Testing USB Camera on Smart Pi One

This page provides instructions for testing a USB camera connected to Smart Pi One on an Armbian Debian system. The camera is typically connected to the /dev/video0 source by default, but this may vary depending on your system configuration. Make sure to check the correct video source (e.g., /dev/video1) and adjust the commands accordingly.

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1. Linux Commands for Camera Testing

Before running the test programs, ensure that your camera is recognized and accessible by following these steps:

• Verify the connected camera device using v4l2-ctl:

sudo apt-get update
sudo apt-get install v4l-utils
v4l2-ctl --list-devices

This will display a list of video devices connected to the system (e.g., /dev/video0, /dev/video1). Identify the correct device and adapt the commands as necessary.

• To test recording video using ffmpeg, install ffmpeg first:

sudo apt-get install ffmpeg

Then, run the following command, replacing /dev/video0 with your detected video source if needed (e.g., /dev/video1):

ffmpeg -f v4l2 -i /dev/video0 -c:v libx264 -preset ultrafast output.mp4

This command captures video from the specified camera and saves it to output.mp4.

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2. Python Camera Test

Install the Required Packages

Before running the Python script, install the necessary OpenCV package:

sudo apt-get update
sudo apt-get install python3-opencv

Create the Python Test Script

1. Use the nano editor to create the Python script:

nano camera_test.py

1. Add the following Python code, making sure to adjust the source (/dev/video0) if necessary. This script captures and displays the video feed using cv2.imshow().

import cv2

# Open the camera (replace /dev/video0 with the correct source if needed)
cap = cv2.VideoCapture('/dev/video0')

if not cap.isOpened():
    print("Error: Could not open video device")
    exit()

# Set camera parameters (optional)
cap.set(cv2.CAP_PROP_FRAME_WIDTH, 640)
cap.set(cv2.CAP_PROP_FRAME_HEIGHT, 480)

while True:
    # Capture frame-by-frame
    ret, frame = cap.read()

    if not ret:
        print("Error: Could not read frame")
        break

    # Display the resulting frame
    cv2.imshow('USB Camera Feed', frame)

    # Press 'q' to exit the window
    if cv2.waitKey(1) & 0xFF == ord('q'):
        break

# When everything is done, release the capture and close windows
cap.release()
cv2.destroyAllWindows()

1. Save and exit by pressing Ctrl + X, then Y, and Enter.

Run the Python Test Script

Run the script to display the live video feed from the camera:

python3 camera_test.py

The video feed will be displayed in a window, and you can press q to exit the window. Remember to adjust the video source (/dev/video0, /dev/video1, etc.) based on the device detected earlier.

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3. C Camera Test

Install the Required Packages

For the C test, you will need OpenCV development libraries:

sudo apt-get update
sudo apt install libopencv-dev

Create the C Test Program

1. Use nano to create the C program:

nano camera_test.c

1. Add the following C code, adjusting the source (/dev/video0) if necessary. This script captures and displays the video feed using imshow():

#include <opencv2/opencv.hpp>
#include <iostream>

using namespace cv;
using namespace std;

int main() {
    // Open the camera (replace /dev/video0 with the correct source if needed)
    VideoCapture cap("/dev/video0");

    if (!cap.isOpened()) {
        cout << "Error: Could not open video device" << endl;
        return -1;
    }

    // Set camera parameters (optional)
    cap.set(CAP_PROP_FRAME_WIDTH, 640);
    cap.set(CAP_PROP_FRAME_HEIGHT, 480);

    Mat frame;
    while (true) {
        // Capture frame-by-frame
        bool ret = cap.read(frame);

        if (!ret) {
            cout << "Error: Could not read frame" << endl;
            break;
        }

        // Display the resulting frame
        imshow("USB Camera Feed", frame);

        // Press 'q' to exit the window
        if (waitKey(1) == 'q') {
            break;
        }
    }

    // Release the camera
    cap.release();
    destroyAllWindows();

    return 0;
}

1. Save and exit by pressing Ctrl + X, then Y, and Enter.

Compile the C Program

Compile the program using the following command:

g++ camera_test.c -o camera_test `pkg-config --cflags --libs opencv4`

Run the C Program

Run the program to display the live video feed from the camera:

./camera_test

The video feed will be displayed in a window, and you can press q to exit the window. Make sure to adjust the video source (/dev/video0, /dev/video1, etc.) based on your setup.