Ignore useless metadata from gstreamer, and metadata that comes while the next track is preloading

src/engines/gstengine.cpp

@@ -288,6 +288,10 @@ void GstEngine::StartPreloading(const QUrl& url) {
   if (!preload_pipeline_)
     return;
 
+  // We don't want to get metadata messages before the track starts playing -
+  // we reconnect this in GstEngine::Load
+  disconnect(preload_pipeline_.get(), SIGNAL(MetadataFound(Engine::SimpleMetaBundle)), this, 0);
+
   preloaded_url_ = url;
   preload_pipeline_->SetState(GST_STATE_PAUSED);
 }
@@ -302,6 +306,9 @@ bool GstEngine::Load(const QUrl& url, Engine::TrackChangeType change) {
   shared_ptr<GstEnginePipeline> pipeline;
   if (preload_pipeline_ && preloaded_url_ == url) {
     pipeline = preload_pipeline_;
+    connect(preload_pipeline_.get(),
+            SIGNAL(MetadataFound(Engine::SimpleMetaBundle)),
+            SLOT(NewMetaData(Engine::SimpleMetaBundle)));
   } else {
     pipeline = CreatePipeline(url);
     if (!pipeline)

src/player.cpp

@@ -308,8 +308,8 @@ void Player::EngineMetadataReceived(const Engine::SimpleMetaBundle& bundle) {
   if (item == NULL)
     return;
 
-  Song song;
-  song.InitFromSimpleMetaBundle(bundle);
+  Song song = item->Metadata();
+  song.MergeFromSimpleMetaBundle(bundle);
 
   // Ignore useless metadata
   if (song.title().isEmpty() && song.artist().isEmpty())

src/song.cpp

@@ -342,19 +342,19 @@ void Song::InitFromLastFM(const lastfm::Track& track) {
   d->length_ = track.duration();
 }
 
-void Song::InitFromSimpleMetaBundle(const Engine::SimpleMetaBundle &bundle) {
+void Song::MergeFromSimpleMetaBundle(const Engine::SimpleMetaBundle &bundle) {
   d->valid_ = true;
 
-  d->title_ = bundle.title;
-  d->artist_ = bundle.artist;
-  d->album_ = bundle.album;
-  d->comment_ = bundle.comment;
-  d->genre_ = bundle.genre;
-  d->bitrate_ = bundle.bitrate.toInt();
-  d->samplerate_ = bundle.samplerate.toInt();
-  d->length_ = bundle.length.toInt();
-  d->year_ = bundle.year.toInt();
-  d->track_ = bundle.tracknr.toInt();
+  if (!bundle.title.isEmpty()) d->title_ = bundle.title;
+  if (!bundle.artist.isEmpty()) d->artist_ = bundle.artist;
+  if (!bundle.album.isEmpty()) d->album_ = bundle.album;
+  if (!bundle.comment.isEmpty()) d->comment_ = bundle.comment;
+  if (!bundle.genre.isEmpty()) d->genre_ = bundle.genre;
+  if (!bundle.bitrate.isEmpty()) d->bitrate_ = bundle.bitrate.toInt();
+  if (!bundle.samplerate.isEmpty()) d->samplerate_ = bundle.samplerate.toInt();
+  if (!bundle.length.isEmpty()) d->length_ = bundle.length.toInt();
+  if (!bundle.year.isEmpty()) d->year_ = bundle.year.toInt();
+  if (!bundle.tracknr.isEmpty()) d->track_ = bundle.tracknr.toInt();
 }
 
 void Song::BindToQuery(QSqlQuery *query) const {

src/song.h

@@ -85,7 +85,7 @@ class Song {
   void InitFromFile(const QString& filename, int directory_id);
   void InitFromQuery(const QSqlQuery& query);
   void InitFromLastFM(const lastfm::Track& track);
-  void InitFromSimpleMetaBundle(const Engine::SimpleMetaBundle& bundle);
+  void MergeFromSimpleMetaBundle(const Engine::SimpleMetaBundle& bundle);
 
   // Save
   void BindToQuery(QSqlQuery* query) const;