Easy way to measure how long it takes to decode frames using OpenCV's VideoCapture class

measure_decode_time_ms.py

import cv2
import time

def measureDecodeTimeMs(src):
  cap = cv2.VideoCapture(src)
  for i in range(10):
    a = time.time()
    ok, frame = cap.read()
    if not ok:
    	print("Error: Unable to read frame")
    	return
    b = time.time()
    print("Time: {}ms".format(1000*(b-a)))

measureDecodeTimeMs("videotestsrc ! appsink")
measureDecodeTimeMs("videotestsrc ! videoscale ! video/x-raw,width=1920,height=1080 ! appsink")