Reinterlacing video is flickery

[ENunn]

Trying to put this old 1080i footage onto a DVD so I can put it on a VHS tape (for funsies). I'm having some problems with reinterlacing, as for some reason it's producing a flickery image (like how the old school Bob deinterlace flickers), and it looks really bad. Is there any way I can not have it flicker?

AVISource("F:\amarec\amarec(20191216-1857).avi", atrack=0, pixel_type="YUY2")
AssumeTFF()
Converttoyv12(matrix="Rec709", interlaced=true)
Normalize(0.8912)
Trim(155,58556)
QTGMC( Preset="Slow", edithreads=6)
CropResize(1440,1080)
Spline64Resize(720,480)
ColorMatrix(mode="Rec.709->Rec.601")
AssumeTFF().SeparateFields().SelectEvery(4, 0, 3).Weave()
Prefetch(6)

Examples attached, ignore the odd aspect ratio and audio dropouts, AviDemux didn't copy the aspect ratio flags and the audio ended up being a bit off.

[poisondeathray]

Spline64 is a sharp resizer, it will make flicker worse. You can use a softer resizer, or another method is to apply a crude lowpass filter by applying a vertical blur before reinterlacing
blur(0,0.5)

[ENunn]

That's helped a ton, but I guess there's no way to completely eliminate it? That's weird. It gets really bad on some areas.

[jagabo]

Interlaced video has always flickered on sharp, high contrast, horizontal edges. Professionally produced video blurred such details to reduce that flicker. Using a stronger vertical blur on these edges will help. Something like:

# sharp progressive video
hzedges = mt_edge(thy1=20, thy2=40, mode="0 -1 0 0 2 0 0 -1 0").mt_expand()
Overlay(last, Blur(0.0, 1.0), mask=hzedges)
# then interlace

Adjust thy1 and thy2 to suit.

Your video is also going have problems with moire artifacts which also require burring the video.

[ENunn]

Interlaced video has always flickered on sharp, high contrast, horizontal edges. Professionally produced video blurred such details to reduce that flicker. Using a stronger vertical blur on these edges will help. Something like:

# sharp progressive video
hzedges = mt_edge(thy1=20, thy2=40, mode="0 -1 0 0 2 0 0 -1 0").mt_expand()
Overlay(last, Blur(0.0, 1.0), mask=hzedges)
# then interlace

Adjust thy1 and thy2 to suit.

Your video is also going have problems with moire artifacts which also require burring the video.

Didn't know that, thanks! That made it better!