Most Complete Guide For Installing, Compiling, and Running OpenCV on Ubuntu!

I went through many guides to install OpenCV on my Ubuntu machine, but most of them are incomplete. A complete installation of OpenCV, with working video encoding/decoding functionalities, requires support of ffmpeg and x264, which in turn depend on many other libraries. 

In this guide, we will first install x264 and ffmpeg, and eventually OpenCV. Finally we will see how to configure OpenCV and compile programs. Most of the information is found at the following three blogs: [1], [2], and [3].

1. Remove old ffmpeg and x264

• sudo apt-get remove ffmpeg x264 libx264-dev libav-tools libvpx-dev

2. Install all dependencies for ffmpeg and x264

• sudo apt-get install build-essential checkinstall git cmake libfaac-dev libjack-jackd2-dev libmp3lame-dev libopencore-amrnb-dev libopencore-amrwb-dev libsdl1.2-dev libtheora-dev libva-dev libvdpau-dev libvorbis-dev libx11-dev libxfixes-dev libxvidcore-dev texi2html yasm zlib1g-dev pkg-config

• Download and install yasm 1.2.0 from here
  • ./configure --prefix=/usr
  • make
  • sudo make install

Image I/O

sudo apt-get install libtiff4-dev libjpeg-dev libjasper-dev

Video I/O

sudo apt-get install libavcodec-dev libavformat-dev libswscale-dev libdc1394-22-dev libxine-dev libgstreamer0.10-dev libgstreamer-plugins-base0.10-dev libv4l-dev

Python

sudo apt-get install python-dev python-numpy

Download and install libjpeg

sudo apt-get install libjpeg8 libjpeg8-dev

Other third-party libraries

sudo apt-get install libtbb-dev 

GUI

sudo apt-get install libqt4-dev libgtk2.0-dev

3. Install x.264 and ffmpeg

In install x264 and ffmpeg, I mainly follow the guide given at [3]. Below are the main steps.

X264


Download and install latest x264 from videolan.org.



git clone --depth 1 git://git.videolan.org/x264


cd x264


./configure --enable-static --enable-shared


make


sudo checkinstall --pkgname=x264 --pkgversion="3:$(./version.sh | awk -F'[" ]' '/POINT/{print $4"+git"$5}')" --backup=no --deldoc=yes --fstrans=no --default

libvpx

git clone --depth 1 http://git.chromium.org/webm/libvpx.git
cd libvpx
./configure --enable-shared
make
sudo checkinstall --pkgname=libvpx --pkgversion="1:$(date +%Y%m%d%H%M)-git" --backup=no \--deldoc=yes --fstrans=no --default

If you get some error like "relocation R_X86_64_32 against `a local symbol' can not be used when making a shared object; recompile with -fPIC",  compile libvpx with  "fPIC" option. You can do it with the following modified configure command": 

CFLAGS=-fPIC ./configure --enable-shared

Install librtmp

apt-get install librtmp-dev

FFMPEG

Downlaod latest ffmpeg 1.2.1 from here. Go to the download folder and run the following commands:

• tar -xvf ffmpeg-1.2.1.tar.bz2
• cd ffmpeg-1.2.1/
• ./configure --enable-gpl --enable-libfaac --enable-libmp3lame --enable-libopencore-amrnb   --enable-libopencore-amrwb --enable-librtmp --enable-libtheora --enable-libvorbis   --enable-libvpx --enable-libx264 --enable-nonfree --enable-version3 --enable-x11grab --enable-shared --enable-pic
• make
• sudo make install

4. Install OpenCV

Get a copy of the latest source code here for OpenCV 2.4.5. Open a terminal and go to the directory where you have downloaded the tar file, and run the following commands:

• tar -xvf opencv-2.4.5.tar.gz
• cd opencv-2.4.5/
• mkdir build
• cd build/
• cmake -D WITH_QT=ON -D WITH_XINE=ON -D WITH_OPENGL=ON -D WITH_TBB=ON -D BUILD_EXAMPLES=ON CMAKE_BUILD_TYPE=RELEASE -D BUILD_NEW_PYTHON_SUPPORT=ON -D CMAKE_INSTALL_PREFIX=/usr/local ..
• make
• sudo make install

5. Configure OpenCV

We need to tell linux where the shared libraries for OpenCV are located by entering the following shell command:

• export LD_LIBRARY_PATH=/usr/local/lib

Add the command to your .bashrc file so that you don’t have to enter every time your start a new terminal.

Alternatively, you can configure the system wide library search path. Using your favorite editor, add a single line containing the text /usr/local/lib to the end of a file named/etc/ld.so.conf.d/opencv.conf. In the standard Ubuntu install, the opencv.conf file does not exist; you need to create it. Using vi, for example, enter the following commands:

• sudo vi /etc/ld.so.conf.d/opencv.conf
• G
• o
• /usr/local/lib
• :wq!

After editing the opencv.conf file, enter the following command:

• sudo ldconfig /etc/ld.so.conf

Using your favorite editor, add the following two lines to the end of /etc/bash.bashrc:

• PKG_CONFIG_PATH=$PKG_CONFIG_PATH:/usr/local/lib/pkgconfig
• export PKG_CONFIG_PATH

After completing the previous steps, your system should be ready to compile code that uses the OpenCV libraries. The following example shows one way to compile code for OpenCV:

• g++ `pkg-config opencv --cflags` my_code.cpp  -o my_code `pkg-config opencv --libs` 

If you are using a Makefile, append CFLAGS and LDFLAGS as follows:

#Compiler flags
CFLAGS=-c `pkg-config opencv --cflags`
#Linker flags
LDFLAGS= `pkg-config opencv --libs`

Note: Sometimes Makefile does not include libraries if you put LDFLAGS in the middle of link command, i.e.

• g++ $(OBJECTS) $(LDFLAGS) -o output

It is better to put $(LDFLAGS) at the end of the command after specifying output file, i.e. 

• g++ $(OBJECTS) -o output $(LDFLAGS)

       

[1] http://karytech.blogspot.ca/2012/05/opencv-24-on-ubuntu-1204.html
[2] http://www.ozbotz.org/opencv-installation/\
[3] https://gist.github.com/faleev/3435377