Fix #962 and restore the frequency after playback

Try to parce center frequncy from a filename and apply it to waterfall.
If parcing the file fails, default to last sample rate/center frequency.
Restore current tuned frequency and offset after playback ends.
My be fixes #977 too.
Remove unused function
Update uiDockRxOpt widgets correctly

src/applications/gqrx/mainwindow.cpp

@@ -283,7 +283,7 @@ MainWindow::MainWindow(const QString& cfgfile, bool edit_conf, QWidget *parent)
     // I/Q playback
     connect(iq_tool, SIGNAL(startRecording(QString)), this, SLOT(startIqRecording(QString)));
     connect(iq_tool, SIGNAL(stopRecording()), this, SLOT(stopIqRecording()));
-    connect(iq_tool, SIGNAL(startPlayback(QString,float)), this, SLOT(startIqPlayback(QString,float)));
+    connect(iq_tool, SIGNAL(startPlayback(QString,float,qint64)), this, SLOT(startIqPlayback(QString,float,qint64)));
     connect(iq_tool, SIGNAL(stopPlayback()), this, SLOT(stopIqPlayback()));
     connect(iq_tool, SIGNAL(seek(qint64)), this,SLOT(seekIqFile(qint64)));
 
@@ -1588,7 +1588,7 @@ void MainWindow::stopIqRecording()
         ui->statusBar->showMessage(tr("I/Q data recoding stopped"), 5000);
 }
 
-void MainWindow::startIqPlayback(const QString& filename, float samprate)
+void MainWindow::startIqPlayback(const QString& filename, float samprate, qint64 center_freq)
 {
     if (ui->actionDSP->isChecked())
     {
@@ -1599,13 +1599,16 @@ void MainWindow::startIqPlayback(const QString& filename, float samprate)
     storeSession();
 
     auto sri = (int)samprate;
+    auto cf  = center_freq;
+    double current_offset = rx->get_filter_offset();
     QString escapedFilename = receiver::escape_filename(filename.toStdString()).c_str();
-    auto devstr = QString("file=%1,rate=%2,throttle=true,repeat=false")
-            .arg(escapedFilename).arg(sri);
+    auto devstr = QString("file=%1,rate=%2,freq=%3,throttle=true,repeat=false")
+            .arg(escapedFilename).arg(sri).arg(cf);
 
     qDebug() << __func__ << ":" << devstr;
 
     rx->set_input_device(devstr.toStdString());
+    updateHWFrequencyRange(false);
 
     // sample rate
     auto actual_rate = rx->set_input_rate(samprate);
@@ -1616,6 +1619,11 @@ void MainWindow::startIqPlayback(const QString& filename, float samprate)
     uiDockRxOpt->setFilterOffsetRange((qint64)(actual_rate));
     ui->plotter->setSampleRate(actual_rate);
     ui->plotter->setSpanFreq((quint32)actual_rate);
+    if (std::abs(current_offset) > actual_rate / 2)
+        on_plotter_newDemodFreq(center_freq, 0);
+    else
+        on_plotter_newDemodFreq(center_freq + current_offset, current_offset);
+
     remote->setBandwidth(actual_rate);
 
     // FIXME: would be nice with good/bad status
@@ -1659,6 +1667,14 @@ void MainWindow::stopIqPlayback()
 
     // restore frequency, gain, etc...
     uiDockInputCtl->readSettings(m_settings);
+    bool centerOK = false;
+    bool offsetOK = false;
+    qint64 oldCenter = m_settings->value("input/frequency", 0).toLongLong(&centerOK);
+    qint64 oldOffset = m_settings->value("receiver/offset", 0).toLongLong(&offsetOK);
+    if (centerOK && offsetOK)
+    {
+        on_plotter_newDemodFreq(oldCenter, oldOffset);
+    }
 
     if (ui->actionDSP->isChecked())
     {

src/applications/gqrx/mainwindow.h

@@ -180,7 +180,7 @@ private slots:
     /* I/Q playback and recording*/
     void startIqRecording(const QString& recdir);
     void stopIqRecording();
-    void startIqPlayback(const QString& filename, float samprate);
+    void startIqPlayback(const QString& filename, float samprate, qint64 center_freq);
     void stopIqPlayback();
     void seekIqFile(qint64 seek_pos);
 

src/qtgui/iq_tool.cpp

@@ -47,6 +47,7 @@ CIqTool::CIqTool(QWidget *parent) :
     bytes_per_sample = 8;
     sample_rate = 192000;
     rec_len = 0;
+    center_freq = 1e8;
 
     //ui->recDirEdit->setText(QDir::currentPath());
 
@@ -83,17 +84,18 @@ void CIqTool::setSampleRate(qint64 sr)
     }
 }
 
+
 /*! \brief Slot activated when the user selects a file. */
 void CIqTool::on_listWidget_currentTextChanged(const QString &currentText)
 {
 
     current_file = currentText;
     QFileInfo info(*recdir, current_file);
 
-    // Get duration of selected recording and update label
-    sample_rate = sampleRateFromFileName(currentText);
+    parseFileName(currentText);
     rec_len = (int)(info.size() / (sample_rate * bytes_per_sample));
 
+    // Get duration of selected recording and update label
     refreshTimeWidgets();
 
 }
@@ -126,7 +128,7 @@ void CIqTool::on_playButton_clicked(bool checked)
             ui->listWidget->setEnabled(false);
             ui->recButton->setEnabled(false);
             emit startPlayback(recdir->absoluteFilePath(current_file),
-                               (float)sample_rate);
+                               (float)sample_rate, center_freq);
         }
     }
     else
@@ -276,8 +278,6 @@ void CIqTool::on_recDirButton_clicked()
         ui->recDirEdit->setText(dir);
 }
 
-
-
 void CIqTool::timeoutFunction(void)
 {
     refreshDir();
@@ -355,22 +355,25 @@ void CIqTool::refreshTimeWidgets(void)
 }
 
 
-/*! \brief Extract sample rate from file name */
-qint64 CIqTool::sampleRateFromFileName(const QString &filename)
+/*! \brief Extract sample rate and offset frequency from file name */
+void CIqTool::parseFileName(const QString &filename)
 {
-    bool ok;
+    bool   sr_ok;
     qint64 sr;
+    bool   center_ok;
+    qint64 center;
 
     QStringList list = filename.split('_');
 
     if (list.size() < 5)
-        return sample_rate;
+        return;
 
     // gqrx_yymmdd_hhmmss_freq_samprate_fc.raw
-    sr = list.at(4).toLongLong(&ok);
+    sr = list.at(4).toLongLong(&sr_ok);
+    center = list.at(3).toLongLong(&center_ok);
 
-    if (ok)
-        return sr;
-    else
-        return sample_rate;  // return current rate
+    if (sr_ok)
+        sample_rate = sr;
+    if (center_ok)
+        center_freq = center;
 }

src/qtgui/iq_tool.h

@@ -64,7 +64,7 @@ class CIqTool : public QDialog
 signals:
     void startRecording(const QString recdir);
     void stopRecording();
-    void startPlayback(const QString filename, float samprate);
+    void startPlayback(const QString filename, float samprate, qint64 center_freq);
     void stopPlayback();
     void seek(qint64 seek_pos);
 
@@ -84,8 +84,7 @@ private slots:
 private:
     void refreshDir(void);
     void refreshTimeWidgets(void);
-    qint64 sampleRateFromFileName(const QString &filename);
-
+    void parseFileName(const QString &filename);
 
 private:
     Ui::CIqTool *ui;
@@ -100,6 +99,7 @@ private slots:
     bool    is_playing;
     int     bytes_per_sample;  /*!< Bytes per sample (fc = 4) */
     int     sample_rate;       /*!< Current sample rate. */
+    qint64  center_freq;       /*!< Center frequency. */
     int     rec_len;           /*!< Length of a recording in seconds */
 };