HDR broadcast is on the rise, as we saw from the increased number of ways to watch this week’s Super Bowl in HDR, but SDR will be with us for a long time. Not only will services have to move seamlessly between SDR and HDR services, but there is a technique that allows HDR itself to be dynamically adjusted to better match the display its on.
Introduced in July 2019, content can now be more accurately represented on any specific display, particularly lower end TVs. Dynamic Mapping (DM), is applies to PQ-10 which is the 10-bit version of Dolby’s Perceptual Quantizer HDR format standardised under SMPTE ST-2084. Because HLG (ARIB STV-B67) works differently, it doesn’t need dynamic mapping. Dynamic Metadata to support this function is defined as SMPTE ST 2094-10, -40 and also as part of ETSI TS 103 433-2.
Stitching all of this together and helping us navigate delivering the best HDR is Dolby’s Jason Power and Virginie Drugeon from Panasonic in this webinar organised by DVB.
The second most popular video of 2019 looked at HDR. A long promised format which routinely wows spectators at conferences and shops a like is increasingly seen, albeit tentatively, in the wild. For instance, this Christmas UK viewers were able to watch HDR Premiership football in HDR with Amazon Prime, but only a third of the matches benefitted from the format. Whilst there are many reasons for this, many of them due to commercial and practical reasons rather than technical reasons, this is an important part of the story.
Brian Alvarez from Amazon Prime Video goes into detail on the background and practicalities of HDR in this talk given at the Video Tech Seattle meet up in August, part of the world-wide movement of streaming video engineers who meet to openly swap ideas and experiences in making streaming work. We are left with a not only understanding HDR better, but with a great insight into the state of the consumer market – who can watch HDR and in what format – as well as who’s transmitting HDR.
HDR and wide colour gamuts are difficult enough in professional settings – how can YouTube get it right with user-generated content?
Viewing conditions have been a challenge right from the beginning of TV but ever more so now with screens of many different shapes and sizes being available with very varied abilities to show brightness and colour. Steven spends some time discussing the difficulty of finding a display suitable for colour grading and previewing your work on – particularly for individual users who are without a large production budget.
Interestingly, we then see that one of the biggest difficulties is in visual perception which makes colours you see after having seen bad colours look much better. HDR can deliver extremely bright and extremely wrong colours. Steven shows real examples from YouTube of where the brain has been tricked into thinking colour and brightness are correct but they clearly are not.
Whilst it’s long been known that HDR and WCG are inextricably linked with human vision, this is a great insight into tackling this at scale and the research that has gone on to bring this under automated control.
This talk is from Streaming Tech Sweden, an annual conference run by Eyevinn Technology. Videos from the event are available to paid attendees but are released free of charge after several months. As with all videos on The Broadcast Knowledge, this is available free of charge after registering on the site.
Software Engineer, YouTube Player Infrastructure
With all the talk of IP, you’d be wrong to think SDI is dead. 12G for 4K is alive and well in many places, so there’s plenty of appetite to understand how it works and how to diagnose problems.
In this double-header, Steve Holmes from Tektronix takes us through the ins and outs of HDR and also SDI for HDR at the SMPTE SF section.
Steve starts with his eye on the SMPTE standards for UHD SDI video looking at video resolutions and seeing that a UHD picture can be made up of 4 HD pictures which gives rise to two well known formats ‘Quad split’ and ‘2SI’ (2 Sample Interleave).
Colour is the next focus and a discussion on the different colour spaces that UHD is delivered with (spoiler: they’re all in use), what these look like on the vector scope and look at the different primaries. Finishing up with a roundup and a look at interlink timing, there’s a short break before hitting the next topic…HDR
High Dynamic Range is an important technology which is still gaining adoption and is often provided in 4K programmes. Steve defines the two places HDR is important; in the acquisition and the display of the video then provides a handy lookup table of terms such as HDR, WCG, PQ, HDR10, DMCVT and more.
Steve gives us a primer on what HDR is in terms of brightness ‘NITS’, how these relate to real life and how we talk about it with respect to the displays. We then look at HDR on the waveform monitor and look at features of waveform monitors which allow engineers to visualise and check HDR such as false colour.
The topic of gamma, EOTFs and colour spaces comes up next and is well explained building on what came earlier. Before the final demo and Q&A, Steve talks about different ways to grade pictures when working in HDR.