AX is a file format used by various media players (and for media streaming). AX files provide video data decompression or rendering capabilites to players and coding and decoding capabilites.

AX file format is associated with DirectShow audio and video streaming technology. AX files may be used as plugins (codecs) for DirectShow Filter. AX files are sometimes used for editing recording various video materials. DirectShow is an alternative to Video for Windows, which doesn’t support MPEG compression.