I want to draw a rectangle in a saved video. While drawing the rectangle,the video must freeze. I am successful in drawing a rectangle on a image,but I don't know how to do the same on a saved video using opencv and python.
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You need to provide your current code. Use comments in the code to highlight where your problem is.Nathaniel Johnson– Nathaniel Johnson2016-04-04 16:01:12 +00:00Commented Apr 4, 2016 at 16:01
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Declare a global char c=waitKey(10).When you start drawing the rectangle, event is LButtonDown, and set char c to waitKey(0). That might freeze the videoSaransh Kejriwal– Saransh Kejriwal2016-04-08 06:11:09 +00:00Commented Apr 8, 2016 at 6:11
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1 Answer
I was in need of a ROI selection mechanism using opencv and I finally figured how to implement it.
The implementation can be found here (opencvdragrect). It uses opencv 3.1.0 and Python 2.7
For a saved video till the time you don't read another frame and display it, the video is considered as paused.
In terms of how to add it to a paused video (frame), this code below might help.
import cv2
import selectinwindow
wName = "select region"
video = cv2.VideoCapture(videoPath)
while(video.isOpened()):
# Read frame
ret, RGB = video.read()
frameCounter += 1
if frameCounter == 1 : # you can pause any frame you like
rectI = selectinwindow.dragRect
selectinwindow.init(rectI, I, wName, I.shape[1], I.shape[0])
cv2.namedWindow(wName)
cv2.setMouseCallback(wName, selectinwindow.dragrect, rectI)
while True:
# display the image
cv2.imshow(wName, rectI.image)
key = cv2.waitKey(1) & 0xFF
# if returnflag is set break
# this loop and run the video
if rectI.returnflag == True:
break
box = [rectI.outRect.x,rectI.outRect.y,rectI.outRect.w,rectI.outRect.h]
# process the video
# ...
# ...
In the (opencvdragrect) library you use double-click to stop the rectangle selection process and continue with video.
Hope this helps.
