If you want to know what video codec Windows Media Encoder or other video converter program is using, you can try a free utility by Microsoft called the Video Decoder Checkup Utility. It’s a simple utility that will display what video codecs are installed on your system and whether they are compatible with Windows Media Player 10 and/or Windows Media Center. For example, below is what I found on my Vista system:
You can use this utility to set the preferred video codec to be used, which is convenient when you have several codecs installed on your system. Vista comes with its own video codec for MPEG-2 videos (which is what most DVDs and Windows Media Center recordings use), so I didn’t need to install any other video codec packs.
So, if you’re having issues with your video conversions, I suggest you try using this utility to see what your system is using for the video codec.