title: Unresolved externals trying to use ffmpeg
body: <p>I'm trying to use some functions from ffmpeg and am running into resilient linker errors. Here's what I did:</p>
  
  <ul>
  <li>Downloaded the latest 32-bit "Dev" build from <a href="http://ffmpeg.zeranoe.com/builds/" rel="noreferrer">http://ffmpeg.zeranoe.com/builds/</a> (i.e. ffmpeg-20130418-git-ee94362-win32-dev)</li>
  <li>Created a "General - empty" C++ project in Visual Studio 2012 Premium</li>
  <li>Added the [ffmpeg]/lib folder to Linker -> Input -> "Additional Library Directories"</li>
  <li>Added "swscale.lib;avutil.lib;avformat.lib;avdevice.lib;avcodec.lib;" to Linker -> Input -> "Additional Dependencies"</li>
  <li>Added the following under C++ -> General -> Additional Include Directories:
  <ul>
  <li>[ffmpeg]/include</li>
  <li>[ffmpeg]/include/libswscale</li>
  <li>[ffmpeg]/include/libavformat</li>
  </ul></li>
  </ul>
  
  <p>This is my main.cpp:</p>
  
  <pre><code>#include "avformat.h"
  
  int main()
  {
      av_register_all();
  } 
  </code></pre>
  
  <p>This fails with:</p>
  
  <blockquote>
    <p>error LNK2019: unresolved external symbol "void __cdecl
    av_register_all(void)" (?av_register_all@@YAXXZ) referenced in
    function _main</p>
  </blockquote>
  
  <p>How can I fix this error?</p>