This is GStreamer, a framework for streaming media.
This builds gstreamer-1.x, which can be installed alongside
the stock gstreamer package included with Slackware.
DO NOT replace the Slackware-provide gstreamer package with
this gstreamer1 package from here!

You'll probably want gst1-plugins-base, gst1-plugins-good,
and gst1-plugins-ugly for the best user experience.