Error: undefined reference to `cvReleaseImage' (opencv + Qt)

Negar_mg · wrote on 27 Jun 2021, 10:11

Hi,
I followed this tutorial:
https://www.youtube.com/watch?v=ox6NFWE8xg4

this is my .pro file:

QT -= gui

CONFIG += c++11 console
CONFIG -= app_bundle

SOURCES +=
main.cpp

qnx: target.path = /tmp/$${TARGET}/bin
else: unix:!android: target.path = /opt/$${TARGET}/bin
!isEmpty(target.path): INSTALLS += target
INCLUDEPATH += C:\Qt\opencv_cv2\OPENCV1\include
LIBS += -LC:\Qt\opencv_cv2\OPENCV1\build-qt\lib
-lopencv_calib3d249d
-lopencv_contrib249d
-lopencv_core249d
-lopencv_features2d249d
-lopencv_flann249d
-lopencv_gpu249d
-lopencv_highgui249d
-lopencv_imgproc249d
-lopencv_legacy249d
-lopencv_ml249d
-lopencv_nonfree249d
-lopencv_objdetect249d
-lopencv_ocl249d
-lopencv_photo249d
-lopencv_stitching249d
-lopencv_superres249d
-lopencv_ts249d
-lopencv_video249d
-lopencv_videostab249d

this is my main file:

#include <iostream>

#include <opencv2/highgui/highgui.hpp>
#include <opencv2/imgproc/imgproc.hpp>
#include <opencv2/core/core.hpp>

using namespace cv;
using namespace std;

int main()
{
string imgloc="D:/ide/111.png";

Mat image = imread(imgloc);

// Check for failure
if (image.empty())
{
cout << "Could not open or find the image" << endl;
return -1;
}

String windowName = "opencv"; //Name of the window

namedWindow(windowName); // Create a window

imshow(windowName, image); // Show our image inside the created window.

waitKey(0); // Wait for any keystroke in the window


return 0;

}

and this is my log output:

14:38:00: Running steps for project opencvtest10...
14:38:00: Starting: "C:\Qt\Qt5.12.11\5.12.11\mingw73_32\bin\qmake.exe" C:\Users\test\Documents\opencvtest10\opencvtest10.pro -spec win32-g++ "CONFIG+=debug" "CONFIG+=qml_debug"
Info: creating stash file C:\Users\test\Documents\build-opencvtest10-Desktop_Qt_5_12_11_MinGW_32_bit-Debug.qmake.stash
14:38:04: The process "C:\Qt\Qt5.12.11\5.12.11\mingw73_32\bin\qmake.exe" exited normally.
14:38:04: Starting: "C:\Qt\Qt5.12.11\Tools\mingw730_32\bin\mingw32-make.exe" -f C:/Users/test/Documents/build-opencvtest10-Desktop_Qt_5_12_11_MinGW_32_bit-Debug/Makefile qmake_all
mingw32-make: Nothing to be done for 'qmake_all'.
14:38:05: The process "C:\Qt\Qt5.12.11\Tools\mingw730_32\bin\mingw32-make.exe" exited normally.
14:38:05: Starting: "C:\Qt\Qt5.12.11\Tools\mingw730_32\bin\mingw32-make.exe" -j4
C:/Qt/Qt5.12.11/Tools/mingw730_32/bin/mingw32-make -f Makefile.Debug
mingw32-make[1]: Entering directory 'C:/Users/test/Documents/build-opencvtest10-Desktop_Qt_5_12_11_MinGW_32_bit-Debug'
g++ -c -fno-keep-inline-dllexport -g -std=gnu++11 -Wall -W -Wextra -fexceptions -mthreads -DUNICODE -D_UNICODE -DWIN32 -DMINGW_HAS_SECURE_API=1 -DQT_QML_DEBUG -DQT_CORE_LIB -I..\opencvtest10 -I. -I........\Qt\opencv_cv2\OPENCV1\include -I........\Qt\Qt5.12.11\5.12.11\mingw73_32\include -I........\Qt\Qt5.12.11\5.12.11\mingw73_32\include\QtCore -Idebug -I........\Qt\Qt5.12.11\5.12.11\mingw73_32\mkspecs\win32-g++ -o debug\main.o ..\opencvtest10\main.cpp
g++ -Wl,-subsystem,console -mthreads -o debug\opencvtest10.exe debug/main.o -LC:\Qt\opencv_cv2\OPENCV1\build-qt\lib -lopencv_calib3d249d -lopencv_contrib249d -lopencv_core249d -lopencv_features2d249d -lopencv_flann249d -lopencv_gpu249d -lopencv_highgui249d -lopencv_imgproc249d -lopencv_legacy249d -lopencv_ml249d -lopencv_nonfree249d -lopencv_objdetect249d -lopencv_ocl249d -lopencv_photo249d -lopencv_stitching249d -lopencv_superres249d -lopencv_ts249d -lopencv_video249d -lopencv_videostab249d C:\Qt\Qt5.12.11\5.12.11\mingw73_32\lib\libQt5Cored.a
debug/main.o: In function main': C:\Users\test\Documents\build-opencvtest10-Desktop_Qt_5_12_11_MinGW_32_bit-Debug/../opencvtest10/main.cpp:14: undefined reference to cv::imread(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, int)'
C:\Users\test\Documents\build-opencvtest10-Desktop_Qt_5_12_11_MinGW_32_bit-Debug/../opencvtest10/main.cpp:25: undefined reference to cv::namedWindow(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, int)' C:\Users\test\Documents\build-opencvtest10-Desktop_Qt_5_12_11_MinGW_32_bit-Debug/../opencvtest10/main.cpp:27: undefined reference to cv::imshow(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, cv::_InputArray const&)'
collect2.exe: error: ld returned 1 exit status
mingw32-make[1]: *** [Makefile.Debug:65: debug/opencvtest10.exe] Error 1
mingw32-make: *** [Makefile:38: debug] Error 2
mingw32-make[1]: Leaving directory 'C:/Users/test/Documents/build-opencvtest10-Desktop_Qt_5_12_11_MinGW_32_bit-Debug'
14:38:13: The process "C:\Qt\Qt5.12.11\Tools\mingw730_32\bin\mingw32-make.exe" exited with code 2.
Error while building/deploying project opencvtest10 (kit: Desktop Qt 5.12.11 MinGW 32-bit)
When executing step "Make"
14:38:13: Elapsed time: 00:13.

is there anyone who knows solution of this problems ? thanks for replies

SGaist · 27 Jun 2021, 11:43

Hi and welcome to devnet,

Do you have OpenCV built for the correct architecture ?
Is it built with MinGW ?

mrjj · S SGaist 27 Jun 2021, 11:13

@SGaist

Hi
The video contains links to a Qt build version it seems. ( 3rd link in the text below)
But its for 5.4 ( and seems to contain virus/unclean ) so I could not check what
was actually inside.

and it seems the poster is using
Qt5.12.11 so I guess that is why it won't link.

@Negar_mg

I think you might have better luck with
https://wiki.qt.io/How_to_setup_Qt_and_openCV_on_Windows
The other video is using something that is really old.

Unless it must be Qt 54. ofc. even if very, very old.

Negar_mg · wrote on 27 Jun 2021, 13:32

i am using
Qt5.12.11 ,
OpenCV-2.4.9- Qt 5.4,
opencv-4.5.2-vc14_vc15
windows10

i did that link's steps but i have some errors in cmake.
this is logs:

{
sizeof(void) = 4 on 64 bit processor. Assume 32-bit compilation mode
Found PythonInterp: C:/Users/test/AppData/Local/Programs/Python/Python37/python.exe (found suitable version "3.7", minimum required is "2.7")
CMake Warning at cmake/OpenCVDetectPython.cmake:81 (message):
CMake's 'find_host_package(PythonInterp 2.7)' found wrong Python version:

PYTHON_EXECUTABLE=C:/Users/test/AppData/Local/Programs/Python/Python37/python.exe

PYTHON_VERSION_STRING=3.7

Consider providing the 'PYTHON2_EXECUTABLE' variable via CMake command line
or environment variables

Call Stack (most recent call first):
cmake/OpenCVDetectPython.cmake:271 (find_python)
CMakeLists.txt:614 (include)

Could NOT find Python2 (missing: Python2_EXECUTABLE Interpreter)
Reason given by package:
Interpreter: Wrong major version for the interpreter "C:/Users/test/AppData/Local/Programs/Python/Python37/python.exe"

}

{
Performing Test HAVE_CXX_WNO_ENUM_COMPARE_SWITCH - Failed
Could NOT find JNI (missing: JAVA_AWT_LIBRARY JAVA_JVM_LIBRARY JAVA_INCLUDE_PATH JAVA_INCLUDE_PATH2 JAVA_AWT_INCLUDE_PATH)
VTK is not found. Please set -DVTK_DIR in CMake to VTK build directory, or to VTK install subdirectory with VTKConfig.cmake file
ADE: Download: v0.1.1f.zip
Try 1 failed
CMake Warning at cmake/OpenCVDownload.cmake:202 (message):
ADE: Download failed: 35;"SSL connect error"

For details please refer to the download log file:

C:/Qt/opencv_cv2/opencv/release/CMakeDownloadLog.txt

Call Stack (most recent call first):
modules/gapi/cmake/DownloadADE.cmake:5 (ocv_download)
modules/gapi/cmake/init.cmake:19 (include)
cmake/OpenCVModule.cmake:298 (include)
cmake/OpenCVModule.cmake:361 (_add_modules_1)
modules/CMakeLists.txt:7 (ocv_glob_modules)

OpenCV Python: during development append to PYTHONPATH: C:/Qt/opencv_cv2/opencv/release/python_loader
Could NOT find PkgConfig (missing: PKG_CONFIG_EXECUTABLE)
FFMPEG: Download: opencv_videoio_ffmpeg.dll
Try 1 failed
CMake Warning at cmake/OpenCVDownload.cmake:202 (message):
FFMPEG: Download failed: 35;"SSL connect error"

For details please refer to the download log file:

C:/Qt/opencv_cv2/opencv/release/CMakeDownloadLog.txt

Call Stack (most recent call first):
3rdparty/ffmpeg/ffmpeg.cmake:20 (ocv_download)
modules/videoio/cmake/detect_ffmpeg.cmake:14 (download_win_ffmpeg)
modules/videoio/cmake/init.cmake:7 (include)
modules/videoio/cmake/init.cmake:18 (add_backend)
cmake/OpenCVModule.cmake:298 (include)
cmake/OpenCVModule.cmake:361 (_add_modules_1)
modules/CMakeLists.txt:7 (ocv_glob_modules)

FFMPEG: Download: opencv_videoio_ffmpeg_64.dll
Try 1 failed
CMake Warning at cmake/OpenCVDownload.cmake:202 (message):
FFMPEG: Download failed: 35;"SSL connect error"

For details please refer to the download log file:

C:/Qt/opencv_cv2/opencv/release/CMakeDownloadLog.txt

Call Stack (most recent call first):
3rdparty/ffmpeg/ffmpeg.cmake:20 (ocv_download)
modules/videoio/cmake/detect_ffmpeg.cmake:14 (download_win_ffmpeg)
modules/videoio/cmake/init.cmake:7 (include)
modules/videoio/cmake/init.cmake:18 (add_backend)
cmake/OpenCVModule.cmake:298 (include)
cmake/OpenCVModule.cmake:361 (_add_modules_1)
modules/CMakeLists.txt:7 (ocv_glob_modules)

FFMPEG: Download: ffmpeg_version.cmake
Try 1 failed
CMake Warning at cmake/OpenCVDownload.cmake:202 (message):
FFMPEG: Download failed: 35;"SSL connect error"

For details please refer to the download log file:

C:/Qt/opencv_cv2/opencv/release/CMakeDownloadLog.txt

Call Stack (most recent call first):
3rdparty/ffmpeg/ffmpeg.cmake:20 (ocv_download)
modules/videoio/cmake/detect_ffmpeg.cmake:14 (download_win_ffmpeg)
modules/videoio/cmake/init.cmake:7 (include)
modules/videoio/cmake/init.cmake:18 (add_backend)
cmake/OpenCVModule.cmake:298 (include)
cmake/OpenCVModule.cmake:361 (_add_modules_1)
modules/CMakeLists.txt:7 (ocv_glob_modules)

}

{
Performing Test HAVE_CXX_WNO_UNUSED_PRIVATE_FIELD - Failed
CMake Warning at cmake/OpenCVGenSetupVars.cmake:54 (message):
CONFIGURATION IS NOT SUPPORTED: validate setupvars script in install
directory
Call Stack (most recent call first):
CMakeLists.txt:1010 (include)

}

SGaist · wrote on 27 Jun 2021, 21:51

What exactly are you trying to build ?

Negar_mg · wrote on 28 Jun 2021, 04:02

I want to write a program to display an image or video from a webcam using Qt and Open CV.
But I was not able to add Open CV to QT. When I used the following link, I encountered those errors in CMake.
/................................................................................................
https://wiki.qt.io/How_to_setup_Qt_and_openCV_on_Windows
/...............................................................................................
And when I used the link from YouTube that I sent in the first comment, I encountered those errors in Qt.

SGaist · wrote on 28 Jun 2021, 21:17

From the looks of it, the OpenCV 4 you downloaded is built with Visual Studio, thus you have to use a Visual Studio build of Qt as well as mixing C++ compilers is not possible.

Negar_mg · 29 Jun 2021, 04:14

You mean you think I can not use opencv with Qt?
Is there no way?

jsulm · wrote on 29 Jun 2021, 04:14

@Negar_mg said in Error: undefined reference to `cvReleaseImage' (opencv + Qt):

You mean you think I can not use opencv with Qt?

No, that's not what @SGaist means.
What he means is that you can't mix binaries built with different C++ compilers.
And because OpenCV you downloaded was built using compiler from Microsoft Visual Studio you also need Qt built with this compiler. So, simply install MSVC2017 or MSVC2019 Qt.

Negar_mg · wrote on 29 Jun 2021, 04:22

thanks alot :)

Negar_mg · 29 Jun 2021, 07:06

If I understand correctly, there are 2 ways to solve this issue:

1- use vc compiler in qt to compile my codes.

Here is a link I found for that, please let me know if it is correct:

https://stackoverflow.com/questions/47773289/debugging-in-qtcreator-using-msvc2017-compiler

2- download and compile opencv using qt compiler, and then refering to that folder in my qt.
Is this compiler called minWG?
Please give me a link or instruction on how to do that.

jsulm · wrote on 29 Jun 2021, 07:06

@Negar_mg said in Error: undefined reference to `cvReleaseImage' (opencv + Qt):

Is this compiler called minWG?

I don't know what compiler you are using. This is something you should know.

To use Visual Studio compiler you first need to install Visual Studio together with C++ tools. You can use the free Community edition. Then install Qt for that Visual Studio version. Then you should have a Kit in QtCreator configured to use Visual Studio compiler. The link you posted looks legit, just download more recent Qt version.

Negar_mg · 29 Jun 2021, 07:22

I do not need vs and i have uninstalled it
But i still get the error mentioned above
How can i install opencv on qt without visual studio?

jsulm · wrote on 29 Jun 2021, 07:22

@Negar_mg Build OpenCV using the compiler you're using with Qt...
@mrjj Already gave you a link: https://wiki.qt.io/How_to_setup_Qt_and_openCV_on_Windows
Also there is official OpenCV documentation for that: https://docs.opencv.org/3.4/d3/d52/tutorial_windows_install.html

Negar_mg · wrote on 29 Jun 2021, 07:40

I have followed the steps in the link you provided, but cmake step raised some errors. Its log is bellow:

Log:
{sizeof(void) = 4 on 64 bit processor. Assume 32-bit compilation mode
Found PythonInterp: C:/Users/test/AppData/Local/Programs/Python/Python37/python.exe (found suitable version "3.7", minimum required is "2.7")
CMake Warning at cmake/OpenCVDetectPython.cmake:81 (message):
CMake's 'find_host_package(PythonInterp 2.7)' found wrong Python version:
PYTHON_EXECUTABLE=C:/Users/test/AppData/Local/Programs/Python/Python37/python.exe
PYTHON_VERSION_STRING=3.7
Consider providing the 'PYTHON2_EXECUTABLE' variable via CMake command line
or environment variables
Call Stack (most recent call first):
cmake/OpenCVDetectPython.cmake:271 (find_python)
CMakeLists.txt:614 (include)
Could NOT find Python2 (missing: Python2_EXECUTABLE Interpreter)
Reason given by package:
Interpreter: Wrong major version for the interpreter "C:/Users/test/AppData/Local/Programs/Python/Python37/python.exe"
}
//..............................
{
Performing Test HAVE_CXX_WNO_ENUM_COMPARE_SWITCH - Failed
Could NOT find JNI (missing: JAVA_AWT_LIBRARY JAVA_JVM_LIBRARY JAVA_INCLUDE_PATH JAVA_INCLUDE_PATH2 JAVA_AWT_INCLUDE_PATH)
VTK is not found. Please set -DVTK_DIR in CMake to VTK build directory, or to VTK install subdirectory with VTKConfig.cmake file
ADE: Download: v0.1.1f.zip
Try 1 failed
CMake Warning at cmake/OpenCVDownload.cmake:202 (message):
ADE: Download failed: 35;"SSL connect error"
For details please refer to the download log file:
C:/Qt/opencv_cv2/opencv/release/CMakeDownloadLog.txt
Call Stack (most recent call first):
modules/gapi/cmake/DownloadADE.cmake:5 (ocv_download)
modules/gapi/cmake/init.cmake:19 (include)
cmake/OpenCVModule.cmake:298 (include)
cmake/OpenCVModule.cmake:361 (_add_modules_1)
modules/CMakeLists.txt:7 (ocv_glob_modules)
OpenCV Python: during development append to PYTHONPATH: C:/Qt/opencv_cv2/opencv/release/python_loader
Could NOT find PkgConfig (missing: PKG_CONFIG_EXECUTABLE)
FFMPEG: Download: opencv_videoio_ffmpeg.dll
Try 1 failed
CMake Warning at cmake/OpenCVDownload.cmake:202 (message):
FFMPEG: Download failed: 35;"SSL connect error"
For details please refer to the download log file:
C:/Qt/opencv_cv2/opencv/release/CMakeDownloadLog.txt
Call Stack (most recent call first):
3rdparty/ffmpeg/ffmpeg.cmake:20 (ocv_download)
modules/videoio/cmake/detect_ffmpeg.cmake:14 (download_win_ffmpeg)
modules/videoio/cmake/init.cmake:7 (include)
modules/videoio/cmake/init.cmake:18 (add_backend)
cmake/OpenCVModule.cmake:298 (include)
cmake/OpenCVModule.cmake:361 (_add_modules_1)
modules/CMakeLists.txt:7 (ocv_glob_modules)
FFMPEG: Download: opencv_videoio_ffmpeg_64.dll
Try 1 failed
CMake Warning at cmake/OpenCVDownload.cmake:202 (message):
FFMPEG: Download failed: 35;"SSL connect error"
For details please refer to the download log file:
C:/Qt/opencv_cv2/opencv/release/CMakeDownloadLog.txt
Call Stack (most recent call first):
3rdparty/ffmpeg/ffmpeg.cmake:20 (ocv_download)
modules/videoio/cmake/detect_ffmpeg.cmake:14 (download_win_ffmpeg)
modules/videoio/cmake/init.cmake:7 (include)
modules/videoio/cmake/init.cmake:18 (add_backend)
cmake/OpenCVModule.cmake:298 (include)
cmake/OpenCVModule.cmake:361 (_add_modules_1)
modules/CMakeLists.txt:7 (ocv_glob_modules)
FFMPEG: Download: ffmpeg_version.cmake
Try 1 failed
CMake Warning at cmake/OpenCVDownload.cmake:202 (message):
FFMPEG: Download failed: 35;"SSL connect error"
For details please refer to the download log file:
C:/Qt/opencv_cv2/opencv/release/CMakeDownloadLog.txt
Call Stack (most recent call first):
3rdparty/ffmpeg/ffmpeg.cmake:20 (ocv_download)
modules/videoio/cmake/detect_ffmpeg.cmake:14 (download_win_ffmpeg)
modules/videoio/cmake/init.cmake:7 (include)
modules/videoio/cmake/init.cmake:18 (add_backend)
cmake/OpenCVModule.cmake:298 (include)
cmake/OpenCVModule.cmake:361 (_add_modules_1)
modules/CMakeLists.txt:7 (ocv_glob_modules)
}
//........................................
{
Performing Test HAVE_CXX_WNO_UNUSED_PRIVATE_FIELD - Failed
CMake Warning at cmake/OpenCVGenSetupVars.cmake:54 (message):
CONFIGURATION IS NOT SUPPORTED: validate setupvars script in install
directory
Call Stack (most recent call first):
CMakeLists.txt:1010 (include)
}

mrjj · wrote on 29 Jun 2021, 07:42

Hi
Could you try with python 2.7 instead?

It seems to complain about the 3.7 version

CMake's 'find_host_package(PythonInterp 2.7)' found wrong Python version:
Could NOT find Python2 (missing: Python2_EXECUTABLE Interpreter)
Wrong major version for the interpreter "C:/Users/test/AppData/Local/Programs/Python/Python37/python.exe"

Negar_mg · 29 Jun 2021, 08:24

How can i try it with python 2.7? What should i change in tutorial steps?

jsulm · wrote on 29 Jun 2021, 08:24

@Negar_mg You should install Python 2.7

mrjj · wrote on 29 Jun 2021, 08:25

@Negar_mg

All steps the same.
Simply install python 2.7 and see if it then
sounds happier

Negar_mg · wrote on 29 Jun 2021, 09:05

I installed Python 2.7, checked that it was installed with the python -v command in cmd, then according to this link

//...........................................................................................

https://wiki.qt.io/How_to_setup_Qt_and_openCV_on_Windows
//...........................................................................................
In cmake, I selected the source and destination, but after clicking the configure button, I encountered these errors:
//...........................................................................................
{
Performing Test HAVE_CXX_WNO_ENUM_COMPARE_SWITCH - Failed
Could NOT find JNI (missing: JAVA_AWT_LIBRARY JAVA_JVM_LIBRARY JAVA_INCLUDE_PATH JAVA_INCLUDE_PATH2 JAVA_AWT_INCLUDE_PATH)
VTK is not found. Please set -DVTK_DIR in CMake to VTK build directory, or to VTK install subdirectory with VTKConfig.cmake file
ADE: Download: v0.1.1f.zip
Try 1 failed
CMake Warning at cmake/OpenCVDownload.cmake:202 (message):
ADE: Download failed: 35;"SSL connect error"

For details please refer to the download log file:

C:/Qt/opencv_cv2/opencv/Release/CMakeDownloadLog.txt

Call Stack (most recent call first):
modules/gapi/cmake/DownloadADE.cmake:5 (ocv_download)
modules/gapi/cmake/init.cmake:19 (include)
cmake/OpenCVModule.cmake:298 (include)
cmake/OpenCVModule.cmake:361 (_add_modules_1)
modules/CMakeLists.txt:7 (ocv_glob_modules)

OpenCV Python: during development append to PYTHONPATH: C:/Qt/opencv_cv2/opencv/Release/python_loader
Could NOT find PkgConfig (missing: PKG_CONFIG_EXECUTABLE)
FFMPEG: Download: opencv_videoio_ffmpeg.dll
Try 1 failed
CMake Warning at cmake/OpenCVDownload.cmake:202 (message):
FFMPEG: Download failed: 35;"SSL connect error"

For details please refer to the download log file:

C:/Qt/opencv_cv2/opencv/Release/CMakeDownloadLog.txt

Call Stack (most recent call first):
3rdparty/ffmpeg/ffmpeg.cmake:20 (ocv_download)
modules/videoio/cmake/detect_ffmpeg.cmake:14 (download_win_ffmpeg)
modules/videoio/cmake/init.cmake:7 (include)
modules/videoio/cmake/init.cmake:18 (add_backend)
cmake/OpenCVModule.cmake:298 (include)
cmake/OpenCVModule.cmake:361 (_add_modules_1)
modules/CMakeLists.txt:7 (ocv_glob_modules)

FFMPEG: Download: opencv_videoio_ffmpeg_64.dll
Try 1 failed
CMake Warning at cmake/OpenCVDownload.cmake:202 (message):
FFMPEG: Download failed: 35;"SSL connect error"

For details please refer to the download log file:

C:/Qt/opencv_cv2/opencv/Release/CMakeDownloadLog.txt

Call Stack (most recent call first):
3rdparty/ffmpeg/ffmpeg.cmake:20 (ocv_download)
modules/videoio/cmake/detect_ffmpeg.cmake:14 (download_win_ffmpeg)
modules/videoio/cmake/init.cmake:7 (include)
modules/videoio/cmake/init.cmake:18 (add_backend)
cmake/OpenCVModule.cmake:298 (include)
cmake/OpenCVModule.cmake:361 (_add_modules_1)
modules/CMakeLists.txt:7 (ocv_glob_modules)

FFMPEG: Download: ffmpeg_version.cmake
Try 1 failed
CMake Warning at cmake/OpenCVDownload.cmake:202 (message):
FFMPEG: Download failed: 35;"SSL connect error"

For details please refer to the download log file:

C:/Qt/opencv_cv2/opencv/Release/CMakeDownloadLog.txt

Call Stack (most recent call first):
3rdparty/ffmpeg/ffmpeg.cmake:20 (ocv_download)
modules/videoio/cmake/detect_ffmpeg.cmake:14 (download_win_ffmpeg)
modules/videoio/cmake/init.cmake:7 (include)
modules/videoio/cmake/init.cmake:18 (add_backend)
cmake/OpenCVModule.cmake:298 (include)
cmake/OpenCVModule.cmake:361 (_add_modules_1)
modules/CMakeLists.txt:7 (ocv_glob_modules)

}