Just download and run the installer.
Note, that there're several install packages, see What's the difference between AC3Filter editions? for more info.
- AC3Filter (32bit) is required for 32bit media players. It may be installed on both 32bit and 64bit Windows. Note, that it may be nessesary even in 64bit Windows for players that work in 32bit mode.
- AC3Filter (64bit) is required for 64bit media players. May be installed only on 64bit Windows.
- AC3Filter ACM Driver (32bit) is required for programs that use an old Video For Windows API. Some programs, still need this to work (for example: VirtualDub). Again, it may be nessesary in 64bit Windows too.
- AC3Filter ACM Driver (64bit) is the same as above, but for 64bit Windows only.
- Language files - required for non-english interface.
- Documentation - install user's manual in PDF.