Always on pipewire.

[Quackdoc]

It would be nice to have an always on pipewire output mode (much like what gamescope has) This would obviously have to be off by default for security reasons. However it would be really nice for testing stuff, Recording, remote desktop etc.

I currently have a usecase where pipewire is preferential to wlr capture, and if possible, avoiding portals would be best as it is added overhead and I would like to avoid as much as possible. (both for performance and squeezing out as much space as possible).

It could be possible for me to make use of ext-image-copy-capture for it, but it would be ideal for me to have a "pipewire only" mode.

[YaLTeR]

Do you mean an ability to record a virtual monitor? Or something else?

avoiding portals would be best as it is added overhead and I would like to avoid as much as possible. (both for performance and squeezing out as much space as possible).

Huh, what overhead?

[Quackdoc]

Do you mean an ability to record a virtual monitor? Or something else?

yeah kinda? I don't need it to be headless or anything specifically since I can probably use vkms if needed or buy a dummy plug, but I won't have any real display hardware in my example use case so having a headless "virtual monitor" would for sure work well. As for other potential use cases, it would be nice to simply output the screen to an always on pipewire node.

Huh, what overhead?

For my current project, I am primarily concerned with very low end SBCs. currently installing xdg portal gnome + xdg portal will bring in about 20-30Mib. They also take cpu time and ram usage to keep them in memory. I would like to minimize both hits as much as possible for my use case.

[YaLTeR]

Well idk how an always-on pipewire node works so I guess someone would have to figure it out

[Quackdoc]

it's more or less just creating a pipewire node and not having a client auto connect to it. This can be done using the dbus bindings directly for niri's mutter screencast scripting support. (though for some reason this isn't working for me with gstreamer for some reason, not super relevant but I did report the issue to pipewire here https://gitlab.freedesktop.org/pipewire/pipewire/-/issues/4711)

I was thinking it would be nice to have a config value that would run pipewire instance at boot. It's understandable if this isn't wanted since you already have the dbus interface and eventually the new capture protocol (or current one), I am just trying to pull as little stuff onto the device as possible. But having a seperate program to use the ext protocol won't be off the table.

#!/usr/bin/python3
import dbus
from gi.repository import GLib
from dbus.mainloop.glib import DBusGMainLoop

DBusGMainLoop(set_as_default=True)
loop = GLib.MainLoop()
bus = dbus.SessionBus()

screen_cast_iface = 'org.gnome.Mutter.ScreenCast'
screen_cast_session_iface = 'org.gnome.Mutter.ScreenCast.Session'
screen_cast_stream_iface = 'org.gnome.Mutter.ScreenCast.Session'

screen_cast = bus.get_object(screen_cast_iface,
                             '/org/gnome/Mutter/ScreenCast')

session_path = screen_cast.CreateSession([], dbus_interface=screen_cast_iface)
session = bus.get_object(screen_cast_iface, session_path)

stream_path = session.RecordMonitor(
    "DP-1", dbus.types.Dictionary({'cursor-mode': dbus.UInt32(1, variant_level=1)}),
    dbus_interface=screen_cast_session_iface)

stream = bus.get_object(screen_cast_iface, stream_path)

def terminate():
    session.Stop(dbus_interface=screen_cast_session_iface)
    loop.quit()

def on_pipewire_stream_added(node_id):
    print("added")
    print(node_id)

stream.connect_to_signal("PipeWireStreamAdded", on_pipewire_stream_added)

session.Start(dbus_interface=screen_cast_session_iface)

try:
    loop.run()
except KeyboardInterrupt:
    print("interrupted")
    terminate()