gstengine: Give pipelines unique names

Currently, most pipelines are named "pipeline". Use a type string in combination
with the stream id to give each pipeline a unique name.

src/engines/gstenginepipeline.cpp

@@ -51,7 +51,7 @@ const int GstEnginePipeline::kEqBandFrequencies[] = {
 GstElementDeleter* GstEnginePipeline::sElementDeleter = nullptr;
 
 GstEnginePipeline::GstEnginePipeline(GstEngine* engine)
-    : GstPipelineBase(),
+    : GstPipelineBase("audio"),
       engine_(engine),
       valid_(false),
       sink_(GstEngine::kAutoSink),
@@ -508,7 +508,7 @@ void GstEnginePipeline::MaybeLinkDecodeToAudio() {
 }
 
 bool GstEnginePipeline::InitFromString(const QString& pipeline) {
-  if (!Init("pipeline")) return false;
+  if (!Init()) return false;
 
   GstElement* new_bin =
       CreateDecodeBinFromString(pipeline.toLatin1().constData());
@@ -527,7 +527,7 @@ bool GstEnginePipeline::InitFromString(const QString& pipeline) {
 
 bool GstEnginePipeline::InitFromReq(const MediaPlaybackRequest& req,
                                     qint64 end_nanosec) {
-  if (!Init("pipeline")) return false;
+  if (!Init()) return false;
 
   current_ = req;
   QUrl url = current_.url_;

src/engines/gstpipelinebase.cpp

@@ -21,8 +21,8 @@
 
 std::atomic<int> GstPipelineBase::sId(1);
 
-GstPipelineBase::GstPipelineBase()
+GstPipelineBase::GstPipelineBase(const QString& type)
-    : QObject(nullptr), pipeline_(nullptr), id_(sId++) {}
+    : QObject(nullptr), pipeline_(nullptr), type_(type), id_(sId++) {}
 
 GstPipelineBase::~GstPipelineBase() {
   if (pipeline_) {
@@ -31,7 +31,8 @@ GstPipelineBase::~GstPipelineBase() {
   }
 }
 
-bool GstPipelineBase::Init(const QString& name) {
+bool GstPipelineBase::Init() {
+  QString name = QString("%1-pipeline-%2").arg(type_).arg(id_);
   pipeline_ = gst_pipeline_new(name.toUtf8().constData());
   return pipeline_ != nullptr;
 }

src/engines/gstpipelinebase.h

@@ -24,10 +24,10 @@
 
 class GstPipelineBase : public QObject {
  public:
-  GstPipelineBase();
+  GstPipelineBase(const QString& type);
   virtual ~GstPipelineBase();
 
-  virtual bool Init(const QString& name);
+  virtual bool Init();
 
   // Globally unique across all pipelines.
   int id() const { return id_; }
@@ -38,6 +38,8 @@ class GstPipelineBase : public QObject {
   GstElement* pipeline_;
 
  private:
+  const QString type_;
+
   // Using == to compare two pipelines is a bad idea, because new ones often
   // get created in the same address as old ones.  This ID will be unique for
   // each pipeline.

src/transcoder/transcoder.cpp

@@ -402,7 +402,7 @@ bool Transcoder::StartJob(const Job& job) {
   // Create the pipeline.
   // This should be a scoped_ptr, but scoped_ptr doesn't support custom
   // destructors.
-  if (!state->Init("pipeline")) return false;
+  if (!state->Init()) return false;
 
   // Create all the elements
   GstElement* src = CreateElement("filesrc", state->Pipeline());

src/transcoder/transcoder.h

@@ -88,7 +88,10 @@ class Transcoder : public QObject {
   class JobState : public GstPipelineBase {
    public:
     JobState(const Job& job, Transcoder* parent)
-        : job_(job), parent_(parent), convert_element_(nullptr) {}
+        : GstPipelineBase("transcode"),
+          job_(job),
+          parent_(parent),
+          convert_element_(nullptr) {}
 
     void PostFinished(bool success);
     void ReportError(GstMessage* msg);