VapourSynth is an application for video manipulation. Or a plugin. Or a
library. It’s hard to tell because it has a core library written in C++
and a Python module to allow video scripts to be created. It came to be
when I started thinking about alternative designs for Avisynth and most
of it was written over a 3 month period.

The software has been heavily inspired by Avisynth and aims to be a 21st
century rewrite, taking advantage of the advancements computers have made
since the late 90s.

The main features compared to Avisynth are:

* Multithreaded
- Frame level multithreading that scales well
* Generalized Colorspaces
- New colorspaces can be specified at runtime
* Per Frame Properties
- Additional metadata can be attached to frames
* Python Based
- The scripting part is implemented as a Python module so you don’t have
to learn a special language
* Support for video with format changes
- Some video just can’t stick to one format or frame size.
* Compatible with a large number of already existing Avisynth plugins