Vaporsynth pseudo "slow-mo"

[serg]

Using Avisynth I can produce "slow-mo" effect using the following settings:

- QTGMC +bob

- FrameRateConverter or MvToolsFPSmod with 96000/1001;

- "Custom" AssumeFPS(23.976) after AdjustFrameRate;

-  Change Speed or Interpolate frame rate 23.976;

https://mediaechelon.com/images/slow_mo_avisynth.mp4



Attempt to reproduce the same effect with Vaporsynth with suggested settings:



[*]set "Filtering->(De-)Interlace/Telecine->Deinterlace/Telecine Settings->Deinterlacer" "QTGMC (Vapoursynth)"
enable "Filtering->(De-)Interlace/Telecine->QTGMC Vapoursynth->Bob" (CHECK: calculated output frame rate and frame count should be doubled)
enable "Filtering->Vapoursynth->Other->Frame Interpolation"
set "Filtering->Vapoursynth->Other->Frame Interpolation" to "Interframe/SVP"
set "Filtering->Vapoursynth->Other->Frame Interpolation->FPS" to "95,9041" (adjust the other Interframe settings if you want) (CHECK: calculated output frame rate and frame count should be doubled)
enable "Filtering->Speed Change->Speed Settings->Change Speed"
set "Filtering->Speed Change->Speed Settings->Change Speed" to "23.976 / "10" or whatever frame rate you want your output to have

caused:
1. Output mp4 - Crashed with exit status 0 (Debug attached);
2. Output AVI (FFvHuff) - produces 23.974 stream with no "slow-mo" effect (Debug attached).

[Selur]

Output AVI (FFvHuff) - produces 23.974 stream with no "slow-mo" effect

Looking at the debug output I see why the 'slow-mo' effect does not work.
The encoding call:

"C:\Program Files\Hybrid\64bit\Vapoursynth\vspipe.exe" "D:\Hybrid_test\encodingTempSynthSkript_2020-10-26@15_09_28_9310.vpy" - --y4m | "C:\Program Files\Hybrid\64bit\ffmpeg.exe" -y -noautorotate -nostdin -threads 4 -f yuv4mpegpipe -i - -an -sn -vf zscale=rangein=tv:range=tv -pix_fmt yuv420p -vsync 0  -vcodec ffvhuff -coder 0 -context 0 "D:\Hybrid_test\input_2020-10-26@15_09_28_9310_03.avi"

does not set a frame rate when encoding to ffvhuff, which is why it uses 96.94fps.
-> will fix

Output mp4 - Crashed with exit status 0

This happens since encoding is aborted due to "y4m [error]: bad sequence header magic" which normally indicates that there is a problem with decoding the used script.
Looking at the script:

# Imports
import os
import sys
import ctypes
# Loading Support Files
Dllref = ctypes.windll.LoadLibrary("C:/Program Files/Hybrid/64bit/vsfilters/Support/libfftw3f-3.dll")
import vapoursynth as vs
core = vs.get_core()
# Import scripts folder
scriptPath = 'C:/Program Files/Hybrid/64bit/vsscripts'
sys.path.append(os.path.abspath(scriptPath))
# Loading Plugins
core.std.LoadPlugin(path="C:/Program Files/Hybrid/64bit/vsfilters/FrameFilter/Interframe/svpflow2_vs64.dll")
core.std.LoadPlugin(path="C:/Program Files/Hybrid/64bit/vsfilters/FrameFilter/Interframe/svpflow1_vs64.dll")
core.std.LoadPlugin(path="C:/Program Files/Hybrid/64bit/vsfilters/GrainFilter/AddGrain/AddGrain.dll")
core.std.LoadPlugin(path="C:/Program Files/Hybrid/64bit/vsfilters/DenoiseFilter/NEO_FFT3DFilter/neo-fft3d.dll")
core.std.LoadPlugin(path="C:/Program Files/Hybrid/64bit/vsfilters/DenoiseFilter/DFTTest/DFTTest.dll")
core.std.LoadPlugin(path="C:/Program Files/Hybrid/64bit/vsfilters/Support/EEDI3.dll")
core.std.LoadPlugin(path="C:/Program Files/Hybrid/64bit/vsfilters/ResizeFilter/nnedi3/vsznedi3.dll")
core.std.LoadPlugin(path="C:/Program Files/Hybrid/64bit/vsfilters/Support/libmvtools.dll")
core.std.LoadPlugin(path="C:/Program Files/Hybrid/64bit/vsfilters/Support/temporalsoften.dll")
core.std.LoadPlugin(path="C:/Program Files/Hybrid/64bit/vsfilters/Support/scenechange.dll")
core.std.LoadPlugin(path="C:/Program Files/Hybrid/64bit/vsfilters/Support/fmtconv.dll")
core.std.LoadPlugin(path="C:/Program Files/Hybrid/64bit/vsfilters/SourceFilter/d2vSource/d2vsource.dll")
# Import scripts
import havsfunc
# source: 'D:\Hybrid_test\input.m2v'
# current color space: YUV420P8, bit depth: 8, resolution: 720x480, fps: 29.97, color matrix: 470bg, yuv luminance scale: limited, scanorder: bottom field first
# Loading D:\Hybrid_test\input.m2v using D2VSource
clip = core.d2v.Source(input="D:/Hybrid_test/2020-10-26@14_39_47_4410.d2v")
# making sure input color matrix is set as 470bg
clip = core.resize.Point(clip, matrix_in_s="470bg",range_s="limited")
# making sure frame rate is set to 29.970
clip = core.std.AssumeFPS(clip=clip, fpsnum=30000, fpsden=1001)
# Setting color range to TV (limited) range.
clip = core.std.SetFrameProp(clip=clip, prop="_ColorRange", intval=1)
# setting field order to what QTGMC should assume (bottom field first)
clip = core.std.SetFrameProp(clip=clip, prop="_FieldBased", intval=1)
# Deinterlacing using QTGMC
clip = havsfunc.QTGMC(Input=clip, Preset="Placebo", TFF=False) # new fps: 59.94
# make sure content is preceived as frame based
clip = core.std.SetFieldBased(clip, 0)
# adjusting frame count with Interframe/SVP
clip = havsfunc.InterFrame(clip, NewNum=9594100, NewDen=100000, OverrideAlgo=13) # new fps: 95.941
# Output
clip.set_output()

I see no problem.
Looking at the encoding call:

"C:\Program Files\Hybrid\64bit\Vapoursynth\vspipe.exe" "D:\Hybrid_test\encodingTempSynthSkript_2020-10-26@14_39_47_4410.vpy" - --y4m | "C:\Program Files\Hybrid\64bit\ffmpeg.exe" -y -loglevel fatal -noautorotate -nostdin -threads 4 -f yuv4mpegpipe -i - -an -sn -vf zscale=rangein=tv:range=tv -pix_fmt yuv420p -vsync 0  -f rawvideo - | "C:\Program Files\Hybrid\64bit\x264.exe" --preset veryfast --bitrate 1500 --profile high --level 4.1 --ref 3 --direct auto --b-adapt 0 --sync-lookahead 6 --ratetol 2.0 --qcomp 0.5 --rc-lookahead 40 --qpmax 81 --partitions i4x4,p8x8,b8x8 --no-fast-pskip --subme 5 --aq-mode 0 --vbv-maxrate 1500 --vbv-bufsize 78125 --sar 8:9 --non-deterministic --range tv --colormatrix bt709 --demuxer y4m  --input-range tv --fps 24000/1001 --output-depth 8 --output "D:\HYBRID~1\2020-10-26@14_39_47_4410_03.264" -

I see the problem. There's an unnecessary ffmpeg decoding call in the middle, which should not be there.
-> I'll try to reproduce and fix this. (would have helped if your debug output, would have also contained the job creation and not just the job processing)


Cu Selur