open-vcdiff is an encoder and decoder for the VCDIFF format, as described in RFC 3284: The VCDIFF Generic Differencing and Compression Data Format. You will need to first synchronize gflags and gtest by running git submodule update --init --recursive. Or if you have system installed gflags and/or gtest libraries you can provide -Dvcdiff_use_system_gflags=ON and -Dvcdiff_use_system_gtest=ON for cma