使用opencv videocapture函数打开jetson tx2板载摄像头

import sys
import argparse
import cv2
WINDOW_NAME = ‘CameraDemo’
def parse_args():
    # Parse input arguments
    desc = ‘Capture and display live camera video on Jetson TX2/TX1’
    parser = argparse.ArgumentParser(description=desc)
    parser.add_argument(‘–rtsp’, dest=’use_rtsp’,
                        help=’use IP CAM (remember to also set –uri)’,
                        action=’store_true’)
    parser.add_argument(‘–uri’, dest=’rtsp_uri’,
                        help=’RTSP URI, e.g. rtsp://192.168.1.64:554’,
                        default=None, type=str)
    parser.add_argument(‘–latency’, dest=’rtsp_latency’,
                        help=’latency in ms for RTSP [200]’,
                        default=200, type=int)
    parser.add_argument(‘–usb’, dest=’use_usb’,
                        help=’use USB webcam (remember to also set –vid)’,
                        action=’store_true’)
    parser.add_argument(‘–vid’, dest=’video_dev’,
                        help=’device # of USB webcam (/dev/video?) [1]’,
                        default=1, type=int)
    parser.add_argument(‘–width’, dest=’image_width’,
                        help=’image width [1920]’,
                        default=1920, type=int)
    parser.add_argument(‘–height’, dest=’image_height’,
                        help=’image height [1080]’,
                        default=1080, type=int)
    args = parser.parse_args()
    return args
def open_cam_rtsp(uri, width, height, latency):
    gst_str = (‘rtspsrc location={} latency={} ! ‘
               ‘rtph264depay ! h264parse ! omxh264dec ! ‘
               ‘nvvidconv ! ‘
               ‘video/x-raw, width=(int){}, height=(int){}, ‘
               ‘format=(string)BGRx ! ‘
               ‘videoconvert ! appsink’).format(uri, latency, width, height)
    return cv2.VideoCapture(gst_str, cv2.CAP_GSTREAMER)
    def open_cam_usb(dev, width, height):
    #     return cv2.VideoCapture(dev)
​    gst_str = (‘v4l2src device=/dev/video{} ! ‘
​               ‘video/x-raw, width=(int){}, height=(int){}, ‘
​               ‘format=(string)RGB ! ‘
​               ‘videoconvert ! appsink’).format(dev, width, height)
​    return cv2.VideoCapture(gst_str, cv2.CAP_GSTREAMER)
def open_cam_onboard(width, height):
    # On versions of L4T prior to 28.1, add ‘flip-method=2’ into gst_str
    gst_str = (‘nvcamerasrc ! ‘
               ‘video/x-raw(memory:NVMM), ‘
               ‘width=(int)2592, height=(int)1458, ‘
               ‘format=(string)I420, framerate=(fraction)30/1 ! ‘
               ‘nvvidconv ! ‘
               ‘video/x-raw, width=(int){}, height=(int){}, ‘
               ‘format=(string)BGRx ! ‘
               ‘videoconvert ! appsink’).format(width, height)
    print(gst_str)
    return cv2.VideoCapture(gst_str, cv2.CAP_GSTREAMER)
def open_window(width, height):
    cv2.namedWindow(WINDOW_NAME, cv2.WINDOW_NORMAL)
    cv2.resizeWindow(WINDOW_NAME, width, height)
    cv2.moveWindow(WINDOW_NAME, 0, 0)
    cv2.setWindowTitle(WINDOW_NAME, ‘Camera Demo for Jetson TX2/TX1’)
def read_cam(cap):
    show_help = True
    full_scrn = False
    help_text = ‘“Esc” to Quit, “H” for Help, “F” to Toggle Fullscreen’
    font = cv2.FONT_HERSHEY_PLAIN
    while True:
        if cv2.getWindowProperty(WINDOW_NAME, 0) < 0:
            # Check to see if the user has closed the window
            # If yes, terminate the program
​            break
​        _, img = cap.read() # grab the next image frame from camera
​        if show_help:
​            cv2.putText(img, help_text, (11, 20), font,
​                        1.0, (32, 32, 32), 4, cv2.LINE_AA)
​            cv2.putText(img, help_text, (10, 20), font,
​                        1.0, (240, 240, 240), 1, cv2.LINE_AA)
​        cv2.imshow(WINDOW_NAME, img)
​        key = cv2.waitKey(10)
​        if key == 27: # ESC key: quit program
​            break
​        elif key == ord(‘H’) or key == ord(‘h’): # toggle help message
​            show_help = not show_help
​        elif key == ord(‘F’) or key == ord(‘f’): # toggle fullscreen
​            full_scrn = not full_scrn
​            if full_scrn:
​                cv2.setWindowProperty(WINDOW_NAME, cv2.WND_PROP_FULLSCREEN,
​                                      cv2.WINDOW_FULLSCREEN)
​            else:
​                cv2.setWindowProperty(WINDOW_NAME, cv2.WND_PROP_FULLSCREEN,
​                                      cv2.WINDOW_NORMAL)
def main():
    args = parse_args()
    print(‘Called with args:’)
    print(args)
    print(‘OpenCV version: {}’.format(cv2.version))
    if args.use_rtsp:
        cap = open_cam_rtsp(args.rtsp_uri,
                            args.image_width,
                            args.image_height,
                            args.rtsp_latency)
    elif args.use_usb:
        cap = open_cam_usb(args.video_dev,
                           args.image_width,
                           args.image_height)
    else: # by default, use the Jetson onboard camera
        cap = open_cam_onboard(args.image_width,
                               args.image_height)
    if not cap.isOpened():
        sys.exit(‘Failed to open camera!’)
    open_window(args.image_width, args.image_height)
    read_cam(cap)
    cap.release()
    cv2.destroyAllWindows()
if name == ‘main‘:
    main()