Merge branch 'sm0svx:master' into audiofilter

src/doc/man/svxlink.conf.5

@@ -1656,6 +1656,15 @@ The destination is specified as ip-address:port.
 
 Example: RAW_AUDIO_UDP_DEST=127.0.0.1:10000
 .TP
+.B AUDIO_FILTER
+Define an audio filter here to improve the frequency response caused by
+unfavorable hardware in the audio path from discriminator to the soundcard
+input. A lot of audio filters are available (Butterworth, Chebyshev, Lowpass,
+Highpass, ...). Look into the src/async/audio/fidlib.c for more information.
+
+Example: AUDIO_FILTER=HsBq1/0.01/-18/3500
+
+
 .B OB_AFSK_ENABLE
 Set to 1 to enable reception of metadata like signal level measurements, DTMF
 digits and tone detections via out-of-band (OB) AFSK. The out-of-band AFSK is
@@ -2381,6 +2390,14 @@ It is possible to specify the same PTY for multiple functions (e.g. squelch,
 ptt etc) in both TX and RX configurations. This may be good if there is one
 script handling all functions.
 .
+.TP
+.B AUDIO_FILTER
+Define an audio filter here to improve the frequency response caused by
+unfavorable hardware in the audio path from discriminator to the soundcard
+input. A lot of audio filters are available (Butterworth, Chebyshev, Lowpass,
+Highpass, ...). Look into the src/async/audio/fidlib.c for more information.
+
+Example: AUDIO_FILTER=HsBq1/0.01/-18/3500
 .SS Networked Transmitter Section
 .
 A networked transmitter section is used to specify the configuration for a

src/svxlink/trx/LocalRxBase.cpp

@@ -529,6 +529,15 @@ bool LocalRxBase::initialize(void)
   prev_src->registerSink(voiceband_filter, true);
   prev_src = voiceband_filter;
 
+  string filterdesc;
+  if (cfg().getValue(name(), "AUDIO_FILTER", filterdesc))
+  {
+    cout << "+++ Init Audiofilter=" << filterdesc << endl;
+    AudioFilter *additional_audiofilter = new AudioFilter(filterdesc);
+    prev_src->registerSink(additional_audiofilter, true);
+    prev_src = additional_audiofilter;
+  }
+
     // Create an audio splitter to distribute the voiceband audio to all
     // other consumers
   AudioSplitter *voiceband_splitter = new AudioSplitter;

src/svxlink/trx/LocalTx.cpp

@@ -472,7 +472,27 @@ bool LocalTx::initialize(void)
     prev_src->registerSink(preemph, true);
     prev_src = preemph;
   }
-
+  
+  string filterdesc;
+  if (cfg.getValue(name(), "AUDIO_FILTER", filterdesc))
+  {
+    cout << "+++ Init Audiofilter=" << filterdesc << endl;
+    AudioFilter *additional_audiofilter = new AudioFilter(filterdesc);
+    prev_src->registerSink(additional_audiofilter, true);
+    prev_src = additional_audiofilter;
+  }
+  
+  /*
+  AudioCompressor *limit = new AudioCompressor;
+  limit->setThreshold(-1);
+  limit->setRatio(0.1);
+  limit->setAttack(2);
+  limit->setDecay(20);
+  limit->setOutputGain(1);
+  prev_src->registerSink(limit, true);
+  prev_src = limit;
+  */
+  
     // Add a limiter to smoothly limit the audio before hard clipping it
   double limiter_thresh = DEFAULT_LIMITER_THRESH;
   cfg.getValue(name(), "LIMITER_THRESH", limiter_thresh);