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View Full Version : StaxRip opens, say, .mp4, but never .avs scripts!


t_2
20th January 2026, 20:54
Greetings! Experimenting with AV1 encoding on Windows 11. Newbie to StaxRip version(2.50.5-x64). Impressive encoder, to say the least!! However, I can't get it to open .avs source files. It spits out an error (See below!). I'm no expert with Avisynth, but VirtualDub2 opens and encodes both the scripts that StaxRip rejected. Here's the error message: (PS. I tried StaxRip version 2.49 but got same error.)

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Script Error

Python exception: name 'core' is not defined

Traceback (most recent call last):
File "src/cython/vapoursynth.pyx", line 3393, in vapoursynth._vpy_evaluate
File "src/cython/vapoursynth.pyx", line 3394, in vapoursynth._vpy_evaluate
File "C:\Users\password\Desktop\DVD2\VIDEO_TS\DCE.avs_temp\DCE_source.vpy", line 1, in <module>
clip = core.avisource.AVISource(r"C:\Users\password\Desktop\DVD2\VIDEO_TS\DCE.avs")
^^^^
NameError: name 'core' is not defined

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When it comes to VapourSynth, I am completely clueless. Found someone on line (when searching about this error) who wrote that VapourSynth, which StaxRip uses to open up my .avs file (for some reason), doesn't work on Python versions later than 3.8.xx. Apparently, I don't have any version of Python installed on my computer. I am using the portable version of StaxRip, which is bundled with python 3.13! At least, I found Python 3.13 files in "StaxRip/Apps/FrameServer/VapourSynth" folder.

Also, StaxRip, does open and encode .mp4 files for me. When it does that, however, I noticed the following curiosity: The VapourSynth script that StaxRip generates and stores in a folder (which it creates in the same folder that contains the video source it opens) has extra lines when it opens the .mp4 file, that are missing from the same script that it generated when it tries to open the .avs file. Namely, the following bold lines appear in the VapourSynth script (when opening .mp4) that are missing entirely from the similar script when it tries to open .avs script in StaxRip.

xxxxxxxxxxxxxxxxxx VapourSynth script when opening .mp4 xxxxxxx
import os, sys
import vapoursynth as vs
core = vs.core

sys.path.append(r"C:\Users\password\Desktop\StaxRip-v2.50.5-x64\Apps\Plugins\VS\Scripts")
core.std.LoadPlugin(r"C:\Users\password\Desktop\StaxRip-v2.50.5-x64\Apps\Plugins\Dual\L-SMASH-Works\LSMASHSource.dll", altsearchpath=True)

clip = core.lsmas.LibavSMASHSource(r"C:\Users\password\Desktop\DVD2\DCE_AVC@1625&192_005.mp4")

clip.set_output()
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xxxxxx VapourSynth script when trying to open .avs xxxxx

clip = core.avisource.AVISource(r"C:\Users\password\Desktop\DVD2\VIDEO_TS\DCE.avs")

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As I said, I'm clueless about VapourSynth but the variable/name "core" seems to be what's undefined in this script, yet defined
in the VapourSynth script generated when trying to open .mp4 file. Sorry about the long post. Since I'm such a newbie, this must be a dumb
question! Thank you in advance for any light on this problem!

EDIT: Read that .avs scripts must be encoded for StaxRip in UTF-8 (without BOM). Tried that, but still no luck.