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I use this node and display the webcam in Rviz. But I want to change my camera to and usb camera, what I have to do?

import rospy
import numpy as np
import cv2
from sensor_msgs.msg import CompressedImage
from __init__ import ROSNode

class CameraPublisher(ROSNode):


def __init__(self):
    """OpenCV feature detectors with ros CompressedImage Topics in python.

    This example subscribes to a ros topic containing sensor_msgs 
    CompressedImage. It converts the CompressedImage into a numpy.ndarray, 
    then detects and marks features in that image. It finally displays 
    and publishes the new image - again as CompressedImage topic.
    """
    self.publisher = rospy.Publisher("/image_raw/compressed", CompressedImage, queue_size=4)
    self.msg = CompressedImage()

    rospy.loginfo('Setting camera level...')
    self.camera = cv2.VideoCapture(int(rospy.get_param('camera_port', 0)))

    self.takeImage(lightSettingSnaps=30)

def takeImage(self, lightSettingSnaps=0):
    for i in range(lightSettingSnaps):
        self.takeImage(lightSettingSnaps=0)
    return self.camera.read()[1]

def publishImage(self):
    image = self.takeImage()
    self.msg.header.stamp = rospy.Time.now()
    self.msg.format = "jpeg"
    self.msg.data = np.array(cv2.imencode('.jpg', image)[1]).tostring()
    # Publish new image
    self.publisher.publish(self.msg)

def main(self):
    r = rospy.Rate(rospy.get_param('imageRate', 30))
    idle = rospy.Rate(30)
    while not rospy.is_shutdown():
        self.publishImage()
        r.sleep()
        idle.sleep()

I tried to change the port 0 to 1 but it does not work