TV and Video Terminology


by

HDMI

Standard Features
1.4 4Kp24
2.0 4Kp60
2.0a 4Kp60 + HDR (see “4K and HDR”)
2.1 10K120 + Dynamic HDR

HDCP

If your source device does not support HDCP 2.2, the signal will be downgraded to 1080p.

HDR

Name Standard type Dynamic HDR Color Dynamic HDR HDMI req.
HDR10 Open No 10-bit No 2.0a
HDR10+ Open Yes 10-bit Yes 2.1
Dolby Vision Proprietary by Dolby Yes 12-bit Yes 2.01
HLG2 Free ? 10-bit ? 2.0b
Advanced HDR ? ? ? ? ?

On top of this, colour gamut is very important to the reproduction of HDR.

Dynamic HDR

The open standard for dynamic HDR is ST 2094 by SMPTE. It uses metadata to calculate adjust the HDR and wide colour gamut (WCG) dynamically compared to regular HDR which only performs the adjustment once.

The proprietary option for dynamic HDR is Dolby Vision by Dolby. The open option is HDR+ by Samsung and Amazon which combines HDR with ST 2094.

Regular HDR10 displays HDR content using image metadata once, whereas Dolby Digital uses the metadata throughout the video—ie dynamically. Check out this excellent article on HDMI 2.1 for more info.

Dolby Vision only requires HDMI 2.0, whereas a standard implementation of Dynamic HDR requires 2.1. The upgrade to HDMI 2.1 will just require a firmware update for some monitors.

Colour gamut

Colour gamut, also known as colour space, is a measure of the representation of colour for a monitor. This is hugely influential on the HDR in particular. Your TV might also come with a setting called “wide color gamut” that you should turn on when watching HDR content and off when not, in my limited understanding.

There are a lot of specifications for colour gamut, but the most relevant one is Rec. 2020 (or BT.2020). The upcoming spec is Rec. 2100. There are currently no TVs that meet a 100% Rec. 2020 gamut; they tend to be between 50–70%. DCI-P3 is easier to accomplish.

There is also colour volume. The distinction is that colour gamut is two-dimensional and colour volume is three-dimensional. The third axis of colour volume is brightness.

When you see charts showing gamut coverage in publications, including here at Reference Home Theater, you see a CIE chart. There are two versions that you’ll see, either the classic CIExy or the [CIEuv](https://en.wikipedia.org/wiki/CIELUV. What you notice from the names is that there are only two variables there, xy or uv. Those colorspaces actually contain a third variable and are either xyY or LUV. That Y and L are the luminance value, which are not captured in the standard chart but tell you how bright a color is. Color volume uses this missing variable which has always been there but previously was not used to determine what colors a display could show.

“Color Volume: Measuring and Understanding What it Means”

Consoles

PlayStation 4

Model HDMI HDCP HDR
Standard Custom 1.43 <2.2 Yes
Slim 2.0a 1.43 Yes
Pro 2.0a 2.2 Yes

The PS4’s HDMI 1.4 was developed to support a higher bandwidth, which allows all devices to show HDR.

Xbox One

Model HDMI HDCP HDR
Standard 1.4a <2.2 No
S 2.0a 2.2 Yes
“Scorpio” ? ? Yes

It is astoundingly difficult to find information about the HDCP support on consoles.

Further Reading

  1. One other difference between Dolby Vision and HDR-10: Dolby Vision doesn’t require HDMI 2.0a. Metadata is sent in-band, as an auxiliary stream within the existing HDMI 2.0 data flow. It requires its own decoding, however, which from what I’ve been able to gather, can’t be added to the mix by a firmware upgrade. That renders the advantage moot.

    “Dolby Vision versus HDR-10 TV: A format war and more”

    ↩︎

  2. Designed for broadcasting by British BBC and Japanese NHK. ↩︎

  3. Rigby guessed last year that the PlayStation 4’s HDMI controller is HDMI 2.0 compatible—meaning, it had been developed with higher bandwidth than the HDMI 1.4 spec required, and it just needed an official update via firmware to unlock and unleash that potential. Now, House has confirmed that it’s coming, because anything rated for HDR specifications is technically also ready for 4K resolution.

    “Sony will wake a sleeping HDR beast via firmware. What else hides in PS4?”

    ↩︎ ↩︎2