Attribute Error with Python Library Vapoursynth

I've installed Python 3.7 and Vapoursynth library from this link.

Now I'm trying to open a .mp4 video, but there's an attribute error:

 AttributeError: No attribute with the name lsmas exists. Did you mistype a plugin namespace?

How do I solve this problem?

2 Answers

As of March 2019, latest compiled FFMS2 and L-SMASH source plugins for VapourSynth for Windows, by Wolfberry you can download from

unzip those and put ffmsindex.exe, ffms2.dll and vslsmashsource.dll into your C:\Program Files (x86)\VapourSynth\plugins64 directory. Then , you can use these lines in your Vapoursynth scripts to load videos,

from vapoursynth import core
clip = core.ffms2.Source(videofile) #for mkv extensions
clip = core.lsmas.LibavSMASHSource(videofile) # for mp4, mov extensions
clip = core.lsmas.LWLibavSource(videofile)  #for ts, m2ts, mts

VapourSynth provides only a core set of filters, mostly inside the namespaces "core", "resize" and "text". Additional filters can be downloaded from other sites, mostly from Doom9 or with Myrsloiks VSRepo. These filters provide Python modules or additional filters accessible by namespaces provided by VapourSynth plugins.

To answer your questions directly: "lsmas" is provided by this Plugin. This is the official dropbox download link provided by the author (as seen in his doom9 release post).

By downloading the plugin and placing it inside <vapoursynth-install-path>/plugins32 or <vapoursynth-install-path>/plugins64 depending on whether you have a 32-bit or 64-bit installation of Python. Refer to this page for more information.

I hope this helps.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Robert Thorne

Robert Thorne

Automotive & Future Transportation Editor

Robert Thorne covers electric vehicle innovations, autonomous driving systems, global mobility trends, and automotive engineering developments.

Share this article
Twitter Facebook Pinterest