HDMI glossary

EDID is the data block a display sends upstream to tell a source which video and audio formats it accepts.

An EDID manager is a device that controls which capability data an HDMI source is allowed to read.

An EDID emulator presents a fixed, known EDID to a source so the source always sees the same capabilities.

AutoMix takes the connected display's EDID and changes selected capability flags before handing it to the source.

A custom EDID is a stored capability table you select or upload instead of using the connected display's own EDID.

DisplayID is a newer capability-data standard used alongside EDID, often in 384-byte or 512-byte blocks.

A DTD is the block inside an EDID that describes one exact video timing, including the display's preferred mode.

EDID is stored in 128-byte blocks, with extension blocks carrying the modern capabilities.

An EDID slot is a storage position for a capability table you can select or overwrite.

EDID sniffing means reading and storing the capability data a connected display sends.

COPY TX SINK mode passes the connected display's own EDID upstream, unchanged.

The Dolby Vision data block is the section of an EDID that declares a display's DV capability.

Video flags are the individual picture capabilities you can switch on or off inside an EDID.

Audio flags are the individual sound capabilities you can switch on or off inside an EDID.

The HDMI handshake is the negotiation between source and display that has to succeed before any picture appears.

A hot plug event is the signal that tells an HDMI source to re-read the EDID and restart the handshake.

RX is the input side of an HDMI device, facing the source; TX is the output side, facing the display.

In HDMI, the source is the device sending the signal and the sink is the device receiving it.

HDMI 2.1 is the specification that raised HDMI bandwidth to 48Gbps and added FRL, VRR, ALLM and eARC.

FRL is the HDMI 2.1 signalling mode that replaces TMDS and carries up to 48Gbps across four lanes.

TMDS is the original HDMI signalling method, used for everything up to 18Gbps before FRL took over.

HDCP is the copy-protection layer that source and display must authenticate before protected content will play.

An HDMI repeater receives the signal, cleans it up and retransmits it at full strength.

A fibre or active optical HDMI cable carries the signal as light, allowing runs far longer than copper.

CEC is the HDMI control channel that lets connected devices switch each other on, off and to the right input.

DSC is a visually lossless compression scheme that lets HDMI carry formats beyond its raw bandwidth.

8K is a resolution of 7680 x 4320 pixels, four times the pixel count of 4K.

4K, or UHD, is 3840 x 2160 pixels — four times Full HD.

4K120 is 4K resolution at 120 frames per second, an HDMI 2.1 mode that requires FRL signalling.

1080p is 1920 x 1080 pixels progressive, the Full HD standard.

2K usually means a horizontal resolution around 2048 pixels, though in consumer use it is often applied to 1440p.

Chroma subsampling reduces colour detail relative to brightness detail to save bandwidth.

Bit depth is how many shades per colour channel a video signal carries, and it decides whether gradients band.

HDMI bandwidth is the data rate a link can carry, and it caps which video formats are possible.

Refresh rate is how many times per second a display draws a new image, measured in hertz.

UHD is the consumer name for 3840 x 2160, and FUHD for the 8K step above it.

DCI is the digital cinema standard, whose 4K format is 4096 x 2160 rather than 3840 x 2160.

RGB sends red, green and blue values for every pixel, with no colour information discarded.

YCbCr encodes video as brightness plus two colour-difference channels, which allows chroma subsampling.

The pixel clock is the rate at which pixels are sent, and it is what MHz figures on HDMI devices refer to.

Deep colour is HDMI's term for bit depths above 8 bits per channel, up to 16.

xvYCC is an extended-gamut colour standard that predates the modern HDR colour spaces.

3D over HDMI carries two images, one per eye, in a defined frame-packing format.

Interlaced video sends alternate lines in each pass instead of complete frames.

VESA PC resolutions are the computer display modes carried over HDMI alongside television formats.

HDMI lanes are the parallel data channels inside the cable, and their number and speed set the total bandwidth.

Scrambling randomises the bit pattern on an HDMI link to reduce electromagnetic interference at high clock rates.

Equalisation compensates for the way a cable degrades a signal, restoring the sharp edges the receiver needs.

A booster or extender increases the distance an HDMI signal can travel reliably.

HDR is a set of formats that carry a wider range of brightness and colour than standard video.

HDR10 is the open, royalty-free HDR format with fixed metadata for a whole title.

HDR10+ adds scene-by-scene metadata to HDR10, as an open alternative to Dolby Vision.

HLG is the HDR format designed for live broadcast, compatible with standard dynamic range displays.

Dolby Vision is a licensed HDR format with dynamic, scene-by-scene metadata and up to 12-bit colour.

LLDV is a Dolby Vision mode where the source does the tone mapping and sends a ready-made signal to the display.

BT.2020 is the very wide colour space used as the container for UHD and HDR content.

DCI-P3 is the cinema colour space, wider than Rec.709 and the realistic target most HDR content is mastered in.

A nit is a unit of brightness, and HDR metadata uses it to describe how bright content was mastered.

Tone mapping compresses HDR content's brightness range to what a display can actually reproduce.

Colour primaries are the exact coordinates of red, green and blue that define a colour space.

Global dimming is a display capability flag telling the source the panel dims its whole backlight together.

Backlight control is a Dolby Vision capability flag describing whether the display can modulate its backlight.

VRR lets a display change its refresh rate on the fly to match the frame rate a game is producing.

ALLM lets a source tell a display to switch to game mode automatically.

Input lag is the delay between an input and the result appearing on screen.

ARC and eARC send audio from a TV back down the HDMI cable to a receiver or soundbar.

Dolby Atmos is object-based surround sound that places sounds in three-dimensional space, including height.

Dolby TrueHD is a lossless compressed audio format used on Blu-ray and as a carrier for Atmos.

DTS:X is object-based surround sound and DTS-HD Master Audio is its lossless multichannel predecessor.

LPCM is uncompressed digital audio, the format every HDMI device is required to support.

Bitstream means sending compressed audio on untouched for another device to decode.

Dolby Digital is a lossy compressed surround format, supported by essentially every AV device.

Dolby Digital Plus is an improved lossy format and the usual carrier for Atmos on streaming services.

One-bit audio, also known as DSD, is the encoding used by SACD and some high-resolution releases.

Sample rate is how many times per second audio is measured, and it is advertised per format in the EDID.

Channel count describes how many speaker channels an audio format carries, with the figure after the dot counting subwoofers.

IEC 61937 is the standard for carrying compressed audio inside a PCM-shaped transport.

HBR is the high-bitrate HDMI audio transport used for lossless multichannel formats.

An embedded web server is a control interface a device serves to any browser on the same network.

Telnet is a plain-text network protocol used to send commands to a device over IP.

IP control means operating a device by sending commands over the network instead of using infrared or a front panel.

HTTP control means sending device commands as ordinary web requests instead of over a raw socket.

DHCP is the service that hands out IP addresses automatically when a device joins a network.

A static IP is a fixed network address configured on the device itself rather than assigned by the router.

mDNS lets devices be reached by a local .local name instead of an IP address.

A hostname is the readable name a device answers to on a network.

RJ45 is the standard eight-pin connector used for wired Ethernet.

A MAC address is a permanent hardware identifier burned into a device's network interface.

An IP port is the numbered channel a network service listens on, alongside the device's address.

IP interrupts make a device report state changes on its own instead of waiting to be asked.

Firmware is the software running inside a device, updatable to add features or fix behaviour.

A config export writes a device's complete settings and state to a text file.

A factory reset returns a device to its original settings, clearing everything you configured.

A rotary switch is a control that turns to navigate and presses to select.

HTPC mode changes how a device reports itself so a PC does not rearrange its desktop when a display sleeps.

TX +5V force controls whether a device reacts to the display's presence signal on the output.

USB-C power supplies 5V over a reversible connector, and the available current decides whether a device runs properly.

OLED is a display technology where each pixel emits its own light, giving true blacks.

An HDMI matrix routes several sources to several displays independently.

An HDMI splitter sends one source to several displays at once.

A scaler converts video from one resolution to another, up or down.

An AV receiver switches HDMI sources, decodes audio and drives speakers — and sits in the middle of the capability chain.

A projector is a display device that usually sits at the end of a long HDMI run with an AVR in between.

A soundbar takes audio from a TV over ARC or eARC, or sits in the video path with HDMI passthrough.

A games console is an HDMI source whose best modes depend entirely on what the chain advertises.

An HTPC is a computer used as an AV source, with the quirks of a computer rather than a player.

A GPU drives displays over HDMI and reads their capability data to build its resolution list.

A streaming box is an HDMI source that adapts its output to the capabilities it reads at startup.

A disc player is an HDMI source whose output format follows the capability data it reads.

A certified HDMI cable has been tested to carry a stated bandwidth, rather than merely claiming to.