Can I use org.gnome.shell.screencast dbus for wayland support?

1

I’m the developer of Blue Recorder (based on green recorder) and I rewritten it in rust with support for Xorg and Wayland

I don’t know if snapd allow connect to org.gnome.shell.screencast which I use for recording wayland session

I built the snap and I connect the session using slot interface

  gnome-shell-screencast:
    bus: session
    interface: dbus
    name: org.gnome.shell.screencast

and it appear is not doing anything
and I got this error message

thread '<unnamed>' panicked at 'called `Result::unwrap()` on an `Err` value: MethodError("org.freedesktop.DBus.Error.AccessDenied", Some("An AppArmor policy prevents this sender from sending this message to this recipient; type=\"method_call\", sender=\":1.826\" (uid=1000 pid=1325666 comm=\"/snap/blue-recorder/x1/blue-recorder \" label=\"snap.blue-recorder.blue-recorder (enforce)\") interface=\"org.gnome.Shell.Screencast\" member=\"ScreencastArea\" error name=\"(unset)\" requested_reply=\"0\" destination=\"org.gnome.Shell.Screencast\" (uid=1000 pid=3159 comm=\"/usr/bin/gnome-shell \" label=\"unconfined\")"), Msg { type: Error, sender: "org.freedesktop.DBus", reply-serial: 2, body: Signature: [
        s (115),
] })', src/ffmpeg_interface.rs:320:18

thread 'main' panicked at 'called `Result::unwrap()` on an `Err` value: MethodError("org.freedesktop.DBus.Error.AccessDenied", Some("An AppArmor policy prevents this sender from sending this message to this recipient; type=\"method_call\", sender=\":1.828\" (uid=1000 pid=1325666 comm=\"/snap/blue-recorder/x1/blue-recorder \" label=\"snap.blue-recorder.blue-recorder (enforce)\") interface=\"org.gnome.Shell.Screencast\" member=\"StopScreencast\" error name=\"(unset)\" requested_reply=\"0\" destination=\"org.gnome.Shell.Screencast\" (uid=1000 pid=3159 comm=\"/usr/bin/gnome-shell \" label=\"unconfined\")"), Msg { type: Error, sender: "org.freedesktop.DBus", reply-serial: 2, body: Signature: [
        s (115),
] })', src/ffmpeg_interface.rs:191:54

source code: https://github.com/xlmnxp/blue-recorder

2

Drop the slot add add a screencast-legacy plug to your app declaration, see https://snapcraft.io/docs/the-screencast-legacy-interface. You will need to connect the plug manually, eg. snap connect <yoursnap>:screencast-legacy system:screencast-legacy.

I would recommend taking a look at the xdg-portal https://flatpak.github.io/xdg-desktop-portal/portal-docs.html#gdbus-org.freedesktop.impl.portal.ScreenCast too.

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3

Note that neither the org.gnome.Shell.Screencast or org.freedesktop.portal.ScreenCast interfaces are going to work on Ubuntu releases prior to 21.04 (hirsute). They rely on gnome-shell (and xdg-desktop-portal for the portal interface) being built with Pipewire support, which wasn’t the case for Ubuntu 20.10 and earlier.

If you are running Hirsute, or some other system with a Pipewire enabled gnome-shell+xdg-desktop-portal, then you should be able to use the portal interface simply by plugging the desktop interface.

4

I use Ubuntu 20.04 and it work fine as native not snap package https://youtu.be/OO3GWWUxORU

5

that fix the problem, thank you Maciej

6

Sorry, I hadn’t double-checked 20.04. The interface is definitely missing in Ubuntu 20.10, likely because they replaced the old implementation with one depending on Pipewire.

The xdg-desktop-portal interface is a wrapper for gnome-shell’s org.gnome.Mutter.ScreenCast D-Bus interface, which definitely isn’t available in the older Ubuntu releases.

7

Someone make issue about this problem
Will the issue fix in 21.04 because Wayland will be default?

8

It should, yes. The screencast interface was made dependent on Pipewire, and gnome-shell in 21.04 is built with Pipewire.

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