A/V Glossary

Ever wonder what an audio/video term means? Well here's your answer...

2 piece projection - A 2 piece projection system consists of a light engine shining light onto a screen. The light engine can be placed in front of (front projection) or behind (rear projection) the screen
2/3 pulldown - Video processing that converts content shot at film (24fps) to video (30fps). This helps reduce motion artifacts when watching film based content on a television
AOC (Active Optical Cable) -A “hybrid” HDMI cable that transmits data over a fiber optic cable inside of the HDMI cable. Copper is still used for some things such as 5v hotplug
Backlight - The light source of an LCD panel. Most commonly CCFL bulb(s) or LEDs
Backlit - Refers to the light source of an LCD TV being behind the panel (rather than the light source being across the bottom or along the edges -see Edgelit)
Banding - (Video artifact) described as abrupt changes or steps between shades of the same color. Symptom of not enough bits in the signal
Bandwidth - maximum rate of data transfer across a given path
Brightness - (TV control) How much gain is taken away from the red, green, and blue signal. Also known as black level
BT.601 (also rec. 601)- standard established in 1982 that describes the parameters (resolution, frame rate, color space, etc) for SDTV
BT.709 (also rec. 709) - standard established in 1990 that describes the parameters (resolution, frame rate, color space, etc) for HDTV
BT.2020 - (also rec. 2020) - standard established in 2012 that describes the parameters (resolution, frame rate, color space, etc) for UHDTV
CalMAN - Software package used to calibrate displays. Made by SpectraCal
Chroma Subsampling - is the practice of encoding images by implementing less resolution for chroma information than for luma information, taking advantage of the human visual system's lower acuity for color differences than for luminance. Typically described as a ratio of the luminance channel to the 2 color channels ex 4:4:4, 4:2:2, 4:2:0
CIE chart - Created by the International Commission on Illumination (CIE) in 1931, the chart shows the range of colors in the visible light spectrum
Clipping - when a signal is overdriven which results in distortion and loss of detail. In video, clipping most commonly refers to contrast being too high and bright details being lost. In audio, a clipped signal usually sounds like distortion and can be dangerous to audio equipment
CMS - (TV control) Color Management System - A set of controls in some displays that allow the calibration of individual primary and secondary colors
Contrast - (TV control) How much gain is added to the red, green, and blue signal. Also known as white level
Colorimeter - tristimulus (three-filtered) device used in display calibration that use a red, green, and blue filter to emulate the response of the human eye to light and color.
Color saturation - (TV control) The amount of color in the image
Color space/color gamut - (TV control) The range of colors that a display can produce.
Color points - Targets for the primary and secondary colors within the CIE chart
Color Temperature (Kelvin) - The “color” of light as described by the Black Body Curve. As things heat up, they change color. A “cool” color temperature (9500K) may look blue-ish white while a “warm” color temperature (3500k) may look orange-ish white
Crushing -Video calibration term that describes the loss of shadow detail when brightness/black level is set too low
D65 - the standard “color” of white as defined by the CIE. the coordinates for D65 on the CIE chart are x=.313, y=.329. D65 resembles daylight
DCI/P3 - (DCI = Digital Cinema Initiatives) a common RGB color space for digital movie projection from the American film industry. DCI-P3 was defined by the Digital Cinema Initiatives (DCI) organization and published by the Society of Motion Picture and Television Engineers (SMPTE)
Dolby Vision -Created by Dolby Laboratories, Dolby Vision was the second “version” of HDR. Dolby Vision uses the PQ EOTF, up to 4k resolution, BT.2020 color, up to 12 bits, and dynamic (frame by frame) metadata. Currently supported by Vizio, LG, Philips, TCL. Unlike HDR10, Dolby Vision is not an open source platform.
Dynamic range - Considered the most important quality of any video or audio system!
-As a video term: dynamic range describes the difference between how bright and how dark an image or a display is.
-As an audio term: dynamic range describes the difference between the quietest and loudest a piece of music or an audio system is
Edgelit - Refers to the light source of an LCD TV being around the edges of the panel (rather than the light source being directly behind the LCD panel -see Backlit)
EDID - Extended Display Identification Data - a type of metadata that display devices use to describe their capabilities to a video source
EOTF - Electro Optical Transfer Function - the process of converting an incoming video signal to light (formally “gamma” in a display)
FALD - Full Array Local Dimming - describes a style of backlight on an LCD panel. LEDs are located behind the panel and are divided into zones. Zones can be controlled and adjust in luminance depending on the source material.
Frame rate/Frames Per Second (fps) - How many still images are shown per second to simulate motion in film (24fps) and video (30fps)
Gamma -(TV control) The relationship between the incoming video signal and the light output of the display. This relationship is non-linear. Higher Gamma values are better for darker rooms, lower Gamma values are better for brighter rooms. If Gamma is set correctly, shadows in dark movies, TV shows, games, etc should be visible regardless of room lighting
Generator - generates test patterns to the display for calibration
Grayscale - The range of gray shades from black to white. When calibrating a display the grayscale should be calibrated to D65 -see D65
HDCP - High bandwidth Digital Content Protection - digital copy protection developed by Intel Corporation to prevent copying of digital audio & video content as it travels across connections. Types of connections that support HDCP include DisplayPort (DP), Digital Visual Interface (DVI), and High-Definition Multimedia Interface (HDMI)
HDMI - High Definition Multimedia Interface. A digital interface that passes audio, video, and communication signals down a single cable
HDR - High Dynamic Range - Greater dynamic range than standard video imaging
HDR10 - The first “version” of HDR. HDR10 uses the PQ EOTF, up to 4k resolution, BT.2020 color, up to 10 bits, and static metadata. Currently supported by Samsung, Sony, Hisense/Sharp, Philips, and LG. HDR10 is an open source technology
HDR10+ - Similar to HDR10 except HDR10+ adds dynamic (frame by frame) metadata to the content. This is done by the display. Supported by Samsung, Panasonic, Amazon, 20th Century Fox, Warner Bros. HDR10+ is an open source technology
HEVC - High Efficiency Video Coding - one standard of video compression. Also known as H.265. Compatible with resolutions up to 8192×4320
HLG - Hybrid Log Gamma. HDR designed for broadcast TV. Backwards compatible with SDR displays
H.264 - one standard of video compression. Most commonly used on Bluray discs, iTunes, and more
H.265 - one standard of video compression. Also known as High Efficiency Video Coding (HEVC). One successor to H.264. Compatible with resolutions up to 8192×4320
Hue/tint -(TV control) The shade or type of color
Interlaced - The process of making an image by combining even and odd lines to make a solid picture
Laser Phosphor - one type of light engine used in a video projector. Lasers excite a color wheel that is coated in phosphor to produce the colors that you see on the screen
LCD - Liquid Crystal Display. Light shines through a liquid crystal to produce color. Does not actually emit light
https://www.youtube.com/watch?v=0B79dGR19Tg
LED - Light Emitting Diode. A small semiconductor that emits light when current is applied. Most commonly in electronics, such as a backlight for a LCD TV
https://www.youtube.com/watch?v=u4L8gfzi3sE
Light meter - used in display calibration to measure light coming off of the screen
Local dimming - The intensity of the light source of the LCD panel can adapt based on the content being shown. This allows for more Dynamic Range than typical LCD display
Luminance - The intensity of light emitted from a screen
Macroblocking - a video artifact (distortion) in which objects or areas of a video image appear to be made up of small squares rather than proper detail and smooth edges.
MaxCLL (Maximum Content Light Level) –Used as a parameter in HDR10, the MaxCLL is the luminance of the brightest pixel in the content (expressed as nits)
Max FALL (Maximum Frame-Average Light Level) – Used as a parameter in HDR10, MaxFALL is the maximum value of the frame-average for all the frames in the content (expressed as nits).
Metadata - additional data (information) that is part of the signal. In the context of HDR, metadata on the disc that tells the display how bright or dark the movie (or frame) should be
Motion interpolation -(TV control) video processing that increases the video's frame rate
Nit - Metric measurement of luminance. Also known as candelas per meter squared (cdm2). 1 foot lambert equals 3.42 nits
Noise Reduction - electronically processing noise out of the image
OETF - Opto Electronic Transfer Function - the process of converting light into a video signal (cameras use OETF)
OLED - Organic Light Emitting Diode - Thin layer of organic film that emits light when voltage is applied
https://www.youtube.com/watch?v=3R_W8Q-e7R4
Primary colors - colors that can be combined to make any other color in the visible spectrum. Red, green, blue
Progressive scan - The process of making an image by showing the entire image at once (vs interlaced which shows even then odd lines)
Quantum Dots - very small semiconductor particles, only several nanometers in size, so small that their optical and electronic properties differ from those of larger particles. Many types of quantum dot will emit light of specific frequencies if electricity or light is applied to them, and these frequencies can be precisely tuned by changing the dots' size, shape and material, giving rise to many applications. Commonly used as a backlight system for an LCD panel
Scaling - video processing that can either decrease or increase resolution
Secondary colors - The products of combining the primary colors. Yellow, cyan, magenta
Sharpness/resolution - The amount of detail in the image
sRGB - a color space that HP and Microsoft created cooperatively in 1996 to use on monitors, printers, and the Internet. Very similar to BT.709
Tone Mapping - is a technique used in image processing to map one set of colors to another to approximate the appearance of high-dynamic-range images on a display that has a more limited dynamic range. An example would be showing 4000nit content on an 800nit display
Video Noise - any distortion or random pixelation in the picture
VP9 - (Developed by Google) one standard of video compression. Competitor to H.265. Used by Youtube as of June 2018. VP9 is customized for video resolutions greater than 1080p (such as UHD) and also enables lossless compression.The VP9 format supports the following color spaces: Rec. 601, Rec. 709, Rec. 2020, and sRGB. VP9 supports HDR video using Hybrid Log-Gamma (HLG) and Perceptual Quantizer (PQ)
White balance - (TV control) The mix of the red, green, and blue signals to get a shade of white. The standard is D65
Wide Color Gamut (WCG) - an increase in available colors. Compared to rec709, rec2020 can be described as WCG

Audio/Video Glossary