There seams to be more problems with AC3 audio than everything else these days. With many complaints daily with playback or editing movies with an AC3 sound track. The fact that the AC3 decompressor is a direct show filter and not a regular codec means its not going to show up in the normal programs.

Download
Moonlight Odio Dekoda V1.23 Freeware
Installation
Installing this filter is giving some people a lot of problems. Some people are running the installation batch file, then deleting the folder, which would then delete the filter. Other people using Windows XP need to copy the filter into C:\Windows\System or C:\Windows\System32 to get it to work. For most people the installation works first time.

1. Make a folder on your hard drive at C:\Program Files\AC3 OdioDec

2. Unpack the OdioDec.zip to a temporary folder

3. Copy mlcom.ax reg.bat and regsvr32.exe to that location

4. Double click the reg.bat to register the codec at that location.

If you never got regsvr32.exe with the program, do a search on your hard drive for it, or test to see if the command will work by clicking START > RUN and type regsvr32.exe If you get no errors then the path of regsvr32.exe has been found so the Reg.Bat will work at any location.

As Previously mentioned, some XP installation require the filter to be placed in the systems folder, you should also copy Reg.bat to that location and run it, just to make sure it is registered with the system. Always re-boot your PC each time you install anything new, or it may not work.

You can also use Gspot to look at your system, select View > Installed Codecs > Audio

All audio codecs will be listed

Double click Moonlight Odio Dekoda to get more information

As you can see, it also shows the path where it is installed.

You can also load the test file above into Gspot, which will show what filter is being used.

Conversion
Read these instructions carefully, most installation problems are people getting some error, and not taking any notice of it, then expect the filter to work. The Odio Dekoda is being used by most people without any problems. If you simply cannot get it to work, then you have no choice but to convert it to something else.

See the AC3 To WAV Conversion guide

Vdub/TMPGEnc
Note: If you load a movie with AC3 into Virtual Dub, and select file > File information the filter will not be listed, but shown as (Unknown). Also Note there is no audio when you use preview with TMPGEnc, but AC3 will play with Setting > Audio > Setting > Play