src-test.py

import cv2

cap = cv2.VideoCapture(0)

fourcc = cv2.VideoWriter_fourcc(*'MJPG')
out = cv2.VideoWriter('appsrc ! videoconvert ! gtksink',
                      fourcc, 20.0, (640, 480))

while cap.isOpened():
    ret, frame = cap.read()
    if ret:
        # frame = cv2.flip(frame, 0)
        out.write(frame)

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

cap.release()
out.release()
cv2.destroyAllWindows()