MP4, also known as MPEG-4 Part 14, is a multimedia container format standard specified as a part of MPEG-4. It is most commonly used to store digital audio and digital video streams, especially those defined by MPEG, but can also be used to store other data such as subtitles and still images.
As to MP4 codec for Window Media Player, because MP4 belongs to video formats, those codecs which can decode and encode video formats also can decode and encode MP4 formats. You can free download related codec pack for Windows Media Player to encode or decoder your MP4 files.
5 Must-Have MP4 Codec Tools
The five tools can help users encode and decode MP4 files and all of them are easy-to-use and powerful.
In order to play MP4 files, you must have MP4 Splitter installed. Not to be confused with MPEG-4 Video, the MP4 Bitstream format is a wrapper format (similar to AVI/OGM/Matroska).
3ivx MPEG-4 5.0.2 is available for Windows, Mac OS X & Linux. 3ivx is an MPEG-4 toolkit that supports MPEG-4 Video, MPEG-4 Audio and the MP4 file format.
FFDShow MPEG-4 Vdieo Decoder is a great DirectShow decoding filter for decompressing DIVX movies, picture postprocessing.
LEAD's MPEG-4 video codec is designed as a multimedia compressor / decompressor that registers into the Windows collection of multimedia drivers.
This Codec Pack provides a wide range of MPEG-4 decoding/encoding solutions, which are offered as DirectShow Filters. Elecard MPEG-4 Codec Pack will enable you to encode and decode various video and audio stream types.