Ideally, I don't think we want to link to libavcodec at all. We should import code for as many filters as native implements, without stepping on patented territory.
How would you benefit from ffmpeg update in a seamlessly manner?
Note that some months ago, I did a version of the wrapper that directly uses source files in the makefile but I realized that taking benefit of acceleration (i386, mmx, sse, etc...) would require merging a lot of things from ffmpeg build to Wine's one. No to mention that I was not sure that ffmpeg sources would be accepted again in Wine tree. That's why I switched back to use the library.
That way, apps that specifically ask for CLSID_CMpegAudioCodec, for example, will get exactly what they want.
I was planning to redirect all these standard DirectShow filters to the wrapper.
Bye, Christian