Support SHM format for PipeWire screencasts

[thepragmaticmero]

Kooha, a GTK4 based flatpak screen recorder, works on GNOME, works on sway. But doesn't work on niri. Journalctl for reference.

# journalctl --no-hostname -eb /usr/bin/niri | tail -n 11 | wl-copy
Jun 20 07:21:28 niri[13861]: 2024-06-20T12:21:28.985830Z DEBUG niri::dbus::mutter_screen_cast: record_monitor connector="DP-1" properties=RecordMonitorProperties { cursor_mode: Some(Embedded), _is_recording: None }
Jun 20 07:21:28 niri[13861]: 2024-06-20T12:21:28.987307Z DEBUG niri::dbus::mutter_screen_cast: start
Jun 20 07:21:28 niri[13861]: 2024-06-20T12:21:28.987352Z DEBUG niri::niri: StartCast session_id=3
Jun 20 07:21:28 niri[13861]: 2024-06-20T12:21:28.987403Z DEBUG niri::pw_utils: pw stream: state changed: Unconnected -> Connecting
Jun 20 07:21:28 niri[13861]: 2024-06-20T12:21:28.988927Z DEBUG niri::pw_utils: pw stream: state changed: Connecting -> Paused
Jun 20 07:21:28 niri[13861]: 2024-06-20T12:21:28.988943Z DEBUG niri::pw_utils: pw stream: sending signal with 68
Jun 20 07:21:29 niri[13861]: 2024-06-20T12:21:29.030720Z DEBUG niri::pw_utils: pw stream: state changed: Paused -> Error("no more input formats")
Jun 20 07:21:29 niri[13861]: 2024-06-20T12:21:29.030735Z  WARN niri::pw_utils: pw error id=2 seq=43 res=-32 no more input formats
Jun 20 07:21:29 niri[13861]: 2024-06-20T12:21:29.044509Z DEBUG niri::dbus::mutter_screen_cast: stop
Jun 20 07:21:29 niri[13861]: 2024-06-20T12:21:29.044652Z DEBUG niri::niri: StopCast session_id=3
Jun 20 07:21:29 niri[13861]: 2024-06-20T12:21:29.044809Z DEBUG niri::pw_utils: pw stream: state changed: Paused -> Unconnected

more info at:
SeaDve/Kooha#301
In a nutshell.... portals I suppose.

	OBS	Kooha
Sway	✔️	✔️
GNOME	✔️	✔️
Niri	✔️	❌

System Information

• niri version: 0.1.6

• Distro: Fedora

• GPU: Rx6600xt

• CPU: Ryzen 3 3100

[YaLTeR]

See my comment there; niri doesn't implement shm screen capture and Kooha can't deal with dmabufs.