updated vision to dismiss buffered frames

compLib/Vision.py

@@ -1,4 +1,7 @@
 import os
+import queue
+from queue import Queue
+
 import cv2
 import logging
 import threading
@@ -40,6 +43,31 @@ class __Streaming:
     grab frames -> do your own processing -> publish frame -> view on http server
     """
 
+    class __NoBufferVideoCapture:
+        def __init__(self, cam):
+            self.cap = cv2.VideoCapture(cam)
+            self.cap.set(3, 640)
+            self.cap.set(4, 480)
+            self.q = queue.Queue(maxsize=5)
+            t = threading.Thread(target=self._reader)
+            t.daemon = True
+            t.start()
+
+        def _reader(self):
+            while True:
+                ret, frame = self.cap.read()
+                if not ret:
+                    break
+                if not self.q.empty():
+                    try:
+                        self.q.get_nowait()
+                    except queue.Empty:
+                        pass
+                self.q.put(frame)
+
+        def read(self):
+            return self.q.get()
+
     def __init__(self):
         """
         Create instance of __Streaming class
@@ -49,7 +77,10 @@ class __Streaming:
         """
         Logging.get_logger().info("capturing rtmp stream is disabled in this version")
         #self.__camera_stream = cv2.VideoCapture(RTMP_SERVER)
-        self.__camera_stream = cv2.VideoCapture(0)
+        #self.__camera_stream = cv2.VideoCapture(0)
+        #self.__camera_stream.set(3, 640)
+        #self.__camera_stream.set(4, 480)
+        self.__camera_stream = self.__NoBufferVideoCapture(0)
         self.__newest_frame = None
         self.__lock = threading.Lock()
         Logging.get_logger().info("Initialized vision")
@@ -60,7 +91,8 @@ class __Streaming:
 
         :return: An opencv frame
         """
-        ret, img16 = self.__camera_stream.read()
+        #ret, img16 = self.__camera_stream.read()
+        img16 = self.__camera_stream.read()
         return img16
 
     def publish_frame(self, image):