1. Remove any installed versions of ffmpeg and x264.
   

   sudo apt-get remove ffmpeg x264 libx264-dev

2. Get all the dependencies for x264 and ffmpeg.
   

   sudo apt-get update
   
   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

3. Download and install gstreamer.
   

   sudo apt-get install libgstreamer0.10-0 libgstreamer0.10-dev gstreamer0.10-tools 
   gstreamer0.10-plugins-base libgstreamer-plugins-base0.10-dev 
   gstreamer0.10-plugins-good gstreamer0.10-plugins-ugly 
   gstreamer0.10-plugins-bad gstreamer0.10-ffmpeg

4. Download and install gtk.
   

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

5. Download and install libjpeg.
   

   sudo apt-get install libjpeg8 libjpeg8-dev

6. Create a directory to hold source code.
   

   cd ~
   mkdir src

7. Download and install install x264.
   1. Download a recent stable snapshot of x264 from ftp://ftp.videolan.org/pub/videolan/x264/snapshots/. The exact version does not seem to matter. To write this guide, I used version x264-snapshot-20120528-2245-stable.tar.bz2, but I have used previous versions too.
      

          cd ~/src
      
          wget ftp://ftp.videolan.org/pub/videolan/x264/snapshots/x264-snapshot-20120528-2245-stable.tar.bz2
      
          tar xvf x264-snapshot-20120528-2245-stable.tar.bz2
      
          cd x264-snapshot-20120528-2245-stable

   2. Configure and build the x264 libraries.
      

      ./configure --enable-static
      
      make
      
      sudo make install

      IMPORTANT: If you are running a 64-bit version of Ubuntu, you must configure x264 as shown in the following command

      ./configure --enable-shared --enable-pic

   3. The -shared and -pic options might also be required when you compile for some other architectures, such as ARM. You know you need these options if you get the following error when compiling OpenCV:

      [ 25%] Building CXX object modules/highgui/CMakeFiles/opencv_highgui.dir/src/bitstrm.cpp.o
      Linking CXX shared library ../../lib/libopencv_highgui.so
      /usr/bin/ld: /usr/local/lib/libavcodec.a(avpacket.o): relocation R_X86_64_32S against `av_destruct_packet' can not be used when making a shared object; recompile with -fPIC
      /usr/local/lib/libavcodec.a: could not read symbols: Bad value

8. Download and install install ffmpeg.
   1. Download ffmpeg version 0.11.1 from http://ffmpeg.org/download.html.
      

      cd ~/src
      
      wget http://ffmpeg.org/releases/ffmpeg-0.11.1.tar.bz2
      
      tar xvf ffmpeg-0.11.1.tar.bz2
      
      cd ffmpeg-0.11.1

   2. Configure and build ffmpeg.
      

      ./configure --enable-gpl --enable-libfaac --enable-libmp3lame 
      --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libtheora 
      --enable-libvorbis --enable-libx264 --enable-libxvid --enable-nonfree 
      --enable-postproc --enable-version3 --enable-x11grab

      make
      
      sudo make install

      IMPORTANT: Just like with x264 in the previous step, you must configure ffmpeg with the -shared and -pic options if you are running a 64-bit version of Ubuntu or some other architectures, such as ARM.

      ./configure --enable-gpl --enable-libfaac --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libtheora --enable-libvorbis --enable-libx264 --enable-libxvid --enable-nonfree --enable-postproc --enable-version3 --enable-x11grab --enable-shared --enable-pic

9. Download and install install a recent version of v4l (video for linux) from http://www.linuxtv.org/downloads/v4l-utils/. For this guide I used version 0.9.3.
   

       cd ~/src
   
       wget http://www.linuxtv.org/downloads/v4l-utils/v4l-utils-0.9.3.tar.bz2
   
       tar xvf v4l-utils-0.9.3.tar.bz2
   
       cd v4l-utils-0.9.3
   
       ./configure
   
       make
   
       sudo make install

10. Download and install install OpenCV 2.4.3.
    1. Download OpenCV version 2.4.3 from http://sourceforge.net/projects/opencvlibrary/files/opencv-unix/2.4.3/OpenCV-2.4.3.tar.bz2/download

           cd ~/src
       
           tar xvf OpenCV-2.4.2.tar.bz2

    2. Create a new build directory and run cmake:
       

       cd OpenCV-2.4.2/
       
       mkdir build
       
       cd build
       
       cmake -D CMAKE_BUILD_TYPE=RELEASE ..

    3. Verify that the output of cmake includes the following text:
       • found gstreamer-base-0.10
       • GTK+ 2.x: YES
       • FFMPEG: YES
       • GStreamer: YES
       • V4L/V4L2: Using libv4l
    4. Build and install OpenCV.
       

       make
       
       sudo make install

11. Configure Linux.
    1. 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
       <Esc>
       :wq!

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

       sudo ldconfig /etc/ld.so.conf

    2. 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_example.cpp -o my_example `pkg-config opencv --libs` 

Sample c++ file here, my_example.cpp, used for opening an image:

#include <stdio.h>
#include <opencv2/opencv.hpp>

using namespace cv;

int main( int argc, char** argv )
{
  Mat image;
  image = imread( argv[1], 1 );

  if( argc != 2 || !image.data )
    {
      printf( "No image data \n" );
      return -1;
    }

  namedWindow( "Display Image", CV_WINDOW_AUTOSIZE );
  imshow( "Display Image", image );

  waitKey(0);

  return 0;
}

Once compiled, run command to see the sweetie :D

./my_example cLena.bmp