AVSLib is an extension library for the Avisynth non-linear video editing script language.

AVSlib offers a general-purpose toolkit to Avisynth script developers for enhancing their ability to perform complex linear and non-linear video editing tasks (such as creating timelines, editing and animating clips, etc.) as well as tools to debug scripts, a rich set of functions to handle script variables, new datatypes (arrays and later matrices and dictionaries) and many more.

Currently, AVSLib offers to Avisynth script developers, among other things:

A new container datatype (the array) for all variable types (including clips' arrays and mixed types' arrays) and numerous functions, including operators, to handle arrays.
A broad set of mathematic and statistical functions, that operate both on single variables and whole arrays.
A standard set of clip-editing functions which in addition they allow user-specified functions for arbitrary post-processing of result's parts, for example: implementation of transitions, filtering, insertion of cover-story (intro clips), etc.
A set of general purpose animation functions that animate position, size and opacity on succesive frame segments in one step, supporting all arguments of Overlay standard Avisynth function.
A set of functions to aid script debugging.
More are planned for the future; see the project's roadmap.

However, the more important thing is that AVSLib offers the tools for the developing of even more advanced applications. See the backgrounders/tutorials section for some examples. See also the developers information page; apart from issues with special interest to developers, it contains useful information for ordinary library's users.

The library is implemented as a set of native Avisynth script language modules (customarily named with the .avsi extension) that can be imported into the script with the Import command or be autoloaded by placing them into the Avisynth's autoload directory. Installation instructions are provided on a separate page.

In order to shorten the learning curve for effectively using AVSLib, a number of tutorials and example scripts are provided in the documentation, along with background information about the library's structure, naming conventions and reserved names.

Before using AVSLib to build scripts, each user should review the limitations that currently exist in library's features use. The project's FAQs also provide information on common questions about the use of the library.

Finally, don't forget in each new release of AVSLib to review the change log in order to be quickly informed about new additions, corrections and bugfixes.