HDMI and AV terms explained

Extended Display Identification Data is a standardized data structure a sink provides over the HDMI DDC channel, describing its supported video timings, color, HDR and audio capabilities.

An EDID manager is an HDMI device placed ahead of the chain that lets the user choose, copy or modify the EDID presented to a source.

An EDID emulator is a device that supplies a stored EDID to an HDMI source in place of the downstream display, keeping the advertised capabilities constant.

AutoMix is an EDID mode that combines the connected sink's copied EDID with user-selected video and audio flag overrides before presenting it to the source.

A custom EDID is a user-selected or uploaded EDID table presented to a source instead of the EDID reported by the connected sink.

DisplayID is a VESA display identification standard that extends classic EDID structures and commonly appears as extra blocks in 384-byte or 512-byte EDID.

A Detailed Timing Descriptor is an 18-byte EDID entry that defines a single video timing exactly, with the first one marking the display's preferred mode.

An EDID block is a 128-byte unit of EDID data: either the base block or one of the extension blocks, such as CTA-861 or DisplayID, that follow it.

An EDID slot is a numbered memory location in an EDID device that holds one table, either a fixed preset or a user-writable entry.

EDID sniffing is the capture and storage of the EDID, and related data blocks, reported by a connected sink device.

COPY TX SINK is a DR HDMI 8K EDID mode that forwards the EDID of the sink connected at the TX output to the source without changes.

The Dolby Vision data block is a vendor-specific EDID data block in which a display declares its Dolby Vision interface, color primaries and luminance range.

Video flags are individually adjustable video capabilities, such as FRL rate, VRR, ALLM, HDR and Dolby Vision, applied when modifying a sink's EDID.

Audio flags are adjustable EDID entries that declare support for individual audio formats, such as PCM, Dolby TrueHD or DTS-HD MA, together with their parameters.

The HDMI handshake is the connection sequence of hot plug detection, EDID reading, link setup and HDCP authentication that precedes video output.

Hot Plug Detect is a dedicated HDMI pin the sink asserts when connected; toggling it prompts the source to re-read the EDID and restart the link.

RX (receive) and TX (transmit) label the input and output sides of an HDMI device, facing the source and the sink respectively.

In HDMI terminology, a source outputs audio and video over a link and a sink receives it; a repeater acts as a sink on its input and a source on its output.

HDMI 2.1 is the HDMI specification revision that introduced Fixed Rate Link signaling up to 48Gbps together with optional features such as VRR, ALLM, eARC and DSC.

Fixed Rate Link is the HDMI 2.1 packet-based signaling mode that runs three or four lanes at fixed rates, from FRL1 (3 x 3Gbps) to FRL6 (4 x 12Gbps).

Transition-minimized differential signaling (TMDS) is the HDMI transmission scheme that sends data on three differential channels plus a clock channel, up to 18Gbps.

High-bandwidth Digital Content Protection is an Intel-developed link encryption scheme that requires HDMI devices to authenticate before protected video is transmitted.

An HDMI repeater is a device that receives an HDMI signal, restores it through equalization and re-clocking, and retransmits it to the next device.

Fiber HDMI is an active optical cable that converts HDMI's high-speed signals to light for transmission over optical fiber, while low-speed lines usually stay on copper.

Consumer Electronics Control (CEC) is an HDMI feature that carries low-speed control commands, such as power, input selection and volume, between connected devices.

Display Stream Compression (DSC) is a VESA standard for low-latency, visually lossless video compression used by HDMI 2.1 and DisplayPort.

8K is a video resolution of 7680 by 4320 pixels, also written 4320p, with roughly 33 million pixels per frame.

In consumer video, 4K means Ultra HD at 3840 by 2160 pixels, while cinema 4K defined by DCI is 4096 by 2160.

4K120 is a 3840 by 2160 video mode at 120Hz, introduced with HDMI 2.1 and normally carried using Fixed Rate Link signaling.

1080p is a progressive-scan video format with a resolution of 1920 by 1080 pixels, commonly called Full HD.

2K refers to a horizontal resolution of about 2,000 pixels, strictly the 2048 x 1080 cinema format, though retailers often apply it to 2560 x 1440.

Chroma subsampling is a video encoding technique that samples color-difference information at a lower resolution than luminance, expressed as ratios such as 4:2:2 or 4:2:0.

Bit depth is the number of bits used to encode each color component of a pixel, which sets how many tonal levels a video signal can represent.

HDMI bandwidth is the maximum data rate of an HDMI link, such as 18Gbps for TMDS in HDMI 2.0 or 48Gbps for FRL in HDMI 2.1.

Refresh rate is the number of times per second a display updates its image, expressed in hertz (Hz).

Ultra High Definition (UHD) is the 3840 x 2160 consumer video resolution, with the 7680 x 4320 step often labeled FUHD or 8K.

DCI (Digital Cinema Initiatives) is a film industry body whose specifications define cinema formats, including DCI 4K at 4096 by 2160 pixels.

RGB is a video color encoding that describes each pixel with separate red, green and blue component values, without chroma subsampling.

YCbCr is a color encoding that represents video as a luma component (Y) plus blue-difference and red-difference chroma components (Cb and Cr).

Pixel clock is the frequency, in megahertz, at which a video interface transmits pixels, set by the resolution, blanking intervals and frame rate.

Deep color is an HDMI capability, introduced with HDMI 1.3, for transmitting video at 10, 12 or 16 bits per color component.

xvYCC (IEC 61966-2-4) is an extended-gamut YCC color space that allows video color values outside the Rec.709 gamut.

Stereoscopic 3D video over HDMI transmits left-eye and right-eye images together using formats such as frame packing, side-by-side or top-and-bottom.

Interlaced video is a scanning format in which each frame is transmitted as two fields containing alternate lines, as in 480i and 1080i.

PC resolutions are VESA-defined computer display timings, such as QFHD or WQUXGA, carried over HDMI in addition to consumer television formats.

HDMI lanes are the differential data channels in an HDMI link: three plus a clock under TMDS, and three or four data lanes under FRL.

In HDMI, scrambling applies a pseudo-random sequence to the transmitted data to spread its spectral energy and reduce EMI at high data rates.

Equalization is signal processing that compensates for frequency-dependent cable loss, reshaping degraded high-speed transitions so a receiver can recover the data.

An HDMI booster or extender is a device that amplifies, regenerates or converts an HDMI signal so it can travel farther than a single cable allows.

High dynamic range is a family of video formats, including HDR10, HDR10+, HLG and Dolby Vision, that cover a far wider luminance range than standard dynamic range.

HDR10 is an open HDR format combining the PQ transfer function, BT.2020 color and 10-bit depth with static metadata such as SMPTE ST 2086 mastering values.

HDR10+ is a royalty-free HDR format that adds dynamic, scene-by-scene metadata to HDR10 video.

Hybrid Log-Gamma is a metadata-free HDR transfer function developed by the BBC and NHK and standardized in ITU-R BT.2100.

Dolby Vision is a proprietary HDR video format from Dolby that uses dynamic metadata and supports up to 12-bit color depth.

Low Latency Dolby Vision (LLDV) is a source-led Dolby Vision mode in which the player performs the tone mapping and sends a display-ready signal.

BT.2020 (ITU-R Recommendation BT.2020, also Rec.2020) defines, among other parameters, a very wide color gamut used as the color container for UHD and HDR video.

DCI-P3 is a color space defined by Digital Cinema Initiatives, with a gamut wider than Rec.709 and smaller than BT.2020.

The nit is the common name for one candela per square meter (cd/m2), the unit used to express display brightness and HDR luminance levels.

Tone mapping is the process of remapping the luminance range of HDR content to the capabilities of a specific display.

Color primaries are the chromaticity coordinates of the red, green and blue reference colors that define the gamut of a color space.

Global dimming is a flag in the Dolby Vision data block indicating that a display dims its entire backlight uniformly.

In a Dolby Vision data block, backlight control indicates support for content-dependent backlight adjustment, alongside a backlight minimum luminance of 25, 50, 75 or 100 nits.

Variable refresh rate (VRR) is an HDMI 2.1 feature that lets a display's refresh rate follow the source's frame rate in real time.

Auto Low Latency Mode (ALLM) is an HDMI feature in which a source signals a display to enter or leave its low-latency game mode automatically.

Input lag is the latency between a user input and its visible result on the display, accumulated across the source, the signal chain and display processing.

ARC (Audio Return Channel) and its enhanced successor eARC carry audio from a TV upstream to an audio system over an HDMI connection.

Dolby Atmos is an object-based immersive audio format that adds height information to surround sound and adapts playback to the speakers available.

Dolby TrueHD is a lossless multichannel audio codec used mainly on Blu-ray and UHD Blu-ray discs, often as the carrier for Dolby Atmos.

DTS:X is an object-based immersive audio format from DTS, usually delivered over HDMI as an extension of a lossless DTS-HD Master Audio stream.

Linear pulse-code modulation (LPCM) is an uncompressed digital audio format that stores a signal as evenly spaced samples of fixed bit depth.

Bitstream is an audio output method in which a source passes encoded audio, such as Dolby TrueHD or DTS-HD MA, to another device for decoding.

Dolby Digital (AC-3) is a lossy multichannel audio codec supporting up to 5.1 channels, used on DVD, broadcast television and Blu-ray.

Dolby Digital Plus (E-AC-3) is a lossy audio codec that extends Dolby Digital with higher efficiency and more channels, and is widely used for streaming Atmos.

One-bit audio is a digital audio encoding, such as Direct Stream Digital (DSD), that represents sound as a high-rate stream of 1-bit samples.

Sample rate is the number of audio samples captured or reproduced per second, expressed in hertz or kilohertz.

Channel count is the number of discrete audio channels in a format or speaker layout, written as main channels followed by LFE channels, as in 5.1 or 7.1.

IEC 61937 is the standard defining how compressed audio bitstreams, such as Dolby Digital and DTS, are transported over IEC 60958-type digital audio interfaces.

High Bit Rate audio is an HDMI audio packet type that carries IEC 61937 bitstreams at rates far above standard audio packets, used for Dolby TrueHD and DTS-HD Master Audio.

An embedded web server is software running on a device that serves its status and configuration pages to web browsers over the local network.

Telnet is an unencrypted, TCP-based protocol for opening an interactive text session with a remote device.

IP control is the operation of a device through commands sent over a TCP/IP network, typically through a raw socket or Telnet session.

HTTP control is a remote-control method in which commands are delivered to a networked device as individual HTTP requests.

Dynamic Host Configuration Protocol (DHCP) is a network protocol that automatically assigns IP addresses and related settings to devices on a network.

A static IP address is a network address configured manually on a device, together with its subnet mask and gateway, instead of being leased via DHCP.

Multicast DNS (mDNS) is a zero-configuration protocol that resolves .local hostnames to IP addresses on a local network without a DNS server.

A hostname is a text label assigned to a network device that name resolution translates into its IP address.

RJ45 is the common name for the 8P8C modular connector used to terminate twisted-pair Ethernet cables.

A media access control (MAC) address is a 48-bit identifier assigned to a network interface, written as six pairs of hexadecimal digits.

An IP port is a number from 0 to 65535 that identifies a specific service on a networked device, used together with that device's IP address.

IP interrupts are status notifications a networked device sends to a connected controller automatically whenever its state changes.

Firmware is software stored in a device's nonvolatile memory that controls its hardware and can be replaced by an update.

A config export is a text file generated by a device that records its configuration and current operating status.

A factory reset restores a device's stored configuration to the manufacturer's default values, discarding all user changes.

A rotary switch is a rotating control, often with a push action, used to scroll through menu items and confirm a selection on a device.

HTPC mode is a DR HDMI 8K configuration option for PC sources that addresses Windows desktop rearrangement when a display turns off or resumes from standby, and is not compatible with HDCP.

TX +5V force is a DR HDMI 8K setting, on by default, that when switched off stops the unit from detecting the display connected to its HDMI output.

USB-C power refers to supplying a device with DC power through a USB Type-C connector, where the usable voltage and current depend on the power source.

An organic light-emitting diode (OLED) display uses self-emissive organic pixels that each produce their own light, without a separate backlight.

An HDMI matrix switch connects multiple HDMI sources to multiple displays and lets each output select its input independently.

An HDMI splitter is a device that distributes one HDMI input signal to multiple outputs simultaneously.

A video scaler is a processor that resamples a video signal to a different resolution, either upscaling or downscaling it.

An AV receiver (AVR) is a home cinema component that switches HDMI inputs, decodes and amplifies audio, and passes video through to a display.

A projector is a display device that forms an image by casting light from an imaging chip through a lens onto a separate screen.

A soundbar is a single-enclosure speaker system that receives TV audio over HDMI ARC or eARC, or through HDMI passthrough from connected sources.

A games console is a gaming device acting as an HDMI source, whose available output modes such as 4K120, VRR and ALLM depend on the EDID it receives.

A home theater PC is a personal computer connected to a TV, projector or AV receiver and used as a media source.

A graphics processing unit is the processor that renders a computer's display output and, over HDMI, derives its default mode list from the connected EDID.

A streaming box is a network media player that delivers content from online services to a TV or AV system over HDMI.

A Blu-ray player is an HDMI source device that plays optical discs, with UHD models outputting 4K HDR video and lossless multichannel audio.

HDMI cable certification is a licensed test program confirming that a cable meets the bandwidth of its category, such as Premium High Speed at 18Gbps or Ultra High Speed at 48Gbps.