building with JACK 2 by default?

[Ricardo Wurmus <rekado@elephly.net>]

Hi Guix,

the official recommendation of the JACK developers used to be to use
whatever JACK version you want as they are compatible anyway and can be
swapped out as needed.  This has now changed and JACK 2 is the only
variant that is under active development.  JACK 1 is in bugfix-only
mode.  See:

  https://github.com/jackaudio/jackaudio.github.com/wiki/Differences-between-jack1-and-jack2

The question is whether we should now build everything with JACK 2
instead of JACK 1.  People like me who still want to use JACK 1
(e.g. because of built-in ALSA MIDI support and support for more than
one soundcard) could simply set LD_LIBRARY_PATH to load the JACK 1
libraries.

We already need to use JACK 2 for some packages which simply won’t build
with JACK 1.  While it may be possible to patch them to accept JACK 1,
which provides almost exactly the same API, I think the more reasonable
approach would be to compromise on JACK 2 for everything.

The downside to building with JACK 2 by default is an increased package
closure due to the larger feature set of JACK 2 (e.g. DBus support).
The upside is that only one version of JACK will be used throughout the
system (we can no longer achieve this with JACK 1, see above) and that
Guix will default to using the recommended version of JACK.

What are your thoughts on this?

-- 
Ricardo