I recently downloaded Sony's Sonic Stage 2.1. It appears that there is a file called atrac3.acm included in the installation files. A quick look revealed that SS didn't install this into my system and the file isn't even copied to program's installation directory.
If this file really is a state-of-the-art atrac3 codec, it would be interesting to get it installed and to test it.
This brings me to my main question. How can I install an ACM codec?

First, copy the atrac3.acm file to C:\Windows\System32 system directory.
Second, copy the highlighted text to notepad and save it to acm.reg (Registry file).

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Drivers32]
"msacm.atrac3acm"="atrac3.acm"

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\drivers.desc]
"atrac3.acm"="Sony ATRAC3 ACM"

Double click the registry file, if no error message, you can use the codec immidietly .

If you want to delete the atrac3 ACM, just go to registry editor, search the word "atrac3.acm", delete the revalant value, and the ACM file at the system directory.

The audio "FOURCC" should appear at audio propeties after reboot.

NOTE: It's only work for Win XP, if anybody want to install the acm in Win 9x or ME, pls tell me...