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'Video' is essentially a series of images played in rapid succession, to give a human spectator the impression of motion (motion picture, moving image). For a movie, this typically amounts to 25 images ('frames') per second (frame rate). (The story is more complicated for TV, for the sake of this explanation we will stick with the analog motion picture example.)
Mozilla Developer Network page on color encoding and chroma subsampling in digital video: https://developer.mozilla.org/en-US/docs/Web/Media/Formats/Video_concepts
"A short guide to choosing a digital format for video archiving masters": https://web.archive.org/web/20221128105156/https://scart.be/?q=en/content/short-guide-choosing-digital-format-video-archiving-masters
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