Jetson AGX Xavier USB camera launch

Autonomous Machines Jetson & Embedded Systems Jetson AGX Xavier
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1

Hi,

I have two USB cameras. I want to launch them on Jetson AGX Xavier Developer Kit at same time. I use a pipeline to capture frames from cameras. But I want to change zoom value of camera after cameras are started. But when I use pipeline (Gstreamer), I cannot use the function of opencv which cap.set(feature,value).

So,

  1. Is it possible that start two cameras like cv2.VideoCapture(/dev/video0) and cv2.VideoCapture(/dev/video1) without pipeline?
  2. Is it possible that update pipeline after start cameras to update zoom value of cameras?
3

Hi,
Not sure but if you run gstreamer pipeline in cv2.VideoCapture(), may not be able to adjust the setting in runtime.

There are some guidance in this webpage:
https://www.e-consystems.com/blog/camera/how-to-access-cameras-using-opencv-with-python/
Please check and give it a try. Looks like cv2.VideoCapture(0) or cv2.VideoCapture(1) can work.

4

Hi DaneLLL,

When I try to launch cameras via cv2.VideoCapture(0), the set function does not work for saturation, brightness etc. But I can set width and height via set function in run time. My problem is that how I can change the values of these features in run time.
My opencv version is: 4.5.1

and I am using following code to set features of cameras.

import cv2
cap = cv2.VideoCapture(" v4l2src device=/dev/video0 ! image/jpeg, format=MJPG, framerate=60/1, wdth=1280, height=720 ! nvv4l2decoder mjpeg=1 ! nvvidconv ! video/x-raw,format=BGRx ! videoconvert ! video/x-raw,format=BGR ! appsink drop=1 ", cv2.CAP_GSTREAMER)

#cap = cv2.VideoCapture(0)
#cap.set(3, 640)
#cap.set(4, 480)
cap.set(cv2.CAP_PROP_FRAME_WIDTH, 1280)
cap.set(cv2.CAP_PROP_FRAME_HEIGHT, 720)
cap.set(cv2.CAP_PROP_SHARPNESS, 100)

#cap2 = cv2.VideoCapture(1)
#cap2.set(cv2.CAP_PROP_FRAME_WIDTH, 1280)
#cap2.set(cv2.CAP_PROP_FRAME_HEIGHT, 720)

while True:
ret, frame = cap.read()
#ret2, frame2 = cap2.read()
cv2.imshow(“a”,frame)

#cv2.imshow(“b”,frame2)

key = cv2.waitKey(1) & 0xFF
if key == ord(‘q’):
cap.set(cv2.CAP_PROP_SHARPNESS, 100)
cap.set(cv2.CAP_PROP_ZOOM, 550)
#cap.set(cv2.CAP_PROP_FRAME_WIDTH, 640)
#cap.set(cv2.CAP_PROP_FRAME_HEIGHT, 480)

cv2.destroyAllWindows()

When I press q on keyboard, I get following warning message on terminal.

setProperty OpenCV | GStreamer warning: GStreamer: unhandled property

Thanks and Regards!

5

Hi,
We don’t have experience in changing some settings in runtime, may not be able to suggest next. We would suggest go to
https://forum.opencv.org/

6

This problem is solved!

Anyone who wants to change camera parameters in run time can use v4l2-ctl tool.
The set operation with python:

import os
os.system(“v4l2-ctl -d /dev/video0 --set-ctrl=zoom_absolute=150”)