Show dictionary
Video and LED terms
The video department’s working vocabulary. The structural concepts (switchers, servers, IMAG, genlock, pixel pitch) have full entries; these are the words that fill the rest of the comms channel.
Program / Preview
#- Program is the live output; preview is the staged next shot. The program/preview pair is the core discipline of switching: build it on preview, check it, take it to program.
M/E (mix/effects)
#- An M/E is a switcher’s compositing bank: its own program/preview with keyers, used to build scenes (camera plus graphics plus background) that the main bus can take as one source.
Key and fill
#- Keying composites one image over another; key-and-fill graphics deliver two signals, the fill (the picture) and the key (its transparency matte), so lower thirds float cleanly over program.
Scaler
#- A scaler converts video between resolutions and formats, buying compatibility at the cost of latency and a generation of processing. Every scaler in a chain is a frame you paid for; count them.
LED processor
#- The LED processor translates a video input into the data LED panels need, handling mapping, color, brightness, and redundancy. It is the wall’s brain; panels are its limbs.
Receiving card
#- Each LED panel contains a receiving card that takes its slice of the processor’s data stream and drives the panel’s LEDs. Loops of panels chain card to card, with backup loops feeding from the far end.
Raster
#- The raster is the pixel canvas a system works in: an output’s resolution, or the total canvas a server renders. "What is the wall’s raster?" is the first content question of any LED show.
Pixel map
#- The pixel map defines where each display surface lives within the server or processor canvas: which pixels feed which wall, sign, or strip. Content lands where the map says, nowhere else.
Moire
#- Moire is the shimmering interference pattern a camera produces shooting an LED wall, caused by the wall’s pixel grid beating against the sensor’s. Cures: change distance, focal length, focus, or angle.
Hot spot
#- A hot spot is the bright center a projection or light source leaves on screen material, strongest with high-gain surfaces viewed on axis. Screen choice and projector placement manage it.
Keystone
#- Keystone is the trapezoidal distortion of an image projected at an angle to the screen. Physical lens shift beats digital keystone correction, which resamples and softens the image.
Stacking
#- Stacking converges two or more projectors onto the same image area to add brightness (or for backup, with one shuttered). Alignment discipline is everything; a soft stack is worse than one projector.
Shutter (projector)
#- The projector shutter (douser) blacks the output without powering down, mechanically or electronically. "Shutter up/down" cues are how projection appears and vanishes on a caller’s go.
NDI
#- NDI is a widely used video-over-IP protocol carrying video, audio, and control on standard networks with low latency. Common for camera feeds, graphics, and monitoring inside show networks.
ST 2110
#- SMPTE ST 2110 is the professional IP video standard carrying uncompressed essence streams (video, audio, data) with PTP timing, the broadcast-grade path video plants use to replace SDI routing.
Chroma subsampling (4:4:4 / 4:2:2 / 4:2:0)
#- Chroma subsampling reduces color resolution relative to brightness to save bandwidth: 4:4:4 keeps everything, 4:2:2 halves color horizontally, 4:2:0 quarters it. Fine text on LED walls shows the difference first.
Related resources
Part of the eventools.io Show Dictionary, a free glossary of live event production terminology.