Multiple transmission channels warning when adding more than one channel

sdrbase/device/devicesinkapi.cpp

@@ -72,6 +72,11 @@ void DeviceSinkAPI::removeThreadedSource(ThreadedBasebandSampleSource* source)
     m_deviceSinkEngine->removeThreadedSource(source);
 }
 
+uint32_t DeviceSinkAPI::getNumberOfSources()
+{
+    return m_deviceSinkEngine->getNumberOfSources();
+}
+
 void DeviceSinkAPI::setSink(DeviceSampleSink* sink)
 {
     m_deviceSinkEngine->setSink(sink);

sdrbase/device/devicesinkapi.h

@@ -47,6 +47,7 @@ public:
     void removeSource(BasebandSampleSource* sink);                 //!< Remove a baseband sample source from device engine
     void addThreadedSource(ThreadedBasebandSampleSource* sink);    //!< Add a baseband sample source that will run on its own thread to device engine
     void removeThreadedSource(ThreadedBasebandSampleSource* sink); //!< Remove a baseband sample source that runs on its own thread from device engine
+    uint32_t getNumberOfSources();
     void setSink(DeviceSampleSink* sink);                          //!< Set device engine sample sink type
     bool initGeneration();                                         //!< Initialize device engine generation sequence
     bool startGeneration();                                        //!< Start device engine generation sequence

sdrbase/dsp/dspdevicesinkengine.h

@@ -72,6 +72,8 @@ public:
 	void addThreadedSource(ThreadedBasebandSampleSource* source); //!< Add a baseband sample source that will run on its own thread
 	void removeThreadedSource(ThreadedBasebandSampleSource* source); //!< Remove a baseband sample source that runs on its own thread
 
+	uint32_t getNumberOfSources() const { return m_basebandSampleSources.size() + m_threadedBasebandSampleSources.size(); }
+
 	void addSpectrumSink(BasebandSampleSink* spectrumSink);    //!< Add a spectrum vis baseband sample sink
 	void removeSpectrumSink(BasebandSampleSink* spectrumSink); //!< Add a spectrum vis baseband sample sink
 

sdrbase/mainwindow.cpp

@@ -829,6 +829,12 @@ void MainWindow::on_channel_addClicked(bool checked)
         }
         else if (deviceUI->m_deviceSinkEngine) // sink device => Tx channels
         {
+            uint32_t nbSources = deviceUI->m_deviceSinkAPI->getNumberOfSources();
+
+            if (nbSources > 0) {
+                QMessageBox::information(this, tr("Message"), tr("%1 channel(s) already in use. Multiple transmission channels is experimental. You may experience performance problems").arg(nbSources));
+            }
+
             m_pluginManager->createTxChannelInstance(deviceUI->m_samplingDeviceControl->getChannelSelector()->currentIndex(), deviceUI->m_deviceSinkAPI);
         }
     }