--vspipe-args not passed into vapoursynth script on subsequent runs

[cyvro]

On Av1an-git commit 0fcc2a8 I am erroring out when running av1an. The output shows that the args passed in through --vspipe-args is only in the fist execution of the vpy script. Av1an seems to be running the vpy script up to 8 times and the args is only seen in the first run.

Environment

OS: Arch
vapoursynth: r70

Command:av1an -i vapour_synth.vpy --vspipe-args source=/SpeedPool/test.mp4 -e svt-av1 -l ./av1an.log -v '--preset 4 --crf 31 --film-grain 8 --psy-rd 0.8 --spy-rd 2 --noise-norm-strength 3 --keyint -1 --scm 0 --tune 3' -o /SpeedPool/temp_test.mp4.mkv

vapour_synth.vpy content:

# vapour_synth.vpy

import vapoursynth as vs

core = vs.core
print("----------------")
path = globals()['source']

clip = core.bs.VideoSource(source=path)

clip.set_output()

result in 0.4.4:

[root@arch-av1 ~]# av1an -i vapour_synth.vpy --vspipe-args source=/SpeedPool/jellyfin/test.mp4 -e svt-av1 -l ./av1an.log -v \'--preset 4 --crf 31 --film-grain 8 --psy-rd 0.8 --spy-rd 2 --noise-norm-strength 3 --keyint -1 --scm 0 --tune 3' -o /SpeedPool/jellyfin/temp_test.mp4.mkv`
----------------
----------------
----------------
----------------
----------------
----------------
----------------
Scene detection
⠁ 00:00:00 ▕                                                                                                              ▏   0%  0/17984 (0 fps, eta unknown)----------------
----------------
⠒ 00:00:02 ▕██▏                                                                                                         ▏   2%  369/17984 (167.46 fps, eta 2m)

result in commit 0fcc2a8:

[root@arch-av1 ~]# av1an -i vapour_synth.vpy --vspipe-args source=/SpeedPool/jellyfin/test.mp4 -e svt-av1 -l ./av1an.log -v '--preset 4 --crf 31 --film-grain 8 --psy-rd 0.8 --spy-rd 2 --noise-norm-strength 3 --keyint -1 --scm 0 --tune 3' -o /SpeedPool/jellyfin/temp_test.mp4.mkv
----------------
----------------
Error: failed to open input file (Python exception: 'source'

Traceback (most recent call last):
  File "src/cython/vapoursynth.pyx", line 3387, in vapoursynth._vpy_evaluate
  File "src/cython/vapoursynth.pyx", line 3388, in vapoursynth._vpy_evaluate
  File "vapour_synth.vpy", line 9, in <module>
    path = globals()['source']
           ~~~~~~~~~^^^^^^^^^^
KeyError: 'source'
)

[shenef]

Can confirm.

But first, the example script doesn't work for me and results in:

PS C:\_ENCODING> av1an -i "input/debugging.vpy" --vspipe-args "source=C:/_ENCODING/input/FoodMarket_source.y4m" -e svt-av1 -o "output/debugging.mkv"
----------------
----------------
Error: failed to open input file (Python exception: 'source'

Traceback (most recent call last):
  File "src\\cython\\vapoursynth.pyx", line 3387, in vapoursynth._vpy_evaluate
  File "src\\cython\\vapoursynth.pyx", line 3388, in vapoursynth._vpy_evaluate
  File "input/debugging.vpy", line 5, in <module>
KeyError: 'source'
)

Modifying the example script without adding a default value:

import vapoursynth as vs
core = vs.core
print("----------------")
path = globals().get("source")
clip = core.bs.VideoSource(source=path)
clip.set_output()

Results in:

Error: failed to open input file (Python exception: VideoSource: argument source is required

Traceback (most recent call last):
  File "src\\cython\\vapoursynth.pyx", line 3387, in vapoursynth._vpy_evaluate
  File "src\\cython\\vapoursynth.pyx", line 3388, in vapoursynth._vpy_evaluate
  File "input/debugging.vpy", line 8, in <module>
  File "src\\cython\\vapoursynth.pyx", line 3123, in vapoursynth.Function.__call__
vapoursynth.Error: VideoSource: argument source is required
)

Finally, adding a default value:

import vapoursynth as vs
core = vs.core
print("----------------")
path = globals().get("source", "C:/_ENCODING/input/10MB.mkv")
clip = core.bs.VideoSource(source=path)
clip.set_output()

Results in:

20250727-1046-51.4292549.mp4

There is a frame count mismatch in the source that is used as the default and it matches the framecount of the highest value the SCD reaches.
That matches the observation of @cyvro that the arguments are not considered on subsequent runs.

---

Windows 11 and Powershell 7

PS C:\_ENCODING> av1an --version
av1an 0.4.4-unstable (rev 0fcc2a8) (Release)

* Compiler
  rustc 1.88.0 (LLVM 20.1)

* Target Triple
  x86_64-pc-windows-msvc

* Date Info
  Commit Date:  2025-07-21

* VapourSynth Plugins
  systems.innocent.lsmas : Found
  com.vapoursynth.ffms2  : Found
  com.vapoursynth.dgdecodenv : Not found
  com.vapoursynth.bestsource : Found
  com.julek.plugin : Not found
  com.julek.vszip : Found
  com.lumen.vship : Not found

PS C:\_ENCODING> vspipe --version
VapourSynth Video Processing Library
Copyright (c) 2012-2025 Fredrik Mellbin
Core R71
API R4.1
API R3.6
Options: -

[BoatsMcGee]

The issue is the result of a bug in av-decoders as described here: rust-av/av-decoders#3

It may take a while to get this fixed as the issue is upstream and the right solution isn't clear yet at least to me.

Thanks,
- Boats M.