What is the best way to convert recorded kinect rosbag into a video file? I am writing the video using OpenCV as following:

import rospy
import cv2
from sensor_msgs.msg import Image
from cv_bridge import CvBridge, CvBridgeError

class image_converter:
  def __init__(self):
    self.bridge = CvBridge()
    self.image_sub = rospy.Subscriber(self.kinect_topic_name, Image, self.callback)
    self.video_writer = cv2.VideoWriter(self.video_file_name,-1,1,(self.width, self.height))    

  def callback(self,data):
    try:
      cv_image = self.bridge.imgmsg_to_cv2(data, "bgr8")
    except CvBridgeError as e:
      print(e)

    cv2.imshow("Image window", cv_image)
    cv2.waitKey(3)
    self.video_writer.write(cv_image)

  def __del__(self):
    self.video_writer.release()

def main(args):
  ic = image_converter()
  rospy.init_node('save_video', anonymous=True)
  try:
    rospy.spin()
  except KeyboardInterrupt:
    print("Shutting down")
  cv2.destroyAllWindows()