.AX File Extension
File TypeDirectShow Filter
What is an AX file?
Used by various video playback programs to process video data streams; provides decoding and encoding capabilities, file parsing, audio and video de-multiplexing, video decompression, and rendering of video files; may also be used in the video recording and editing process.
DirectShow is sometimes referred to as "Quartz" and was developed as a replacement for Microsoft's "Video for Windows" format.