Dear Firefox Team,
Currently, Firefox on Windows cannot play HEVC (H.265) DRM 4K streams, even with the Microsoft HEVC codec installed. This works fine on Linux and in Chrome/Edge on Windows.
Key technical context:
Firefox on Windows relies on Windows Media Foundation + Widevine for DRM.
WMF does not expose HEVC for DRM streams, so playback fails.
Non-DRM HEVC files play fine, showing the codec itself is functional.
Adding HEVC + DRM support on Windows would let users enjoy 4K content in Firefox without switching browsers, improving the experience and keeping Firefox competitive.
Thank you for considering this feature!
Best regards,
De_Lo_
