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TECHNOLOGY CLASS: HDR theory in practise. Mr MXF thinks... I wonder if we’re heading towards brightness regulations? Bruce Devlin Amsterdam Canals Photo royalty free © Scorpionka | Dreamstime I like IBC in the same way that I find NAB grating. Maybe I have been living in the UK for too long, but the bright morning Amsterdam sun breaking through clouds and reﬂecting off the canal while fit young things on bicycles pedal to college; snapchatting with their friends and avoiding collisions with practised ease has a certain charm. You just don’t see that in the after-party morning-after haze of the Las Vegas Strip in the harsh desert sunlight. I have photos of IBC going back nearly 3 decades that completely fail to capture the dynamic range of this Amsterdam scene. In fact, I’m pretty sure that the dynamic range of my eyes today is a few stops short of the (probably) 12 to 14 stops that they could achieve in the early 1990s. Camera technology has overtaken the ability of my eyes to see these scenes and looking around IBC there were visible improvements in the quality of High Dynamic Range (HDR) presentations compared to NAB. And here in lies the quandary for the future. Assuming that we can support HDR in the whole broadcast and distribution chain (more of that later), how should we acquire imagery so that we both optimise the user experience and prevent a “brightness arms race” to win new viewers as this new story telling technology rolls out? Looking at the various IBC screens showing HDR content, there were many more displays that seemed to show dark blacks, specular highlights, bright whites and good detail. Many of the clips were shot especially for the show with a great many being night shots where HDR seems to give a lot of “Bang for the buck” compared to Standard Dynamic Range (SDR). And there’s the rub for acquisition. If the brave new world is going to be HDR UHD (or maybe even HD) in the high value markets within the next 2 years, then what should you be shooting today if 48 | KITPLUS - THE TV-BAY MAGAZINE: ISSUE 118 OCTOBER 2016 that’s your target market? Not everyone has the technically skilled team to recreate Ang Lee’s 120fps HDR masterpiece Billy Lynn’s Half Time Walk (https://youtu.be/mUULFJ_I048) and maybe the HDR / HFR combination won’t suit every genre. If HDR does become the mainstream technology that I think it will, then a Standard Dynamic Range title shot today will have a very “2016” look compared to its HDR cousins within a few short years. Modern Cameras can shoot 13 to 16 stops of dynamic range and the RAW and HDR compression codecs used in edit software can keep most of this dynamic range through to the final transcode for distribution. At that stage I can see the need for Dynamic Range transcoding to up-convert SDR for HDR consumptions as well as to down-convert HDR for SDR consumption. Looking around IBC there were a number of algorithms on display that did a decent job of retaining the creative intent of the original material and if you had no access to that original then you probably wouldn’t notice anything strange. What we haven’t seen yet is a body of converted material shown back to back (as in a broadcast or stream) with the option of switching channels to a parallel stream of parallel content. In the audio world we have still not quite mastered the challenge of consistent loudness within a channel and between channels despite 5-6 year of regulation and operational struggle to get it right. Will brightness be next on the list? If HDR is likely to use its higher brightness range to show specular white rather than average-white then will a station’s SDR white level on a domestic screen be shown at a brightness of HDR peak-white or HDR average white? Who chooses and where in the chain do they choose? I would love to have all the answers and if anyone out there really knows (and how the ITU regulations are likely to affect inter-station operational practise), then I’d love to have a chat. Until then I’m going to sit back and enjoy some radio.