Audio Input: added dataReady() signal to AudioFifo and use it to avoid CPU burn loop. Basic implementation

plugins/samplesource/audioinput/audioinputthread.cpp

@@ -46,6 +46,7 @@ AudioInputThread::~AudioInputThread()
 
 void AudioInputThread::startWork()
 {
+    connect(m_fifo, SIGNAL(dataReady()), this, SLOT(handleAudio()));
     m_startWaitMutex.lock();
 
     start();
@@ -60,6 +61,7 @@ void AudioInputThread::startWork()
 
 void AudioInputThread::stopWork()
 {
+    disconnect(m_fifo, SIGNAL(dataReady()), this, SLOT(handleAudio()));
     m_running = false;
     wait();
 }
@@ -71,19 +73,15 @@ void AudioInputThread::run()
 
     while (m_running)
     {
-        workIQ(m_convBufSamples);
+        std::this_thread::sleep_for(std::chrono::milliseconds(100));
     }
 
     qDebug("AudioInputThread::run: running loop stopped");
     m_running = false;
 }
 
-void AudioInputThread::workIQ(unsigned int samples)
+void AudioInputThread::workIQ(unsigned int nbRead)
 {
-    // Most of the time, this returns 0, because of the low sample rate.
-    // Could be more efficient in this case to have blocking wait?
-    uint32_t nbRead = m_fifo->read((unsigned char *) m_buf, samples);
-
     // Map between left and right audio channels and IQ channels
     if (m_iqMapping == AudioInputSettings::IQMapping::L)
     {
@@ -139,3 +137,12 @@ void AudioInputThread::workIQ(unsigned int samples)
 
     m_sampleFifo->write(m_convertBuffer.begin(), it);
 }
+
+void AudioInputThread::handleAudio()
+{
+    uint32_t nbRead;
+
+    while ((nbRead = m_fifo->read((unsigned char *) m_buf, m_convBufSamples)) != 0) {
+        workIQ(nbRead);
+    }
+}

plugins/samplesource/audioinput/audioinputthread.h

@@ -57,7 +57,10 @@ private:
     Decimators<qint32, qint16, SDR_RX_SAMP_SZ, 16, true> m_decimatorsIQ;
 
     void run();
-    void workIQ(unsigned int samples);
+    void workIQ(unsigned int nbRead);
+
+private slots:
+    void handleAudio();
 };
 
 #endif // INCLUDE_AUDIOINPUTTHREAD_H

sdrbase/audio/audiofifo.cpp

@@ -97,6 +97,7 @@ uint AudioFifo::write(const quint8* data, uint32_t numSamples)
 	}
 
 	m_mutex.unlock();
+	emit dataReady();
 	return total;
 }
 

sdrbase/audio/audiofifo.h

@@ -60,6 +60,9 @@ private:
 	uint32_t m_tail;
 
 	bool create(uint32_t numSamples);
+
+signals:
+	void dataReady();
 };
 
 #endif // INCLUDE_AUDIOFIFO_H