For what parts do you need the webservices? To start timeshifting and get the rtsp streams? Couldn't you just include the tvserver dlls and write the method yourself (WebTvResult StartTimeShifting(int idChannel))?
I'm not really good with VB but afaik it shouldn't be a problem using a c# dll in a vb project?!?
I'm not really good with VB but afaik it shouldn't be a problem using a c# dll in a vb project?!?