dshow.h -->*come with CodeBlocks installation.
Wrong - its part of the compiler we bundle with C::B in a 
special setup package.
Update the compiler, annoy to the compiler provider or simply google and add the missing SDK.
Please note that such compiler errors are 
not Code::Blocks errors and therefore don't belong in this forum.
Also, please note what you agreed to when registering with the forum. Thank you.