Screen recording on Wayland

phw 2018-01-18 08:53:54 UTC #1

With Wayland being the default now in Ubuntu 17.10 my Snap of my small screen recording utility Peek became unusable for users installing it from the Ubuntu Store, expecting it to work out of the box.

Is there any work done on getting screen recording working from inside the Sandbox? I know Pipewire might become the goto solution in the future, but is there anything usable today?

For e.g. Flatpak I easily can expose the Gnome Shell DBus service org.gnome.Shell.Screencast, but one cannot open up the Snap sandbox in a similar way.

See also related discussion on https://github.com/phw/peek/issues/245

jdstrand 2018-01-18 13:10:03 UTC #2

Can you expand on this? Is the recording application supposed to bind to this DBus interface as a server or is this the DBus api your application would use to record? Either way, this sounds like it needs to be a new interface.

phw 2018-01-18 13:31:58 UTC #3

GNOME Shell provides this interface. The point is that in Flatpak it is easy to open up the sandbox for your app to allow access to this interface, whereas Snap does not allow this (*). So yes, Snap would need to provide some kind of interface to allow access to the screen. Hence my question whether there is already some work in progress or talk about such an interface.

(*) As far as I have understood that is mainly a difference in how Flatpak and Snap approach the sandboxing security: Both projects envision a system, where all apps are sandboxed and given access only in a secuire and controlled way to external resources. But while Flatpak tries to be usable right now and allows quite some flexibility for individual apps to poke holes into the sandbox, in the hope they can tighten this up later, Snap maintains a security first approach where only selected interfaces that are considered save enough now are allowed.

jdstrand 2018-01-18 15:51:16 UTC #4

I’ve added this interface to the roadmap.

I’d also like to be clear that snaps are meant to be usable right now too and the snap system also allows a lot of flexibility for applications to use different resources on the system, though what is exposed will sometimes be different from other sandboxing mechanisms where access to those resources may be automatic or based on user choice depending on the request. In this particular case, the only reason why the interface isn’t available today is because no one expressed a need for it until now.

jdstrand 2018-01-18 15:55:44 UTC #5

It wasn’t clear (to me) that Peek understands how to use org.gnome.Shell.Screencast. Can you comment? If it does we can use Peek as a test case when developing the interface.

phw 2018-01-18 16:16:23 UTC #6

Actually I am not sure org.gnome.Shell.Screencast is necesarily the right basis for an interface. I just use it in Peek because it is easily available and it was the only existing way to implement screencasting in Gnome on Wayland.

But AFAIK it is mainly an intermediary solution Gnome developers put into place to support screen recording in Wayland. To my knowledge they aim to move to a more standardized interface, which is suited for sandboxed applications and takes care of security, based on pipewire.

I am fine with every interface that allows screen recording and satisfies Peek’s requirements. But right now one is mostly out of luck doing this on Wayland with sandboxing technology.