While CES 2015 was full of 4K displays, delivery standards have yet to be defined.
At NAB 2015, it is a given that many companies will dazzle attendees with stories of how 4K television is virtually here. For those susceptible to such celebratory hype, it might be good to think about the issue for a bit and be armed with some intelligent questions to ask manufacturers who are promoting it.
Yes, 4K production cameras and consumer displays are already here — and the cost is coming down fast. But delivering 4K video to the home takes four times the bandwidth of standard high-definition television. That is a giant leap to make.
And when we speak of 4K, we really mean four times the pixels of HD. There are many serious television engineers who question whether four times the pixels alone will sufficiently impress consumers hungry for the next “Wow” experience.
In order to get the dramatically improved television images consumers who pay for 4K TV displays expect, most engineers agree it will take more than just an increase in pixel count. Other enhancements — like increasing the frame rates of images and including high dynamic range encoding and decoding — will also be needed to make the images really pop out of the television set.
CES & 4K: Don't be fooled again
At CES in January, manufacturers of 4K gear were already talking enhancements beyond pixel count. HDR, as the high dynamic range feature is called, is a way to reproduce a greater dynamic range of luminosity than is possible using standard digital imaging techniques. This is an important addition to 4K video in order to represent a greater range of luminance levels found in real-world scenes.
Sony, Panasonic, Samsung, LG and Disney Research showed high-dynamic range video displays at CES. Netflix announced that it is now shooting all its new shows in both 4K and HDR. However, a standardized HDR technology must be widely implemented throughout the broadcast chain and that hasn’t happened yet.
Online services will deliver 4K first since they use IP delivery. Bandwidth can be more easily increased over Internet-based systems. Traditional broadcast, cable and satellite services will have to do far more enhancements to their basic technology in order to be ready if 4K becomes economically viable for them.
HEVC (H.265), or high efficiency video coding — which doubles the data compression ratio over today’s H.264 encoding — is considered essential to handling 4K signals. The first version was approved in 2013 and earlier this year a new version was published supporting higher bit depths, 4:0:0-monocrome, 4:2:2 and 4:4:4 chroma sampling formats, scalable coding extensions (SHVC) and multi-view extensions (MV-HEVC).
Today's 4K solutions are incomplete
Many vendors are so desperate to sell 4K technology that they are ready to deliver 4K resolution without the image enhancements. If this happens, 4K runs the risk of being a consumer disappointment. That could kill the whole movement before the additional imaging improvements can be made. Just look at what happened to 3-D technology.
Another important factor are the vendors who design and build equipment for use within the television broadcast chain. For example, take the technology that does the contribution of sports or news programming to the studio base. Vislink, a global company with offices in the UK, North and South America, Asia and the Middle East, is a specialist in broadcast contribution and has been promoting the use of 4K for future systems.
Vislink is reminding television broadcasters of the importance of 4K to the broadcast infrastructure chain in delivering high-quality 4K video from events in the field to home viewers. The company will demonstrate working 4K contribution systems at NAB, though it has not announced final products.
In an op-ed article promoting 4K contribution, the company said in addition to the 50 percent reduction that H.265 provides in bitrate over its predecessors, there are a number of microwave transmission technologies that can be used to compensate for another 25 per cent of additional bandwidth.
“For example, in point-to-point microwave or satcom applications, DVB-S2X (DVB-S2 with extensions) enables steeper roll-offs in the modulation scheme enabling more carriers to be squeezed into the available bandwidth,” said Ashley Dove, vice president of solutions at Vislink.
“Also, for non line-of-sight MIMO (multi-input multi-output) OFDM transmission techniques can be used to increase throughput by utilizing multiple antenna techniques with antenna de-correlation to create two independent video streams.
Other improvements can be achieved using LDPC (low density parity check codes).
Ashley Dove, vice president of solutions at Vislink.
“FEC techniques can alternatively be used to help offset the additional 4K bandwidth. LMS-T modulation techniques with LDPC codes increases data throughput for a comparative signal to noise ratio. Additionally, LTE technology, as used in 4G cellular transmissions, can be utilized in private frequency bands for local networks.”
However, Dove agrees that increasing frame rates and adding HDR technologies are necessary features for 4K to be successful for consumers. “Increasing the frame rate and high dynamic range encoding and decoding is very much on our agenda,” Dove said.
Though Vislink has prototypes capable of handing 4K using H.265 compression (and will demonstrate them at NAB), the company cannot yet handle increased frame rates or HDR. There lies the problem. Do you just release 4K video and then gradually develop the technology that will make it more impressive to consumers?
Vislink, because it is dealing with only contribution, can create its own solution, Dove added. “In our world, where we are dealing with point-to-point contribution from the field back to the base, we can implement our own image enhancements without having to deal with the H.265 standard. Other manufacturers will be doing the same. Eventually, we get into interoperability issues, which normally arise after this has been first implemented in the field.”
Though Dove predicts his company will launch a 4K contribution product in 2015, he suspects it will take another year or two before it is enhanced with frame rate and HDR features.
“We specialize in ultra low delay encoding within the wireless camera market,” Dove added. “Here we must have one frame delivery. The H.265 and H.264 standards don’t accommodate this. So we had to develop a way of doing it. Others manufacturers may do the same. Then eventually we either work together or decide to go our separate ways — though we hope for interoperability.”
Dove noted that 4K contribution gear can be effectively split into four 1080p HD signals when needed. “With H.265 encoding, we can handle a 4K signal or it can also be used for four 1080p HD signals with the same encoding engine,” he noted. “This gives users a choice of one 4K or four HD signals. It’s all the same hardware and it’s quite flexible.”
More 4K questions than answers
While vendors will be demonstrating 4K technology at NAB, visitors should question the optimistic time frame predictions for roll-outs and whether delivering 4K to the home without visual enhancements is even a good idea.
It should be remembered that H.265 is not the be all and end all of 4K standards. In addition to the extra bandwidth needed, there are many diverse components in the delivery chain that gets the television signal to home viewers.
Will 4K come together in a cohesive way that gives consumers a genuine boost in image quality and real value for their money, or will it improve in gradual increments over the year few years? That is a key question that could determine the success or failure of the entire 4K movement.
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