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Last active October 11, 2023 08:20
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Capture and display video from either IP CAM, USB webcam, or the Tegra X2/X1 onboard camera.
# --------------------------------------------------------
# Camera sample code for Tegra X2/X1
# This program could capture and display video from
# IP CAM, USB webcam, or the Tegra onboard camera.
# Refer to the following blog post for how to set up
# and run the code:
# Written by JK Jung <>
# --------------------------------------------------------
import sys
import argparse
import subprocess
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)',
parser.add_argument('--uri', dest='rtsp_uri',
help='RTSP URI, e.g. rtsp://',
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)',
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):
# We want to set width and height here, otherwise we could just do:
# return cv2.VideoCapture(dev)
gst_str = ('v4l2src device=/dev/video{} ! '
'video/x-raw, width=(int){}, height=(int){} ! '
'videoconvert ! appsink').format(dev, width, height)
return cv2.VideoCapture(gst_str, cv2.CAP_GSTREAMER)
def open_cam_onboard(width, height):
gst_elements = str(subprocess.check_output('gst-inspect-1.0'))
if 'nvcamerasrc' in gst_elements:
# 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)
elif 'nvarguscamerasrc' in gst_elements:
gst_str = ('nvarguscamerasrc ! '
'video/x-raw(memory:NVMM), '
'width=(int)1920, height=(int)1080, '
'format=(string)NV12, framerate=(fraction)30/1 ! '
'nvvidconv flip-method=2 ! '
'video/x-raw, width=(int){}, height=(int){}, '
'format=(string)BGRx ! '
'videoconvert ! appsink').format(width, height)
raise RuntimeError('onboard camera source not found!')
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'
while True:
if cv2.getWindowProperty(WINDOW_NAME, 0) < 0:
# Check to see if the user has closed the window
# If yes, terminate the program
_, img = # 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
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.setWindowProperty(WINDOW_NAME, cv2.WND_PROP_FULLSCREEN,
def main():
args = parse_args()
print('Called with args:')
print('OpenCV version: {}'.format(cv2.__version__))
if args.use_rtsp:
cap = open_cam_rtsp(args.rtsp_uri,
elif args.use_usb:
cap = open_cam_usb(args.video_dev,
else: # by default, use the Jetson onboard camera
cap = open_cam_onboard(args.image_width,
if not cap.isOpened():
sys.exit('Failed to open camera!')
open_window(args.image_width, args.image_height)
if __name__ == '__main__':
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Do you have any idea about known issues of opencv 4.1.1 with gstreamer. If i run the image capture for 5 seconds in a thread the pipeline closes fine and if ran for a large number of seconds, it just stays and does not closes.

Sorry. It does not ring a bell for me.

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niteshgaba commented Dec 2, 2021 via email

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