implemented a footage viewer

Essentially a minor derivation of a viewer type that can automatically view
footage from the project (i.e. not in a sequence).

app/node/input/media/media.cpp

@@ -20,6 +20,8 @@
 
 #include "media.h"
 
+#include "common/timecodefunctions.h"
+
 MediaInput::MediaInput() :
   connected_footage_(nullptr)
 {
@@ -45,6 +47,20 @@ void MediaInput::Retranslate()
   footage_input_->set_name(tr("Footage"));
 }
 
+NodeValueTable MediaInput::Value(const NodeValueDatabase &value) const
+{
+  NodeValueTable table = value.Merge();
+
+  if (connected_footage_) {
+    rational media_duration = Timecode::timestamp_to_time(connected_footage_->duration(),
+                                                          connected_footage_->timebase());
+
+    table.Push(NodeInput::kRational, QVariant::fromValue(media_duration), "length");
+  }
+
+  return table;
+}
+
 void MediaInput::FootageChanged()
 {
   StreamPtr new_footage = footage_input_->get_standard_value().value<StreamPtr>();

app/node/input/media/media.h

@@ -38,6 +38,8 @@ public:
 
   virtual void Retranslate() override;
 
+  virtual NodeValueTable Value(const NodeValueDatabase& value) const override;
+
 protected:
   NodeInput* footage_input_;