GStreamer Base Plug-ins is a well-groomed and well-maintained
collection of GStreamer plug-ins and elements, spanning the
range of possible types of elements one would want to write
for GStreamer. It also contains helper libraries and base
classes useful for writing elements. A wide range of video
and audio decoders, encoders, and filters are included.

This build requires both liboil and gstreamer. Both slackbuilds
are available at slackbuilds.org.