Video Editing Tools: An Introduction to AviSynth

AviSynth is one of the video editing tools available to you for altering and using digital video footage. In relation to other similar tools, it's very powerful, more so even than VirtualDub, although that software is better for capturing footage. It's extremely useful for matching footage from different sources.

AviSynth is what's known as a frame server program. This means that it serves video frames and audio to different programs. AviSynth is focused on AVS files, or text files, that have been specially formatted to allow AviSynth to execute them. When AviSynth has done its job, these scripts can be read by different programs such as Windows Media Player and a host of other programs, in exactly the same way as ordinary video streams would. This allows any file to be read, modified and made accessible in another program. As such, it's an extremely important tool. Video files that could not otherwise be played due to their format can be put through AviSynth and made available to all. 


AviSynth started life as a software project by Ben Rudiak-Gould, a student at Berkley. Since being developed, it has proved to be both popular and useful and many versions have now been made openly available to the public.

What is it?

In simple terms, AviSynth is a scripting language targeted at the post-production video editing market. Since AviSynth is useful for both audio and visual, it's extremely useful for post-production work on real film. AviSynth allows video to be transformed using relatively simple text files. It's not a stand-alone program, but acts as a go-between for videos and video applications.


AviSynth is a powerful post-production tool in that it presents near-unlimited scope for processing and editing videos. It provides scope for filtering and joining videos.

Firstly, a simple text document is created with special commands called a script. This file makes reference to videos and filters to be run on them. Then a video application such as VirtualDub is used to open the script file. AviSynth then comes into play, for opening the referenced videos and applying filters.

4 Main Functions

The 4 main functions of AviSynth are to join videos, filter videos, open unsupported types of video and retain disk space.

These days, videos of all kinds are making their way into the public domain on sites such as YouTube and the public appetite for film is stronger than it has ever been. It's not just mainstream clips, film and videos that are popular. Virtually any kind of video has the potential to go viral, given the right market. For anything to suddenly gain popularity it has to be available and it will be no surprise to learn that a great many video files are in formats that are not widely supported. This is where the usefulness of AviSynth becomes apparent, as it's precisely this software that allows the conversion of video files, so that they can be played and made public. For this reason, AviSynth is an important tool for everyone with an interest in film or video. Though the complexities of AviSynth may take some time to figure out, the things you're able to do with it make the effort worthwhile.