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3rdparty/opencv-4.5.4/samples/python/video_v4l2.py 2.18 KB
f4334277   Hu Chunming   提交3rdparty
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  #!/usr/bin/env python
  
  '''
  VideoCapture sample showcasing  some features of the Video4Linux2 backend
  
  Sample shows how VideoCapture class can be used to control parameters
  of a webcam such as focus or framerate.
  Also the sample provides an example how to access raw images delivered
  by the hardware to get a grayscale image in a very efficient fashion.
  
  Keys:
      ESC    - exit
      g      - toggle optimized grayscale conversion
  
  '''
  
  # Python 2/3 compatibility
  from __future__ import print_function
  
  import numpy as np
  import cv2 as cv
  
  def main():
  
      def decode_fourcc(v):
          v = int(v)
          return "".join([chr((v >> 8 * i) & 0xFF) for i in range(4)])
  
      font = cv.FONT_HERSHEY_SIMPLEX
      color = (0, 255, 0)
  
      cap = cv.VideoCapture(0)
      cap.set(cv.CAP_PROP_AUTOFOCUS, 0)  # Known bug: https://github.com/opencv/opencv/pull/5474
  
      cv.namedWindow("Video")
  
      convert_rgb = True
      fps = int(cap.get(cv.CAP_PROP_FPS))
      focus = int(min(cap.get(cv.CAP_PROP_FOCUS) * 100, 2**31-1))  # ceil focus to C_LONG as Python3 int can go to +inf
  
      cv.createTrackbar("FPS", "Video", fps, 30, lambda v: cap.set(cv.CAP_PROP_FPS, v))
      cv.createTrackbar("Focus", "Video", focus, 100, lambda v: cap.set(cv.CAP_PROP_FOCUS, v / 100))
  
      while True:
          _status, img = cap.read()
  
          fourcc = decode_fourcc(cap.get(cv.CAP_PROP_FOURCC))
  
          fps = cap.get(cv.CAP_PROP_FPS)
  
          if not bool(cap.get(cv.CAP_PROP_CONVERT_RGB)):
              if fourcc == "MJPG":
                  img = cv.imdecode(img, cv.IMREAD_GRAYSCALE)
              elif fourcc == "YUYV":
                  img = cv.cvtColor(img, cv.COLOR_YUV2GRAY_YUYV)
              else:
                  print("unsupported format")
                  break
  
          cv.putText(img, "Mode: {}".format(fourcc), (15, 40), font, 1.0, color)
          cv.putText(img, "FPS: {}".format(fps), (15, 80), font, 1.0, color)
          cv.imshow("Video", img)
  
          k = cv.waitKey(1)
  
          if k == 27:
              break
          elif k == ord('g'):
              convert_rgb = not convert_rgb
              cap.set(cv.CAP_PROP_CONVERT_RGB, 1 if convert_rgb else 0)
  
      print('Done')
  
  
  if __name__ == '__main__':
      print(__doc__)
      main()
      cv.destroyAllWindows()