[HELP] Problems with de-interlacing

[Selur]

Looking at the used VapourSynth script:

ClearAutoloadDirs()
SetFilterMTMode("DEFAULT_MT_MODE", MT_MULTI_INSTANCE)
LoadPlugin("C:\Program Files\Hybrid\64bit\Avisynth\avisynthPlugins\LSMASHSource.dll")
LoadPlugin("C:\Program Files\Hybrid\64bit\Avisynth\avisynthPlugins\hqdn3d.dll")
LoadPlugin("C:\Program Files\Hybrid\64bit\Avisynth\avisynthPlugins\MedianBlur2.dll")
LoadPlugin("C:\Program Files\Hybrid\64bit\Avisynth\avisynthPlugins\grunt-x64.dll")
LoadPlugin("C:\Program Files\Hybrid\64bit\Avisynth\avisynthPlugins\Average.dll")
LoadPlugin("C:\Program Files\Hybrid\64bit\Avisynth\avisynthPlugins\TIVTC.dll")
LoadPlugin("C:\Program Files\Hybrid\64bit\Avisynth\avisynthPlugins\nnedi3.dll")
LoadPlugin("C:\Program Files\Hybrid\64bit\Avisynth\avisynthPlugins\mvtools2.dll")
LoadPlugin("C:\Program Files\Hybrid\64bit\Avisynth\avisynthPlugins\masktools2.dll")
LoadPlugin("C:\Program Files\Hybrid\64bit\Avisynth\avisynthPlugins\RgTools.dll")
Import("C:\Program Files\Hybrid\64bit\Avisynth\avisynthPlugins\mtmodes.avsi")
Import("C:\Program Files\Hybrid\64bit\Avisynth\avisynthPlugins\MCDegrainSharp.avs")
Import("C:\Program Files\Hybrid\64bit\Avisynth\avisynthPlugins\Srestore.avsi")
Import("C:\Program Files\Hybrid\64bit\Avisynth\avisynthPlugins\Zs_RF_Shared.avsi")
Import("C:\Program Files\Hybrid\64bit\Avisynth\avisynthPlugins\QTGMC.avsi")
# loading source: S:\Sinister Trailers\Captures - FCP exports\Dusk To Dawn 07 FCP.mov
# color sampling YV411@8, matrix: bt601, scantyp: bottom field first, luminance scale: limited
LWLibavVideoSource("S:\Sinister Trailers\Captures - FCP exports\Dusk To Dawn 07 FCP.mov",cache=false,format="YUV411P8", prefer_hw=0)
# current resolution: 720x480
# deinterlacing
propDelete("_ChromaLocation")
ConvertToYV12(interlaced=true)
AssumeBFF()
QTGMC(Preset="Slow", ediThreads=2)
# removing ghosting
srestore(frate=23.976,omode=6)
Preroll(Int(last.FrameRate()))
# cropping
Crop(10,4,-6,-6)# 704x470
Levels(0,1.00,255,0,255)
Tweak(sat=0.90)
hqdn3d(cs=3.00,ct=4.50,restart=7)
McDegrainSharp(frames=1)
# scaling to 960x720
nnedi3_rpow2(rfactor=2,cshift="LanczosResize",fwidth=960,fheight=720)
# Converting from 8 to 10bit for encoder
ConvertBits(10)
# adjust color to YV16 (color matrix: Rec601)
ConvertToYUV422()
# setting output fps to 23.97600fps
AssumeFPS(24000,1001)
#  output: color sampling YV16@10, matrix: bt601, scantyp: progressive, luminance scale: limited
return last

the output should be progressive.

Looking at the encoding call:

"C:\Program Files\Hybrid\64bit\ffmpeg.exe" -y -noautorotate -nostdin -threads 8     -color_range tv -i "M:\5994-2997 Prog-Temp\encodingTempSynthSkript_2026-03-19@16_43_13_0010_0.avs" -an -sn -color_primaries bt470m -color_trc bt709 -colorspace bt470bg -color_range tv  -pix_fmt yuv422p10le -strict -1 -fps_mode auto -r 24000/1001  -vcodec prores_ks -profile:v 2 -vtag apcn -metadata encoding_tool="Hybrid 2026.03.07.1" -aspect 960:720 -f mov "M:\5994-2997 Prog-Temp\Dusk To Dawn 07 FCP_1_2026-03-19@16_43_13_0010_03.mov"

There are no container flags to indicate interlaced signaling.

But FFmpeg does report the input as BFF:

Input #0, avisynth, from 'M:\5994-2997 Prog-Temp\encodingTempSynthSkript_2026-03-19@16_43_13_0010_0.avs':
  Duration: 01:41:26.00, start: 0.000000, bitrate: 0 kb/s
  Stream #0:0: Video: rawvideo (Y3[10][10] / 0xA0A3359), yuv422p10le(tv, smpte170m/smpte170m/bt709, bottom first), 960x720, 23.98 fps, 23.98 tbr, 23.98 tbn

and consequently the output also BFF too:

Stream mapping:
  Stream #0:0 -> #0:0 (rawvideo (native) -> prores (prores_ks))
Output #0, mov, to 'M:\5994-2997 Prog-Temp\Dusk To Dawn 07 FCP_1_2026-03-19@16_43_13_0010_03.mov':
  Metadata:
    encoding_tool   : Hybrid 2026.03.07.1
    encoder         : Lavf62.10.101
  Stream #0:0: Video: prores (Standard) (apcn / 0x6E637061), yuv422p10le(tv, bt470bg/smpte170m/bt709, bottom coded first (swapped)), 960x720 [SAR 1:1 DAR 4:3], q=2-31, 200 kb/s, 23.98 fps, 24k tbn
    Metadata:
      encoder         : Lavc62.24.101 prores_ks

=> Seems like the problem is with the AviSynth script or with ffmpeg. I would have assumed that an explicit 'AssumeFrameBased()', wouldn't be necessary and after QTGMC AviSynth should not signal BFF anymore.

I'll look into it.

Cu Selur