SmoothVideo Project — Unable to initilize vapoursynth 4.0 API

Re: Unable to initilize vapoursynth 4.0 API

null@example.com (Alexkral) — Thu, 17 Jul 2025 22:23:48 +0000

I encountered the same issue with a fresh installation without duplicate versions of Vaporsynth or Python. It seems to have been resolved by simply deleting the PYTHONPATH environment variable.

Re: Unable to initilize vapoursynth 4.0 API

null@example.com (Chainik) — Fri, 25 Apr 2025 17:48:18 +0000

no idea what else you have installed
Vapoursynth and/or other Python versions

Re: Unable to initilize vapoursynth 4.0 API

null@example.com (vulcan78) — Fri, 25 Apr 2025 17:42:46 +0000

Chainik wrote:

> I have a similar issue
nothing similar
you probably have system Vapoursynth installation but w/o needed plugins
if you DO need Vapoursynth installation then add MiscFilters.dll into its plugins folder (you can copy it from SVP 4\mpv64\vapoursynth64\plugins)

I just tried this and MPC-BE still presents the error "Unable to initialize Vapoursynth API 4.0" and closes. Why am I having this problem?

Re: Unable to initilize vapoursynth 4.0 API

null@example.com (Chainik) — Wed, 24 Jan 2024 08:31:10 +0000

> I have a similar issue

nothing similar
you probably have system Vapoursynth installation but w/o needed plugins
if you DO need Vapoursynth installation then add MiscFilters.dll into its plugins folder (you can copy it from SVP 4\mpv64\vapoursynth64\plugins)

Re: Unable to initilize vapoursynth 4.0 API

null@example.com (chesley96) — Wed, 24 Jan 2024 01:49:52 +0000

I have a similar issue that has persisted for many months now. SVP doesn't work with TensorRT Rife in MPC-HC or MPC-BE for me but works in MPV. It used to work on my last windows installation. I am using 4.6.0.263. I assume I may have other software interfering but do not know how to find out.

Re: Unable to initilize vapoursynth 4.0 API

null@example.com (Chainik) — Tue, 23 Jan 2024 14:54:24 +0000

> Now it just says "TensorRT requires vapoursythn inorder to work"

because you're running Avisynth Filter (which is by default)

---
"D:\Program Files (x86)\mpv64" ??

Re: Unable to initilize vapoursynth 4.0 API

null@example.com (AMG-EATER) — Tue, 23 Jan 2024 12:54:32 +0000

Hi Chainik jan,

Matter of fact, I do have other Python & Vapoursynth installations. These stem from FlowFrames, FrameGUI etc. from what I could gather. Please see a screenshot below of everything that I could find pertaining to Python & VapourSynth:

I'm at a loss here - I even wiped windows installation (but kept personal files) and still doesn't want to work. Now it just says "TensorRT requires vapoursythn inorder to work"

Re: Unable to initilize vapoursynth 4.0 API

null@example.com (Chainik) — Tue, 23 Jan 2024 08:52:17 +0000

> I have checked every single one of these settings and they are all present / installed:

is it possible you have other Vapoursynth and/or Python installations somewhere?

> Do you set Pythonpath for both User AND system or just for the User only?

no, these values are combined by the system

Re: Unable to initilize vapoursynth 4.0 API

null@example.com (AMG-EATER) — Tue, 23 Jan 2024 05:21:45 +0000

I have checked every single one of these settings and they are all present / installed:

Question regarding the environmental variables: Do you set Pythonpath for both User AND system or just for the User only?

Please see reference below:

How about Path? Do you also set path for both user and system? If so, can you please shed some light on which exact folders and variables need to be included along with the keystrings?

Thanks so much!!

Re: Unable to initilize vapoursynth 4.0 API

null@example.com (flowreen91) — Fri, 12 Jan 2024 00:13:49 +0000

Hmm, don't know what could cause it then.
You already have all these installed and still crashes right?
https://gyazo.com/5defd01e5568a340b364ea340026b271

Also you've already tried clicking this button right?
https://gyazo.com/dae1ef8eb66abf91c46685c13932769e

it should add the mpv64 folder in system PATH variables and add the PYTHONPATH:
https://gyazo.com/67584d6eb4a71b5fed466e1896020f3d

Also you have this red file present in this folder?
https://gyazo.com/9e5e100306455ee46c1fa4edb2d43593

If issue persists we should let the SVP devs take a look.

Re: Unable to initilize vapoursynth 4.0 API

null@example.com (AMG-EATER) — Thu, 11 Jan 2024 23:18:05 +0000

Thanks so much for Q&A this on your own system and letting me know of the results. I will go ahead and do a clean install and report back with the results.

Will follow up shortly.

After completely uninstalling SVP 4 and even running RevoUninstaller on it, the same error is present upon activating Vapoursynth. Here is also what MPC crashed with:

Any ideas as to what else I could try to remedy this error?

Re: Unable to initilize vapoursynth 4.0 API

null@example.com (flowreen91) — Thu, 11 Jan 2024 20:55:36 +0000

I'm running into the same popup error if i delete this vapoursynth file:
https://gyazo.com/9e5e100306455ee46c1fa4edb2d43593
i would suggest to try a clean reinstall of SVP since only using the "Add or remove components" Setup Wizard did not fully fix the issue for me.
Follow their recommended setup afterwards:
https://www.svp-team.com/wiki/RIFE_AI_interpolation

Unable to initilize vapoursynth 4.0 API

null@example.com (AMG-EATER) — Thu, 11 Jan 2024 13:15:39 +0000

Hi SVP Dev team,

Hope you're all doing well.

I'm running into this strange problem that occurs only when i'm trying to use TensorRT with non MPV players such as MPC / PotPlayer / MPC BE. etc.

I've attached an error log along with a screenshot of the error. Can you please look into this and let me know if I've misconfigured something?

In the filters, I'm only picking Vapoursynth and clicking it off to prefer.

Thanks!