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1）linux查看opencv安装路径及版本号
查看linux下的opencv安装库：
pkg-config opencv --libs
查看linux下的opencv安装版本：
pkg-config opencv --modversion
查看linux下的opencv安装路径：
find / -iname "*opencv*"
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2）编译指令
创建库目录： mkdir install
创建生成目录 ： mkdir build
进入目录： cd build
执行生成Makefile:
cmake -D WITH_CUDA=OFF \
-D CMAKE_BUILD_TYPE=Release \
-D CMAKE_INSTALL_PREFIX=cmake -D WITH_CUDA=OFF \
-D CMAKE_BUILD_TYPE=Release \
-D CMAKE_INSTALL_PREFIX=/home/packages/opencv/install \
-D WITH_IPP=OFF \
-D WITH_FFMPEG=ON \
-D BUILD_TESTS=OFF \
-D BUILD_PERF_TESTS=OFF \
-D INSTALL_PYTHON_EXAMPLES=OFF \
-D INSTALL_C_EXAMPLES=OFF \
-D PYTHON_EXECUTABLE=$(which python) \
-D BUILD_EXAMPLES=OFF .. \
-D WITH_IPP=OFF \
-D WITH_FFMPEG=ON \
-D BUILD_TESTS=OFF \
-D BUILD_PERF_TESTS=OFF \
-D INSTALL_PYTHON_EXAMPLES=OFF \
-D INSTALL_C_EXAMPLES=OFF \
-D PYTHON_EXECUTABLE=$(which python) \
-D BUILD_EXAMPLES=OFF ..
生成安装：make && make install
编译异常
1）[ 98%] Linking CXX executable ../../bin/opencv_performance
../../lib/libopencv_highgui.so.2.4.9: undefined reference to `avcodec_alloc_frame'
../../lib/libopencv_highgui.so.2.4.9: undefined reference to `avcodec_encode_video'
collect2: error: ld returned 1 exit status
apps/haartraining/CMakeFiles/opencv_performance.dir/build.make:105: recipe for target 'bin/opencv_performance' failed
make[2]: *** [bin/opencv_performance] Error 1
CMakeFiles/Makefile2:3388: recipe for target 'apps/haartraining/CMakeFiles/opencv_performance.dir/all' failed
make[1]: *** [apps/haartraining/CMakeFiles/opencv_performance.dir/all] Error 2
Makefile:149: recipe for target 'all' failed
make: *** [all] Error 2
问题：undefined reference to `avcodec_alloc_frame'
通过grep -r "avcodec_alloc_frame" / 查询全局文本返回空
最新版本的FFmpeg该函数的实现名称已经改变，下载ffmpeg-2.3.tar.bz2源码编译
2）已经编译ffmpeg-2.3.tar.bz2，生成libswresample.so.0无法找到，将libswresample.so.0拷贝到/lib64目录下
/usr/bin/ld: warning: libswresample.so.0, needed by //home/dong/ffmpeg/ffmpeg-2.3/build/lib/libavcodec.so.55, not found (try using -rpath or -rpath-link)
//home/dong/ffmpeg/ffmpeg-2.3/build/lib/libavcodec.so.55: undefined reference to `swr_init@LIBSWRESAMPLE_0'
//home/dong/ffmpeg/ffmpeg-2.3/build/lib/libavcodec.so.55: undefined reference to `swr_close@LIBSWRESAMPLE_0'
//home/dong/ffmpeg/ffmpeg-2.3/build/lib/libavcodec.so.55: undefined reference to `swr_is_initialized@LIBSWRESAMPLE_0'
//home/dong/ffmpeg/ffmpeg-2.3/build/lib/libavcodec.so.55: undefined reference to `swr_free@LIBSWRESAMPLE_0'
//home/dong/ffmpeg/ffmpeg-2.3/build/lib/libavcodec.so.55: undefined reference to `swr_alloc@LIBSWRESAMPLE_0'
//home/dong/ffmpeg/ffmpeg-2.3/build/lib/libavcodec.so.55: undefined reference to `swr_convert@LIBSWRESAMPLE_0'
collect2: error: ld returned 1 exit status
apps/haartraining/CMakeFiles/opencv_performance.dir/build.make:105: recipe for target 'bin/opencv_performance' failed
make[2]: *** [bin/opencv_performance] Error 1
CMakeFiles/Makefile2:3388: recipe for target 'apps/haartraining/CMakeFiles/opencv_performance.dir/all' failed
make[1]: *** [apps/haartraining/CMakeFiles/opencv_performance.dir/all] Error 2
Makefile:149: recipe for target 'all' failed
make: *** [all] Error
3）export PKG_CONFIG_PATH=/home/dong/opencv-2.4.9/install/lib/pkgconfig/;$PKG_CONFIG_PATH
指定OpenCV优先查找编译好的FFmpeg,而不是系统的FFmpeg库