diff --git a/tools/sim_video_3d_cap_ext.py b/tools/sim_video_3d_cap_ext.py
index f9e78ef31076d93f625b8521d2bee761080af28c..7045f6ee8241d93f886c94941108b637908b255d 100644
--- a/tools/sim_video_3d_cap_ext.py
+++ b/tools/sim_video_3d_cap_ext.py
@@ -148,7 +148,7 @@ def video_write(video, l_frames, r_frames):
 
 def handle_3d_video(video, l_frames, r_frames):
     temp_frame_data = get_frame_temp_data()
-
+    cnt = 0
     if temp_frame_data is not None:
         cnt = len(temp_frame_data)
         for idx, (f, data) in enumerate(temp_frame_data):