should now reset the camera after stopped on Linux,Windows.

src/playback_thread.cpp

@@ -40,7 +40,13 @@ bool Playback::setVideoCamera(int device, int res, cv::VideoWriter wr, bool reco
     mode = MODE_CAMERA;
     mutex.lock();
     if(capture.isOpened()) {
-        
+#if defined(__linux__) || defined(_WIN32)
+        capture.open(device);
+        if(!capture.isOpened()) {
+            mutex.unlock();
+            return false;
+        }
+#endif
     } else {
         capture.open(device);
         if(!capture.isOpened()) {

src/playback_thread.h

@@ -30,6 +30,7 @@ private:
     std::vector<std::pair<int, int>> current;
     bool isPaused, isStep;
     VideoMode mode;
+    int device_num;
 public:
     Playback(QObject *parent = 0);
     ~Playback();