use different signals when the audio invalidates vs the video

Both audio and video renderers were working off the same invalidation signal
(i.e. changing audio would also trigger a re-render of the video). This is
obviously suboptimal and now they are separate.

app/render/backend/audiorenderbackend.cpp

@@ -44,12 +44,17 @@ void AudioRenderBackend::InvalidateCache(const rational &start_range, const rati
   CacheNext();
 }
 
-void AudioRenderBackend::ViewerNodeChangedEvent(ViewerOutput *node)
+void AudioRenderBackend::ConnectViewer(ViewerOutput *node)
 {
-  if (node != nullptr) {
-    // FIXME: Hardcoded format
-    SetParameters(AudioRenderingParams(node->audio_params(), SAMPLE_FMT_FLT));
-  }
+  connect(node, SIGNAL(AudioChangedBetween(const rational&, const rational&)), this, SLOT(InvalidateCache(const rational&, const rational&)));
+
+  // FIXME: Hardcoded format
+  SetParameters(AudioRenderingParams(node->audio_params(), SAMPLE_FMT_FLT));
+}
+
+void AudioRenderBackend::DisconnectViewer(ViewerOutput *node)
+{
+  disconnect(node, SIGNAL(AudioChangedBetween(const rational&, const rational&)), this, SLOT(InvalidateCache(const rational&, const rational&)));
 }
 
 bool AudioRenderBackend::GenerateCacheIDInternal(QCryptographicHash &hash)

app/render/backend/audiorenderbackend.h

@@ -26,7 +26,9 @@ public slots:
   virtual void InvalidateCache(const rational &start_range, const rational &end_range) override;
 
 protected:
-  virtual void ViewerNodeChangedEvent(ViewerOutput* node) override;
+  virtual void ConnectViewer(ViewerOutput* node) override;
+
+  virtual void DisconnectViewer(ViewerOutput* node) override;
 
   /**
    * @brief Internal function for generating the cache ID

app/render/backend/renderbackend.cpp

@@ -72,7 +72,7 @@ const QString &RenderBackend::GetError() const
 void RenderBackend::SetViewerNode(ViewerOutput *viewer_node)
 {
   if (viewer_node_ != nullptr) {
-    disconnect(viewer_node_, SIGNAL(TextureChangedBetween(const rational&, const rational&)), this, SLOT(InvalidateCache(const rational&, const rational&)));
+    DisconnectViewer(viewer_node_);
 
     Decompile();
   }
@@ -80,10 +80,8 @@ void RenderBackend::SetViewerNode(ViewerOutput *viewer_node)
   viewer_node_ = viewer_node;
 
   if (viewer_node_ != nullptr) {
-    connect(viewer_node_, SIGNAL(TextureChangedBetween(const rational&, const rational&)), this, SLOT(InvalidateCache(const rational&, const rational&)));
+    ConnectViewer(viewer_node_);
   }
-
-  ViewerNodeChangedEvent(viewer_node_);
 }
 
 void RenderBackend::SetCacheName(const QString &s)
@@ -148,7 +146,12 @@ void RenderBackend::SetError(const QString &error)
   error_ = error;
 }
 
-void RenderBackend::ViewerNodeChangedEvent(ViewerOutput *node)
+void RenderBackend::ConnectViewer(ViewerOutput *node)
+{
+  Q_UNUSED(node)
+}
+
+void RenderBackend::DisconnectViewer(ViewerOutput *node)
 {
   Q_UNUSED(node)
 }

app/render/backend/renderbackend.h

@@ -56,7 +56,8 @@ protected:
 
   void SetError(const QString& error);
 
-  virtual void ViewerNodeChangedEvent(ViewerOutput* node);
+  virtual void ConnectViewer(ViewerOutput* node);
+  virtual void DisconnectViewer(ViewerOutput* node);
 
   /**
    * @brief Function called when there are frames in the queue to cache

app/render/backend/videorenderbackend.cpp

@@ -112,12 +112,17 @@ void VideoRenderBackend::CloseInternal()
   cache_frame_load_buffer_.clear();
 }
 
-void VideoRenderBackend::ViewerNodeChangedEvent(ViewerOutput *node)
+void VideoRenderBackend::ConnectViewer(ViewerOutput *node)
 {
-  if (node != nullptr) {
-    // FIXME: Hardcoded format, mode, and divider
-    SetParameters(VideoRenderingParams(node->video_params(), olive::PIX_FMT_RGBA16F, olive::kOffline, 2));
-  }
+  connect(node, SIGNAL(VideoChangedBetween(const rational&, const rational&)), this, SLOT(InvalidateCache(const rational&, const rational&)));
+
+  // FIXME: Hardcoded format, mode, and divider
+  SetParameters(VideoRenderingParams(node->video_params(), olive::PIX_FMT_RGBA16F, olive::kOffline, 2));
+}
+
+void VideoRenderBackend::DisconnectViewer(ViewerOutput *node)
+{
+  disconnect(node, SIGNAL(VideoChangedBetween(const rational&, const rational&)), this, SLOT(InvalidateCache(const rational&, const rational&)));
 }
 
 const VideoRenderingParams &VideoRenderBackend::params() const

app/render/backend/videorenderbackend.h

@@ -71,7 +71,9 @@ protected:
     QByteArray hash;
   };
 
-  virtual void ViewerNodeChangedEvent(ViewerOutput* node) override;
+  virtual void ConnectViewer(ViewerOutput* node) override;
+
+  virtual void DisconnectViewer(ViewerOutput* node) override;
 
   const char *GetCachedFrame(const rational& time);