Atomicmpc has one of the better video codec comparisons that I have seen in a while. The article gives a good synopsis of why we need to compress video, how we compress video (easy stuff like discrete cosine transformation and macroblocks), and compares some of the more popular codecs available. Specifically, the x264, WMV9, DivX, XviD, and CinePak codecs are all compared with summaries of weaknesses and strengths. Screenshots are also included to show quality at different bitrates and in different types of scenes.
