Build Google WebM library under WindowsDaniele Esposti's Blog, in 07 March 2012
Google WebM is the new lossy encoder for images (and videos) which promise a better compression than the old and well known JPEG format. The source code is available anche can be build on Linux, Mac OS X and Windows as well.
Anyway, on Windows if you follow the instructions in the README you’ll ended up with this error message:
cwebp.obj : error LNK2019: unresolved external symbol _GUID_WICPixelFormat32bppRGBA referenced in function _ReadPictureWithWIC output\release-static\x86\bin\cwebp.exe : fatal error LNK1120: 1 unresolved externalsNMAKE : fatal error U1077: '"C:\Program Files\Microsoft Visual Studio 9.0\VC\BIN\link.exe"' : return code '0x460' Stop.
That’s happen because Windows SDK 7.0 is missing on your system.
Just download the web installer from here, take a cup of the during the long install procedure and at the end build WebM again, now it will work without problems.