Saving every nth packet from a UDP stream

Question

I am parsing embedded KLV data in an MPEG-TS video stream sent to a UDP port from a UAV to use in a real time map. I am getting 25 packets per second (tied to the video frame rate) at the moment and can save all of this data but I want to only save the data once a second. Every 40ms is too much. I have attempted using threading to run 2 functions. One to get the data and write to a global variable and one to read that variable every second and print/save.

#setup code (UDP socket etc)

#global variable for KLV metadata
metadata = {}

#Function to parse KLV data from UDP Stream using klvdata module
def getData():
    while True:
        data, address = sock.recvfrom(2048)
        for packet in klvdata.StreamParser(data):
            global metadata
            metadata=packet.MetadataList()
           
           
#Prints selected keys at 1 sec intervals. Add more keys as required           
def printData():
     while True:
        global metadata
        time.sleep(1)
        
        long = round(float(metadata[14][3]),6)
        print(f"Sensor Longitude: {long}")
        
        lat = round(float(metadata[13][3]),6)
        print(f"Sensor Latitude: {lat}")



if __name__ == '__main__':
    t1 = Thread(target=getData)
    t1.start()
            
    t2 = Thread(target=printData)
    t2.start()

This has had mixed success. If the UDP stream is not running I get a key error as the dict is empty and the while loop in the printData func is infinite regardless of new data or not. I understand both of errors and why they happen. What I am wondering is if there is a better way to do this than the path I'm on now.

Thanks

Answer 1

This code works so far but I will test more.

#global variable for KLV metadata
metadata = None

#Function to parse KLV data from UDP Stream using klvdata module
def getData():
    global metadata
    while True:
        data, address = sock.recvfrom(2048)
        for packet in klvdata.StreamParser(data):
            metadata=packet.MetadataList()
           
           
           
#Prints selected keys at 1 sec intervals. Add more keys as required           
def printData():
    global metadata
    while True:
        time.sleep(1)
        if metadata is not None:
            long = round(float(metadata[14][3]),6)
            print(f"Sensor Longitude: {long}")
        
            lat = round(float(metadata[13][3]),6)
            print(f"Sensor Latitude: {lat}")

            metadata = None