What is 4K 60p HDR HLG

Hybrid Log Gamma (HLG): Why this HDR format is so important!

Hybrid Log Gamma (HLG) is the third and perhaps most important HDR format alongside HDR10 and Dolby Vision. You can find all information about Hybrid Log Gamma (HLG) here!


Hybrid Log Gamma is another High Dynamic Range (HDR) standard that attracted a lot of attention, especially at IFA 2016. Some users are unsettled: "Do I have to buy a new TV soon?". "I thought my 4K / HDR television is future-proof?". We explain to you in this article and show that Hybrid Log Gamma (HLG) could be one of the most important HDR standards alongside HDR10.

Hybrid Log Gamma story

HLG was developed by the British BBC and the Japanese NHK. The broadcasters are considered pioneers in the development and implementation of new standards and are also significantly involved in the Ultra HD standard. HLG is no longer in development, but was already adopted on July 6, 2016 by the ITU in its BT.2100 papers. The two HDR transmission paths Hybrid Log Gamma and PQ (HDR10 / Dolby Vision) are defined in BT.2100. Broadcasters and streaming providers will use these guidelines to transmit their HDR content via satellite, cable or antenna. The first test streams were started in May 2016. The HLG demo transmitter "HOTBIRD 4k2 HDR“Started on September 7th, 2016 on Eutelsat.

Why do we need Hybrid Log Gamma?

The answer to this question is called “capacity”. Broadcasters have to share a limited transponder bandwidth (satellite transmission) and cannot simply switch on any number of channels. The available capacities are consistently exhausted. If an SDR and HDR version had to be provided for every UHD station, this would not only drive up the costs of the stations, but would simply not be possible due to the limited bandwidth. Hybrid Log Gamma makes it possible to provide a video stream that can be received by SDR devices as well as HDR devices. Compatible 4K / HDR televisions and SDR devices can play HLG videos as no metadata has to be processed. This means that HLG is also an option for streaming providers who could also save bandwidth and capacity.

Which devices support HLG?

As a rule, one can assume that the new model series from the TV manufacturers from 2017 are already Hybrid Log-Gamma-compatible. Well-known manufacturers are already equipping their premium models from 2016 with HLG updates. Sony's new 4K home theater projector VPL-VW550ES will also be able to process HLG videos after an update. Android TVs such as those offered by Sony, for example, must first be updated to Android 6.0 or 7.0 so that they can also process hybrid log gamma videos without any problems. There were already the first "problems" with the HLG edition of Sky UHD in England. One advantage of HLG is that the standard can usually be "retrofitted" with a firmware update.

Popular 4K TVs with HLG (display):

outlook

Hybrid log gamma will play a very important role especially in television broadcasting. HLG is already showing its potential in the first test broadcasts, which could also be seen at many exhibition stands at IFA 2016 (see videos at the end of the article). Future transmissions at 4K / 100Hz would also be no problem with HLG and have already been presented on current TV sets from LG. When buying a new 4K television or projector, you should specifically ask the seller or manufacturer whether the device can process HLG-HDR without any problems or whether it will receive an HLG update at a later date. HLG has been part of the HDMI 2.0b standard since November. All TV sets that have an HDMI 2.0b interface can also process HLG-HDR after an update. The first linear 4K television program with Hybrid Log Gamma will be launched by Sky Deutschland in autumn this year.

HLG demo channel reception parameters:

  • Surname:HDR test
  • Frequency: 10.714 MHz
  • Symbol rate: 23.500
    FEC 5/6 DVB-S2 / 8PSK

Video HLG presentations at IFA 2016:

[https://www.youtube.com/watch?v=IZJkfAcYCpE