title: FFmpeg on windows 7, encode video in mp4 for HTML 5 video fail
body: <p>I try to encode my video with FFmpeg, to convert to mp4.
  But the video doesn't work on html 5. I don't understand why.</p>
  
  <p>I found this command on the web and I tried it:</p>
  
  <pre>
  ffmpeg.exe -i wildlife.wmv -b 1500k -vpre slow -vpre baseline -vcode libx264 \
    -g 30 wildlife.mp4
  </pre>
  
  <p>But it fails, and I have this error :</p>
  
  <pre><code>File for preset 'slow' not found
  </code></pre>
  
  <p>I check the folder "presets" and the preset is on the folder, so I don't understand why it's telling me this error.
  I tried with the complete path, it fails too.</p>