select best kernel using KNN

refer to image!

Find and search which webcam is online on your computer.

 python code:

.

import cv2

import time

def check_cameras():

print("\nChecking camera indices 0-9...")

print("----------------------------------------")

working_cameras = []

for i in range(10):

cap = cv2.VideoCapture(i)

if cap.isOpened():

# Try to read a frame

ret, frame = cap.read()

if ret:

# Get camera properties

width = int(cap.get(cv2.CAP_PROP_FRAME_WIDTH))

height = int(cap.get(cv2.CAP_PROP_FRAME_HEIGHT))

fps = cap.get(cv2.CAP_PROP_FPS)

# Get backend info

backend = cap.getBackendName()

print(f"\n✓ Camera {i} is ONLINE:")

print(f" Resolution: {width}x{height}")

print(f" FPS: {fps}")

print(f" Backend: {backend}")

print(f" Frame shape: {frame.shape}")

# Try to get more detailed format information

fourcc = int(cap.get(cv2.CAP_PROP_FOURCC))

fourcc_str = "".join([chr((fourcc >> 8 * i) & 0xFF) for i in range(4)])

print(f" Format: {fourcc_str}")

working_cameras.append(i)

# Test a few more frames to ensure stability

frames_to_test = 5

success_count = 0

for _ in range(frames_to_test):

ret, frame = cap.read()

if ret:

success_count += 1

time.sleep(0.1)

print(f" Stability test: {success_count}/{frames_to_test} frames captured successfully")

else:

print(f"✗ Camera {i}: Device found but cannot read frames")

cap.release()

else:

print(f"✗ Camera {i}: Not available")

print("\n----------------------------------------")

print("Summary:")

if working_cameras:

print(f"Working camera indices: {working_cameras}")

else:

print("No working cameras found")

print("----------------------------------------")

def main():

print("Starting camera detection...")

check_cameras()

print("\nCamera check complete!")

if __name__ == "__main__":

main()

..

output is looks like:

Starting camera detection...

Checking camera indices 0-9...

----------------------------------------

✓ Camera 0 is ONLINE:

  Resolution: 640x480

  FPS: 30.0

  Backend: V4L2

  Frame shape: (480, 640, 3)

  Format: YUYV

  Stability test: 5/5 frames captured successfully

[ WARN:0@0.913] global cap_v4l.cpp:999 open VIDEOIO(V4L2:/dev/video1): can't open camera by index

[ERROR:0@0.972] global obsensor_uvc_stream_channel.cpp:158 getStreamChannelGroup Camera index out of range

✗ Camera 1: Not available

✓ Camera 2 is ONLINE:

  Resolution: 640x480

  FPS: 30.0

  Backend: V4L2

  Frame shape: (480, 640, 3)

  Format: YUYV

  Stability test: 5/5 frames captured successfully

[ WARN:0@1.818] global cap_v4l.cpp:999 open VIDEOIO(V4L2:/dev/video3): can't open camera by index

[ERROR:0@1.820] global obsensor_uvc_stream_channel.cpp:158 getStreamChannelGroup Camera index out of range

✗ Camera 3: Not available

[ WARN:0@1.820] global cap_v4l.cpp:999 open VIDEOIO(V4L2:/dev/video4): can't open camera by index

[ERROR:0@1.822] global obsensor_uvc_stream_channel.cpp:158 getStreamChannelGroup Camera index out of range

✗ Camera 4: Not available

[ WARN:0@1.822] global cap_v4l.cpp:999 open VIDEOIO(V4L2:/dev/video5): can't open camera by index

[ERROR:0@1.823] global obsensor_uvc_stream_channel.cpp:158 getStreamChannelGroup Camera index out of range

✗ Camera 5: Not available

[ WARN:0@1.824] global cap_v4l.cpp:999 open VIDEOIO(V4L2:/dev/video6): can't open camera by index

[ERROR:0@1.825] global obsensor_uvc_stream_channel.cpp:158 getStreamChannelGroup Camera index out of range

✗ Camera 6: Not available

[ WARN:0@1.825] global cap_v4l.cpp:999 open VIDEOIO(V4L2:/dev/video7): can't open camera by index

[ERROR:0@1.828] global obsensor_uvc_stream_channel.cpp:158 getStreamChannelGroup Camera index out of range

✗ Camera 7: Not available

[ WARN:0@1.828] global cap_v4l.cpp:999 open VIDEOIO(V4L2:/dev/video8): can't open camera by index

[ERROR:0@1.830] global obsensor_uvc_stream_channel.cpp:158 getStreamChannelGroup Camera index out of range

✗ Camera 8: Not available

[ WARN:0@1.830] global cap_v4l.cpp:999 open VIDEOIO(V4L2:/dev/video9): can't open camera by index

[ERROR:0@1.831] global obsensor_uvc_stream_channel.cpp:158 getStreamChannelGroup Camera index out of range

✗ Camera 9: Not available

----------------------------------------

Summary:

Working camera indices: [0, 2]

----------------------------------------

Camera check complete!

so you can know which one is online

Thank you!