bbs.mldev.org

1. List all my 3 web cameras

   Code: Select all

   $v4l2-ctl --list-devices
   C922 Pro Stream Webcam (usb-0000:00:14.0-1):
   	/dev/video0
   	/dev/video1
   
   USB Webcam gadget: UVC HD Camer (usb-0000:00:14.0-2):
   	/dev/video2
   	/dev/video3
   
   Integrated Camera: Integrated C (usb-0000:00:14.0-8):
   	/dev/video4
   	/dev/video5
   

   1. Find if the webcam support FPS 60

   Code: Select all

   $ v4l2-ctl --list-formats-ext
   ...
   		Size: Discrete 1280x720
   			Interval: Discrete 0.017s (60.000 fps)
   			Interval: Discrete 0.033s (30.000 fps)
   			Interval: Discrete 0.042s (24.000 fps)
   			Interval: Discrete 0.050s (20.000 fps)
   			Interval: Discrete 0.067s (15.000 fps)
   			Interval: Discrete 0.100s (10.000 fps)
   			Interval: Discrete 0.133s (7.500 fps)
   			Interval: Discrete 0.200s (5.000 fps)
   ...
   

   1. use guvcview to set the default FPS to 60

   2. verify the FPS with python code

   Code: Select all

   #!/usr/bin/python
   import cv2
   
   cap = cv2.VideoCapture(0, cv2.CAP_V4L2)
   cap.set(cv2.CAP_PROP_FOURCC, cv2.VideoWriter_fourcc('M', 'J', 'P', 'G'))
   cap.set(cv2.CAP_PROP_FRAME_WIDTH, 1280)
   cap.set(cv2.CAP_PROP_FRAME_HEIGHT, 720)
   cap.set(cv2.CAP_PROP_FPS, 60)
   
   width, height = (
           cap.get(cv2.CAP_PROP_FRAME_WIDTH),
           cap.get(cv2.CAP_PROP_FRAME_HEIGHT),
       )
   print(f"Camera dimensions: {width, height}")
   print(f"Camera FPS: {cap.get(cv2.CAP_PROP_FPS)}")
   
   import time
   start = time.monotonic()
   count= 0
   while 1:
       ret, image = cap.read()
       #....
       count+=1
       if count%30==0:
           end = time.monotonic()
           print(30/(end-start))
           start = end
   
   cap.release()
   cv2.destroyAllWindows()
   

In jetson nano, I only got ₂₉ FPS.