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What is AviSynth? 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. AviSynth is free open-source software, and licensed under the GNU General Public License GPLv2.
New to AviSynth – Start Here Your first script – A guide for total newbies. Getting started – An introductory guide. Grammar – An introduction to the AviSynth scripting language. Filter introduction – An introductory guide to most common AviSynth filters. Script examples – Putting everything together in the real world. AviSynth FAQ – Answers to many common problems. More information (How does it work? When is it useful? Why no GUI? What applications work well with AviSynth?) Guides – Guides explaining the basics, tips on specific conversion types and common tasks. Troubleshooting your scripts and configuration.	Download AviSynth Official builds v.2.6.0 ST, 32-bit at SourceForge Unofficial builds v.2.6.0 MT, 32-bit, author SET at forum.doom9.org Forks AviSynth+ : new features, backward compatible. Original project page (avs-plus.net)  New project page (github)  Latest release (github)  Discussion at forum.doom9.org AvxSynth - AviSynth 2.5.8 running on Ubuntu 32/64. Deprecated v.2.5.8 MT, 32-bit, author SET, discussion at forum.doom9.org v.2.5.8 MT, 64-bit, author SET, compiled by JoshyD at forum.doom9.org Bugs and issues Known Issues in v2.58. Known Issues in v2.60.
Script Syntax The official reference documentation. AviSynth Syntax overview Script variables – How to declare and use them in scripts. Operators – Available operators and relative precedence. Internal functions – General purpose functions for math, logic etc. Clip properties – Properties such as Width, Height, Framerate etc. Control structures – Language constructs for script flow control. User defined script functions – How to define and use them in scripts. Plugins – How to load them (AviSynth, VirtualDub, VFAPI and C-plugins); autoloading and name-precedence explained. Most External filters are plugins; the rest are regular scripts. Runtime environment – Scripting on a per-clip frame basis.	Filters and Utilities Internal filters – Included media filters, organized by category. External filters – Hundreds of separately downloadable filters, organized by category. User pages hosted on this site: AviSynth Filter Collection – Warpenterprises Fizick’s AviSynth plugins vcmohan’s Plugin Filters stickboy’s AviSynth Stuff Shared functions – Commonly used script functions. Utilities – A list of GUIs, command-line, batch and other AviSynth related utilities.
Scripting reference Beyond scripting basics Scripting reference overview The full AviSynth grammar – The AviSynth grammar revisited and explained in detail. The script execution model – The steps behind the scenes from the script to the final video clip output. The filter graph. Scope and lifetime of variables. Evaluation of runtime scripts. User functions – How to effectively write and invoke user defined script functions; common pitfalls to avoid; ways to organise your function collection and create libraries of functions, and many more. Block statements – Techniques and coding idioms for creating blocks of AviSynth script statements. Arrays – Using arrays (and array operators) for manipulating collections of data in a single step. Scripting at runtime – How to unravel the power of runtime filters and create complex runtime scripts that can perform interesting (and memory/speed efficient) editing/processing operations and effects.
Advanced topics Advanced Scripting Tips – Using recursion, weaving 3 clips, and other programming tips. Advanced topics – Chroma Upsampling Error, color conversions, hybrid video, motion compensation, and other advanced subjects. Aspect ratios explained – Introduction to aspect ratios (DAR, PAR, SAR), and how to use that for resizing your clip. High bit-depth (Deep Color) support with AviSynth	Development Want to get involved? The official project. Learn how to install compilers and setup environments. Learn how to compile AviSynth, AviSynth plugins and console applications that access AviSynth. Learn how to debug AviSynth, AviSynth plugins and console applications that access AviSynth. Filter SDK – AviSynth plugin programming tips. Avisynth Plugin Development in C – A tutorial to write a plugin with C. AviSynth Developer Forum The ongoing changelist. About the development of AviSynth v3 (which will be platform independent). References to image processing algorithms.
About This Website We need your help to build and improve our site! Editing is easy! Please see Editing pages and Formatting. To port this site to another language, please see the MediaWiki Localisation Guide. Filter and script authors – please see Submit your Documentation on doom9.org, and the documentation template ExampleFilter.	Documentation Copyright AviSynth documentation is Copyright (c) 2002-2024 AviSynth developers and contributors. The contents of avisynth.org and avisynth.nl are released under the Creative Commons Attribution-ShareAlike 3.0 License (CC BY-SA 3.0).