Windows 7, unlike previous Microsoft operating systems, comes with extended capabilities to play video files out of the box.
The operating system comes with codecs to play Divx, Xvid, H.264, AAC and several other popular formats.
Videos that are encoded with these formats can be played with any media player like the included Windows Media Player.
But there are still formats such as flv or mkv that are not supported by the operating system right away and users who come upon videos that do not play in their favorite media player are faced with a difficulty decision.
They can either hunt down the specific codec that is needed to play the video (see Video Inspector or Missing video codecs), install a media player that uses binary codecs (which means that the codecs come with the media player and will only work in that media player) or download and install a codec pack for the operating system to add codecs to the computer system.
Windows 7 users should not install the first codec pack that they come upon as it has happened in the past that codec packs were used to infect a computer system with malicious software.
We recommend the following two codec packs for Windows 7:
Windows 7 Codecs
The Windows 7 Codecs offered here do not change or interfere with the support Microsoft provides concerning native codec support in Windows Media Player 12 and Media Center.
Alternative hardware accelerated (DXVA) H264 codecs are also provided by the codec installation for use by all players.
The following filetypes are enabled and SUPPORTED by the installation of the Windows 7 Codecs.
amr | mpc | ofr | divx | mka | ape | flac | evo | flv | m4b | mkv | ogg | ogv | ogm | rmvb | xvid
All of the above filetypes can be queued to the Windows Media Player Playlist using a right-click.
Windows 7 Codec Pack Download: here
K-Lite Codec Pack
There are several different versions of the K-Lite Codec Pack ranging from a very small bundle that contains only the most essential decoders to a large and more comprehensive bundle.
Download K-Lite Codec Pack: here
We suggest you check out both codec packages before you make a decision. Both add support for many different media formats to Windows 7 and are good choice especially if you are using a player that relies on system-wide codecs.
A good alternative to those Windows 7 codec packs are players like SMPlayer or SPlayer which can play all video formats without codec pack installation.