use IDs for multiple decoders

app/project/item/footage/footage.cpp

@@ -101,6 +101,16 @@ Item::Type Footage::type() const
   return kFootage;
 }
 
+const QString &Footage::decoder()
+{
+  return decoder_;
+}
+
+void Footage::set_decoder(const QString &id)
+{
+  decoder_ = id;
+}
+
 void Footage::ClearStreams()
 {
   if (streams_.empty()) {

app/project/item/footage/footage.h

@@ -185,6 +185,20 @@ public:
    */
   virtual Type type() const override;
 
+  /**
+   * @brief Get the Decoder ID set when this Footage was probed
+   *
+   * @return
+   *
+   * A decoder ID
+   */
+  const QString& decoder();
+
+  /**
+   * @brief Used by decoders when they Probe to attach itself to this Footage
+   */
+  void set_decoder(const QString& id);
+
 private:
   /**
    * @brief Internal function to delete all Stream children and empty the array
@@ -236,6 +250,11 @@ private:
    */
   Status status_;
 
+  /**
+   * @brief Internal attached decoder ID
+   */
+  QString decoder_;
+
 };
 
 using FootagePtr = std::shared_ptr<Footage>;