[LAD] RFC: Default discovery paths for LADSPA, LRDF, LV2 and DSSI (and more?)

[Stefano D'Angelo]

Hello

LADSPA, LV2 and DSSI specifications do not reccomend default discovery
paths where hosts may look for plugins, which IMO is bad for the end
user because:

* end users shouldn't be asked to know about path environment
variables by reading documentation in header files or looking for it
on the web;
* when their environment path variables are not set, some hosts choose
to scan some hard-coded directories, but this changes among hosts and
gets a lot worse on non UNIX-like operating systems (read Windows) -
for example some might look inside some subdirectory of the current
user's home, others might only look in /usr/lib/<api>, etc.

Hereby I propose some default paths which could be used, in the hope
that API authors lurking around here might want to recommend them and
host authors might want to use them:

LADSPA
  Unix-like OSes with FHS/Unix-like filesystem layout:
/usr/lib/ladspa, /usr/local/lib/ladspa, ~/.ladspa
  Windows: %PROGRAMFILES%\LADSPA, %APPDATA%\LADSPA
  Mac OS X: /Library/Audio/Plug-Ins/LADSPA, ~/Library/Audio/Plug-Ins/LADSPA

DSSI
  Unix-like OSes with FHS/Unix-like filesystem layout: /usr/lib/dssi,
/usr/local/lib/dssi, ~/.dssi
  Windows: %PROGRAMFILES%\DSSI, %APPDATA%\DSSI
  Mac OS X: /Library/Audio/Plug-Ins/DSSI, ~/Library/Audio/Plug-Ins/DSSI

LV2
  Unix-like OSes with FHS/Unix-like filesystem layout: /usr/lib/lv2,
/usr/local/lib/lv2, ~/.lv2
  Windows: %PROGRAMFILES%\LV2, %APPDATA%\LV2
  Mac OS X: /Library/Audio/Plug-Ins/LV2, ~/Library/Audio/Plug-Ins/LV2

Plus, we could do the same for LRDF data:
  Unix-like OSes with FHS/Unix-like filesystem layout:
/usr/share/ladspa/rdf, /usr/local/share/ladspa/rdf, ~/.ladspa/rdf
  Windows: %PROGRAMFILES%\LADSPA\rdf, %APPDATA%\LADSPA\rdf
  Mac OS X: /Library/Audio/Plug-Ins/LADSPA/rdf,
~/Library/Audio/Plug-Ins/LADSPA/rdf

What do you think about it?

Stefano