Last month as part of the GTK 4.14 release, GTK gained support for directly importing DMABufs on Wayland. Among other things, this allows to pass decoded video frames from hardware decoders to GTK, and then under certain circumstances allows GTK to directly forward the DMABuf to the Wayland compositor. And under even more special circumstances, this can then be directly passed to the GPU driver. Matthias wrote some blog posts about the details.
In short, this reduces CPU usage and power consumption considerably when using a suitable hardware decoder and running GTK on Wayland. A suitable hardware decoder in this case is one provided by e.g. Intel or (newer) AMD GPUs via VA but unfortunately not NVIDIA because they simply don't support DMABufs.
I've added support for this to the GStreamer GTK4 video sink,
gtk4paintablesink that exists as part of the GStreamer Rust plugins.
Previously it was only possible to pass RGB system memory (i.e. after
downloading from the GPU in case of hardware decoders) or GL textures (with
all kinds of complications) from GStreamer to GTK4.
In general the GTK4 sink now offers the most complete GStreamer / UI toolkit integration, even more than the QML5/6 sinks, and it is used widely by various GNOME applications.
