streamlined viewable-based lengths

app/project/item/footage/footage.cpp

@@ -57,6 +57,12 @@ void Footage::Retranslate()
   SetInputName(kFilenameInput, tr("Filename"));
 }
 
+QVector<QString> Footage::inputs_for_output(const QString &output) const
+{
+  Q_UNUSED(output)
+  return {kFilenameInput};
+}
+
 bool Footage::LoadCustom(QXmlStreamReader *reader, XMLNodeData &xml_node_data, uint version, const QAtomicInt* cancelled)
 {
   if (reader->name() == QStringLiteral("timestamp")) {

app/project/item/footage/footage.h

@@ -76,6 +76,8 @@ public:
 
   virtual void Retranslate() override;
 
+  virtual QVector<QString> inputs_for_output(const QString &output) const override;
+
   /**
    * @brief Reset Footage state ready for running through Probe() again
    *