Hello,

Currently in Firefox, WebRTC screen capture works only on X11. In Wayland,
only XWayland windows can be captured.

Wayland doesn't support screen capture by defaults but GNOME supports the feature
using pipewire. The pipewire support is already in Firefox source since version 68
(media/webrtc/trunk/webrtc/modules/desktop_capture/linux/base_capturer_pipewire.*)
but it is not built as a default.

Debian GNOME desktop is running on Wayland as defaults since buster, and its
default browser is Firefox. So I think the Debian Firefox package needs to be
built with pipewire capture support.

In Fedora, pipewire support is enabled with this patch:
https://src.fedoraproject.org/rpms/firefox/blob/master/f/firefox-pipewire.patch

This bug is all the more important now that Gnome launches over
Wayland by default.  And more so again in COVID times when we're using
video conferencing more heavily.

There's more discussion of the issue at

https://bugzilla.mozilla.org/show_bug.cgi?id=1430775

https://github.com/emersion/xdg-desktop-portal-wlr/wiki/Screencast-Compatibility

On Tue, 28 Jul 2020 23:05:02 +0800 Drew Parsons <dparsons@debian.org> wrote:
 > Package: firefox
 > Version: 78.0.2-1
 > Followup-For: Bug #960645
 >
 > This bug is all the more important now that Gnome launches over
 > Wayland by default. And more so again in COVID times when we're using
 > video conferencing more heavily.

Anything blocking this?

Is it acceptable to use the Fedora patch in debian or should be patch be
upstreamed first?

Having this fixed is more than welcome I think.

In Firefox 88.0.1-1, this seems to work great under GNOME Shell and
https://meet.jit.si for both single windows and full screen.