DivX
Also known as: DivX codec, .divx file, DivX video
DivX is an MPEG-4 Part 2 video codec that became hugely popular in the early 2000s for shrinking DVD-quality movies to a fraction of their size, often small enough to fit on a CD. It is a codec (and brand), not a container, and is largely superseded by H.264.
- MPEG-4 Part 2 video codec, not a container
- Defined the DVD-rip era; often wrapped in AVI
- Superseded by H.264 for new video
Why DivX mattered
DivX was the codec of the DVD-rip era. It compressed video using MPEG-4 Part 2, letting people store movies that previously needed a whole DVD in a much smaller file, frequently inside an AVI container. That efficiency made it the default for sharing video files before streaming.
DivX is technically distinct from the open-source Xvid codec, though the two were close rivals and produce broadly similar files. Many "DivX" players were certified to handle both.
DivX now
Newer codecs like H.264 offer better quality at smaller sizes, so DivX is rarely used for new encodes. Old DivX/AVI files still play in players like VLC, and converting them to MP4 makes them work on phones and modern apps.