Update issue 2137

Mono playback implemented; available in preferences

src/engines/gstengine.cpp

@@ -80,6 +80,7 @@ GstEngine::GstEngine(TaskManager* task_manager)
     rg_preamp_(0.0),
     rg_compression_(true),
     buffer_duration_nanosec_(1 * kNsecPerSec), // 1s
+    mono_playback_(false),
     seek_timer_(new QTimer(this)),
     timer_id_(-1),
     next_element_id_(0)
@@ -173,6 +174,8 @@ void GstEngine::ReloadSettings() {
   rg_compression_ = s.value("rgcompression", true).toBool();
 
   buffer_duration_nanosec_ = s.value("bufferduration", 4000).toLongLong() * kNsecPerMsec;
+
+  mono_playback_ = s.value("monoplayback", false).toBool();
 }
 
 
@@ -688,6 +691,7 @@ shared_ptr<GstEnginePipeline> GstEngine::CreatePipeline() {
   ret->set_output_device(sink_, device_);
   ret->set_replaygain(rg_enabled_, rg_mode_, rg_preamp_, rg_compression_);
   ret->set_buffer_duration_nanosec(buffer_duration_nanosec_);
+  ret->set_mono_playback(mono_playback_);
 
   ret->AddBufferConsumer(this);
   foreach (BufferConsumer* consumer, buffer_consumers_) {

src/engines/gstengine.h

@@ -189,6 +189,8 @@ class GstEngine : public Engine::Base, public BufferConsumer {
 
   qint64 buffer_duration_nanosec_;
 
+  bool mono_playback_;
+
   mutable bool can_decode_success_;
   mutable bool can_decode_last_;
 

src/engines/gstenginepipeline.cpp

@@ -62,6 +62,7 @@ GstEnginePipeline::GstEnginePipeline(GstEngine* engine)
     rg_compression_(true),
     buffer_duration_nanosec_(1 * kNsecPerSec),
     buffering_(false),
+    mono_playback_(false),
     end_offset_nanosec_(-1),
     next_beginning_offset_nanosec_(-1),
     next_end_offset_nanosec_(-1),
@@ -111,6 +112,10 @@ void GstEnginePipeline::set_buffer_duration_nanosec(qint64 buffer_duration_nanos
   buffer_duration_nanosec_ = buffer_duration_nanosec;
 }
 
+void GstEnginePipeline::set_mono_playback(bool enabled) {
+  mono_playback_ = enabled;
+}
+
 bool GstEnginePipeline::ReplaceDecodeBin(GstElement* new_bin) {
   if (!new_bin) return false;
 
@@ -328,6 +333,7 @@ bool GstEnginePipeline::Init() {
       NULL);
   GstCaps* caps32 = gst_caps_new_simple ("audio/x-raw-float",
       "width", G_TYPE_INT, 32,
+      !mono_playback_ ? NULL : "channels", G_TYPE_INT, 1,
       NULL);
 
   // Link the elements with special caps

src/engines/gstenginepipeline.h

@@ -52,6 +52,7 @@ class GstEnginePipeline : public QObject {
   void set_output_device(const QString& sink, const QString& device);
   void set_replaygain(bool enabled, int mode, float preamp, bool compression);
   void set_buffer_duration_nanosec(qint64 duration_nanosec);
+  void set_mono_playback(bool enabled);
 
   // Creates the pipeline, returns false on error
   bool InitFromUrl(const QUrl& url, qint64 end_nanosec);
@@ -197,6 +198,8 @@ class GstEnginePipeline : public QObject {
   quint64 buffer_duration_nanosec_;
   bool buffering_;
 
+  bool mono_playback_;
+
   // The URL that is currently playing, and the URL that is to be preloaded
   // when the current track is close to finishing.
   QUrl url_;