Problems converting WMVs in WVC1 format

[biskoppen]

I have a bunch of WMV files here.. some in WVC1 format and some in WMV3

The ones WVC1 makes any video converter software go down or make 0 kb files when trying to convert'em

Do I miss some sort of codec of something here?

[VGeorgie]

This is not surprising if you're using any converter based on FFmpeg, as it doesn't support all VC1 profiles or features (as I recall it won't do interlaced VC1). VC1 is a much more sophisticated codec than WMV3. You should probably transcode the VC1 to WMV3 first, but if you're going to do that, you might think about using a more robust converter. You don't mention what you're converting to, but if it's H.264 or FLV I'd try Sorenson Squeeze.