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The coming of age of 12G

With recent advances in product design, it’s increasingly apparent that many in the broadcast industry are going to bypass quad-link solutions in favour of 12G-SDI for 4K/UHD, writes PHABRIX's Martin Mulligan

Ever since 4K/UHD production started to become a realistic proposition, the need to have a supporting infrastructure capable of dealing efficiently with its high-bandwidth requirements has become increasingly acute. Factor in the rise of higher frame rates, wide colour gamut and higher dynamic range, and it’s clear that you have the conditions for the most significant step-change in broadcast technology for many years.

Consequently, broadcasters around the world have lately been engaged in reworking their infrastructures in order to cope with the demands of these new technologies. As ever, the overarching objective has been to ensure that there is full support for the latest SMPTE standards, ideally over a single cable to reduce the complexity of implementation. And with data rates continuing to soar, systems designers and integrators need to have a keen awareness of how requirements are likely to develop over the next few years in order to futureproof broadcasters’ investments.

In 2015, SMPTE introduced 12G-SDI with standards catering for single-link (1 x 12G), dual-link (2 x 6G) and quad-link (4 x 3G) solutions to help support 4K 4:4:4 30fps and 4:2:2 60fps formats. Until recently, it was common for 4K/UHD content to be delivered via quad-link connections (4 x 3G) cables. There are several reasons for this approach, including familiarity with 3G-capable systems, which are well-proven and reliable, and the initial complexity and challenges associated with making 12G chipsets and cabling. 

But it was only a matter of time before single-link 12G-SDI solutions became more workable, and there are growing signs that that moment has now arrived. There are numerous benefits to adopting a single-cable solution, including reduced complexity, weight and cost – all issues of particular concern to providers of outside broadcast trucks and flyaways.

With many manufacturers having now overcome the challenges of designing 12G products, the impetus to bypass the intermediate step of using 4 x 3G-SDI in favour of 12G-SDI is increasingly apparent.

Meanwhile, in the IP world, SMPTE developed its now widely-adopted standards suite, ST 2110, to be somewhat agnostic to image size, with 2110-20 being able to address image sizes up to 32K. And with the advent of 25GE networks, 4K/UHD over IP (a 12G signal) can be easily accommodated.

Simultaneously, the use of UHD for virtual-studio applications (including VR and AR) and large video walls in entertainment venues is becoming increasingly commonplace. These applications often require huge computer-generated images as their backdrops, scenes or graphics, heightening the demand for Extended UHD (eUHD) formats. These generally involve 18-21Gb/s data rates in order to accommodate 4K/UHD output up to 60p RGB 4:4:4 12-bit.

Looking ahead, it is likely that there will be demand for 8K content, so in preparation for this some manufacturers are now working on enabling quad-link 12G (4 x 12G-SDI). 

With the industry’s overall ‘direction of travel’ now being clear to see, PHABRIX has developed its Qx range of test and measurement products to cater for 12G-SDI and ST 2110 IP workflows. Designed to support compliance testing and interoperability between vendors, the range includes price-performant 12G-SDI solutions as well as industry-leading SDI-STRESS testing tools. Meanwhile, the QxL family is targeted at being price performant in the 25GE ST 2110 IP market, with the option to support the new eUHD formats. 

So whilst 12G-SDI undoubtedly represents a major shift for the industry, the tools to make it a workable reality are now becoming accessible to all.