GStreamer does not take pixel aspect ratio into account for overlay rectangles.
If we do so, we end up with subtitles that are displayed off-center.
Behave like any other GStreamer sink on this matter.
We do not support zero width/height (described in our caps). Set initial video
dimensions to 1x1. They are going to be updated on first buffer after video info is set.
This avoids running into https://gitlab.freedesktop.org/gstreamer/gstreamer/-/issues/1139
and makes sure we do not do any divisions by zero here either.
Add new GStreamer plugin with custom video sink for Clapper video player.
The main difference is that unlike the old one, this does not operate using `GtkGLArea`
anymore, but processes and displays `GdkTextures` directly through `GtkPicture` widget.
Also this one is installed like any other GStreamer plugin, thus can be used via
`gst-launch-1.0` binary or even by other GTK4 apps if they wish to integrate it.
In order to not depend on GL stuff at build time, this plugin uses seperate GModules
called "importers" in order to import different kind of memories into GdkTexture. This
allows expanding its capabilities further then we were able to do before.
