Every term, in plain language

Handshake

Before any picture appears, source and display negotiate: the source reads the display's EDID, checks copy protection, and picks a format both ends claim to support. A failed handshake is the black screen everyone recognises.

On this unitAlmost every problem this box solves is a handshake that went wrong.

EDID

Extended Display Identification Data: a small block of data inside every display listing the resolutions, refresh rates, colour formats and audio formats it accepts, plus its name and manufacturer.

On this unitDr.HDMI 4K stores forty of them and hands your source whichever one you pick.

EDID bank

One stored EDID in the unit's memory. Forty in total: eight FHD, twenty-four UHD in three audio variants, seven you can overwrite, and one holding a copy of your display.

Hot-plug event (HPD)

The pin that tells a source a display has just been connected. Pull it low and back high and the source re-reads the EDID and reconfigures its output.

On this unitChanging bank fires one automatically; it takes about two seconds.

DDC

The small data channel in an HDMI cable that carries EDID requests and copy-protection traffic. The unit watches it and answers only the EDID questions, leaving the rest alone.

Sink and source

Source is anything sending a picture: player, console, HTPC. Sink is anything receiving one: TV, projector, receiver. Copy sink means copying the EDID of the sink downstream.

HDCP

High-bandwidth Digital Content Protection, the encryption on commercial video. Version 1.4 and 2.2 do not mix freely, which is a common cause of black screens.

On this unitThis unit passes HDCP through untouched. Converting between versions needs a Vertex² or VRROOM.

18Gbps / 600MHz

The maximum data rate of HDMI 2.0b. Enough for 4K at 60Hz with full 4:4:4 colour, or 4K60 4:2:2 at 12-bit. Everything you ask for has to fit inside it.

Chroma subsampling (4:4:4, 4:2:2, 4:2:0)

How much colour detail is sent relative to brightness. 4:4:4 is full colour and costs the most bandwidth; 4:2:0 halves it in both directions and is how 4K60 fits through older gear.

On this unitBank names spell this out: 444, 420, and the clock in MHz.

Colour depth (8b, 10b, 12b)

Bits per colour channel. More bits means smoother gradients and more bandwidth. 12-bit at 4:2:0 is a common compromise for 4K60 HDR.

HDR10

The baseline high dynamic range format: static metadata describing the whole film's brightness range. Supported by effectively every HDR display.

HDR10+

HDR10 with dynamic, scene-by-scene metadata. Used by Samsung, Amazon and others.

HLG

Hybrid Log-Gamma, the broadcast HDR format, designed so one signal looks right on both HDR and SDR sets. Common on satellite and streaming sport.

Dolby Vision

Dolby's dynamic HDR format. Display-led Dolby Vision requires a licensed display; the whole chain has to support it.

LLDV

Low-Latency Dolby Vision, also called player-led DV. The source does the Dolby Vision tone mapping itself and outputs a signal an ordinary HDR display can show.

On this unitDr.HDMI 4K can trigger it by presenting a DV-capable EDID. Your display still needs a forced HDR mode, and the max luminance has to be set in the EDID itself. For LLDV with actual settings, see the Arcana 2.

Tone mapping

Squeezing a bright HDR master into what your screen can actually produce. Done by the display, or by the player in the case of LLDV.

On this unitDr.HDMI 4K does not tone map. It only changes what the source is told.

BT.2020

The wide colour space used by UHD and HDR material. An EDID that doesn't advertise it will keep a source in the older, narrower BT.709.

ALLM

Auto Low Latency Mode: a flag telling a display to switch to game mode by itself when a console starts sending.

Full audio, SPDIF, stereo

The three audio flavours of every UHD bank. Full audio advertises everything including Atmos and DTS:X; SPDIF caps it at what an optical return carries; stereo is two channels only.

On this unitStart on green (full audio) and step down only if audio drops out.

Dolby Atmos and DTS:X

Object-based surround formats carried inside TrueHD and DTS-HD Master Audio. They need an EDID that advertises the lossless formats underneath them.

eARC / ARC

Audio return channel: sending sound backwards from a TV to a receiver.

On this unitNot something this unit does. Extraction needs an Arcana 2, Vertex² or VRROOM.

HTPC mode

A mode that hides the sink status from the source, so a computer never notices the display went away and keeps its resolution and desktop layout.

Repeater and equalisation

The unit re-clocks and cleans the incoming signal, compensating cable losses up to about 50 metres before passing it on.

+5V injector

HDMI carries a small 5V supply that active and optical cables need. Some sources are stingy with it; with its own power supply attached, this unit provides it.

RS232

A serial control connection on the 3.5 mm jack, used by installers to switch banks from a control system.

DVI-D

The video-only predecessor of HDMI, electrically compatible with it. The unit emulates and repeats DVI-D chains as well as HDMI ones.