Here is another rtsp cv2.VideoCapture onvif camera Nonmatching transport and -215:Assertion failed size and width > 0

edit

Change this:

cap.isOpened();  
    while(True):

to:

while cap.isOpened():

Thank you for response. The fact is I tested whether the VideoCapture was opened by asking

cap.isOpened()

and the result was False.
So the while loop never was invoked. That is the program stopped when VideoCapture was opened. Even if I put the loop of while cap.isOpened() the program would never get the frame data because the status of isOpened() is False thus the while loop is not invoked. Suppose isOpened() was True, the while(True) loop would be invoked and would be stopped by

 if cv2.waitKey(1) & 0xFF == ord('q'):
        break

But isOpened() = False, and if what you suggested to include isOpened() in the loop would not work because it is False.

Hence I could not retrieve a single Frame.

But thank you anyway,

Anthony of Sydney

U should attempt this: ret, frame = cap.read()

 if(ret): 
     cv2.imshow('frame',frame)
     if cv2.waitKey(1) & 0xFF == ord('q'):
          break
    cap.release()
    cv2.destroyAllWindows()

Try this:

import cv2
import numpy as np
import os
os.environ["OPENCV_FFMPEG_CAPTURE_OPTIONS"] = "rtsp_transport;udp"
cap = cv2.VideoCapture(url3,cv2.CAP_FFMPEG)
while cap.isOpened:
ret, frame = vcap.read()
    if ret == False:
        print("Frame is empty")
        break;
    else:
        cv2.imshow('VIDEO', frame)
        cv2.waitKey(1)

Thank you again, for your response. It does not work. The cv2.isOpened() is False ! However, your code with a USB camera, works. BUT your code does not work with an IP camera.

The original code below works with a USB camera. the cap.isOpened() prints True

The original code that I did WORKS for USB Camera

import numpy as np
import cv2, os
cap = cv2.VideoCapture(1)
cap.isOpened(); #prints True, and program. Program continues.
while(True):
    ret, frame = cap.read()
    #print(frame)
    cv2.imshow('frame',frame)
    if cv2.waitKey(1) & 0xFF == ord('q'):
        break
cap.release()
cv2.destroyAllWindows()

BUT same code does not work for a IP web camera

Thank you,

Anthony of Sydney

pc or laptop? I am using linux on raspberry pi 4. I am off for holiday.

Thank you for your reply. Please have a safe trip and come back safely. As per top of the page, I mentioned the specifications, which was a Laptop with Win 7. It is not RPi. It still does not answer the question why other applications on my PC via the router and even my smartphone via the router, other applications work, even VLC on Python IDLE and DOS/cmd. Even the "Media Player Classic" using the FMMPEG works. So why am I having a problem with cv2 and IPCamera, BUT NOT cv2 and usb camera.Please refer to my section in my question on what works. Thank you Anthony of Sydney

This is my friend using pc. Here is code:

import numpy as np
import cv2

#cap = cv2.VideoCapture(0)

cap = cv2.VideoCapture('rtsp://username:[email protected]:554/1') # Test

while(cap.isOpened()):
    ret, frame = cap.read()
    cap.set(3, 1280)
    cap.set(4, 720)
    try:
        cv2.imshow('Frame',frame)
    except:
        print('EOF')
        break

    k = cv2.waitKey(30) & 0xff
    if k == 27:
        break

cap.release()
cv2.destroyAllWindows()

HaHa. I see that u r using win7. Actually, OpenCV 3.4.x is obsoleted. The latest is OpenCV4.5.0