K-Lite Codec Pack is a collection of codecs and related tools. Codec is short for Compressor-Decompressor. Codecs are needed for encoding and decoding (playing) audio and video. The K-Lite Codec Pack is designed as a user-friendly solution for playing all your movie files. With the K-Lite Codec Pack you should be able to play all the popular movie formats and even some rare formats.

The K-Lite Mega Codec Pack combines the contents of three codec packs:
K-Lite Codec Pack Full
QuickTime Alternative
Real Alternative

Plus some extra features:
BSplayer
DC-DSP filter