环境：
系统 ubuntu20.04
opencv 版本 3.2.0

问题一

ippicv_linux_20151201.tgz下载过慢问题

插件下载：
git: https://github.com/wei2023/ippicv_linux_20151201
插件位置：

opencv3.2.0->ippic->downloads->linux-xxxxxx enjoy!

问题二

Error compiling OpenCV, fatal error: stdlib.h: No such file or director

cmake时增加-DENABLE_PRECOMPILED_HEADERS=OFF可以解决

配置如下：

cmake .. -DCMAKE_BUILD_TYPE=RELEASE -DCMAKE_INSTALL_PREFIX=/usr/local -DBUILD_NEW_PYTHON_SUPPORT=ON -DINSTALL_PYTHON_EXAMPLES=ON -DWITH_TBB=ON -DWITH_V4L=ON -DINSTALL_C_EXAMPLES=ON -DBUILD_EXAMPLES=ON -DWITH_QT=ON -DWITH_OPENGL=ON -DWITH_OPENCL=ON -DWITH_EIGEN=ON -DWITH_OPENEXR=ON  -DENABLE_PRECOMPILED_HEADERS=OFF

问题三

FFMPEG 编译报错

提示AV_CODEC_FLAG_GLOBAL_HEADER 错误

‘CODEC_FLAG_GLOBAL_HEADER’ was not declared in this scope; did you
mean ‘AV_CODEC_FLAG_GLOBAL_HEADER’?

在 opencv-3.2.0/modules/videoio/src/cap_ffmpeg_impl.hpp 里最顶端添加了：

#define AV_CODEC_FLAG_GLOBAL_HEADER (1 << 22)
#define CODEC_FLAG_GLOBAL_HEADER AV_CODEC_FLAG_GLOBAL_HEADER
#define AVFMT_RAWPICTURE 0x0020

如下：

问题四

const char* 转char*报错
在 opencv-3.2.0/modules/python/src2/cv2.cpp 730行改为

char* str = (char*)PyString_AsString(obj);

mkdir build
cd build
cmake -D CMAKE_BUILD_TYPE=Release -D CMAKE_INSTALL_PREFIX=/usr/local ..
sudo make -j4
sudo make install