Fadeout in gstreamer engine

src/engines/gstengine.cpp

@@ -36,6 +36,7 @@
 #include <QSettings>
 #include <QtDebug>
 #include <QCoreApplication>
+#include <QTimeLine>
 
 #include <gst/gst.h>
 #include <iostream>
@@ -100,6 +101,8 @@ void GstEngine::ReloadSettings() {
 
   sink_ = s.value("sink", kAutoSink).toString();
   device_ = s.value("device").toString();
+  fadeout_enabled_ = s.value("FadeoutEnabled", true).toBool();
+  fadeout_duration_ = s.value("FadeoutDuration", 2000).toInt();
 }
 
 
@@ -307,6 +310,9 @@ bool GstEngine::play( uint offset ) {
     return false;
   }
 
+  // Stop any active fadeout
+  fadeout_pipeline_.reset();
+
   // If "Resume playback on start" is enabled, we must seek to the last position
   if (offset) seek(offset);
 
@@ -320,10 +326,27 @@ bool GstEngine::play( uint offset ) {
 void GstEngine::stop() {
   m_url = QUrl(); // To ensure we return Empty from state()
 
+  if (fadeout_enabled_) {
+    fadeout_pipeline_ = current_pipeline_;
+    disconnect(fadeout_pipeline_.get(), 0, 0, 0);
+    ClearScopeQ();
+
+    QTimeLine* fadeout = new QTimeLine(fadeout_duration_, this);
+    connect(fadeout, SIGNAL(valueChanged(qreal)), fadeout_pipeline_.get(), SLOT(SetVolumeModifier(qreal)));
+    connect(fadeout, SIGNAL(finished()), SLOT(FadeoutFinished()));
+    connect(fadeout_pipeline_.get(), SIGNAL(destroyed()), fadeout, SLOT(deleteLater()));
+    fadeout->setDirection(QTimeLine::Backward);
+    fadeout->start();
+  }
+
   current_pipeline_.reset();
   emit stateChanged(Engine::Empty);
 }
 
+void GstEngine::FadeoutFinished() {
+  fadeout_pipeline_.reset();
+}
+
 void GstEngine::pause() {
   if (!current_pipeline_)
     return;

src/engines/gstengine.h

@@ -103,6 +103,7 @@ class GstEngine : public Engine::Base {
   void NewMetaData(const Engine::SimpleMetaBundle& bundle);
   void NewBuffer(GstBuffer* buf);
   void ClearScopeQ();
+  void FadeoutFinished();
 
  private:
   // Callbacks
@@ -127,7 +128,11 @@ class GstEngine : public Engine::Base {
   QString sink_;
   QString device_;
 
+  bool fadeout_enabled_;
+  int fadeout_duration_;
+
   boost::shared_ptr<GstEnginePipeline> current_pipeline_;
+  boost::shared_ptr<GstEnginePipeline> fadeout_pipeline_;
 
   //////////
   // scope

src/engines/gstenginepipeline.cpp

@@ -24,6 +24,8 @@ GstEnginePipeline::GstEnginePipeline()
   : QObject(NULL),
     valid_(false),
     sink_(GstEngine::kAutoSink),
+    volume_percent_(100),
+    volume_modifier_(1.0),
     pipeline_(NULL),
     src_(NULL),
     decodebin_(NULL),
@@ -293,5 +295,16 @@ void GstEnginePipeline::SetEqualizerParams(int preamp, const QList<int>& band_ga
 }
 
 void GstEnginePipeline::SetVolume(int percent) {
-  g_object_set(G_OBJECT(volume_), "volume", double(percent) * 0.01, NULL);
+  volume_percent_ = percent;
+  UpdateVolume();
+}
+
+void GstEnginePipeline::SetVolumeModifier(qreal mod) {
+  volume_modifier_ = mod;
+  UpdateVolume();
+}
+
+void GstEnginePipeline::UpdateVolume() {
+  float vol = double(volume_percent_) * 0.01 * volume_modifier_;
+  g_object_set(G_OBJECT(volume_), "volume", vol, NULL);
 }

src/engines/gstenginepipeline.h

@@ -53,6 +53,9 @@ class GstEnginePipeline : public QObject {
   qint64 length() const;
   GstState state() const;
 
+ public slots:
+  void SetVolumeModifier(qreal mod);
+
  signals:
   void EndOfStreamReached();
   void MetadataFound(const Engine::SimpleMetaBundle& bundle);
@@ -68,6 +71,8 @@ class GstEnginePipeline : public QObject {
   static void HandoffCallback(GstPad*, GstBuffer*, gpointer);
   static void EventCallback(GstPad*, GstEvent*, gpointer);
 
+  void UpdateVolume();
+
  private:
   static const int kGstStateTimeout = 10000000;
 
@@ -76,6 +81,9 @@ class GstEnginePipeline : public QObject {
   QString device_;
   bool forwards_buffers_;
 
+  int volume_percent_;
+  qreal volume_modifier_;
+
   GstElement* pipeline_;
 
   // Bins