Enable AV1 Support in Firefox

Firefox 63 was released yesterday. The browser includes a newly added experimental support for the open source patent-free codec AV1, which is disabled by default. Here is how to enable it.

Firefox 63 represents the branch built with the new Quantum engine. It comes with a refined user interface, codenamed "Photon". The browser now comes without support for XUL-based add-ons, so all of the classic add-ons are deprecated and incompatible. See

Must have add-ons for Firefox Quantum

Thanks to the changes made to the engine and the UI, the browser is amazingly fast. The user interface of the app is more responsive and it also starts up noticeably faster. The engine renders web pages much faster than it ever did in the Gecko era.

AV1 is the latest and greatest of the open video formats. It is designed as a successor to VP9, that competes directly with the proprietary (and costly) HEVC/H.265 codec. It is intended to be  paired with the Opus audio codec in a WebM container for HTML5 web video. It is royalty free and backed by a number of industry giants (Amazon, AMD, Apple, Arm, Cisco, Facebook, Google, IBM, Intel, Microsoft, Mozilla, Netflix, Nvidia, etc.), who together formed the Alliance for Open Media (AOMedia). Here is how to try AV1 in Firefox.

To enable AV1 support in Firefox, do the following.

1. Type about:config in the address bar. Confirm that you will be careful if a warning message appears for you.
2.  Enter the following text in the search box: media.av1.enabled.
3. Set the value media.av1.enabled to true.
4. Restart Firefox.

Now, go to youtube.com/testtube and enable AV1.

Once enabled, certain videos will now play in AV1.

That's it.

Related articles:

• Remove Top Sites Search Shortcuts in Firefox
• Disable Ctrl+Tab Thumbnail Previews in Firefox
• Disable Updates in Firefox 63 and above
• Firefox 63: Everything you need to know