Which video formats does Remotion support?

Remotion supports a variety of video codecs.

Output formats: Videos can be rendered to H.264 (MP4), H.265, (HEVC), VP8 and VP9 (WebM), ProRes as well as GIFs. See the Encoding guide for more detail.

Codecs supported for <Video>: Remotion uses the default <video> tag for playback and therefore inherits codec support from the browser.
During rendering this means that the Chrome codecs are supported. During Preview and in the Player, the codec support from the browser in which the webpage is hosted in applies.
Codec support varies between browsers and changes from time to time. Refer to this MDN article for browser support.

Codecs supported for <OffthreadVideo>: The same support that applies to <Video> applies to <OffthreadVideo> as well, however, more codecs can be supported during rendering since FFmpeg is used under the hood to read the video file. We however don't maintain an exact list of supported video codecs.