Error when excute make

[Deeer]

gcc -Isrc/inc -O2 -Wall -DPA_USE_COREAUDIO pkg-config --cflags opencv src/video.c -c -o objs/video.o In file included from src/video.c:1: In file included from /usr/local/Cellar/opencv/3.4.0/include/opencv/cv.h:63: In file included from /usr/local/Cellar/opencv/3.4.0/include/opencv2/core/core_c.h:48: /usr/local/Cellar/opencv/3.4.0/include/opencv2/core/types_c.h:929:13: warning: implicit declaration of function 'cvRound' is invalid in C99 [-Wimplicit-function-declaration] ipt.x = cvRound(point.x); ^ src/video.c:18:8: error: unknown type name 'CvCapture' static CvCapture* cv_cap; ^ src/video.c:52:3: warning: implicit declaration of function 'cvReleaseCapture' is invalid in C99 [-Wimplicit-function-declaration] cvReleaseCapture( &cv_cap ); ^ src/video.c:99:12: warning: implicit declaration of function 'cvCaptureFromCAM' is invalid in C99 [-Wimplicit-function-declaration] cv_cap = cvCaptureFromCAM(0); ^ src/video.c:107:17: warning: implicit declaration of function 'cvQueryFrame' is invalid in C99 [-Wimplicit-function-declaration] color_img = cvQueryFrame(cv_cap); ^ 4 warnings and 1 error generated. make: *** [objs/video.o] Error 1

[tinutomson]

same here.

/usr/local/Cellar/opencv/3.4.1_5/include/opencv2/core/cvdef.h:485:1: error: unknown type name 'namespace'
namespace cv {
^
/usr/local/Cellar/opencv/3.4.1_5/include/opencv2/core/cvdef.h:485:13: error: expected ';' after top level declarator
namespace cv {
            ^
            ;
In file included from src/video.c:1:
In file included from /usr/local/Cellar/opencv/3.4.1_5/include/opencv/cv.h:63:
In file included from /usr/local/Cellar/opencv/3.4.1_5/include/opencv2/core/core_c.h:48:
/usr/local/Cellar/opencv/3.4.1_5/include/opencv2/core/types_c.h:513:5: warning: implicit declaration of function '__assert_rtn' is
      invalid in C99 [-Wimplicit-function-declaration]
    assert( (unsigned)CV_MAT_DEPTH(type) <= CV_64F );
    ^
/usr/include/assert.h:93:34: note: expanded from macro 'assert'
    (__builtin_expect(!(e), 0) ? __assert_rtn(__func__, __FILE__, __LINE__, #e) : (void)0)
                                 ^
In file included from src/video.c:1:
In file included from /usr/local/Cellar/opencv/3.4.1_5/include/opencv/cv.h:63:
In file included from /usr/local/Cellar/opencv/3.4.1_5/include/opencv2/core/core_c.h:48:
/usr/local/Cellar/opencv/3.4.1_5/include/opencv2/core/types_c.h:929:13: warning: implicit declaration of function 'cvRound' is
      invalid in C99 [-Wimplicit-function-declaration]
    ipt.x = cvRound(point.x);
            ^
In file included from src/video.c:2:
In file included from /usr/local/Cellar/opencv/3.4.1_5/include/opencv/highgui.h:46:
/usr/local/Cellar/opencv/3.4.1_5/include/opencv2/highgui/highgui_c.h:139:7: warning: type specifier missing, defaults to 'int'
      [-Wimplicit-int]
CVAPI(cv::Rect)cvGetWindowImageRect(const char* name);
      ^
/usr/local/Cellar/opencv/3.4.1_5/include/opencv2/highgui/highgui_c.h:139:9: error: expected ';' after top level declarator
CVAPI(cv::Rect)cvGetWindowImageRect(const char* name);
        ^
        ;
/usr/local/Cellar/opencv/3.4.1_5/include/opencv2/core/types_c.h:93:49: note: expanded from macro 'CVAPI'
#  define CVAPI(rettype) CV_EXTERN_C CV_EXPORTS rettype CV_CDECL
                                                ^
In file included from src/video.c:2:
In file included from /usr/local/Cellar/opencv/3.4.1_5/include/opencv/highgui.h:46:
/usr/local/Cellar/opencv/3.4.1_5/include/opencv2/highgui/highgui_c.h:139:10: error: expected identifier or '('
CVAPI(cv::Rect)cvGetWindowImageRect(const char* name);
         ^
src/video.c:18:8: error: unknown type name 'CvCapture'
static CvCapture* cv_cap;
       ^
src/video.c:52:3: warning: implicit declaration of function 'cvReleaseCapture' is invalid in C99 [-Wimplicit-function-declaration]
  cvReleaseCapture( &cv_cap );
  ^
src/video.c:99:12: warning: implicit declaration of function 'cvCaptureFromCAM' is invalid in C99 [-Wimplicit-function-declaration]
  cv_cap = cvCaptureFromCAM(0);
           ^
src/video.c:107:17: warning: implicit declaration of function 'cvQueryFrame' is invalid in C99 [-Wimplicit-function-declaration]
    color_img = cvQueryFrame(cv_cap);
                ^
6 warnings and 5 errors generated.
make: *** [objs/video.o] Error 1

[youngqqcn]

I just have issue : src/video.c:18:8: error: unknown type name 'CvCapture'

solved by:

add #include "opencv2/videoio/videoio_c.h" in video.c