Pixels per universe
Each colour of a pixel takes one DMX channel at 8-bit and two at 16-bit (a coarse and a fine byte, for smoother dimming). A pixel is never split across two universes, so any channels left over at the end of a universe stay unused.
To budget universes, divide the pixel count by the per-universe figure and round up. Your pixel-mapping software and the controller must agree on the same figure, or everything after the first universe boundary shifts along the run.
Pixels per controller port
A port sends pixel data down one line at a fixed bit rate, and every dot on that line must be refreshed once per frame. So the frame rate, not only the universes, sets how many dots one port can drive:
µs per dot = bits per dot ÷ 800 kbps (16-bit RGBW: 64 bits = 80 µs)
Smart PXL at 800 kbps, 16-bit, with a 300 µs reset between frames. Pixel Designer uses 40 fps unless you choose another rate.
A port carries the lower of that figure and what its universes hold:
Worked example: a 20 × 8 m facade
- Dots: 27 rows of 67 at 300 mm = 1,809 Smart PXL60 RGBW dots.
- Universes: 1,809 ÷ 64 = 28.3, so at least 29. Pixel Designer counts 35, because each controller output starts on a fresh universe and the last one on each output is part-filled.
- Ports: 8 outputs on 2 × OCTO MK3, about 226 dots each, within the 308 a port refreshes at 40 fps.
Work it out for your own layout
Pixel Designer is ENTTEC's free online tool for planning pixel dot installations. Enter your layout's size and dot spacing and it applies every rule on this page: strings, controllers and ports, universes, power supplies, injection points and cabling, with a parts list. No account needed.
Questions
How many pixels are in one DMX universe?
At 8-bit, 170 RGB pixels (3 channels each, 510 of the 512 channels) or 128 RGBW pixels (4 channels each). At 16-bit every colour takes two channels, so 85 RGB or 64 RGBW pixels.
Why 170 RGB pixels per universe and not 170.67?
A pixel is never split across two universes, because the two halves could update at slightly different times. Pixel 171 would need channels 511 to 513, and channel 513 does not exist, so channels 511 and 512 stay unused.
How many pixel dots can one controller port drive?
The lower of two limits: what the port's universes hold, and what the data rate refreshes at your frame rate. At 800 kbps and 40 fps one port refreshes at most 308 RGBW or 411 RGB 16-bit Smart PXL dots.
Do Smart PXL dots use 8-bit or 16-bit?
Pixel Designer plans Smart PXL dots at 16-bit, so it counts 64 RGBW or 85 RGB dots per universe. Your pixel-mapping software and controller must use the same setting, or the colours shift along the run.
How many universes does a 20 × 8 m pixel facade need?
At 300 mm spacing it holds 1,809 RGBW dots: at least 29 universes at 64 dots each. Pixel Designer counts 35, because each controller output starts on a fresh universe.
More pixel planning guides
- LED pixel power calculator
- Voltage drop and power injection for pixel dots
- How far can pixel data run?
- LED media facade planner
The figures on this page come from Pixel Designer's own engine and settings, which follow the Smart PXL, OCTO, PIXELATOR and PLink manuals and datasheets. Background reading on the ENTTEC support site: How many pixels fit in a DMX universe?, Design your Pixel Dot system with Pixel Designer.