What is GIFV?

GIFV is the name Imgur introduced in 2014 for uploaded GIFs that it converts to MP4 or WebM video and plays back like a looping GIF. The .gifv extension is a naming convention for that presentation, not a distinct codec or container.

How GIFV works

Imgur announced the name in October 2014 together with a change that converts uploaded GIF files into WebM or MP4, depending on browser support, and marks the converted versions with a .gifv extension. The announcement says the extension signals a GIF-like experience and defines no file structure for it; in the comments, the post’s author described a .gifv link as an HTML5 page with a video tag that plays MP4. The pattern itself is not specific to Imgur: encode the animation as video, then present it with a video element that autoplays, loops, stays muted, and plays inline, so that it behaves like an animated image. The saving comes from the encoding. Each GIF frame is a set of LZW-compressed indexes into a color table of at most 256 entries, which WebKit calls a very expensive way to encode animation compared with a video codec such as H.264.

Key facts

What does a .gifv URL return? Not a file in a GIFV format, because Imgur’s announcement defines none. It says converted videos are denoted with the extension, and the post’s author described the link as an HTML5 page that plays an MP4. Software that needs the media itself has to find the underlying MP4 or WebM resource; treating the .gifv response as an image or as a video file fails. This describes Imgur in 2014, and other sites are free to use the suffix differently.
Which attributes make a video behave like a GIF, and what happens without them? autoplay, loop, muted, and playsinline. Chrome always allows muted autoplay but allows autoplay with sound only under conditions such as earlier user interaction with the site. Under the policy WebKit introduced with iOS 10, a video autoplays without a user gesture only if it is muted or has no audio track, pauses when it is no longer visible on screen, and on iPhone enters fullscreen when playback starts unless playsinline is present.
How much smaller is the video? It depends on the clip and the encoder settings, and the published figures are single examples: Imgur showed a 50 MB GIF that became a 3.4 MB video, web.dev shows a 3.7 MB GIF that became a 551 KB MP4 and a 341 KB WebM, and WebKit reported that GIFs can cost up to twelve times the bandwidth of H.264 video. None of these is a guarantee for a particular file, so measure your own output.
What does replacing an img with a video cost? The result is no longer an image. web.dev’s conversion example crops GIFs with odd dimensions because the H.264 encoder it uses needs an even width and height. Contexts that accept only images cannot show the video, which is why WebKit’s example keeps the original GIF inside the video element and swaps it in when no source is supported. One statement in web.dev’s guide is out of date for Chrome: it says a video element without a poster image is not a Largest Contentful Paint candidate, but Chrome’s metrics changelog records that since Chrome 116 a video can become a candidate, timed at its first presented frame.

What is GIFV?

How GIFV works

Key facts

When GIFV matters

How Transloadit helps with GIFV

Sources

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