The file h264decfilter.ax is part of the ArcSoft H.264 Decoder (Filter) from Arcsoft. H.264 is a video compression format standard. An ax file is a filter that is used by a codec (coder-decoder). A codec is a program that translates digital data, like video, into a format your computer recognizes.
If you get an error with this file, you may not be able to view videos that use the H.264/MPEG-4 AVC video format. Fixing this file may require reinstalling the codex, but first you might try cleaning your registry.
The registry is a database that acts as an information desk for your operating system. When you start a program, Windows checks the registry to find out where all the files that belong to that program are located on your drive, and how to use those files.
If there is a mistake in the registry, the program may not run. ZookaWare PC Cleaner deals with those mistakes. ZookaWare PC Cleaner finds and fixes every error in your registry, getting your system running smoothly again.