Firefox

Same codec support on Linux, Windows, and macOS. H.264 needs Cisco's OpenH264 plugin, which Firefox installs separately from the browser itself; H.265 never works over WebRTC.

All platforms

Codec	WebRTC
H.264	With the OpenH264 plugin
H.265	No
AV1	Yes (recent versions)

Need HEVC? Use Chrome, Edge, or Safari on your OS.
OS guides: Linux, Windows, macOS

H.264 missing

Firefox decodes H.264 over WebRTC only through Cisco's OpenH264 plugin. Open about:addons → Plugins: if "OpenH264 Video Codec provided by Cisco Systems" is missing or set to "Never activate", enable it and restart Firefox — a fresh profile, or a machine that could not reach Mozilla's download servers, often has no copy of it. Without it the session still works, but it falls back to AV1, which Firefox may decode in software.

← Back to overview