Does HDR video play in a browser?
The screen decides, not the file.

The web standards show where the uncertainty sits. MDN documents a dynamic-range media feature that lets a page test whether the browser and the output device support high peak brightness, high contrast and more than 8 bits per colour component. It has been available across browsers since May 2022. MDN is explicit about its limit: some devices have HDR capability that must be activated, and the feature does not test whether that capability is active, only whether the device is capable of it.

A second feature, video-dynamic-range, asks the same question of the video plane specifically. The W3C Media Queries Level 5 draft notes that the video plane may differ from the graphics plane, which is why the two exist. MDN marks video-dynamic-range as limited availability and not Baseline, because it does not work in some of the most widely used browsers. The dynamic-range-limit CSS property, which caps how bright HDR content may get on a page, is limited availability too. So the honest summary is: a page can learn whether a screen could show HDR, it cannot confirm the screen is showing it, and the finer tools are not everywhere yet.

YouTube’s help page says it detects the HDR metadata and processes it, producing HDR transcodes for HDR devices and an SDR downconversion for other devices, and that viewers on non-HDR devices see the video as SDR. It also lets you give its SDR downconversion a hint in the form of a 3D LUT. That is real work done on your behalf: someone else decides what your HDR grade looks like on an ordinary screen, and you can steer it.

Vimeo handles HDR as its own rendition. Vimeo publishes maximum delivery bitrates by rendition: up to 22 Mbps for 4K H.264 and 16 Mbps for its 4K HDR/HEVC rendition. Actual output can be lower; these are not upload recommendations or universal visual-quality scores. Its help page lists the same split at 1080p: a maximum of 7 Mbps for H.264 and 5 Mbps for HDR/HEVC, both up to 60 fps.

Browser playback uses your uploaded export without another platform re-encode. Codec, device and connection requirements still apply. For HDR that means the file you upload, with whatever colour tags and HDR metadata it carries, is the file the viewer’s browser receives. We generate no SDR version, no HDR rendition and no other rendition. The web player is a standard HTML video element; it applies no tone mapping or colour conversion of its own and does not check the viewer’s screen. Upload inspection reads the container, codec, resolution, duration and bitrate, not colour or HDR metadata. How an HDR file looks is left entirely to the viewer’s browser, operating system and display, and nothing here proves that an HDR file displays correctly on any given screen. We have not tested it across browsers and displays, so we do not claim it.

That makes the choice straightforward. If you publish HDR to a broad audience on unknown screens and want someone to handle the SDR version for you, YouTube does that job and we do not; stay there for it. If you deliver to a known client on a known screen, you can upload the HDR master and an SDR export as two films (two films at once needs a paid plan; Starter holds one), check both on that screen, and send the one that looks right.