Add LADSPA based transmitted audio shaping

It's now possible to apply LADSPA plugin audio processing to the
transmitted audio. Plugins are set up using the LADSPA_PLUGINS
configuration variable.

src/doc/man/svxlink.conf.5

@@ -1,4 +1,4 @@
-.TH SVXLINK.CONF 5 "AUGUST 2024" Linux "File Formats"
+.TH SVXLINK.CONF 5 "SEPTEMBER 2024" Linux "File Formats"
 .
 .SH NAME
 .
@@ -2502,6 +2502,35 @@ The TONE_SIGLEV_LEVEL configuration variable is used to set the tone level.
 It is a value in the 1-100 range which indicate the output level in percent
 of the maximum possible level. The default is 10.
 .TP
+.B LADSPA_PLUGINS
+Used to set up one or more LADSPA plugins to process the transmitted audio.
+The processing chain is applied right at the top of the transmitter audio
+processing and will only affect how the audio sounds. Any digital signal
+processing done on the audio after that, like DTMF, CTCSS etc, is unaffected.
+
+LADSPA is a framework for sharing pluggable audio components and there are
+numerous plugins to choose from. Each plugin has a name ("label") and zero or
+more configuration parameters ("control input ports"). To find out which
+plugins are installed on your system, use the "listplugins" command. If you
+are missing some plugin it may be available to install using your package
+system (rpm/yum/dnf, deb/apt etc). To find out more information about a
+plugin, use the "analyseplugin" command (e.g. analyseplugin filter hpf). Learn
+more about the LADSPA framework in their official documentation.
+
+In SvxLink only plugins that have exactly one audio input and one audio
+output can be used, so all stereo plugins are excluded for example.  The same
+thing is valid for input-only or output-only plugins.
+
+The analyseplugin utility will, among other things, list the ports. All ports
+that are typed as "input, control" can be used to configure the plugin. Valid
+range and a default value may also be listed. The format for the
+LADSPA_PLUGINS configuration variable in SvxLink is
+"label1:port1:port2:...:portN,label2:port1:port2:...:portN,...". Note that
+only control input ports are counted here so when applying the parameters any
+intermingled ports of other types are skipped.
+
+Example: LADSPA_PLUGINS=hpf:1000,tap_dynamics_m:4:500:15:15:13
+.TP
 .B MASTER_GAIN
 This configuration variable can be used to fine tune or increase the audio
 gain for all transmitted sound if it's not possible to do using the normal

src/svxlink/ChangeLog

@@ -31,6 +31,9 @@
   ACCEPT_CALLSIGN and REJECT_CALLSIGN configuration variables. That is done
   for both AUTH_KEY connections and certificate connections.
 
+* It's now possible to apply LADSPA plugin audio processing to the transmitted
+  audio. Plugins are set up using the LADSPA_PLUGINS configuration variable.
+
 
 
  1.8.0 -- 25 Feb 2024

src/svxlink/svxlink/svxlink.conf.in

@@ -310,6 +310,7 @@ PREEMPHASIS=0
 DTMF_TONE_LENGTH=100
 DTMF_TONE_SPACING=50
 DTMF_DIGIT_PWR=-15
+#LADSPA_PLUGINS=hpf:1000
 #MASTER_GAIN=0.0
 #OB_AFSK_ENABLE=0
 #OB_AFSK_VOICE_GAIN=-6

src/svxlink/trx/LocalTx.cpp

@@ -8,7 +8,7 @@ This file contains a class that implements a local transmitter.
 
 \verbatim
 SvxLink - A Multi Purpose Voice Services System for Ham Radio Use
-Copyright (C) 2003-2023 Tobias Blomberg / SM0SVX
+Copyright (C) 2003-2024 Tobias Blomberg / SM0SVX
 
 This program is free software; you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
@@ -75,6 +75,9 @@ Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 #include <HdlcFramer.h>
 #include <AfskModulator.h>
 #include <AsyncAudioFsf.h>
+#ifdef LADSPA_VERSION
+#include <AsyncAudioLADSPAPlugin.h>
+#endif
 
 
 /****************************************************************************
@@ -457,7 +460,61 @@ bool LocalTx::initialize(void)
   prev_src->registerSink(comp, true);
   prev_src = comp;
   */
-
+
+#ifdef LADSPA_VERSION
+  std::vector<std::string> ladspa_plugin_cfg;
+  if (cfg.getValue(name(), "LADSPA_PLUGINS", ladspa_plugin_cfg))
+  {
+    for (const auto& pcfg : ladspa_plugin_cfg)
+    {
+      std::istringstream is(pcfg);
+      std::string label;
+      std::getline(is, label, ':');
+      //std::cout << "### pcfg=" << pcfg << "  label=" << label << std::endl;
+      auto plug = new Async::AudioLADSPAPlugin(label);
+      if (!plug->initialize())
+      {
+        std::cerr << "*** ERROR: Could not instantiate LADSPA plugin "
+                     "instance with label '" << label << "' "
+                  << "specified in configuration variable "
+                  << name() << "/LADSPA_PLUGINS." << std::endl;
+        return false;
+      }
+      unsigned long portno = 0;
+      LADSPA_Data val;
+      while (is >> val)
+      {
+        while ((portno < plug->portCount()) &&
+               !(plug->portIsControl(portno) && plug->portIsInput(portno)))
+        {
+          ++portno;
+        }
+        if (portno >= plug->portCount())
+        {
+          std::cerr << "*** ERROR: Too many parameters specified for LADSPA "
+                       "plugin \"" << plug->label()
+                    << "\" specified in configuration variable "
+                    << name() << "/LADSPA_PLUGINS." << std::endl;
+          return false;
+        }
+        plug->setControl(portno++, val);
+        char colon = 0;
+        if ((is >> colon) && (colon != ':'))
+        {
+          std::cerr << "*** ERROR: Illegal format for " << name()
+                    << "/LADSPA_PLUGINS configuration variable" << std::endl;
+          return false;
+        }
+      }
+
+      plug->print(name() + ": ");
+
+      prev_src->registerSink(plug, true);
+      prev_src = plug;
+    }
+  }
+#endif
+
     // If preemphasis is enabled, create the preemphasis filter
   if (cfg.getValue(name(), "PREEMPHASIS", value) && (atoi(value.c_str()) != 0))
   {

src/versions

@@ -11,7 +11,7 @@ LIBECHOLIB=1.3.4
 LIBASYNC=1.7.99.4
 
 # SvxLink versions
-SVXLINK=1.8.99.4
+SVXLINK=1.8.99.5
 MODULE_HELP=1.0.0
 MODULE_PARROT=1.1.1
 MODULE_ECHO_LINK=1.6.0