We require different audio or video codecs to be able to play a song or movie in some media player that is presently unable to play the media.
There are lots of codec packs also available for this purpose on net but what if you had forgotten if you have installed the pack or not? You can easily find out if you have already installed the codec pack on your system or not by simply listing all the codecs present in your machine.
Here is a tool called InstalledCodec that is a small utility which displays the list of all Codec drivers and DirectShow filters currently installed on your system. For each component the following information is displayed: Display Name, Type, Disabled Status, Installed/Modified Time, Description, Company Name, Filename etc.
The tool will also allow you to disable or enable any codec out of the list generated. You can also export the list into a text or html file and save it for future use.