AviSynth is a powerful tool for video post-production. It provides ways of editing and processing videos. AviSynth works as a frameserver, providing instant editing without the need for temporary files.

AviSynth itself does not provide a graphical user interface (GUI), but instead relies on a script system that allows advanced non-linear editing. While this may at first seem tedious and unintuitive, it is remarkably powerful and is a very good way to manage projects in a precise, consistent, and reproducible manner. Because text-based scripts are human readable, projects are inherently self-documenting. The scripting language is simple yet powerful, and complex filters can be created from basic operations to develop a sophisticated palette of useful and unique effects.

AvsP is at its core a tabbed text editor with features specific for creating AviSynth scripts. It has text editing features such as AviSynth-specific syntax highlighting and autocompletion to simplify the task of writing scripts. However, its primary advantage over other editors is its integrated video preview, which remains attached to the main window at all times. Comparing the visual results of several different scripts is as easy as writing the scripts into several different tabs and activating the video preview, switching between tabs gives instantaneous feedback on visual differences (anyone remember lining up multiple instances of VirtualDub and alt-tabbing?). Furthermore, the program offers a unique way for the user to define sliders for any number in the script, giving AviSynth a unique graphical interface never known before. The following are an outline of the program's main features:

• Tabbed text editor
• Avisynth-specific syntax highlighting and autocompletion
• Integrated video preview for easy script comparison
• Unique user-defined sliders for rapid filter setting comparison
• Built-in crop editor in video preview
• Bookmark any number of frames for quick access
• Complete macro language using the Python programming language
• Graphical front-end for command-line compression tool avs2avi

The AvsP project was abandoned by its original author by late 2007.
AvsPmod is an ongoing community effort to maintain and provide some enhancements to AvsP:

• Improved syntax highlighting
• Code folding
• Improved function autocomplete
• Importing of function definitions, including from online wiki
• Snippets of text
• Better Unicode support
• HTML export and printing
• Move, rename, group and undo close tabs
• Video preview usability improvements
• YUV -> RGB options for previewing
• Support for AviSynth 2.6.0 new colorspaces
• Autocrop
• Bookmark titles
• Improved macro API with several scripts included
• Native *nix support through AvxSynth
• Codebase updated to Python 2.7 and wxPython 2.8
• Many bug fixes

AviSynth, AviSynth+ (Windows) or AvxSynth (*nix) is required. When not using the AvsPmod builds, currently only supplied for Windows, the following is also needed:

• Python 2.6-2.7
• wxPython 2.8-2.9
• Additionally for AviSynth+ x86-64 (Windows):
  • cffi module
  • pycparser module
  • Visual Studio 2008
  • avisynth_c.h

In that case start AvsPmod by running avsp.py, i.e. python -O avsp.py, pythonw recommended on Windows.

To update AvsPmod just overwrite the previous files. Personal preferences and customizations are preserved. However note that edited macro scripts, preset files and translations must be backed up first.

In case you want to backup the preferences or clean-up old files not longer used, these are the relevant files:

• options.dat: main preferences
• tools/*.dat: tool preferences
• macros/macros.dat: macro preferences
• last_session.ses: auto-saved session info

Development: https://github.com/AvsPmod/AvsPmod

Releases: https://github.com/AvsPmod/AvsPmod/releases

Filter database wiki: https://github.com/AvsPmod/AvsPmod/wiki/Filter-database

Discussion: http://forum.doom9.org/showthread.php?t=153248

AvsP homepage: http://avisynth.nl/users/qwerpoi/

AviSynth wiki: http://avisynth.nl/index.php/Main_Page

AvxSynth wiki: https://github.com/avxsynth/avxsynth/wiki

_{AviSynth description extracted from the AviSynth wiki (CC BY-SA 3.0)}