Samuel Onoja
baca852ee9
Render selected toplevels through a private portal-only capture protocol, preserve logical snapshot geometry, and renegotiate PipeWire video on window resizing. Bound outstanding snapshots and retry temporary contention; stop on source closure and session locking. Validation: portal unit tests (31), capture budget unit, private-bus portal contracts, and real nested/PipeWire isolation, workspace, resize, close and paused-lock tests pass. Independent review cleared. Monitor restore integration timed out on both this build and the unchanged previous compositor under the current nested host.
7.6 KiB
Screen sharing and recording
Ferese includes a ScreenCast portal backend, xdg-desktop-portal-ferese.
Applications use the standard desktop portal to request a display or window, then receive
video through PipeWire. A recorder or conferencing application handles encoding,
saving files, or sending video; those tasks do not run inside the compositor.
Record from the top bar
- Click the screen-recording icon in the top bar to open the display picker.
- Choose a monitor in the native picker and click Share.
- The icon changes to a stop square and shows elapsed time. Click it to stop.
The recorder finishes the video before sending a notification with its saved
path. Videos are saved as VP8 WebM files under
Videos/Ferese (using your configured XDG Videos folder). Audio is off.
The icon uses the same theme accent, hover effect, and corner radius as the
other bar controls.
Encoding runs in a separate native ferese-record process using GStreamer.
The shell remains responsive while a file is recorded or finalized. If saving
fails, an error appears in the notification center; an unfinished .webm.part file
may remain at the path shown in the error.
Start sharing
Use a Wayland screen-sharing or recording source in your application. Ferese opens a native source picker. Depending on what the application requests, choose from displays, windows, or both and press Share. Nothing is selected by default. Applications that request multiple sources can select up to eight. Display and window choices are grouped separately. Windows show their title and application. Window streams capture only the selected app's toplevel and subsurfaces, even when covered or on another workspace. Separate popups and compositor decorations are excluded. Resizing a shared window updates the video size without ending the session. Closing that window ends sharing. The picker uses your Ferese theme colors, font, and shell corner radius. Its background uses the same compositor material as popovers and authentication prompts: opaque in solid mode, or blurred and translucent using the shared Appearance → Shell opacity and blur settings. Text and icons remain opaque.
Other applications keep a screen sharing window with a Stop sharing button. Ferese’s built-in recorder uses the top-bar stop control instead, leaving your windows accessible after display selection. The command-line recorder keeps the sharing window when it is not launched by the shell. Press Stop sharing or close the sharing window to revoke an ordinary application’s session. Closing the requesting application, locking Ferese, disconnecting the selected display, or changing a monitor's capture size also ends sharing. By default, each request asks for consent. If an application requests saved permissions, the picker offers an Allow without asking switch, off by default. Permissions can last while the application runs or until revoked, as requested by the app. The standard portal frontend owns permission storage and revocation. A changed or missing display, different app, or changed cursor options asks again. Displays without a reliable EDID identity, including nested previews, always need fresh consent. Window selections also require fresh consent and cannot enable saved display permissions. Stopping a stream ends that stream; it does not erase a previously saved permission. Everything visible on a shared display, including notifications, is included.
Installation
The standard installer builds and installs the backend, its
D-Bus activation entry, and a Ferese-specific portal preference file. Install
pipewire, a PipeWire session manager such as wireplumber,
xdg-desktop-portal, and xdg-desktop-portal-gtk using your distribution's package
manager. The GTK backend supplies standard dialogs such as file selection. Ferese also
provides native Settings, Screenshot and Wallpaper services; see
desktop portals.
The built-in recorder also needs GStreamer’s PipeWire, base, and good plugins
(pipewiresrc, videoconvert, vp8enc, and webmmux). The installation guide
includes these packages.
Log into a new Ferese session after installation. The session launcher imports its Wayland display into the D-Bus activation environment. Nested previews leave the host activation environment alone.
Existing custom window rules can float the picker and sharing indicator:
window-rule app-id="dev.ferese.ScreenShare" floating=#true
The packaged example configuration already includes this rule. Existing user configuration is preserved during installation.
Current capabilities
- Monitor and isolated window capture, one PipeWire stream per source, up to 30 fps.
- Window streams keep working across workspace switches and renegotiate on resize.
- Hidden or embedded pointer, as requested by the application.
- Logical stream position and size, including fractional output scales.
- Wayland parent-window relationships for the consent picker.
- Bounded frame storage and reusable shared-memory buffers.
- Cancellation during selection, an explicit stop control, and process cleanup.
- ScreenCast backend version 4 with explicit opt-in saved display permissions.
Region selection and audio capture in Ferese’s recorder are not implemented yet. The top-bar recorder currently requests monitors. Other recording applications can handle audio separately. Video currently uses CPU copies through the compositor's shared-memory screencopy path, not DMA-BUF zero-copy. High-resolution or multiple-display recording can therefore use significant CPU and memory bandwidth. A paused stream checks capture availability once per second so locking also ends sessions without an active consumer.
Development checks
Build the backend after installing the native dependencies in the installation guide:
cargo build --release --locked -p xdg-desktop-portal-ferese
cargo test --locked -p xdg-desktop-portal-ferese
# Exercise real video encoding and playback (requires the plugins above):
cargo test --locked -p xdg-desktop-portal-ferese --bin ferese-record encoder_finishes_a_real_webm -- --ignored
The opt-in integration test opens a temporary nested compositor and uses a
private D-Bus session. It requires built Ferese and locker binaries, Python
GI/GStreamer with pipewiresrc, dbus-daemon, xdg-desktop-portal, and bwrap.
It checks capture delivery and timestamps, cancellation, frontend loss, and lock
revocation:
FERESE_TEST_PORTAL=1 \
FERESE_TEST_PORTAL_BINARY=target/release/xdg-desktop-portal-ferese \
python3 scripts/tests/test_portal_isolated.py
Add FERESE_TEST_PORTAL_CONSENT=1 to exercise the native picker and restricted
PipeWire connection. Select the temporary display and click Share when
prompted. Tests capture only the nested preview and leave host PAM policies and
D-Bus activation unchanged.
Troubleshooting
Confirm that XDG_CURRENT_DESKTOP contains Ferese, PipeWire is running, and
FERESE_ENABLE_SCREENCOPY was not set to 0 before launching the session.
The installed preference is
/usr/share/xdg-desktop-portal/ferese-portals.conf. A user override under
~/.config/xdg-desktop-portal/ can take precedence. Its ScreenCast preference
should name ferese:
[preferred]
default=gtk;
org.freedesktop.impl.portal.ScreenCast=ferese;
If capture dimensions change, stop and start sharing again. Ferese ends the old session instead of feeding incorrectly sized frames to the application.
For development, xdg-desktop-portal-ferese --sources lists displays available
on the current WAYLAND_DISPLAY. This command does not start a stream.