版本及配置

opencv 3.4.2

opencv_contribute 3.4.2

ubuntu 16

cmake 3.12.2

cmake 进行编译配置

勾选 ENABLE_CXX11

设置安装路径 CMAKE_INSTALL_PREFIX   /usr/local

设置 OPENCV_EXTRA_MUDOULES_PATH

存在的问题

问题一：

opencv-3.4.1/3rdparty/libpng/pngstruct.h:30:18: fatal error: zlib.h: No such file or directory

~/opencv-3.4.2/CMakeLists.txt，大概514行增加以上代码： ocv_include_directories(./3rdparty/zlib/)

......
ocv_include_directories(${OPENCV_CONFIG_FILE_INCLUDE_DIR})
ocv_include_directories(./3rdparty/zlib/) 
......

问题二：

[ 43%] Building CXX object apps/visualisation/CMakeFiles/opencv_visualisation.dir/opencv_visualisation.cpp.obj
[ 43%] Linking CXX executable ../../bin/opencv_annotation
../../lib/libopencv_core.so: undefined reference to `pthread_mutexattr_destroy'
../../lib/libopencv_imgcodecs.so: undefined reference to `pthread_create'
../../lib/libopencv_core.so: undefined reference to `pthread_key_create'
../../lib/libopencv_imgcodecs.so: undefined reference to `png_init_filter_functions_neon'
../../lib/libopencv_core.so: undefined reference to `pthread_getspecific'
../../lib/libopencv_core.so: undefined reference to `dlopen'
../../lib/libopencv_core.so: undefined reference to `pthread_mutex_trylock'
../../lib/libopencv_core.so: undefined reference to `pthread_key_delete'
../../lib/libopencv_core.so: undefined reference to `dlclose'
../../lib/libopencv_core.so: undefined reference to `dlsym'
../../lib/libopencv_core.so: undefined reference to `pthread_mutexattr_settype'
../../lib/libopencv_imgcodecs.so: undefined reference to `pthread_join'
../../lib/libopencv_core.so: undefined reference to `pthread_setspecific'
../../lib/libopencv_core.so: undefined reference to `pthread_mutexattr_init'
collect2: error: ld returned 1 exit status

解决办法1：CMakeCache.txt上约273行，CMAKE_EXE_LINKER_FLAGS和CMAKE_EXE_LINKER_FLAGS_DEBUG，

添加： -lpthread -lrt -ldl

......
//Flags used by the linker.
CMAKE_EXE_LINKER_FLAGS:STRING=-lpthread -lrt -ldl
 
//Flags used by the linker during debug builds.
CMAKE_EXE_LINKER_FLAGS_DEBUG:STRING=-lpthread -lrt -ldl
 
......

解决方法2：cmake-gui配置的时候设定，可以参考

 

问题三：

[ 43%] Linking CXX executable ../../bin/opencv_annotation
../../lib/libopencv_imgcodecs.so: undefined reference to `png_init_filter_functions_neon'
collect2: error: ld returned 1 exit status
apps/annotation/CMakeFiles/opencv_annotation.dir/build.make:99: recipe for target 'bin/opencv_annotation' failed
make[2]: *** [bin/opencv_annotation] Error 1
CMakeFiles/Makefile2:4431: recipe for target 'apps/annotation/CMakeFiles/opencv_annotation.dir/all' failed
make[1]: *** [apps/annotation/CMakeFiles/opencv_annotation.dir/all] Error 2
make[1]: *** Waiting for unfinished jobs....

解决如下：~/opencv-3.4.2/3rdparty/libpng/pngpriv.h 

128 /* 注释掉 该行 #  if (defined(__ARM_NEON__) || defined(__ARM_NEON)) && \*/
129 #  改为 if defined(PNG_ARM_NEON) && (defined(__ARM_NEON__) || defined(__ARM_NEON)) && \

问题四：

~/opencv_contrib/modules/xfeatures2d/src/boostdesc.cpp:673:20: fatal error: boostdesc_bgm.i: No such file or directory

解决方法：

查看 build 文件夹下的日志文件 CMakeDownloadLog.txt，在日志文件CMakeDownloadLog.txt中搜索 boostdesc_bgm.i 关键词。日志文件里就有它的下载地址，到指定位置下载即可。https://github.com/opencv/opencv_contrib/issues/1301，点开上面这个网址往下拉，有人提供了缺失的各个文件的链接，点击保存. 或者直接在这个网页里搜索 BenbenIO 这个用户的回答。

或者到本文提供的下载镜像去下载：boostdesc_bgm.i,vgg_generated_48.i等.rar

下载后，直接拷贝源码并生存同名文件，放在 opencv_contrib/modules/xfeatures2d/src/ 路径下即可。

编译时有些文件是联网下载的，所以问题四如果联网下载成功的话，应该就不需要自己去下载以上链接的文件。

见下面的输出：

 

问题五：

In file included from /home/john/cross_compile/src/opencv-3.4.2/modules/stitching/include/opencv2/stitching.hpp:49:0,
                 from /home/john/cross_compile/src/opencv-3.4.2/modules/stitching/src/precomp.hpp:59,
                 from /home/john/cross_compile/src/opencv-3.4.2/modules/stitching/src/camera.cpp:43:
/home/john/cross_compile/src/opencv-3.4.2/modules/stitching/include/opencv2/stitching/detail/matchers.hpp:52:42: fatal error: opencv2/xfeatures2d/cuda.hpp: No such file or directory
 #  include "opencv2/xfeatures2d/cuda.hpp"
                                          ^
compilation terminated.
modules/stitching/CMakeFiles/opencv_stitching.dir/build.make:68: recipe for target 'modules/stitching/CMakeFiles/opencv_stitching.dir/src/camera.cpp.o' failed
make[2]: *** [modules/stitching/CMakeFiles/opencv_stitching.dir/src/camera.cpp.o] Error 1
CMakeFiles/Makefile2:7779: recipe for target 'modules/stitching/CMakeFiles/opencv_stitching.dir/all' failed
make[1]: *** [modules/stitching/CMakeFiles/opencv_stitching.dir/all] Error 2
make[1]: *** Waiting for unfinished jobs....

在编译stitching模块时会提示以上信息。

解决方法：

opencv/modules/stitching/CMakeLists.txt文件中加入一条语句使其include opencv_contrib/modules/xfeatures2d/include，可以是绝对路径，如

INCLUDE_DIRECTORIES("/home/john/cross_compile/src/opencv_contrib-3.4.2/modules/xfeatures2d/include"）

问题六：

如图，video I/O模块总是“NO”。

解决方法：

安装ffmpeg，网络搜罗一堆文章，介绍如何编译ffmpeg，但是都不能完成整个编译到安装的流程。最终结合多篇文章，使用入选命令进行编译，编译安装成功。

./configure --enable-cross-compile --target-os=linux --cc=aarch64-linux-gnu-gcc --arch=arm --enable-shared --disable-static --enable-gpl --enable-nonfree --enable-ffmpeg --disable-ffplay --enable-ffserver --enable-swscale --enable-pthreads --disable-yasm --disable-stripping --enable-libx264 --extra-cflags=-I/usr/aarch64-linux/include --extra-ldflags=-L/usr/aarch64-linux/lib --prefix=/usr/aarch64-linux --cpu=cortex-a73 --disable-asm

 

将ffmpeg加入pkg-config

执行#sudo gedit /etc/bash.bashrc，在末尾加入

export LD_LIBRARY_PATH=/usr/aarch64-linux/lib/

export PKG_CONFIG_PATH=$PKG_CONFIG_PATH:/usr/aarch64-linux/lib/pkgconfig

export PKG_CONFIG_LIBDIR=$PKG_CONFIG_LIBDIR:/usr/aarch64-linux/lib/

完毕后使用命令：

source /etc/bash.bashrc

或者单独使用三个export，不过寿命只在一个终端中，终端关闭时就失效。
 

接下来修改opencv/platflrms/linux/目录下的arm-gnueabi.toolchain.cmake，将其所有删掉，写入：

set( CMAKE_SYSTEM_NAME Linux )

set( CMAKE_SYSTEM_PROCESSOR arm )

set( CMAKE_C_COMPILER aarch64-linux-gnu-gcc )

set( CMAKE_CXX_COMPILER aarch64-linux-gnu-g++ )

在opencv目录下新建build目录，进入build目录，执行命令：

cmake -DCMAKE_TOOLCHAIN_FILE=../platforms/linux/arm-gnueabi.toolchain.cmake ../

见下图 “NO”变为“YES”，就OK了。

使用cmake-gui打开CMakeCache.txt，去掉所有的无关项，修改CMAKE_INSTALL_PREFIX，来确定make install的目录。

然后

make & make install

问题七：

[ 72%] Linking CXX executable ../../../../bin/opencv_waldboost_detector
/home/john/linaro/gcc-linaro-6.3.1-2017.05-x86_64_aarch64-linux-gnu/bin/../lib/gcc/aarch64-linux-gnu/6.3.1/../../../../aarch64-linux-gnu/bin/ld: warning: libavcodec.so.56, needed by ../../../../lib/libopencv_videoio.so.3.4.2, not found (try using -rpath or -rpath-link)
/home/john/linaro/gcc-linaro-6.3.1-2017.05-x86_64_aarch64-linux-gnu/bin/../lib/gcc/aarch64-linux-gnu/6.3.1/../../../../aarch64-linux-gnu/bin/ld: warning: libavformat.so.56, needed by ../../../../lib/libopencv_videoio.so.3.4.2, not found (try using -rpath or -rpath-link)
/home/john/linaro/gcc-linaro-6.3.1-2017.05-x86_64_aarch64-linux-gnu/bin/../lib/gcc/aarch64-linux-gnu/6.3.1/../../../../aarch64-linux-gnu/bin/ld: warning: libavutil.so.54, needed by ../../../../lib/libopencv_videoio.so.3.4.2, not found (try using -rpath or -rpath-link)
/home/john/linaro/gcc-linaro-6.3.1-2017.05-x86_64_aarch64-linux-gnu/bin/../lib/gcc/aarch64-linux-gnu/6.3.1/../../../../aarch64-linux-gnu/bin/ld: warning: libswscale.so.3, needed by ../../../../lib/libopencv_videoio.so.3.4.2, not found (try using -rpath or -rpath-link)
../../../../lib/libopencv_videoio.so.3.4.2: undefined reference to `av_codec_get_tag@LIBAVFORMAT_56'

分析该问题中所链接的库无法找到，通过搜索发现"libavcodec.so.56"库正是编译ffmpeg所生成的库，问题也变得开朗了。既然库存在，那么就想办法将其链接起来。

方法1：修改CMakeCach.txt文件。

原始文件：

……
 349 //Flags used by the CXX compiler during all build types.
 350 CMAKE_CXX_FLAGS:STRING=
……
 372 //Flags used by the C compiler during all build types.
 373 CMAKE_C_FLAGS:STRING=
……

添加ffmpeg库路径（即问题六中交叉编译的ffmpeg文件路径，该路径下可能还包括以下交叉编译库，见下图）

添加完毕路径后：

……
 349 //Flags used by the CXX compiler during all build types.
 350 CMAKE_CXX_FLAGS:STRING=-Wl,-rpath-link=/usr/aarch64-linux/lib
……
 372 //Flags used by the C compiler during all build types.
 373 CMAKE_C_FLAGS:STRING=-Wl,-rpath-link=/usr/aarch64-linux/lib
……

在执行编译命令make & make install

问题八：

根据网络上教程，自己在编译时存在的问题。ffmpeg在编译之前需要安装部分依赖库，根据搜索来的"./configure"命令，发现存在某一个库并非是交叉编译生成的，这就会导致在编译ffmpeg时提示无法找到某一个库的错误信息。详细信息查看config.log，log中的关键词

skipping incompatible /usr/aarch64-linux/lib/libxvidcore.so when searching …………

使用命令查看xxx.so文件

readelf -h xxx.so

我这里存在该问题的库是libxvid。见下图

 

 

参考：

https://blog.csdn.net/yfkyfk521/article/details/89375419

https://www.cnblogs.com/arxive/p/11778731.html

https://blog.csdn.net/u011736771/article/details/85960300

https://blog.csdn.net/u012321968/article/details/106654012/

https://my.oschina.net/u/1250206/blog/850302

http://blog.sina.com.cn/s/blog_753b6c170102uz7o.html