主要是通过cmake工具来编译的(cmake3.8.0),一般编译会出现两个问题：
1.在opencv3.2的configure阶段，主要错误如下:
file DOWNLOAD HASH mismatchfor file: [D:/Program Files (x86)/opencv/sources/3rdparty/ffmpeg/downloads/35fe6ccdda6d7a04e9056b0d73b98e76/opencv_ffmpeg_64.dll]expected hash: [35fe6ccdda6d7a04e9056b0d73b98e76]actual hash: [f112aef8bcfad76757e2ebf06c7cf6e5]status: [28;"Timeout was reached"]
原因：一般是下载opencv_ffmpeg_64超时，我的解决办法是再次点击configure就解决了，如果没解决，可以参考网上下载该文件放置到具体目录下。
2.在添加contrib时，点击configure时，出现如下错误：
file DOWNLOAD HASH mismatchfor file: [D:/Program Files (x86)/opencv/sources/3rdparty/ffmpeg/downloads/35fe6ccdda6d7a04e9056b0d73b98e76/opencv_ffmpeg_64.dll]expected hash: [35fe6ccdda6d7a04e9056b0d73b98e76]actual hash: [f112aef8bcfad76757e2ebf06c7cf6e5]status: [28;"Timeout was reached"] CMake Error at H:/OpenCV/opencv/sources/cmake/OpenCVUtils.cmake:1005 (file): file MD5 failed to read file "H:/OpenCV/Library/3rdparty/protobuf/": Permission denied Call Stack (most recent call first): H:/OpenCV/opencv_contrib-master/modules/dnn/cmake/OpenCVFindLibProtobuf.cmake:32 (ocv_download) H:/OpenCV/opencv_contrib-master/modules/dnn/CMakeLists.txt:5 (include)
原因：个人猜测可能与contrib包有问题和protobuf没下载好的关系，有些contrib编译不行或者没有与opencv版本匹配吧。解决办法：
下载protobuf-cpp-3.1.0.tar.gz，那么就手动下载它并放在：Cmake编译所需 存放位置： D:\MyConfig\opencv_contrib-master\modules\dnn\.download\bd5e3eed635a8d32e2b99658633815ef\v3.1.0 处。
如果在dnn中没有.download，下载一个有download的contrib包。
file DOWNLOAD HASH mismatchfor file: [D:/Program Files (x86)/opencv/sources/ 3 rdparty/ffmpeg/downloads/ 35 fe6ccdda6d7a04e9056b0d73b98e76/opencv_ffmpeg_64 .dll ]expected hash: [ 35 fe6ccdda6d7a04e9056b0d73b98e76]actual hash: [f112aef8bcfad76757e2ebf06c7cf6e5] status: [ 28 ;"Timeout was reached"]
