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.
sr-convert is a sample-rate conversion utility for WAV files. It supports a wide variety of sampling rates and can convert from any of the supported rates to any other. It runs under either x86 Linux or Windows and uses SSE instructions if they are available. Great pains have been taken to make sure that the sound quality of the conversion is excellent.