WMV9 uses a VC-1 codec that was available till now only through win32 dlls. Not anymore.
Thanks to Kostya’s diligent, Google-sponsored work, FFmpeg now has a native, open source VC-1 decoder module that is working quite well for most WMV3 media found on the internet. It’s working well enough that there should not be much good reason to be using my old convoluted process for incorporating the SMPTE reference VC-1 decoder into FFmpeg. There are some bugs remaining in Kostya’s code that he is quickly ironing out but it’s time to cut over to it, at least for non-x86 platforms. Some more advanced features are known to be missing. This is primarily because no sample media can be found that exercises those features. If you have some, please pass it along.