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Open Source Computer Vision Library
https://opencv.org/
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78 lines
2.2 KiB
78 lines
2.2 KiB
#!/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, False) # 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, convert_rgb) |
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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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