opencv wasm build fails on windows

Question

I am trying to build the wasm version of OpenCV 4.0.0 on Windows 10 and I cannot succeed. I read a lot of posts about similar issues here and on github issue pages about both opencv and emscripten, tried the suggested solutions but none seems to work for me.

My setup is:
OS - Windows 10 64-bit
OpenCV - v4.0.0 (stable) - I tried cloning from github and downloading prebuilt binaries, also v3.4.5
emscripten - v1.38.22
python - bundled with emscripten (2.7.13.1_64bit), also tried 3.6.4
C++ compiler - minGW64
cmake - 3.13.0
openCL headers - from github
binaryen - version_63 from github - I also tried installing it with emsdk install command
git - GitBash windows version

Things that DO work:
- cmake (in GUI and command line, as some posts suggest)
- minGW64 g++ can generate proper executables for win64
- opencv works with g++
- emscripten can compile [hello world].cpp

Things that DO NOT work:
- emscripten fails to generate LLVM bitcode from opencv library but works fine for zlib - here I followed instructions from emscripten docs
- it also fails to compile a simple .cpp file that uses opencv functions like imread and imshow:

error: undefined symbol: _ZN2cv17destroyAllWindowsEv
warning: To disable errors for undefined symbols use `-s ERROR_ON_UNDEFINED_SYMBOLS=0`
error: undefined symbol: _ZN2cv3Mat10deallocateEv
error: undefined symbol: _ZN2cv6imreadERKNSt3__212basic_stringIcNS0_11char_traitsIcEENS0_9allocatorIcEEEEi
error: undefined symbol: _ZN2cv6imshowERKNSt3__212basic_stringIcNS0_11char_traitsIcEENS0_9allocatorIcEEEERKNS_11_InputArrayE
error: undefined symbol: _ZN2cv7waitKeyEi
error: undefined symbol: _ZN2cv8fastFreeEPv
error: undefined symbol: _ZN2cv9thresholdERKNS_11_InputArrayERKNS_12_OutputArrayEddi
Error: Aborting compilation due to previous errors

Here I tried the flag -s ERROR_ON_UNDEFINED_SYMBOLS=0 as suggested in github issues and it indeed turned the errors to warnings but the resulting .js still doesn't work and finds these exact errors as undefined functions.

When I try to build opencv.js with or without --build_wasm option I get:

C:\opencv>python platforms\js\build_js.py build_wasm --build_wasm --emscripten_dir d:\Download\gitEMSDK\emsdk\emscripten\1.38.22
Args: Namespace(build_dir='build_wasm', build_doc=False, build_test=False, build_wasm=True, clean_build_dir=False, config_only=False, disable_wasm=False, emscripten_dir='d:\Download\gitEMSDK\emsdk\emscripten\1.38.22', enable_exception=False, opencv_dir='C:\opencv', skip_config=False)
Check dir C:\opencv\build_wasm (create: True, clean: False)
Check dir C:\opencv (create: False, clean: False)
Check dir d:\Download\gitEMSDK\emsdk\emscripten\1.38.22 (create: False, clean: False)
=====
===== Config OpenCV.js build for wasm
=====
Executing: ['cmake', '-DCMAKE_BUILD_TYPE=Release', "-DCMAKE_TOOLCHAIN_FILE='d:\Download\gitEMSDK\emsdk\emscripten\1.38.22\cmake\Modules\Platform\Emscripten.cmake'", "-DCPU_BASELINE=''", "-DCPU_DISPATCH=''", '-DCV_TRACE=OFF', '-DBUILD_SHARED_LIBS=OFF', '-DWITH_1394=OFF', '-DWITH_ADE=OFF', '-DWITH_VTK=OFF', '-DWITH_EIGEN=OFF', '-DWITH_FFMPEG=OFF', '-DWITH_GSTREAMER=OFF', '-DWITH_GTK=OFF', '-DWITH_GTK_2_X=OFF', '-DWITH_IPP=OFF', '-DWITH_JASPER=OFF', '-DWITH_JPEG=OFF', '-DWITH_WEBP=OFF', '-DWITH_OPENEXR=OFF', '-DWITH_OPENGL=OFF', '-DWITH_OPENVX=OFF', '-DWITH_OPENNI=OFF', '-DWITH_OPENNI2=OFF', '-DWITH_PNG=OFF', '-DWITH_TBB=OFF', '-DWITH_PTHREADS_PF=OFF', '-DWITH_TIFF=OFF', '-DWITH_V4L=OFF', '-DWITH_OPENCL=OFF', '-DWITH_OPENCL_SVM=OFF', '-DWITH_OPENCLAMDFFT=OFF', '-DWITH_OPENCLAMDBLAS=OFF', '-DWITH_GPHOTO2=OFF', '-DWITH_LAPACK=OFF', '-DWITH_ITT=OFF', '-DBUILD_ZLIB=ON', '-DBUILD_opencv_apps=OFF', '-DBUILD_opencv_calib3d=ON', '-DBUILD_opencv_dnn=ON', '-DBUILD_opencv_features2d=ON', '-DBUILD_opencv_flann=ON', '-DBUILD_opencv_gapi=OFF', '-DBUILD_opencv_ml=OFF', '-DBUILD_opencv_photo=ON', '-DBUILD_opencv_imgcodecs=OFF', '-DBUILD_opencv_shape=OFF', '-DBUILD_opencv_videoio=OFF', '-DBUILD_opencv_videostab=OFF', '-DBUILD_opencv_highgui=OFF', '-DBUILD_opencv_superres=OFF', '-DBUILD_opencv_stitching=OFF', '-DBUILD_opencv_java=OFF', '-DBUILD_opencv_js=ON', '-DBUILD_opencv_python2=OFF', '-DBUILD_opencv_python3=OFF', '-DBUILD_EXAMPLES=OFF', '-DBUILD_PACKAGE=OFF', '-DBUILD_TESTS=OFF', '-DBUILD_PERF_TESTS=OFF', '-DBUILD_DOCS=OFF', "-DCMAKE_C_FLAGS='-s WASM=1 '", "-DCMAKE_CXX_FLAGS='-s WASM=1 '", 'C:\opencv']
Re-run cmake no build system arguments
-- Building for: Visual Studio 15 2017
-- Found PythonInterp: D:/Download/gitEMSDK/emsdk/python/2.7.13.1_64bit/python-2.7.13.amd64/python.exe (found suitable version "2.7.13", minimum required is "2.7")
-- Could NOT find PythonLibs (missing: PYTHON_LIBRARIES PYTHON_INCLUDE_DIRS) (Required is at least version "2.7")
-- Cannot probe for Python/Numpy support (because we are cross-compiling OpenCV)
-- If you want to enable Python/Numpy support, set the following variables:
--   PYTHON2_INCLUDE_PATH
--   PYTHON2_LIBRARIES (optional on Unix-like systems)
--   PYTHON2_NUMPY_INCLUDE_DIRS
--   PYTHON3_INCLUDE_PATH
--   PYTHON3_LIBRARIES (optional on Unix-like systems)
--   PYTHON3_NUMPY_INCLUDE_DIRS
-- Could NOT find PythonInterp: Found unsuitable version "2.7.13", but required is at least "3.2" (found D:/Download/gitEMSDK/emsdk/python/2.7.13.1_64bit/python-2.7.13.amd64/python.exe)
-- Performing Test HAVE_CXX_FSIGNED_CHAR
-- Performing Test HAVE_CXX_FSIGNED_CHAR - Failed
-- Performing Test HAVE_C_FSIGNED_CHAR
-- Performing Test HAVE_C_FSIGNED_CHAR - Failed
-- Performing Test HAVE_CXX_W
-- Performing Test HAVE_CXX_W - Failed
-- Performing Test HAVE_C_W
-- Performing Test HAVE_C_W - Failed
-- Performing Test HAVE_CXX_WALL
-- Performing Test HAVE_CXX_WALL - Failed
-- Performing Test HAVE_C_WALL
-- Performing Test HAVE_C_WALL - Failed
-- Performing Test HAVE_CXX_WERROR_RETURN_TYPE
-- Performing Test HAVE_CXX_WERROR_RETURN_TYPE - Failed
-- Performing Test HAVE_C_WERROR_RETURN_TYPE
-- Performing Test HAVE_C_WERROR_RETURN_TYPE - Failed
-- Performing Test HAVE_CXX_WERROR_NON_VIRTUAL_DTOR
-- Performing Test HAVE_CXX_WERROR_NON_VIRTUAL_DTOR - Failed
-- Performing Test HAVE_C_WERROR_NON_VIRTUAL_DTOR
-- Performing Test HAVE_C_WERROR_NON_VIRTUAL_DTOR - Failed
-- Performing Test HAVE_CXX_WERROR_ADDRESS
-- Performing Test HAVE_CXX_WERROR_ADDRESS - Failed
-- Performing Test HAVE_C_WERROR_ADDRESS
-- Performing Test HAVE_C_WERROR_ADDRESS - Failed
-- Performing Test HAVE_CXX_WERROR_SEQUENCE_POINT
-- Performing Test HAVE_CXX_WERROR_SEQUENCE_POINT - Failed
-- Performing Test HAVE_C_WERROR_SEQUENCE_POINT
-- Performing Test HAVE_C_WERROR_SEQUENCE_POINT - Failed
-- Performing Test HAVE_CXX_WFORMAT
-- Performing Test HAVE_CXX_WFORMAT - Failed
-- Performing Test HAVE_C_WFORMAT
-- Performing Test HAVE_C_WFORMAT - Failed
-- Performing Test HAVE_CXX_WERROR_FORMAT_SECURITY
-- Performing Test HAVE_CXX_WERROR_FORMAT_SECURITY - Failed
-- Performing Test HAVE_C_WERROR_FORMAT_SECURITY
-- Performing Test HAVE_C_WERROR_FORMAT_SECURITY - Failed
-- Performing Test HAVE_CXX_WMISSING_DECLARATIONS
-- Performing Test HAVE_CXX_WMISSING_DECLARATIONS - Failed
-- Performing Test HAVE_C_WMISSING_DECLARATIONS
-- Performing Test HAVE_C_WMISSING_DECLARATIONS - Failed
-- Performing Test HAVE_CXX_WMISSING_PROTOTYPES
-- Performing Test HAVE_CXX_WMISSING_PROTOTYPES - Failed
-- Performing Test HAVE_C_WMISSING_PROTOTYPES
-- Performing Test HAVE_C_WMISSING_PROTOTYPES - Failed
-- Performing Test HAVE_CXX_WSTRICT_PROTOTYPES
-- Performing Test HAVE_CXX_WSTRICT_PROTOTYPES - Failed
-- Performing Test HAVE_C_WSTRICT_PROTOTYPES
-- Performing Test HAVE_C_WSTRICT_PROTOTYPES - Failed
-- Performing Test HAVE_CXX_WUNDEF
-- Performing Test HAVE_CXX_WUNDEF - Failed
-- Performing Test HAVE_C_WUNDEF
-- Performing Test HAVE_C_WUNDEF - Failed
-- Performing Test HAVE_CXX_WINIT_SELF
-- Performing Test HAVE_CXX_WINIT_SELF - Failed
-- Performing Test HAVE_C_WINIT_SELF
-- Performing Test HAVE_C_WINIT_SELF - Failed
-- Performing Test HAVE_CXX_WPOINTER_ARITH
-- Performing Test HAVE_CXX_WPOINTER_ARITH - Failed
-- Performing Test HAVE_C_WPOINTER_ARITH
-- Performing Test HAVE_C_WPOINTER_ARITH - Failed
-- Performing Test HAVE_CXX_WSHADOW
-- Performing Test HAVE_CXX_WSHADOW - Failed
-- Performing Test HAVE_C_WSHADOW
-- Performing Test HAVE_C_WSHADOW - Failed
-- Performing Test HAVE_CXX_WSIGN_PROMO
-- Performing Test HAVE_CXX_WSIGN_PROMO - Failed
-- Performing Test HAVE_C_WSIGN_PROMO
-- Performing Test HAVE_C_WSIGN_PROMO - Failed
-- Performing Test HAVE_CXX_WUNINITIALIZED
-- Performing Test HAVE_CXX_WUNINITIALIZED - Failed
-- Performing Test HAVE_C_WUNINITIALIZED
-- Performing Test HAVE_C_WUNINITIALIZED - Failed
-- Performing Test HAVE_CXX_WINCONSISTENT_MISSING_OVERRIDE
-- Performing Test HAVE_CXX_WINCONSISTENT_MISSING_OVERRIDE - Failed
-- Performing Test HAVE_C_WINCONSISTENT_MISSING_OVERRIDE
-- Performing Test HAVE_C_WINCONSISTENT_MISSING_OVERRIDE - Failed
-- Performing Test HAVE_CXX_WNO_NARROWING
-- Performing Test HAVE_CXX_WNO_NARROWING - Failed
-- Performing Test HAVE_C_WNO_NARROWING
-- Performing Test HAVE_C_WNO_NARROWING - Failed
-- Performing Test HAVE_CXX_WNO_DELETE_NON_VIRTUAL_DTOR
-- Performing Test HAVE_CXX_WNO_DELETE_NON_VIRTUAL_DTOR - Failed
-- Performing Test HAVE_C_WNO_DELETE_NON_VIRTUAL_DTOR
-- Performing Test HAVE_C_WNO_DELETE_NON_VIRTUAL_DTOR - Failed
-- Performing Test HAVE_CXX_WNO_UNNAMED_TYPE_TEMPLATE_ARGS
-- Performing Test HAVE_CXX_WNO_UNNAMED_TYPE_TEMPLATE_ARGS - Failed
-- Performing Test HAVE_C_WNO_UNNAMED_TYPE_TEMPLATE_ARGS
-- Performing Test HAVE_C_WNO_UNNAMED_TYPE_TEMPLATE_ARGS - Failed
-- Performing Test HAVE_CXX_WNO_COMMENT
-- Performing Test HAVE_CXX_WNO_COMMENT - Failed
-- Performing Test HAVE_C_WNO_COMMENT
-- Performing Test HAVE_C_WNO_COMMENT - Failed
-- Performing Test HAVE_CXX_FDIAGNOSTICS_SHOW_OPTION
-- Performing Test HAVE_CXX_FDIAGNOSTICS_SHOW_OPTION - Failed
-- Performing Test HAVE_C_FDIAGNOSTICS_SHOW_OPTION
-- Performing Test HAVE_C_FDIAGNOSTICS_SHOW_OPTION - Failed
-- Performing Test HAVE_CXX_PTHREAD
-- Performing Test HAVE_CXX_PTHREAD - Failed
-- Performing Test HAVE_C_PTHREAD
-- Performing Test HAVE_C_PTHREAD - Failed
-- Performing Test HAVE_CXX_QUNUSED_ARGUMENTS
-- Performing Test HAVE_CXX_QUNUSED_ARGUMENTS - Failed
-- Performing Test HAVE_C_QUNUSED_ARGUMENTS
-- Performing Test HAVE_C_QUNUSED_ARGUMENTS - Failed
-- Performing Test HAVE_CXX_FFUNCTION_SECTIONS
-- Performing Test HAVE_CXX_FFUNCTION_SECTIONS - Failed
-- Performing Test HAVE_C_FFUNCTION_SECTIONS
-- Performing Test HAVE_C_FFUNCTION_SECTIONS - Failed
-- Performing Test HAVE_CXX_FDATA_SECTIONS
-- Performing Test HAVE_CXX_FDATA_SECTIONS - Failed
-- Performing Test HAVE_C_FDATA_SECTIONS
-- Performing Test HAVE_C_FDATA_SECTIONS - Failed
-- Performing Test HAVE_CPU_BASELINE_FLAGS
-- Performing Test HAVE_CPU_BASELINE_FLAGS - Failed
CMake Error at cmake/OpenCVCompilerOptimizations.cmake:524 (message):
  Compiler doesn't support baseline optimization flags:
Call Stack (most recent call first):
  cmake/OpenCVCompilerOptions.cmake:270 (ocv_compiler_optimization_options)
  CMakeLists.txt:682 (include)


-- Configuring incomplete, errors occurred!
See also "C:/opencv/build_wasm/CMakeFiles/CMakeOutput.log".
See also "C:/opencv/build_wasm/CMakeFiles/CMakeError.log".
Traceback (most recent call last):
  File "platforms\js\build_js.py", line 224, in 
    builder.config()
  File "platforms\js\build_js.py", line 164, in config
    execute(cmd)
  File "platforms\js\build_js.py", line 23, in execute
    raise Fail("Child returned: %s" % retcode)
__main__.Fail: Child returned: 1

even though I followed this post and used python2 with opencl, binaryen, cmake, emscripten_dir provided

I also tried direct cmake command with options from here like:

cmake -DCMAKE_BUILD_TYPE=Release -DCMAKE_TOOLCHAIN_FILE='d:/microSoft/emsdk/emscripten/1.38.21/cmake/Modules/Platform/Emscripten.cmake' -DCPU_BASELINE='' -DCPU_DISPATCH='' -DCV_TRACE=OFF -DBUILD_SHARED_LIBS=OFF -DWITH_1394=OFF -DWITH_ADE=OFF -DWITH_VTK=OFF -DWITH_EIGEN=OFF -DWITH_FFMPEG=OFF -DWITH_GSTREAMER=OFF -DWITH_GTK=OFF -DWITH_GTK_2_X=OFF -DWITH_IPP=OFF -DWITH_JASPER=OFF -DWITH_JPEG=OFF -DWITH_WEBP=OFF -DWITH_OPENEXR=OFF -DWITH_OPENGL=OFF -DWITH_OPENVX=OFF -DWITH_OPENNI=OFF -DWITH_OPENNI2=OFF -DWITH_PNG=OFF -DWITH_TBB=OFF -DWITH_PTHREADS_PF=OFF -DWITH_TIFF=OFF -DWITH_V4L=OFF -DWITH_OPENCL=OFF -DWITH_OPENCL_SVM=OFF -DWITH_OPENCLAMDFFT=OFF -DWITH_OPENCLAMDBLAS=OFF -DWITH_GPHOTO2=OFF -DWITH_LAPACK=OFF -DWITH_ITT=OFF -DBUILD_ZLIB=ON -DBUILD_opencv_apps=OFF -DBUILD_opencv_calib3d=ON -DBUILD_opencv_dnn=ON -DBUILD_opencv_features2d=ON -DBUILD_opencv_flann=ON -DBUILD_opencv_gapi=OFF -DBUILD_opencv_ml=OFF -DBUILD_opencv_photo=ON -DBUILD_opencv_imgcodecs=OFF -DBUILD_opencv_shape=OFF -DBUILD_opencv_videoio=OFF -DBUILD_opencv_videostab=OFF -DBUILD_opencv_highgui=OFF -DBUILD_opencv_superres=OFF -DBUILD_opencv_stitching=OFF -DBUILD_opencv_java=OFF -DBUILD_opencv_js=ON -DBUILD_opencv_python2=OFF -DBUILD_opencv_python3=OFF -DBUILD_EXAMPLES=OFF -DBUILD_PACKAGE=OFF -DBUILD_TESTS=OFF -DBUILD_PERF_TESTS=OFF -DPYTHON_EXECUTABLE=d:/microSoft/emsdk/python/2.7.13.1_64bit/python-2.7.13.amd64/python.exe -DPYTHON_INCLUDE_DIRS=d:/microSoft/emsdk/python/2.7.13.1_64bit/python-2.7.13.amd64/include -DPYTHON_LIBRARY=d:/microSoft/emsdk/python/2.7.13.1_64bit/python-2.7.13.amd64/libs/libpython27.a -S . -B build_js

This finished but mingw32-make failed

If you find anything odd in my setup or the command I try please let me know. Any suggestion is welcome. Thanks a lot.

opencv wasm build fails on windows

Answers (1)

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