MDegrain issue - Unprocessed pixels along frame borders for blksize=16,24,32

[vasyl-zabolotniy]

The number of unfiltered pixels depends on overlap parameter and frame size. Left and top is not affected, only bottom and or right. Changing hpad/vpad does not affect results. Maybe it's broken? Because old trick with AddBorders()+Crop() seems to work fine.

Functions checked: MDegrain3, MDegrainN. Standard 8bit yuv420 input.
Confirmed for mvtools 2.7.41, 2.7.32. Avisynth versions: MT-2772, 3.4.0_20191020.

Details, what I've found :

blksize=16,overlap=0, 1280x720 >> OK
blksize=16,overlap=0, 1920x1080 >> 8 lowermost px
blksize=16,overlap=0, 3840x2160 >> OK

blksize=16,overlap=2, 1280x720 >> 4/4 (rightmost, lowermost)
blksize=16,overlap=2, 1920x1080 >> OK
blksize=16,overlap=2, 3840x2160 >> OK

blksize=16,overlap=4, 1280x720 >> 4 rightmost / 8 lowermost pixels
blksize=16,overlap=4, 1920x1080 >> 8/ 8
blksize=16,overlap=4, 3840x2160 >> 8/ 8
blksize=16,overlap=8 >> OK

---

1280x720, blksize=24,overlap=0 >> 8 rightmost
1280x720, blksize=24,overlap=2 >> 2 rightmost / 14 lowermost pixels
1280x720, blksize=24,overlap=4 >> 16/ 16
1280x720, blksize=24,overlap=8 >> 8 / 8
1280x720, blksize=24,overlap=12 >> 8 rightmost

1920x1080, blksize=24,overlap=0 >> OK
1920x1080, blksize=24,overlap=2 >> 2 rightmost
1920x1080, blksize=24,overlap=4 >> 16 / 16
1920x1080, blksize=24,overlap=8 >> 8 rightmost
1920x1080, blksize=24,overlap=12 >> OK

3840x2160, blksize=24,overlap=0 >> OK
3840x2160, blksize=24,overlap=2 >> 8 rightmost
3840x2160, blksize=24,overlap=4 >> 16/ 16
3840x2160, blksize=24,overlap=8 >> 8 / 8
3840x2160, blksize=24,overlap=12 >> OK

---

1280x720, blksize=32,overlap=0 >> 16 lowermost
1280x720, blksize=32,overlap=4 >> 16 / 16
1280x720, blksize=32,overlap=8 >> 16 lowermost
1280x720, blksize=32,overlap=16 >> OK

1920x1080, blksize=32,overlap=0 >> 24 lowermost
1920x1080, blksize=32,overlap=4 >> 12/ 12
1920x1080, blksize=32,overlap=8 >> 16/ 16
1920x1080, blksize=32,overlap=16 >> 8 lowermost

3840x2160, blksize=32,overlap=0 >> 16 lowermost
3840x2160, blksize=32,overlap=4 >> OK
3840x2160, blksize=32,overlap=8 >> 16/ 16
3840x2160, blksize=32,overlap=16 >> OK

[pinterf]

Well, it's not impossible that the very egdes are unprocessed, anyway, I'll check it after the holiday.