Xvid (formerly XviD) is an open source MPEG-4 video codec, implementing MPEG-4 Simple Profile, Advanced Simple Profile, and Advanced Video Coding standards. It is written in C with assembler optimizations for quality and speed (including MMX, SSE, and 3Dnow! code for i386 and AltiVec for PowerPC), and is especially optimized towards offline, multi-pass compression for storage and archival purposes.
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