list_cams.py

"""List available camera devices by probing indices.

On Windows this uses the DirectShow backend which gives more reliable results
for local webcams vs virtual cameras.

Usage:
    python list_cams.py --max 8

Then run an exercise with the chosen index, e.g.:
    python PushUp.py --time 30 --cam 1
"""
import argparse
import cv2


def probe(index, backend=cv2.CAP_DSHOW):
    cap = cv2.VideoCapture(index, backend)
    ok, frame = False, None
    if cap is None or not cap.isOpened():
        return False, None
    try:
        ok, frame = cap.read()
    finally:
        cap.release()
    return ok, frame


def main():
    parser = argparse.ArgumentParser(description='Probe camera indices')
    parser.add_argument('--max', type=int, default=8, help='Maximum index to probe')
    args = parser.parse_args()

    found = []
    print(f"Probing camera indices 0..{args.max - 1} (DirectShow backend)...")
    for i in range(args.max):
        ok, frame = probe(i)
        if ok and frame is not None:
            h, w = frame.shape[:2]
            print(f"Index {i}: OK - resolution {w}x{h}")
            found.append(i)
        else:
            print(f"Index {i}: no capture")

    if not found:
        print("No camera devices detected. If you expect a webcam, try unplugging virtual cameras or check OS privacy settings.")
    else:
        print("\nTry running e.g. `python PushUp.py --cam <index>` with the correct index from above.")


if __name__ == '__main__':
    main()