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Confusion over UHD spec delays

Last week, Sky CEO Jeremy Darroch stated that Sky in the UK would start Ultra-HD transmissions later in 2016. Documentation issued at his press conferences talks about UHD at 3840 x 2160 pixels.  He declined to give a specific start date, but he was enthusiastic in saying that Sky’s introduction of its all-new Sky Q premium set-top box would be capable of handling UHD reception.

However, almost simultaneously, the European TV standards-setting body (DVB Project) put out a major statement saying that “they are close” to receiving a UHDTV technical specification, and that the new spec would “potentially become available” to broadcasters during 2017.

This 2017 date is not a surprise, and the world’s various technical bodies have frequently talked about 2017-2019/2020 for ‘full’ UHD to emerge with complete and agreed standards.

The DVB Project admits that it will take a further 12 months to see its ‘UHD-1 Phase 2’ delivery format translated by broadcasters. The meeting of the DVB Steering Board in Geneva examined the phasing in UHD in three or four or five steps. The first being 4K including 60 frames per second, the next likely to be High Dynamic Range (HDR) and then a wider colour gamut (WCG). DVB has said that HDR is likely to be one of the first features included in the newly approved UHD-1 Phase 2.

DVB UHD-1 Phase 1 was the first system developed in 2014, delivering a 2160p resolution at 60fps – four times that of HDTV, and it is this formula that today’s 4K transmissions are being made under.

The DVB Project says: “The next challenge for DVB is to convert the requirements into a specification for submission to the European Telecommunications Standards Institute (ETSI) for standardisation. It is expected that the specification will be finalised in 2016. We should expect the first DVB UHD-1 Phase 2 services including HDR, to become available from 2017 onwards.”

“As well as HDR, the standards body also mentions phasing in a higher frame rate (HFR) into the specification, which is the capability to provide images with sharper moving objects. The development of consumer equipment capable of supporting HFR is expected to take several years longer than other features. There are TVs out there that support 60 frames a second and some that refresh at 240 times a second (240 Hz), but this does not translate to being able to handle 60 frames of 4K HDR.”

Separately to the DVB’s work, the Society of Motion Picture and Television Engineers (SMPTE) is also working via various expert groups of finalise its own set of standards, not least those covering High Dynamic Range, Wider Colour Gamut and Higher Frame Rates, and it suggests its work will come together (for the various key elements) in the 2018-2020 timeframe.

However, consumers are buying into UHD sets today, even though there are many displays which – by any measure – will not meet the emerging higher-end specifications.

There is also uncertainty as to whether some (so-called 4K) displays now being used will be able to handle these upcoming ‘full UHD’ specifications. In particular there are concerns about some displays which depend on a RGBW panel and have only 2880 lines of pixels, and not the ‘full’ UHD spec of 3840 lines of active pixels.  The International Committee for Display Metrology (ICDM), which is part of the Society for Information Display’s Definitions & Standards Committee, and which defines performance measurements, quality and fundamental parameters of all display technologies, is urgently considering revising its Measurement Specifications to prevent low resolution TV panels being misleadingly sold as 4K UHD TVs.

In many ways the current problem is similar to the early days of HDTV when so-called “HD Ready” lower-cost displays flooded the market with less-than-perfect technology. Today, some displays from the current crop of (mostly) Chinese-manufactured units now available are generally failing to deliver true 4K resolution.

Critics of the RGBW technology say that the final image is simply diluted and that colour fidelity information is lost, and the ‘premium’ offering damaged. One negative comment from the well-regarded Vincent Teoh of HDTV Test, suggested: “[They are] trying to shoehorn RGB video signals into an RGBW matrix, [where] colour information is lost, and users will never be able to enjoy movies in the manner intended by the director.”

Worse, perhaps, is that the buying public has no way of identifying these less-than-perfect units. There is simply no notification or labelling to indicate the display’s core structure.  The “RGBW” issue was highlighted at the recent Eurodisplay 2015 – the International Display Research Conference – held in Ghent, Belgium. The ICDM is now contemplating revising its Measurement Specifications to prevent RGBW-based panels being misrepresented as supporting 3840 pixels per line and thereby qualifying as ‘true’ UHD TVs.

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