A second Emmy for our work on High Dynamic Range television
Posted by Andrew Cotton on , last updated
We were immensely pleased to hear that we have won another Emmy® for our work on high dynamic range television (HDR-TV). The first Television Academy Emmy® was awarded last year to the ITU-R for Recommendation – the international standard that specifies both the ±«Óătv/NHK Hybrid Log-Gamma (HLG) HDR-TV system and Dolby’s PQ. This second has been awarded to the ±«Óătv for our work on developing what has become known as the “single-stream” HDR live production workflow, and the format conversion LUTs (look-up tables) that we developed to support the workflow. I would also like to note that US broadcaster NBC have received an award too, for their developments on single-stream workflows.
Statue © ATAS/NATAS
Early trials of live HDR TV production used a parallel production workflow, whereby both the HDR and standard dynamic range (SDR) outputs were taken from cameras and passed through largely separate HDR and SDR production infrastructure, to protect the SDR signal chain and the SDR audience experience. In many cases the HDR signal path supported UHD resolution (3840 x 2160 pixels) whilst the SDR signal path only needed to support HD resolution (1920 x 1080 pixels). To avoid the need to have two Vision Mixer (switcher) operators, the HDR mixer would be configured to follow the SDR mixer. It quickly became clear that the parallel workflow was both costly in terms of equipment, and difficult to configure – particularly ensuring that the audio and video were correctly timed through the various HDR and SDR signal paths. Just as it had been when we migrated from 4:3 to widescreen production, and standard definition (SD) to high definition (HD) production, if HDR production were to become mainstream, the ±«Óătv recognised that it would be essential to run a single UHD HDR format through the production infrastructure. The SDR programme output would need to be automatically derived from the HDR programme output, without compromising the signal delivered to both HDR and SDR audiences.
Our 2018 UHD HDR coverage of the wedding of the Duke and Duchess of Sussex demonstrated that it was possible to derive a high quality SDR output from a UHD HDR production chain. At that time, the ±«Óătv’s domestic HD SDR output was derived from a parallel signal chain, but both the UHD SDR feed for Sky and the international HD SDR programme feeds, were derived from the UHD HDR output through one of our early HDR to SDR conversion LUTs. That gave us the confidence we needed to remove the parallel HD SDR signal path from our UHD HDR coverage of the FA Cup the following year. From the quarter finals onwards, the ±«Óătv One HD (SDR) feed was entirely derived from the UHD HDR programme output.
As my 2019 FA Cup article explained, even with the huge amount of planning and testing that we carried out ahead of the quarter final at Millwall, we encountered operational issues that we hadn’t anticipated. Of particular concern was the importance to the Vision Supervisors that the UHD HDR and HD SDR programme feeds have an identical “look”, and that the SDR programme output derived via the output HDR to SDR “down-mapping” LUT not only looked the same as that seen by the camera “racks” (shading) engineers, but also measured the same on a waveform monitor. Until that point, most R&D engineers working on the development of HDR TV had been comfortable with the HDR and SDR signals having a different appearance - after all, HDR TV had been designed to more accurately reproduce the scene in front of the camera. So, through our coverage of the semi-final and final matches we refined the workflow and format conversion LUTs to precisely meet their requirements. We developed what has now become known as the industry’s “single-stream” live HDR production workflow.
The workflow has proven to be extremely robust, reliable and repeatable. Not only does it deliver spectacular HDR images, but the SDR audience benefits too. Our format conversion LUTs have matured to such a degree that one of the UK’s most respected Vision Supervisors said to me recently, when the HDR output has been “painted” to give an artistically pleasing image, the SDR output derived from the HDR via our LUTs exceeds the quality of the native SDR camera outputs.
Throughout the development of HLG we have shared our experiences with the industry through our project website and blog posts. We have also documented the live production workflow as it developed in Report ITU-R , the and most recently the . Not only has the workflow been used by the ±«Óătv for FA Cup football, , our coverage of the 2020 Euros and the Coronation of King Charles III and Queen Camilla, but it has also been adopted by Sky TV for their UHD HDR sports coverage; for the Olympics; for the FIFA World Cup; for their Euros match coverage; for the Wimbledon Tennis Championships and US broadcasters NBC, CBS and Fox.
We’re thrilled to have received the Emmy® and have our work recognised internationally. The Technology & Engineering Emmy® awards are given for “engineering technologies that either represent so extensive an improvement on existing methods or are so innovative in nature, that they materially have affected television”.
We couldn’t be more proud our work and grateful to our partners in , ±«Óătv Sport and the ±«Óătv iPlayer teams, who enthusiastically supported the technology trials that were necessary to develop the workflow. I would also like to thank our outside broadcast providers and the vision supervisors, whose patience and feedback was critical in developing the workflow. A workflow that is now proven to meet operational and artistic requirements, as well as delighting our television audiences too.