Xvid (formerly XviD) is an open source video codec based on MPEG-4 technology standards. Xvid was created to offer a free alternative to commercial codecs. The Xvid codec makes it possible to compress a feature-length, DVD-quality movie so that it is able to fit on one or two CDs without sacrificing image quality.
Because Xvid is a file type and not a video format, a decoding program or DVD/Blu-ray player is required to open an Xvid file. In addition to the Xvid codec, there are numerous decoding applications and extensions that are free to download for Apple, Windows, and Linux devices including VLC Media Player and Windows Media Player.
Xvid vs. DivX
While there is some debate about which is the better codec, Xvid and DivX are both widely used and effectively perform the same function. Both leverage Advanced Simple Profile (ASP) features such as b-frames, H.263, and lumi masking, and both can compress large video files without any visible reduction in quality. One key difference is that Xvid is a free codec offered under the GNU General Public License and DivX is a commercial product (although it does offer a free download with limited functionalities). Additionally, some Xvid advocates favor its wider range of encoding features and its output file size controls, whereas DivX users are critical of Xvid s lack of stability and occasional compatibility issues.