基于CMakeLists编译GStreamer-OpenCV插件时遇未定义引用错误求助

问题背景 #

从GStreamer的gst-plugins-bad中复制了gstcvequalizehist相关文件，计划修改其中的OpenCV帧处理逻辑，但编译时出现未定义引用错误，涉及gst_opencv_video_filter_get_type和gst_opencv_video_filter_set_in_place函数。

目录结构 #

└── gstreamer-filter
    ├── build
    ├── CMakeLists.txt
    ├── gstcvequalizehist.cpp
    ├── include
    │   ├── gstcvequalizehist.h
    │   └── gstopencvvideofilter.h
    └── main.cpp

当前CMakeLists.txt内容 #

cmake_minimum_required(VERSION 3.10)

project(VideoFilter)

find_package(OpenCV REQUIRED)
find_package(PkgConfig REQUIRED)
pkg_check_modules(GSTREAMER REQUIRED gstreamer-1.0)
pkg_check_modules(GST_APP REQUIRED gstreamer-app-1.0)

include_directories(include)
include_directories(${OpenCV_INCLUDE_DIRS})
include_directories(${GSTREAMER_INCLUDE_DIRS})
include_directories(${GST_APP_INCLUDE_DIRS})
include_directories(${GST_OPENCV_INCLUDE_DIRS})
link_directories(${GST_OPENCV_LIBRARY_DIRS})


# Link directories
link_directories(${OpenCV_LIBRARY_DIRS})
link_directories(${GSTREAMER_LIBRARY_DIRS})
link_directories(${GST_APP_LIBRARY_DIRS})

add_executable(VideoFilter main.cpp gstcvequalizehist.cpp)

target_link_libraries(VideoFilter ${GSTREAMER_LIBRARIES} ${GST_APP_LIBRARIES} ${OpenCV_LIBRARIES} ${GST_OPENCV_LIBRARIES})

编译错误输出 #

-- The C compiler identification is GNU 11.4.0
-- The CXX compiler identification is GNU 11.4.0
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working C compiler: /usr/bin/cc - skipped
-- Detecting C compile features
-- Detecting C compile features - done
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Check for working CXX compiler: /usr/bin/c++ - skipped
-- Detecting CXX compile features
-- Detecting CXX compile features - done
CMake Warning (dev) at /usr/local/lib/cmake/opencv4/OpenCVConfig.cmake:86 (find_package):
  Policy CMP0146 is not set: The FindCUDA module is removed.  Run "cmake
  --help-policy CMP0146" for policy details.  Use the cmake_policy command to
  set the policy and suppress this warning.

Call Stack (most recent call first):
  /usr/local/lib/cmake/opencv4/OpenCVConfig.cmake:108 (find_host_package)
  CMakeLists.txt:7 (find_package)
This warning is for project developers.  Use -Wno-dev to suppress it.

-- Performing Test CMAKE_HAVE_LIBC_PTHREAD
-- Performing Test CMAKE_HAVE_LIBC_PTHREAD - Success
-- Found Threads: TRUE  
-- Found CUDA: /usr/local/cuda (found suitable exact version "12.1") 
-- Found OpenCV: /usr/local (found version "4.7.0") 
-- Found PkgConfig: /usr/bin/pkg-config (found version "0.29.2") 
-- Checking for module 'gstreamer-1.0'
--   Found gstreamer-1.0, version 1.20.3
-- Checking for module 'gstreamer-app-1.0'
--   Found gstreamer-app-1.0, version 1.20.1
-- Configuring done (1.0s)
-- Generating done (0.0s)
-- Build files have been written to: gstreamer-filter/build
[ 33%] Building CXX object CMakeFiles/VideoFilter.dir/main.cpp.o
[ 66%] Building CXX object CMakeFiles/VideoFilter.dir/gstcvequalizehist.cpp.o
[100%] Linking CXX executable VideoFilter
/usr/bin/ld: CMakeFiles/VideoFilter.dir/gstcvequalizehist.cpp.o: in function `gst_cv_equalize_hist_get_type_once()':
gstcvequalizehist.cpp:(.text+0x10a): undefined reference to `gst_opencv_video_filter_get_type'
/usr/bin/ld: CMakeFiles/VideoFilter.dir/gstcvequalizehist.cpp.o: in function `gst_cv_equalize_hist_init(_GstCvEqualizeHist*)':
gstcvequalizehist.cpp:(.text+0x26f): undefined reference to `gst_opencv_video_filter_set_in_place'
collect2: error: ld returned 1 exit status
make[2]: *** [CMakeFiles/VideoFilter.dir/build.make:182: VideoFilter] Error 1
make[1]: *** [CMakeFiles/Makefile2:83: CMakeFiles/VideoFilter.dir/all] Error 2
make: *** [Makefile:91: all] Error 2

解决方案 #

1. 安装依赖包 #

未定义的函数来自GStreamer的OpenCV扩展库，先安装对应的开发包：

sudo apt-get install libgstreamer-opencv1.0-dev

2. 修正CMakeLists.txt #

原配置中GST_OPENCV变量未被正确初始化，需要通过pkg-config引入gstreamer-opencv模块，修改后的配置如下：

cmake_minimum_required(VERSION 3.10)

project(VideoFilter)

find_package(OpenCV REQUIRED)
find_package(PkgConfig REQUIRED)
pkg_check_modules(GSTREAMER REQUIRED gstreamer-1.0)
pkg_check_modules(GST_APP REQUIRED gstreamer-app-1.0)
# 添加gstreamer-opencv模块
pkg_check_modules(GST_OPENCV REQUIRED gstreamer-opencv-1.0)

include_directories(include)
include_directories(${OpenCV_INCLUDE_DIRS})
include_directories(${GSTREAMER_INCLUDE_DIRS})
include_directories(${GST_APP_INCLUDE_DIRS})
include_directories(${GST_OPENCV_INCLUDE_DIRS})

link_directories(${OpenCV_LIBRARY_DIRS})
link_directories(${GSTREAMER_LIBRARY_DIRS})
link_directories(${GST_APP_LIBRARY_DIRS})
link_directories(${GST_OPENCV_LIBRARY_DIRS})

add_executable(VideoFilter main.cpp gstcvequalizehist.cpp)

target_link_libraries(VideoFilter 
    ${GSTREAMER_LIBRARIES} 
    ${GST_APP_LIBRARIES} 
    ${OpenCV_LIBRARIES} 
    ${GST_OPENCV_LIBRARIES}
)

3. 重新编译 #

清理旧编译文件后重新执行编译流程：

cd build
rm -rf *
cmake ..
make

说明 #

gst_opencv_video_filter是GStreamer OpenCV插件的基础类，提供了OpenCV帧处理的通用逻辑，必须链接对应的库才能解决未定义引用问题。

内容的提问来源于stack exchange，提问作者Ja_cpp