Headblur example (still) does not work

[ifo20]

Expected Behavior

Running the example script headblur.py, provided necessarily packages have been installed and necessary files are saved, should work.

Actual Behavior

Running the script errors, firstly with a trivial import error, then with a (afaik) non-trivial error:

cv2.error: OpenCV(4.5.5) :-1: error: (-5:Bad argument) in function 'blur'
> Overload resolution failed:
>  - Can't parse 'ksize'. Sequence item with index 0 has a wrong type
>  - Can't parse 'ksize'. Sequence item with index 0 has a wrong type

Steps to Reproduce the Problem

[from project root]

• Firstly fix the missing imports by adding from moviepy.editor import VideoFileClip, vfx to examples/headblur.py (or changing from moviepy import * to from moviepy.editor import *)
• Uncomment the line manual_tracking(clip, fps=6, savefile="blurred_trajectory.txt")
• Run the code, do the clicking
• Observe the error (which repeats re-running the code after re-commenting out the manual_tracking line):

.../venv38/lib/python3.8/site-packages/moviepy/video/fx/headblur.py", line 44, in fl
    blurred = cv2.blur(orig, (r_blur, r_blur))
cv2.error: OpenCV(4.5.5) :-1: error: (-5:Bad argument) in function 'blur'
> Overload resolution failed:
>  - Can't parse 'ksize'. Sequence item with index 0 has a wrong type
>  - Can't parse 'ksize'. Sequence item with index 0 has a wrong type

Note: the variable r_blur is a float, if I replace that with int(r_blur), I get the below error instead:

..../venv38/lib/python3.8/site-packages/moviepy/video/fx/headblur.py", line 45, in fl
    im[y1:y2, x1:x2] = mask * blurred + (1 - mask) * orig
ValueError: assignment destination is read-only

Specifications

• Python Version: 3.8
• Moviepy Version: 2.0.0.dev2 (same issue with v1.0.3)
• Platform Name: ubuntu
• Platform Version: 20.04
• opencv-python==4.5.5.64

[ifo20]

For clarity: I started trying to use the headblur script from the docs ( https://zulko.github.io/moviepy/examples/headblur.html ), but moved to using the updated version on master branch ( https://github.com/Zulko/moviepy/blob/master/examples/headblur.py ), as I saw issues had been raised & closed regarding the doc version.

This issue relates to the updated instructions on master branch