slackbuilds/audio/jack-tools/README_VST.txt

jack-tools includes a utility called "rju-lxvst", which is a host
for Linux native VST plugins, and a utility called "lxvst-query"
which shows information on a native VST plugin (names and types of
parameters, e.g).

For licensing reasons, the VST headers (copyright Steinberg) cannot be
included in this SlackBuild. If you need VST support, you'll have to
register as a developer at https://www.steinberg.net/ and download the
VST developers' kit from there. You want version 2.x of the dev kit
(which may no longer be available; not sure if version 3.x works with
jack-tools). Once you've downloaded the files and extracted them, do
one of these things:

- Copy or symlink the files aeffect.h and aeffectx.h to the jack-tools
  directory (the one that contains jack-tools.SlackBuild).

- Or, export VST_HEADERS=<path> in the environment before running the
  SlackBuild. <path> is the directory that contains the files aeffect.h
  and aeffectx.h. Example: export VST_HEADERS=/usr/local/include/VST

If all went well, when you install the jack-tools package, the description
will say "This package was built WITH Steinberg Linux VST support". Just
to be on the safe side, do not redistribute the package. I'm not a lawyer
and I'm not sure whether Steinberg's license would allow redistribution
of a compiled binary using the VST headers.

If you did the above but the build fails to compile, you might be using
the wrong version of the VST headers. This would be a problem for upstream
(the actual author of jack-tools) to fix, so report it there.

The above only has to be done if you actually need rju-lxvst. If you
don't know whether you need it, read this FAQ:

Q: What is VST?
A: If you don't know, you don't need rju-lxvst, and you can stop
   reading now.

Q: What is a Linux native VST?
A: The vast majority of VST plugins (effects and instruments) are
   distributed as Windows executables (or DLLs). A Linux native VST is a
   Linux executable (or shared library), either distributed as source and
   compiled by the user, or (more often) as a precompiled binary. Linux
   native VST plugins are pretty rare, although they do exist.

   If you don't use or plan to use Linux native VSTs, you don't need
   rju-lxvst!

Q: What is rju-lxvst?
A: rju-lxvst is a standalone host for Linux native VSTs. What it does is
   run the VST plugin as a JACK client, so you can connect other JACK apps
   (such as DAWs or jack-rack) to it.

Q: I want to use Linux native VST plugins in my DAW, which has Linux
   native VST support. Do I need rju-lxvst?
A: No. If your DAW supports Linux native VST plugins, you don't need a
   separate host for them (such as rju-lxvst). It will act as its own host.

Q: I have this Windows VST plugin I want to use on Linux, do I need
   rju-lxvst?
A: No. rju-lxvst is only for Linux native VST plugins. For Windows VSTs,
   try wineasio. Ardour can also be built with Windows VST support,
   using WINE. Whatever solution you find for Windows VSTs on Linux
   will pretty much have to involve WINE somehow.

Q: I have a Linux native VST I want to use with my DAW, but my DAW
   doesn't have VST support. Can I use rju-lxvst for this?
A: Yes. This is the intended use for rju-lxvst.