GTK 4 Sink & Paintable

GTK 4 provides gtk::Video & gtk::Picture for rendering media such as videos. As the default gtk::Video widget doesn't offer the possibility to use a custom gst::Pipeline. The plugin provides a gst_video::VideoSink along with a gdk::Paintable that's capable of rendering the sink's frames.

The sink can generate GL Textures if the system is capable of it, but it needs to be compiled with either waylandegl, x11glx or x11egl cargo features. On Windows and macOS this is enabled by default.

Additionally, the sink can render DMABufs directly on Linux if GTK 4.14 or newer is used. For this the dmabuf feature needs to be enabled.

Depending on the GTK version that is used and should be supported as minimum, new features or more efficient processing can be opted in with the gtk_v4_10, gtk_v4_12 and gtk_v4_14 features. The minimum GTK version required by the sink is GTK 4.4 on Linux without GL support, and 4.6 on Windows and macOS, and on Linux with GL support.

The sink will provides a simple test window when launched via gst-launch-1.0 or gst-play-1.0 or if the environment variable GST_GTK4_WINDOW=1 is set. Setting GST_GTK4_WINDOW_FULLSCREEN=1 will make the window launch in fullscreen mode.

Flatpak Integration

To build and include the plugin in a Flatpak manifest, you can add the following snippet to your json manifest:

{
    "sdk-extensions": [
        "org.freedesktop.Sdk.Extension.rust-stable"
    ],
    "build-options": {
        "append-path": "/usr/lib/sdk/rust-stable/bin",
    },
    "modules": [
        {
            "name": "gst-plugins-rs",
            "buildsystem": "simple",
            "sources": [
                {
                    "type": "archive",
                    "url": "https://crates.io/api/v1/crates/gst-plugin-gtk4/0.12.5/download",
                    "dest-filename": "gst-plugin-gtk4-0.12.5.tar.gz",
                    "sha256": "56e483cb1452f056ae94ccd5f63bdec697e04c87b30d89eb30c3f934042e1022"
                },
                "gst-plugin-gtk4-sources.json"
            ],
            "build-options": {
                "env": {
                    "CARGO_HOME": "$FLATPAK_BUILDER_BUILDDIR/cargo"
                }
            },
            "build-commands": [
                "cargo cinstall --offline --release --features=waylandegl,x11glx,x11egl,dmabuf --library-type=cdylib --prefix=/app"
            ]
        }
    ]
}

To generate the additional file gst-plugin-gtk4-sources.json which will contain links to all the Cargo dependencies for the plugin to avoid making network requests while building, you need to use the flatpak-cargo-generator tool from flatpak-builder-tools:

wget https://crates.io/api/v1/crates/gst-plugin-gtk4/0.12.5/download
tar -xf download
sha256sum download # update the sha256 in the Flatpak manifest
cd gst-plugin-gtk4-0.12.5/
/path/to/flatpak-cargo-generator Cargo.lock -o gst-plugin-gtk4-sources.json