Add support for LADSPA audio processing

LADSPA  is  a framework for sharing pluggable audio components and there
are numerous plugins to choose from. SvxLink now support using LADSPA
plugins to shape receiver audio.

src/CMakeLists.txt

@@ -295,6 +295,22 @@ add_definitions(${SIGC2_DEFINITIONS})
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${SIGC2_CXX_FLAGS}")
 set(LIBS ${LIBS} ${SIGC2_LIBRARIES})
 
+find_package(LADSPA)
+if(LADSPA_FOUND)
+  if(DEFINED LADSPA_VERSION_MAJOR)
+    include_directories(${LADSPA_INCLUDE_DIRS})
+    add_definitions(${LADSPA_DEFINITIONS})
+  else()
+    message(WARNING
+      "Found LADSPA but version could not be resolved. "
+      "Will proceed without LADSPA.")
+  endif()
+else(LADSPA_FOUND)
+  message("--   LADSPA is an optional dependency. The build will complete")
+  message("--   without it but support for loading LADSPA plugins will")
+  message("--   be unavailable.")
+endif(LADSPA_FOUND)
+
 # Find the chown utility
 include(FindCHOWN)
 

src/async/ChangeLog

@@ -67,6 +67,9 @@
 * Bugfix Async::HttpServerConnection: EOL handling failed with newer
   compilers.
 
+* New class Async::AudioLADSPAPlugin which enable the use of LADSPA plugins to
+  process audio.
+
 
 
  1.6.0 -- 01 Sep 2019