a #GList of #GstElementFactory to filter
a #GstCaps
a #GstPadDirection to filter on
whether to filter on caps subsets or not.
Return: a #GList of #GstElementFactory elements that match the given requisites. Use #gst_plugin_feature_list_free after usage.
Filter out all the elementfactories in @list that can handle @caps in the given direction.
If @subsetonly is %TRUE, then only the elements whose pads templates are a complete superset of @caps will be returned. Else any element whose pad templates caps can intersect with @caps will be returned.