NFM modulator: try to improve audio input

plugins/channeltx/modnfm/nfmmodgui.cpp

@@ -279,6 +279,12 @@ void NFMModGUI::on_mic_toggled(bool checked)
     applySettings();
 }
 
+void NFMModGUI::on_compressor_toggled(bool checked)
+{
+    m_settings.m_compressorEnable = checked;
+    applySettings();
+}
+
 void NFMModGUI::on_feedbackEnable_toggled(bool checked)
 {
     m_settings.m_feedbackAudioEnable = checked;
@@ -581,6 +587,7 @@ void NFMModGUI::displaySettings()
     ui->dcsCode->setText(tr("%1").arg(m_settings.m_dcsCode, 3, 8, QLatin1Char('0')));
     ui->dcsPositive->setChecked(m_settings.m_dcsPositive);
     ui->bpf->setChecked(m_settings.m_bpfOn);
+    ui->compressor->setChecked(m_settings.m_compressorEnable);
 
     ui->channelMute->setChecked(m_settings.m_channelMute);
     ui->playLoop->setChecked(m_settings.m_playLoop);
@@ -729,6 +736,7 @@ void NFMModGUI::makeUIConnections()
     QObject::connect(ui->tone, &ButtonSwitch::toggled, this, &NFMModGUI::on_tone_toggled);
     QObject::connect(ui->morseKeyer, &ButtonSwitch::toggled, this, &NFMModGUI::on_morseKeyer_toggled);
     QObject::connect(ui->mic, &ButtonSwitch::toggled, this, &NFMModGUI::on_mic_toggled);
+    QObject::connect(ui->compressor, &ButtonSwitch::toggled, this, &NFMModGUI::on_compressor_toggled);
     QObject::connect(ui->play, &ButtonSwitch::toggled, this, &NFMModGUI::on_play_toggled);
     QObject::connect(ui->playLoop, &ButtonSwitch::toggled, this, &NFMModGUI::on_playLoop_toggled);
     QObject::connect(ui->navTimeSlider, &QSlider::valueChanged, this, &NFMModGUI::on_navTimeSlider_valueChanged);

plugins/channeltx/modnfm/nfmmodgui.h

@@ -122,6 +122,7 @@ private slots:
     void on_tone_toggled(bool checked);
     void on_morseKeyer_toggled(bool checked);
     void on_mic_toggled(bool checked);
+    void on_compressor_toggled(bool checked);
     void on_play_toggled(bool checked);
 
     void on_playLoop_toggled(bool checked);

plugins/channeltx/modnfm/nfmmodgui.ui

@@ -589,6 +589,16 @@
         </property>
        </widget>
       </item>
+      <item>
+       <widget class="ButtonSwitch" name="compressor">
+        <property name="toolTip">
+         <string>Audio input compressor on/off</string>
+        </property>
+        <property name="text">
+         <string>CMP</string>
+        </property>
+       </widget>
+      </item>
       <item>
        <widget class="Line" name="line_3">
         <property name="orientation">

plugins/channeltx/modnfm/nfmmodsettings.cpp

@@ -75,6 +75,7 @@ void NFMModSettings::resetToDefaults()
     m_feedbackAudioDeviceName = AudioDeviceManager::m_defaultDeviceName;
     m_feedbackVolumeFactor = 0.5f;
     m_feedbackAudioEnable = false;
+    m_compressorEnable = false;
     m_streamIndex = 0;
     m_useReverseAPI = false;
     m_reverseAPIAddress = "127.0.0.1";
@@ -135,6 +136,7 @@ QByteArray NFMModSettings::serialize() const
     s.writeBool(30, m_hidden);
     s.writeBool(31, m_preEmphasisOn);
     s.writeBool(32, m_bpfOn);
+    s.writeBool(33, m_compressorEnable);
 
     return s.final();
 }
@@ -224,6 +226,7 @@ bool NFMModSettings::deserialize(const QByteArray& data)
         d.readBool(30, &m_hidden, false);
         d.readBool(31, &m_preEmphasisOn, true);
         d.readBool(32, &m_bpfOn, true);
+        d.readBool(33, &m_compressorEnable, false);
 
         return true;
     }

plugins/channeltx/modnfm/nfmmodsettings.h

@@ -63,6 +63,7 @@ struct NFMModSettings
     QString m_feedbackAudioDeviceName; //!< This is the audio device you send the audio samples to for audio feedback
     float m_feedbackVolumeFactor;
     bool m_feedbackAudioEnable;
+    bool m_compressorEnable;
     int m_streamIndex;
     bool m_useReverseAPI;
     QString m_reverseAPIAddress;

plugins/channeltx/modnfm/nfmmodsource.cpp

@@ -55,6 +55,16 @@ NFMModSource::NFMModSource() :
 
 	m_magsq = 0.0;
 
+    m_audioCompressor.initSimple(
+        m_audioSampleRate,
+        -8,    // pregain (dB)
+        -20,   // threshold (dB)
+        20,    // knee (dB)
+        15,    // ratio (dB)
+        0.003, // attack (s)
+        0.25   // release (s)
+    );
+
     applySettings(m_settings, true);
     applyChannelSettings(m_channelSampleRate, m_channelFrequencyOffset, true);
 }
@@ -242,7 +252,16 @@ void NFMModSource::pullAF(Real& sample)
     case NFMModSettings::NFMModInputAudio:
         if (m_audioBufferFill < m_audioBuffer.size())
         {
-            sample = ((m_audioBuffer[m_audioBufferFill].l + m_audioBuffer[m_audioBufferFill].r) / 65536.0f) * m_settings.m_volumeFactor;
+            if (m_settings.m_compressorEnable)
+            {
+                sample = ((m_audioBuffer[m_audioBufferFill].l + m_audioBuffer[m_audioBufferFill].r) / 3276.8f);
+                sample = clamp<float>(m_audioCompressor.compress(sample), -1.0f, 1.0f) * m_settings.m_volumeFactor * 3.0f;
+            }
+            else
+            {
+                sample = ((m_audioBuffer[m_audioBufferFill].l + m_audioBuffer[m_audioBufferFill].r) / 3276.8f) * m_settings.m_volumeFactor;
+            }
+
             m_audioBufferFill++;
         }
         else
@@ -365,6 +384,8 @@ void NFMModSource::applyAudioSampleRate(int sampleRate)
     m_cwKeyer.setSampleRate(sampleRate);
     m_cwKeyer.reset();
     m_preemphasisFilter.configure(m_preemphasis*sampleRate);
+    m_audioCompressor.m_rate = sampleRate;
+    m_audioCompressor.initState();
     m_audioSampleRate = sampleRate;
     applyFeedbackAudioSampleRate(m_feedbackAudioSampleRate);
 

plugins/channeltx/modnfm/nfmmodsource.h

@@ -34,6 +34,7 @@
 #include "util/movingaverage.h"
 #include "dsp/cwkeyer.h"
 #include "audio/audiofifo.h"
+#include "audio/audiocompressorsnd.h"
 
 #include "nfmmodsettings.h"
 #include "nfmmoddcs.h"
@@ -124,6 +125,8 @@ private:
     std::ifstream *m_ifstream;
     CWKeyer m_cwKeyer;
 
+    AudioCompressorSnd m_audioCompressor;
+
     QMutex m_mutex;
 
     static const int m_levelNbSamples;

plugins/channeltx/modnfm/readme.md

@@ -122,7 +122,7 @@ You should aim at keeping the peak value below 100% using the volume control
 
 <h3>10: Input source control</h3>
 
-![Modulator input source control GUI](../../../doc/img/ModControls.png)
+![Modulator input source control GUI](../../../doc/img/NFMMod_plugin_input.png)
 
 <h4>10.1: Tone input select</h4>
 
@@ -142,6 +142,10 @@ Left click to switch to the audio input. You must switch it off to make other in
 
 Right click to select audio input device. See [audio management documentation](../../../sdrgui/audio.md) for details.
 
+<h4>10.5: Audio input compression</h4>
+
+Toggles the compressor for the audio input.
+
 <h3>11: Audio feedback</h3>
 
 Activate or de-activate the input source audio feedback