title: Error with including ffmpeg to a project
body: <p>I have faced problem with compilation project including ffmpeg library and I have no idea what to do with that error.</p>
  
  <pre><code>/usr/lib/i386-linux-gnu/libavformat.a(utils.o): undefined reference to symbol 'av_reduce@@LIBAVUTIL_51' ffmpeg          C/C++ Problem
  </code></pre>
  
  <p>and here is my linker</p>
  
  <pre><code>Invoking: GCC C++ Linker
  g++ -L/usr/lib/i386-linux-gnu -o "ffmpeg"  ./ffmpeg.o   -lpthread -lswscale -lavdevice -lavutil -lavformat -lavcodec -lavfilter -lm -lz -lmp3lame -lpostproc -ldl -lX11 -lSDL -lrt -lswresample
  </code></pre>
  
  <p>If someone could help me t will be great.
  Thx</p>