Web cam not access

Technical Support
1

i have write a program in python but when i run this program it will break at cv2.imshow(“frame” , frame). and i try to use web cam but my program can not able to access web cam

2

Hi, I’m the Toradex AI Assistant. The Toradex Support team will follow up with you shortly!

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:+1: :-1:

Based on the context provided, it seems like you are trying to use a webcam with a Python program using OpenCV on Torizon. Here are a few steps and considerations that might help resolve the issue:

  1. Ensure Camera Access in Container: Make sure that your Docker container has access to the webcam device. You need to pass the webcam device (e.g., /dev/video0) to the container using the --device parameter in your Docker run command or in your Docker Compose file.

  2. Check Bind Mounts: Ensure that the necessary directories are bind-mounted to the container to allow access to the webcam. This is crucial for hardware access from within a container.

  3. Device Permissions: Verify that the container has the necessary permissions to access the webcam. You might need to add specific cgroup rules in your Docker Compose file under the extraparms parameter, such as:

    extraparms:
  key: device_cgroup_rules
  value: [ "c 199:* rmw", "c 226:* rmw" ]

  4. Running GUI Applications: If you are using cv2.imshow, ensure that your container is set up to run GUI applications. This typically involves running a Weston container to handle the display output.

  5. Check for Errors: Look for any error messages that OpenCV might be providing when it fails at cv2.imshow. This can give you more insight into what might be going wrong.

  6. Test with GStreamer: As a troubleshooting step, you might want to test the webcam using a GStreamer pipeline to ensure that the device is working correctly outside of your Python application.

If these steps do not resolve the issue, you may need to provide more specific error messages or logs to further diagnose the problem.

Please, also check if these links can help you solve your problem:

Camera capture with OpenCV (c++) and GStreamer pipeline.

3

Hi @vishal

Are you using Torizon OS?

Can you see the camera device under /dev?

4

hi @allan.tx

we are using Torizon OS
i have added /dev/video0 in Docker Compose file

version: "3.9"
services:
  project1-debug:
    build:
      context: .
      dockerfile: Dockerfile.debug
    image: ${LOCAL_REGISTRY}:5002/project1-debug:${TAG}
    ports:
      - ${DEBUG_SSH_PORT}:${DEBUG_SSH_PORT}
      - ${DEBUG_PORT1}:${DEBUG_PORT1}
    

  project1:
    build:
      context: .
      dockerfile: Dockerfile
    image: ${DOCKER_LOGIN}/project1:${TAG}
    devices:
      - /dev/video0:/dev/video0  # Use the identified video device

and i check command ls /dev/video*
result : /dev/video0 /dev/video1 /dev/video2 /dev/video3
does i am doing something wrong in Docker Compose file.

5

hi @allan.tx

Now i am able take images from webcam by /dev/video2.
But my program will break at cv2.imshow without any error and for GUI i install package v4l-utils\

6

Hi @vishal

So, you are also using the Torizon IDE extension… Which template are you using?

can you provide your python script?

we have an article with instructions to add external dependencies to the project.

7

hi @allan.tx

python program is

import cv2



cap = cv2.VideoCapture("/dev/video2")  # Open the webcam


if not cap.isOpened():
    print("Cannot open webcam")
    exit()

while True:
    ret, frame = cap.read()  # Capture frame-by-frame
    if not ret:
        print("Can't receive frame (stream end?). Exiting...")
        break

    cv2.imshow('Webcam', frame)  # Program will break at this point

    if cv2.waitKey(1) == ord('q'):  # Press 'q' to exit
        break

cap.release()
cv2.destroyAllWindows()

Best Regards,
Vishal