### OpenCV安装(Linux)

@(gr_self)[ffmpeg | openCV]

#@author:       gr
#@date:         2015-09-02
#@email:        forgerui@gmail.com   

1.安装基础依赖包

yum install autoconf automake gcc gcc-c++ git libtool make nasm pkgconfig zlib-devel

2. 安装其它依赖

Yasm

Yasm is an assembler used by x264 and FFmpeg.

mkdir ~/ffmpeg_sources
cd ~/ffmpeg_sources  
curl -O http://www.tortall.net/projects/yasm/releases/yasm-1.2.0.tar.gz  
tar xzvf yasm-1.2.0.tar.gz  
cd yasm-1.2.0  
./configure --prefix="$HOME/ffmpeg_build" --bindir="$HOME/bin"  
make  
make install  
make distclean  
export "PATH=$PATH:$HOME/bin"  

libx264

H.264 video encoder.

cd ~/ffmpeg_sources  
git clone --depth 1 git://git.videolan.org/x264  
cd x264  
./configure --prefix="$HOME/ffmpeg_build" --bindir="$HOME/bin" --enable-static  
make  
make install  
make distclean  

libx265

cd ~/ffmpeg_sources 
wget https://bitbucket.org/multicoreware/x265/downloads/x265_1.7.tar.gz
    (ffmpeg3.2.5, 需要新的x265, 可以使用2.4版本，wget https://bitbucket.org/multicoreware/x265/downloads/x265_2.4.tar.gz)
tar xzvf x265_1.7.tar.gz
cd x265_1.7/build/linux
./make-Makefiles.bash
make -j20
make install

如果出现找不到ccmake命令，可以直接修改make-Makefiles.bash将ccmake改为cmake，或者安装sudo apt install cmake-curses-gui。

libfdk_aac

AAC audio encoder.

cd ~/ffmpeg_sources  
git clone --depth 1 git://git.code.sf.net/p/opencore-amr/fdk-aac  
cd fdk-aac  
autoreconf -fiv  
./configure --prefix="$HOME/ffmpeg_build" --disable-shared  
make  
make install  
make distclean  

libmp3lame

Opus audio decoder and encoder.

# wget http://nchc.dl.sourceforge.net/project/lame/lame/3.99/lame-3.99.5.tar.gz
# tar xzvf lame-3.99.5.tar.gz
# cd lame-3.99.5
# ./configure --prefix="$HOME/ffmpeg_build"
# make 
# make install

opus

cd ~/ffmpeg_sources  
curl -O http://downloads.xiph.org/releases/opus/opus-1.1.tar.gz  
tar xzvf opus-1.1.tar.gz  
cd opus-1.1  
./configure --prefix="$HOME/ffmpeg_build" --disable-shared  
make  
make install  
make distclean  

libogg

Ogg bitstream library. Required by libtheora and libvorbis.

cd ~/ffmpeg_sources  
curl -O http://downloads.xiph.org/releases/ogg/libogg-1.3.1.tar.gz  
tar xzvf libogg-1.3.1.tar.gz  
cd libogg-1.3.1  
./configure --prefix="$HOME/ffmpeg_build" --disable-shared  
make  
make install  
make distclean  

libvorbis

Vorbis audio encoder. Requires libogg.

cd ~/ffmpeg_sources  
curl -O http://downloads.xiph.org/releases/vorbis/libvorbis-1.3.4.tar.gz  
tar xzvf libvorbis-1.3.4.tar.gz  
cd libvorbis-1.3.4  
./configure --prefix="$HOME/ffmpeg_build" --with-ogg="$HOME/ffmpeg_build" --disable-shared  
make  
make install  
make distclean  

libvpx

VP8/VP9 video encoder.

cd ~/ffmpeg_sources  
git clone --depth 1 https://chromium.googlesource.com/webm/libvpx.git  
cd libvpx  
./configure --prefix="$HOME/ffmpeg_build" --disable-examples  
make  
make install  
make clean  

注意：由于国内最近无法访问Google所以libvpx无法git clone ,此时可以去别处下载：http://yunpan.cn/QhNk5tDqQV3MM 访问密码 45f6

xvid

cd ~/ffmpeg_sources
svn checkout http://svn.xvid.org/trunk --username anonymous
cd trunk/xvidcore/build/generic
./configure  
make && make install
cp /usr/local/lib/libxvidcore.so /usr/lib
ldconfig

libav

 wget http://libav.org/releases/libav-10.7.tar.gz
 tar xzvf libav-10.7.tar.gz
 cd libav-10.7
 ./configure --enable-shared --extra-cflags=-fPIC 
 make && make install

FFmpeg

cd ~/ffmpeg_sources
git clone --depth 1 git://source.ffmpeg.org/ffmpeg
cd ffmpeg
PKG_CONFIG_PATH="$HOME/ffmpeg_build/lib/pkgconfig"
export PKG_CONFIG_PATH
./configure --prefix="$HOME/ffmpeg_build" --enable-shared --extra-cflags=-fPIC --extra-cflags="-I$HOME/ffmpeg_build/include" --extra-ldflags="-L$HOME/ffmpeg_build/lib" --bindir="$HOME/bin" --extra-libs=-ldl --enable-gpl --enable-nonfree --enable-libfdk_aac --enable-libmp3lame --enable-libopus --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libx265 --enable-libxvid
make
make install
make distclean
hash -r
. ~/.bash_profile

安装结束查看版本

ffpmeg -version

3. OpenCV

cd opencv
mkdir -p build && cd build
cmake ../
make all -j24 && make install

1. 如果需要装一个intel加速包ippcv，这个东西下载很慢，并且有时会断掉，可以手动下载之后再安装。
2. 如果是opencv3以上，要使用SIFT等特征，需要一个第三方包，可以到github上（https://github.com/opencv/opencv_contrib）找对应的release版本下来，再通过-DOPENCV_EXTRA_MODULES_PATH=<opencv_contrib>/modules去配置编译。
3. 如果要把opencv编译成静态库，加上-D BUILD_SHARED_LIBS=NO

4. Problems

问题一：

/usr/lib64/gcc/x86_64-linux/4.2.0/../../../../x86_64-linux/bin/ld: /usr/local/libavcodec.a(z.o): relocation R_X86_64_32 against `a local symbol' can not be used when making a shared object; recompile with -fPIC

解决方法：
加上fPIC选项，./configure --enable-shared --extra-cflags=-fPIC 。

问题二：

In file included from /home/aman/opencv/opencv/modules/videoio/src/cap_ffmpeg.cpp:45:0:
/home/aman/opencv/opencv/modules/videoio/src/cap_ffmpeg_impl.hpp: In function ‘int icv_av_write_frame_FFMPEG(AVFormatContext*, AVStream*, uint8_t*, uint32_t, AVFrame*)’:
/home/aman/opencv/opencv/modules/videoio/src/cap_ffmpeg_impl.hpp:1269:72: error: ‘avcodec_encode_video’ was not declared in this scope
     out_size = avcodec_encode_video(c, outbuf, outbuf_size, picture);

This is because libav has changed API and removed some stuff it's still used in OpenCV. Ubuntu 14.10 uses libav API version 11 and OpenCV still uses API version 9. The problem is that CODEC_ID_* was changed to AV_CODEC_ID_*.

解决方法：
之前下载的libav版本太新，opencv不支持。重新下载libav9，编译安装。

问题三：

装了许多视频解码器，仍无法播放视频。

解决方法：
cmake ../发现v4l没有找到，安装v4l。命令：yum install libv4l-devel。