added OIIO decoder

app/decoder/frame.h

@@ -27,6 +27,9 @@
 #include "common/rational.h"
 #include "render/pixelformat.h"
 
+class Frame;
+using FramePtr = std::shared_ptr<Frame>;
+
 /**
  * @brief Video frame data or audio sample data from a Decoder
  *
@@ -40,6 +43,8 @@ public:
   /// Normal constructor
   Frame();
 
+  static FramePtr Create();
+
   /**
    * @brief Get frame's width in pixels
    */
@@ -107,6 +112,4 @@ private:
 
 };
 
-using FramePtr = std::shared_ptr<Frame>;
-
 #endif // FRAME_H