This is the software publisher's description.

DivX 7 for Windows is a free download that provides everything consumers need to enjoy high-quality digital videos on the computer, including HD H.264 (.mkv) videos with AAC audio and videos created using all previous versions of DivX technology. Consumers can also play DivX files (.divx, .avi) on millions of DivX Certified(R) devices today. Look for DivX Plus Certified devices later this year that will support playback of all DivX and DivX Plus files, as well as .mkv (H.264/AAC) videos from the Internet.

The popular video software is based on the cutting-edge H.264 video compression standard, which allows for high-performance, high-quality digital video at up to 1080p HD resolution. The software is available in two versions, the free DivX for Windows download which supports DivX video playback

The DivX Player, which is included in all versions of the DivX software download, offers free support for H.264 files that use the popular .mkv file extension.

Note that the free DivX only allows basic playback of video. You’ll need to purchase the Pro version if you want to create DivX content.