Voukoder - Use the best encoders available in Adobe Premiere CC!
K-Lite Codec Pack - K-Lite Codec Pack is a collection of codecs, DirectShow filters and tools.
3ivx - 3ivx is a video codec suite, created by 3ivx Technologies
CCCP: Combined Community Codec Pack - The CCCP: Combined Community Codec Pack is a codec pack specifically built for playing videos (including mkv).
FFmpeg - Open source multimedia suite for conversion, playback, profiling, and streaming.
LAVfilters - LAV Filters are a set of open-source DirectShow filters, aimed to eventually replace the better...