If you ’re looking for a new video , you ’d have no doubtfulness been on a clangor course of tech acronym – UHD , HDR , WCG and more are all terms to grip with . Well , here ’s another . HLG .
HLG – or Hybrid Log - Gamma as it ’s also known as – is another HDR data formatting , but how does it disagree from the HDR offer through streaming service or onUHD Blu - ray . Read on to bring out what it is and what it mean to your video streaming experience .
What is Hybrid Log-Gamma?
Hybrid Log - Gamma is dissimilar to related HDR engineering in several direction .
It was jointly acquire by the BBC and Nipponese state broadcaster NHK and was think to correct the conundrum of how broadcastUHD TV help with HDRcan be made rearward compatible with even HD TVs .
A of rearwards compatibility was a major stumbling block for TV company . Without it they would need to simulcast channel or programmes , and that has immense cost implications from a studio workflow point of view and for bandwidth .
Even salutary , HLG allow the live yield ecosystem for SDR TV to be used for HDR output – it also provide a mode to circularize live HDR .
The “ hybrid ” part of Hybrid Log - Gamma refers to the fact that HLG does n’t reinvent the bike . It adjust traditional picture - making techniques that have been a part of television set image lore since the former day of the CRT television , slapping a bit of new take - it - or - leave alone - it information on top – the so - call Log file .
therefore , HLG HDR signal are inherently backward compatible with all standard dynamic range TVs .
How does HLG differ from HDR10 and Dolby Vision?
HDR already comes in multiple flavours . HDR10 is the manufacture standard , used on UHD Blu - ray and by cyclosis service of process . HDR10 apply “ static metadata ” to relay the HDR information to a compatible display – a guide to what ’s about to be receive , as it were .
Dolby Visionis a proprietary alternative that uses frame - by - frame dynamic metadata , which means there ’s signal information in every frame for greater picture accuracy .
But both HDR systems still swear on metadata , and that does n’t work for TV transmissions and , in picky , live broadcasts . It only suit pre - produced content .
For representative , HDR10 contains Maximum Content Light Level and Maximum Frame Average Light Level as part of the get the hang metadata information , neither of which survive in a live context .
Another trouble with a metadata - ground HDR broadcast solution happens when content gets re - lot around a connection or append to affiliate broadcasters who may need to top - and - tail ( trim off the top and bottom ) . The metadata HDR information in the signal could simply fell in an editing entourage .
The attraction of Hybrid Log - Gamma is that there are no such metadata complications .
To reiterate , streaming services – Netflix , Prime Video , Disney+ , etc – do n’t need to occupy about errant metadata , as they only deal in pre - produced and encode HDR content , stream from their own server to a TV or other twist . Streaming help control the entire chemical chain . Broadcast TV with live programming just does n’t have that luxury .
How does Hybrid Log-Gamma work?
Unlike rival HDR systems , which bank on pre - encoded signalling metadata to explain an HDR characterization to a compatible tv , HLG is a picture - referred system of rules .
That ’s to say , the delivered sign reflects the brightness in the original scene , just like it was buck . Exactly what ’s been photographed in the studio or out-of-door program is delivered to yourhome TVorprojector , without any need for plaguy metadata .
From a broadcast point of view , there ’s just a flag which get a receive set - top corner know that it need to enjoin your TV via HDMI that there ’s some lovely HLG UHD images get over with 10 - bit colouring material depth .
All that any HLG - compatible TV at home penury to be aware of is its own technical capabilities and of the environment the content is being view in .
This latter point is a giving deal . HLG can alter the HDR image based on the watch surround – light room , dark room , even specific brightness levels measure in nit . This feature make HLG fundamentally different from HDR10 .
presently , some HDR10 goggle box do n’t let the substance abuser neuter the Average Picture Level of HDR mental object , which means in an averagely bright living room , HDR material take care too dark . Hybrid Log - Gamma correct the picture harmonize to the surround ambient light story , to ensure the image always looks acceptable .
Where can I watch programming in HLG?
For this enquiry , we ’ll focus on the UK as we ’re not too sure about HLG ’s use in other countries . We can say that in the UK , BBC and Sky have take away up the HLG baton .
For the BBC HLG HDR content is only available through its iPlayer streaming service . It still seems to be run trials in HLG since 2016 – this is patently due to government legislation on what the Beeb can do – so you wo n’t find every computer program available in HLG HDR , but since the end of 2022 / beginning of 2023 , there ’s been a marked gain in HDR capacity on the service .
While TNT Sports ( formerly BT Sports ) broadcasts in HDR , we ’re have n’t been capable to confirm ( yet ) whether it circularise in HDR10 or HLG . We do have sex that from attend the first ever8 K HDR broadcast at the Emirates Stadiumin 2020 that it was in HDR10 , and it ’s our understanding that nothing has changed on that front .
The summer of 2024 will see Wimbledon Tennis tournament and the Paris Olympics broadcast in HLG HDR ; while the Euro 2024 football game tournament is slated to beproduced in 1080p HDRto be streamed to hoi polloi ’s homes and mobile gadget .
