Opening a Camera

import cv2
import time

def live_camera_demo(camera_index=0, duration_sec=30):
    """
    Capture from a live camera and display the feed.
    Press 'q' to quit early.
    camera_index: 0 = default webcam, 1 = second camera, etc.
    """
    cap = cv2.VideoCapture(camera_index)

    if not cap.isOpened():
        print(f"Error: Could not open camera {camera_index}")
        print("Try a different index (0, 1, 2...)")
        return

    # Set camera resolution (if supported)
    cap.set(cv2.CAP_PROP_FRAME_WIDTH, 640)
    cap.set(cv2.CAP_PROP_FRAME_HEIGHT, 480)
    cap.set(cv2.CAP_PROP_FPS, 30)

    print(f"Camera opened: {int(cap.get(cv2.CAP_PROP_FRAME_WIDTH))}x"
          f"{int(cap.get(cv2.CAP_PROP_FRAME_HEIGHT))} @ "
          f"{cap.get(cv2.CAP_PROP_FPS):.0f} FPS")

    frame_count = 0
    start_time = time.time()

    while True:
        ret, frame = cap.read()
        if not ret:
            print("Failed to read frame")
            break

        # Process frame here...

        frame_count += 1
        elapsed = time.time() - start_time
        fps = frame_count / elapsed if elapsed > 0 else 0
        cv2.putText(frame, f"FPS: {fps:.1f}", (10, 30),
                   cv2.FONT_HERSHEY_SIMPLEX, 1.0, (0, 255, 0), 2)

        cv2.imshow("Live Camera", frame)

        # 'q' to quit, or stop after duration
        if cv2.waitKey(1) & 0xFF == ord("q"):
            break
        if elapsed >= duration_sec:
            break

    cap.release()
    cv2.destroyAllWindows()
    print(f"Camera closed: {frame_count} frames captured")

live_camera_demo(camera_index=0, duration_sec=10)