Avidemux is a free and open-source software application for non-linear video editing and transcoding multimedia files.

An integral and important part of the design of the program is its project system, which uses the SpiderMonkey JavaScript engine.

It also supports a non-project system just like VirtualDub, where users can simply create all of their configurations and save the video directly without making a project file.

Avidemux was written from scratch, but additional code from FFmpeg, MPlayer, Transcode and Avisynth has been used on occasion as well.

The built-in libavcodec library from the FFmpeg project is used for decoding and encoding various audio and video formats, such as MPEG-4 ASP.