AviSynth is a powerful tool for video post-production. AviSynth is free open-source software . It can apply a large variety of editing and processing functions (called filters) to a video stream before passing along the results as if it were a legitimate file being read. Filter capabilities include trimming, cropping, deinterlacing, inverse telecine, loading and splicing still images, doing color corrections, denoising, and many other things. AviSynth filters work in several color spaces including RGB, YUY2 and YV12.
This is necessary to allow all kinds of video input and output. Also, certain functions only work on certain color spaces, making conversion mandatory.
AviSynth itself does not provide a graphical user interface (GUI), but instead relies on a scripting system that allows advanced non-linear editing. Technically, it acts as a codec for AviSynth scripts, which are text files written in the AviSynth scripting language. [advt]
The scripting language can be extended through the use of plugins. A plugin list is maintained at AviSynth Filter Collection. This script file can be opened in most media players. AviSynth acts as a non-linear video editor (without a GUI) controlled entirely by scripting.
It stands as an intermediary between a digital video source, like an AVI or MPEG file, and a VFW receiving program, which is typically a media player, video editing software, or an encoder.
AviSynth works as a frameserver, providing instant editing without the need for temporary files. AviSynth does not contain any adware or spyware.