clock, and it's easily implementable in today's submicron process technologies -- meaning the DP interface can be integrated."

Replacement

However, to move to DisplayPort would require a complete replacement of the existing HDMI cables. It is unlikely consumers or the industry are ready to unplug one cable for another. It also would mean that a new port would be required in future set-top boxes, Blu-ray players and game consoles. That would require a lot of updating of equipment.

"DisplayPort has its champions," said Schreiner.

"We are at a crossroads of sorts, moving towards terrific resolution with greater simplicity, and I'm not sure that the market could bear a transition to DisplayPort as yet another format," she added.

In general, there seems to be enough confusion by consumers -- and they are just getting their heads around 1080p," noted Schreiner. "TV manufacturers are also wary as profit margins are squeezed, and investments have been made in HDMI designs and manufacturing for the foreseeable future."

Further, there is the issue that perhaps more can be put through the next generation of HDMI to keep it plugged in for years to come.

"DisplayPort is a pipe, just like HDMI is a pipe," observed Heiss.

"You can put in what you want, up to the bandwidth limit. Yes, DisplayPort can handle all this stuff, but what isn't so visible is the copy protection -- and that is another issue that will have to be resolved," he said.

"Sure, some people like DisplayPort because it has greater bandwidth and it has higher resolution," acknowledged Heiss. "Apple and Panasonic use it -- but most TV sets don't have DisplayPort. That is not a knock on the technology. It is just that HDMI has billions and billions served."