This gstreamer source and sink was recently added to gst-plugins-bad by upstream. Here's a simple ebuild for that plugin, using the gst-plugins-bad eclass, which is tested and working. Thanks!
Created attachment 143556 [details] ebuild for gst-plugins-jack, part of -bad.
hmm, gst-plugins-ladspa-0.10.5 is in portage already?
jack and LADSPA are not the same. jack is a system for interprocess audio streaming; LADSPA is a plugin architecture for applying effects to an audio stream. A number of jack clients support running sound through LADSPA plugins (jack-rack, for instance, does exclusively that), which makes them appear closely coupled, but the two systems are in fact completely independent of each other.
This has reached the tree with bug 324711 for some months now. *** This bug has been marked as a duplicate of bug 324711 ***