问题一

modules\videoio\CMakeFiles\opencv_videoio.dir\build.make:262: recipe for target 'modules/videoio/CMakeFiles/opencv_videoio.dir/src/cap_dshow.cpp.obj' failed
mingw32-make[2]: *** [modules/videoio/CMakeFiles/opencv_videoio.dir/src/cap_dshow.cpp.obj] Error 1
CMakeFiles\Makefile2:4734: recipe for target 'modules/videoio/CMakeFiles/opencv_videoio.dir/all' failed
mingw32-make[1]: *** [modules/videoio/CMakeFiles/opencv_videoio.dir/all] Error 2
Makefile:159: recipe for target 'all' failed
mingw32-make: *** [all] Error 2

解决办法

保存，然后重新mingw32-make