diff --git a/src/playback_thread.cpp b/src/playback_thread.cpp
index 0bbcfad..fdeb504 100644
--- a/src/playback_thread.cpp
+++ b/src/playback_thread.cpp
@@ -45,9 +45,7 @@ void Playback::setOptions(bool n, int c) {
 }
 
 void Playback::setDisplayed(bool shown) {
-    mutex_shown.lock();
     video_shown = shown;
-    mutex_shown.unlock();
 }
 
 void Playback::run() {
@@ -86,12 +84,7 @@ void Playback::run() {
             writer.write(frame);
         }
         mutex.unlock();
-        bool shown_var;
-        mutex_shown.lock();
-        shown_var = video_shown;
-        mutex_shown.unlock();
-        
-        if(shown_var == true) {
+        if(video_shown == true) {
             if(frame.channels()==3) {
                 cv::cvtColor(frame, rgb_frame, CV_BGR2RGB);
                 img = QImage((const unsigned char*)(rgb_frame.data), rgb_frame.cols, rgb_frame.rows, QImage::Format_RGB888);
diff --git a/src/playback_thread.h b/src/playback_thread.h
index 8cc2a63..14c0251 100644
--- a/src/playback_thread.h
+++ b/src/playback_thread.h
@@ -9,7 +9,8 @@ class Playback : public QThread {
     Q_OBJECT
 private:
     std::atomic<bool> stop;
-    QMutex mutex,mutex_shown,mutex_add, mutex_start;
+    std::atomic<bool> video_shown;
+    QMutex mutex, mutex_shown, mutex_add;
     QWaitCondition condition;
     cv::Mat frame;
     int frame_rate;
@@ -20,7 +21,6 @@ private:
     QImage img;
     std::vector<std::pair<int, int>> current;
     bool isPaused, isStep;
-    bool video_shown;
 public:
     Playback(QObject *parent = 0);
     ~Playback();