Compiling MinGW libs for OpenCV under Windows

Question

I am trying to compile OpenCV 3.0 static libraries for MINGW under Windows 7. To do so, I:

1. downloaded and unpacked OpenCV
2. downloaded and installed MingW
3. downloaded and installed CMake

I also added path to the system "Path" variable to the "bin" directories of OpenCV, MinGW and CMake.

After that I:

4. run cmake-gui

   4.1. configured with source code "opencv/sources"

   4.2. generated makefile

Everything seems to be OK so far, Makefile already exist in the opencv/sources.

Now I want to compile with make:

c:\OpenCV_3_0\opencv\sources>i:\MinGW\msys\1.0\bin\make.exe
Microsoft Windows [Version 6.1.7601]
Copyright (c) 2009 Microsoft Corporation. All rights reserved.

And nothing happened. Could anyone help me what can be wrong?

Make version seem to be OK: i:\OpenCV_3_0\opencv\sources>make -v GNU Make 3.81 Copyright (C) 2006 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

This program built for i686-pc-msys

Also g++ seems to be OK:

i:\OpenCV_3_0\opencv\sources>g++ -v
Using built-in specs.
COLLECT_GCC=g++
COLLECT_LTO_WRAPPER=i:/mingw/bin/../libexec/gcc/mingw32/4.8.1/lto-wrapper.exe
Target: mingw32
Configured with: ../gcc-4.8.1/configure --prefix=/mingw --host=mingw32 --build=m
ingw32 --without-pic --enable-shared --enable-static --with-gnu-ld --enable-lto
--enable-libssp --disable-multilib --enable-languages=c,c++,fortran,objc,obj-c++
,ada --disable-sjlj-exceptions --with-dwarf2 --disable-win32-registry --enable-l
ibstdcxx-debug --enable-version-specific-runtime-libs --with-gmp=/usr/src/pkg/gm
p-5.1.2-1-mingw32-src/bld --with-mpc=/usr/src/pkg/mpc-1.0.1-1-mingw32-src/bld --
with-mpfr= --with-system-zlib --with-gnu-as --enable-decimal-float=yes --enable-
libgomp --enable-threads --with-libiconv-prefix=/mingw32 --with-libintl-prefix=/
mingw --disable-bootstrap LDFLAGS=-s CFLAGS=-D_USE_32BIT_TIME_T
Thread model: win32
gcc version 4.8.1 (GCC)

Solution

there are 3 relevant folders here:

• the source tree. leave it untouched (until you absolutely know what you're doing) . don't build into that one, else you can never cleanup properly.
• the build folder. all cmake / make generated temp files go here. it can be anywhere on your disk, and you may even delete it later (expect ~2gb temp files)
• the install folder, that's where the final libs/exe/headers/data go

---

1. decide, wether or not you want the contrib_repo contents, evt. dl that.
2. create a build folder, cd into it.
3. run cmake/cmake-gui from there . if you're using the cmdline, the last arg should be the opencv source folder (where CmakeLists.txt lives)
4. rinse and repeat, until you're total happy with the cmake output
5. run: mingw32-make
6. if there were no errors run: mingw32-make install

---

• using mingw is a bit tricky, you will have to explicitly specify your compiler / make tool in the cmake-settings
• if you add the contrib modules, you might have to exclude some of them (not all build properly atm.)
• -D BUILD_SHARED_LIBS=OFF for static libs
• -D CMAKE_INSTALL_PREFIX=your_install_dir // please set that properly.

---

here's what i finally used: (please don't slavishly copy that..)

cmake -G "MinGW Makefiles" -D CMAKE_CXX_COMPILER="D:\Programme\MinGW\bin\mingw32-g++.exe" -D CMAKE_MAKE_PROGRAM="D:\Programme\MinGW\bin\mingw32-make.exe" -D OPENCV_EXTRA_MODULES_PATH="../../opencv_contrib/modules" -D WITH_IPP=OFF -D WITH_OPENCL=OFF -D BUILD_TIFF=ON -D WITH_TIFF=ON -D BUILD_PNG=ON -D WITH_PNG=ON -D BUILD_ZLIB=ON -D WITH_JASPER=OFF -D WITH_OPENEXR=OFF -D BUILD_OPENEXR=OFF -D BUILD_SHARED_LIBS=OFF -D BUILD_TESTS=OFF -D BUILD_PERF_TESTS=OFF -D BUILD_opencv_apps=OFF -D BUILD_examples=OFF -D BUILD_opencv_datasets=OFF -D BUILD_opencv_line_descriptor=OFF  ..
mingw32-make
mingw32-make install