Compress the etc format texture with zlib.
compress file
CompressETCTexture pack ~/Desktop/test.pvr ~/Desktop/compressed.pvr
uncompress file
CompressETCTexture unpack ~/Desktop/compressed.pvr ~/Desktop/test_compressed.pvr
build for xcode
mkdir build
cd build
cmake -G "Xcode" ..
build for vs2013 (only for win32)
mkdir build
cd build
cmake -G "Visual Studio 12 2013" ..