The open source XviD video codec is currently available for download. The beta 1 version with the codname "Aloha" offers a new API, a special mode for animations as well as DivX support. - New API.
- New Motion Estimation system with SAD based algorithms, or Rate Distortion optimized algorithms.
- Dynamic frame type decision based on a fast motion estimation pass
- Support for bvops and svops (up to 3 warp points).
- QuarterPel precision.
- Trellis optimization for h263 and MPEG quantization schemes.
- Special mode for cartoons/anime like futuruma/the simpsons or any animation with flat color areas.
- Mod 2 resolution support.
- Two pass algorithm

More information available in here. You can download the source come in the XViD website.