When confetti rains down at the end of the Super Bowl, or when meteorologists report from a blizzard, the quality of the broadcast usually takes a nosedive. This isn't in your head: as Tom Scott explains in this video spotted by Sploid, adding snow or confetti to a video is a quick way to turn it into a pixelated mess.
Compression is the driving factor behind this phenomenon. Nearly everything we watch, whether it's on TV or on our phones, is a compressed version of raw video. Instead of feeding a device information for every pixel that appears in a frame, compressed files observe and predict visual patterns in order to save space. This means that if two actors are performing against a still backdrop, that background information gets reused, leaving more data to devote to the people moving on screen.
This goes unnoticed a majority of the time. Issues start to arise when you have numerous, tiny components moving randomly across the screen all at once. That's exactly the case with snow and confetti: the information in each upcoming frame becomes harder to predict and the video starts consuming more bits per second to keep up. So even if the big game looks crystal clear on your screen one minute, your HD TV is still no match for the confetti shower on its way. For more, watch a visual illustration of this effect in the video above.
All images courtesy of YouTube.