SMPTE Show: Super Hi-Vision, 4K Are Closer Than You Think
The annual SMPTE conference in Los Angeles always provides an opportunity to take a look at developments related to next-generation technologies. Conference sessions at last month’s gathering made both Super Hi-Vision and 4K major points of discussion.
“The goal is to make 120 Hz a reality,” said Hiroshi Shimamoto, during his session on 120-Hz–frame-rate Super Hi-Vision capture and display devices. He has worked on Super Hi-Vision since 1993 as part of NHK’s Science and Technology Research Labs. “And important devices have been developed, like a 120-Hz camera that uses three sensors and a 120-Hz LCD projector.”
The current Super Hi-Vision specification calls for resolution of 7,680×4,320 at 59.94, 60, or 120 Hz and with bit depth of 10 or 12. Wide-gamut RGB is also on the docket. The reason for the move to 120 Hz is that it will cut down on observable motion blur, an important step if the goal is to have a viewing experience that replicates the real world.
The prototype Super Hi-Vision camera system currently has three CMOS chips with 33 megapixels requiring 51.2 Gbps of output for each chip.
“The major challenge is high-speed operations while maintaining low power consumption because, if there is too much power needed, then the temperature and noise rises,” Shimamoto added.
A new two-stage cyclical analog-to-digital converter is part of the solution: the first stage converts the upper four bits of the image, and the second converts the lower eight bits. Parallel operation speeds A-D conversion.
The camera head has three image sensors delivering a 150-Gbps signal that currently requires 72 HD-SDI cables to get signals out of the camera.
That massive data throughput remains one of the biggest, if not the biggest, challenge to any dreams of 4K production and broadcasting. With the vast majority of the broadcast industry still making the transition to a 3 Gbps infrastructure, how will it be possible to make the move to an infrastructure that could require bandwidth in excess of 100 Gbps, the rate needed for 4K transport at 12-bit quality?
The answer lies in the evolution of the HD-SDI interface by SMPTE. A single-link HD-SDI interface could provide throughput of 1.5 Gbps. In 2006, dual-link HD-SDI was introduced, getting the industry to the current 3 Gbps rate.
By early 2013, two quad links will be introduced, 425-5 (for 4K progressive needs) and 425-6 (for 2K progressive stereo signals for 3D). Compatible with existing 3 Gbps infrastructures, they will provide 12 Gbps of throughput.
According to John Hudson, director of product definition and broadcast technology for the Gennum Products Group of Semtech Corp., that pragmatic approach will allow creation of 4K production islands, a similar philosophy to that deployed in the early days of HD production.
“The broadcast space should start to look at other industries to see what technologies we can borrow and leverage in our own,” he says. “The datacom and telecom industries continually develop optical and copper modules for higher data rates.”
One technology to track is the Quad Small Form-factor Pluggable (QSFP) interconnect system. In another five to seven years, connectivity of 25 Gbps will be reliable, and the cost of that system should drop as data-intensive companies like Google and others bring it into their facilities.
“It leads to an interesting opportunity for standardizing on one or two form factors that can get up to 100 Gbps by borrowing from data-center technologies,” Hudson adds.
For the broadcast industry, that means, eventually, helping evolve the HD-SDI interface to get to 200 Gbps.
“The first target is broadcasting, and the final is to provide a full-resolution system,” said Shimamoto of 4K. And, although a single-chip color camera with more than 100 megapixels may eventually be possible, the first cameras will need three large-format sensors.
“The ⅔-in. sensor is a tough target,” he added. “It is much smaller, and the size is not good for sensitivity and dynamic range.”
Nonetheless, as the move to HD proved, expect to be surprised with what the engineering community can accomplish with some hard work, ingenuity, and the help of Moore’s Law.