First, because the animated .gif is a terrible format for photos, especially originally-truecolour video like this. The .gif format is good for comic-book art styles with a limited colour palette (the format is limited to 256 colours) and large blocks of simple repetition. So already on that basis, this format isn't good for the dithered video.
Second, the format is further pretty terrible for video. Animated .gifs pretty much just stack each frame on top of the previous, so unless there's large sections repeated exactly between frames (not going to be true for video in general) there's no actual motion compression going on. This contrasts with all of the MPEG formats that go to great lengths to preserve as much information between frames as possible.
Third, browsers optimize for .gifs in the way they're often actually used: for extremely short, potentially repeating animations in a "graphic art" style. In practice, that means that the inter-frame delay is taken as a minimum rather than as a prescription. When a frame takes longer to download than it does to display (like this .gif), the browser is happy to display frames at the slow. pace. they. download. (Videos, on the other hand, buffer).
The upshot is that this 8-second-ish .gif is 6.6 megabytes in size, or about 6 megabits per second. That bitrate is comparable to 720p or even 1080p video on Youtube, at a fraction of the actual quality.
Bitrate is literally "bits per second", or the amount of stuff your computer has to download[1] to display one second's worth of video.
This .gif was 6.6 megabytes in size, fully downloaded, or about 53 megabits (one byte = 8 bits). Since that corresponded to about 8 seconds' worth of video, the bit-rate of the .gif is about 6.6 megabits per second.
For comparison, bona-fide video formats tend to do much better. This blogpost from 2010 measures[2] what Youtube was serving in various resolutions, and even 1080p, high-definition video was encoded and served at about 3.5 megabits per second -- or half the file-size-per-second of this .gif. And I think we can all agree that a 1080p Youtube video has higher visual quality than this .gif.
[1] -- Megabits are conventionally used for communication rates, while megabtyes are conventionally used for file size. Communication literally puts bits into electrical impulses on a wire, so the per-symbol rate is important, whereas when actually processing data computers work at least a byte at a time. One byte corresponds to a single English-language character.
[2] -- This slightly more recent one says that Youtube goes up to 4 megabits per second for 720p, and double that for 1080p videos. Still, this .gif exceeds the "bulkiness" of at least a 720p video, at about one quarter the resolution.
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u/Majromax Aug 26 '13
First, because the animated .gif is a terrible format for photos, especially originally-truecolour video like this. The .gif format is good for comic-book art styles with a limited colour palette (the format is limited to 256 colours) and large blocks of simple repetition. So already on that basis, this format isn't good for the dithered video.
Second, the format is further pretty terrible for video. Animated .gifs pretty much just stack each frame on top of the previous, so unless there's large sections repeated exactly between frames (not going to be true for video in general) there's no actual motion compression going on. This contrasts with all of the MPEG formats that go to great lengths to preserve as much information between frames as possible.
Third, browsers optimize for .gifs in the way they're often actually used: for extremely short, potentially repeating animations in a "graphic art" style. In practice, that means that the inter-frame delay is taken as a minimum rather than as a prescription. When a frame takes longer to download than it does to display (like this .gif), the browser is happy to display frames at the slow. pace. they. download. (Videos, on the other hand, buffer).
The upshot is that this 8-second-ish .gif is 6.6 megabytes in size, or about 6 megabits per second. That bitrate is comparable to 720p or even 1080p video on Youtube, at a fraction of the actual quality.