HDMI signals

BT.2020

ITU-R BT.2020, the wide colour gamut of UHD

BT.2020 is a claim carried alongside the picture rather than a change to the pixels. On the Diva you can add that claim, take it away, or write it by hand.

BT.2020 is shorthand for ITU-R Recommendation BT.2020, published in 2012 to define the parameters of ultra high definition television. It sets out resolutions, frame rates and bit depths, but the part people mean when they say BT.2020 is the colour gamut: three primaries far more saturated than the BT.709 set that HD used, covering a much larger area of what the eye can see.

No consumer display reproduces the whole of it. BT.2020 works as a container: content is mastered inside a smaller real gamut, usually DCI P3, and encoded within BT.2020 coordinates, and the display maps what arrives into whatever it can actually show. That is why BT.2020 nearly always travels with HDR, and why a signal flagged BT.2020 on a display that ignores the flag comes out undersaturated.

The flag matters as much as the pixels. Colorimetry is announced in the AVI infoframe sent alongside each frame, and advertised in the sink's EDID. Get either wrong and the picture is decoded against the wrong primaries.

Where BT.2020 appears on the HDfury Diva

The incoming signal line on the OLED, and the IN row in the INFO section, name the colorimetry directly, for example 4K50 4:2:2 BT2020 12b LLDV 594MHz 2.2. That is what the source is really sending, so it is the first place to confirm that BT.2020 left the source at all.

In AUTOMIX the flag 2020/xvYCC forces the mixed EDID to present BT.2020 and xvYCC support, so a source sends wide gamut even when the mixed capabilities of your sinks would not have asked for it. Over RS232 or IP that is set edid bt2020 on. The flag only adds: if the sink already declares BT.2020 in its own EDID, switching the flag off does not take it away.

Forcing BT.2020 when the source will not

If a television has a BT.2020 picture mode that never engages, the usual cause is content whose AVI infoframe does not say so. The custom AVI infoframe generator in the HDR/DV section exists for that: choose the value under Primaries, click Create IF, then Send AVI. Ready-made strings are listed in the manual, among them 00:E8:64:5D:00 for BT.2020 RGB and 40:E8:64:5D:00 for BT.2020 YCbCr 4:4:4.

Custom Scaling offers the matching colour space choices for the TX0 output: RGB BT2020, 4:4:4 BT2020, 4:2:2 BT2020 and 4:2:0 BT2020, alongside Follow Input, which is the default. BT2020 is also one of the axes the ninety predefined EDID tables are built on, so table 11 is 4K60-444 600MHz HDR BT2020 All Sound while table 17 is the same description without it.

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