Support for background streams.

src/engines/enginebase.cpp

@@ -32,6 +32,7 @@ Engine::Base::Base()
     fadeout_enabled_(true),
     fadeout_duration_(2000),
     crossfade_enabled_(true),
+    next_background_stream_id_(0),
     about_to_end_emitted_(false)
 {
 }
@@ -73,3 +74,7 @@ void Engine::Base::EmitAboutToEnd() {
   about_to_end_emitted_ = true;
   emit TrackAboutToEnd();
 }
+
+int Engine::Base::AddBackgroundStream(const QUrl& url) {
+  return -1;
+}

src/engines/enginebase.h

@@ -51,6 +51,9 @@ class Base : public QObject, boost::noncopyable {
   virtual void Unpause() = 0;
   virtual void Seek( uint ms ) = 0;
 
+  virtual int AddBackgroundStream(const QUrl& url);
+  virtual void StopBackgroundStream(int id) {}
+
   virtual State state() const = 0;
   virtual uint position() const = 0;
   virtual uint length() const { return 0; }
@@ -60,6 +63,7 @@ class Base : public QObject, boost::noncopyable {
   bool Play(const QUrl &u, TrackChangeType c) { return Load(u, c) && Play(); }
   void SetVolume( uint value );
 
+
   // Simple accessors
   inline uint volume() const { return volume_; }
   virtual const Scope &scope() { return scope_; }
@@ -105,6 +109,7 @@ class Base : public QObject, boost::noncopyable {
   int fadeout_duration_;
   bool crossfade_enabled_;
   bool autocrossfade_enabled_;
+  int next_background_stream_id_;
 
  private:
   bool about_to_end_emitted_;

src/engines/gstengine.cpp

@@ -739,3 +739,32 @@ void GstEngine::RemoveBufferConsumer(BufferConsumer *consumer) {
   if (current_pipeline_)
     current_pipeline_->RemoveBufferConsumer(consumer);
 }
+
+int GstEngine::AddBackgroundStream(const QUrl& url) {
+  shared_ptr<GstEnginePipeline> pipeline = CreatePipeline(url);
+  if (!pipeline) {
+    return -1;
+  }
+  // We don't want to get metadata messages or end notifications.
+  disconnect(pipeline.get(), SIGNAL(MetadataFound(Engine::SimpleMetaBundle)), this, 0);
+  disconnect(pipeline.get(), SIGNAL(EndOfStreamReached(bool)), this, 0);
+  connect(pipeline.get(), SIGNAL(EndOfStreamReached(bool)), SLOT(BackgroundStreamFinished()));
+  if (!pipeline->SetState(GST_STATE_PLAYING)) {
+    qWarning() << "Could not set thread to PLAYING.";
+    pipeline.reset();
+    return -1;
+  }
+  pipeline->SetNextUrl(url);
+  int stream_id = next_background_stream_id_++;
+  background_streams_[stream_id] = pipeline;
+  return stream_id;
+}
+
+void GstEngine::StopBackgroundStream(int id) {
+  background_streams_.remove(id);  // Removes last shared_ptr reference.
+}
+
+void GstEngine::BackgroundStreamFinished() {
+  GstEnginePipeline* pipeline = qobject_cast<GstEnginePipeline*>(sender());
+  pipeline->SetNextUrl(pipeline->url());
+}

src/engines/gstengine.h

@@ -25,10 +25,11 @@
 #include "enginebase.h"
 #include "bufferconsumer.h"
 
-#include <QString>
-#include <QTimerEvent>
+#include <QHash>
 #include <QList>
+#include <QString>
 #include <QStringList>
+#include <QTimerEvent>
 
 #include <gst/gst.h>
 #include <boost/shared_ptr.hpp>
@@ -65,6 +66,9 @@ class GstEngine : public Engine::Base, public BufferConsumer {
 
   bool CanDecode(const QUrl& url);
 
+  int AddBackgroundStream(const QUrl& url);
+  void StopBackgroundStream(int id);
+
   uint position() const;
   uint length() const;
   Engine::State state() const;
@@ -111,6 +115,7 @@ class GstEngine : public Engine::Base, public BufferConsumer {
   void AddBufferToScope(GstBuffer* buf, GstEnginePipeline* pipeline);
   void FadeoutFinished();
   void SeekNow();
+  void BackgroundStreamFinished();
 
  private:
   // Callbacks
@@ -168,6 +173,8 @@ class GstEngine : public Engine::Base, public BufferConsumer {
   uint seek_pos_;
 
   int timer_id_;
+
+  QHash<int, boost::shared_ptr<GstEnginePipeline> > background_streams_;
 };