K-Lite Codec Pack is a collection of components needed for audio and video playback in DirectShow players such as Windows Media Player, Media Center, and Media Player Classic.
It contains everything you need to play all common Audio
file formats. It also provides additional functionality such a thumbnail generation in Explorer.
The pack has a very advanced installer which is highly flexible and has unique problem solving capabilities.
There are four variants of the K-Lite Codec Pack: Basic, Standard, Full, and Mega. There also is a 64-bit version of the pack. It is recommended to install both a 32-bit variant of the pack as well as the 64-bit pack on 64-bit versions of windows
The Basic variant contains all the essentials needed to play all common video formats. It is small, but still very powerful.
The Standard variant contains the same as Basic, plus Media Player Classic and MediaInfo Lite.
The Full variant contains the same as Standard, plus support for a few additional (lossless) audio formats, and GraphStudioNext tool.
The Mega variant contains several extra components compared to Full. For example ACM/VFW codecs
that can be used for encoding.