work on decoder classes

decoders/decoder.cpp

@@ -1,12 +1,29 @@
 #include "decoder.h"
 
-Decoder::Decoder() :
+Decoder::Decoder(QObject *parent) :
+  QObject(parent),
   open_(false)
 {
+}
 
+Decoder::Decoder(FootageStream *fs) :
+  open_(false),
+  stream_(fs)
+{
 }
 
 Decoder::~Decoder()
 {
+}
 
+FootageStream *Decoder::stream()
+{
+  return stream_;
+}
+
+void Decoder::set_stream(FootageStream *fs)
+{
+  Close();
+
+  stream_ = fs;
 }