FFmpeg

FFmpeg is the leading multimedia framework, able to decode, encode, transcode,
mux, demux, stream, filter and play pretty much anything that humans and
machines have created. It supports the most obscure ancient formats up to the
cutting edge. No matter if they were designed by some standards committee, the
community or a corporation. It is also highly portable: FFmpeg compiles, runs,
and passes our testing infrastructure FATE across Linux, Mac OS X, Microsoft
Windows, the BSDs, Solaris, etc. under a wide variety of build environments,
machine architectures, and configurations.