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