Show multi core / thread CPU usage when rendering
Submitted by Jeff F.T.
When rendering, I love to watch my CPU burn. Rather, I like to have a visual confirmation that it is being used to its full potential.
- Users will stop complaining that Pitivi is slow at rendering when they can visually see that their encoder choice doesn't use all the CPU cores (bug https://gitlab.freedesktop.org/gstreamer/gst-plugins-base/issues/59), or that it actually does use all the CPU cores ("hey, that looks like an expensive operation!")
- If the render hangs, the CPU usage will drop to zero... a clearer indication that something went wrong.
Imported from https://bugzilla.gnome.org/show_bug.cgi?id=681548