title: FFMPEG installed but not found
body: <p>I'm trying to install <a href="http://www.phash.org/" rel="nofollow">pHash</a> , but when I execute <code>./configure</code> this message is returned:</p>
  
  <pre><code>...
  
  *** Configuring video Hash ***
  
  checking whether FFmpeg is present... checking for avcodec_alloc_frame in -lavcodec... no
  configure: error: 
  
  *** libavcodec not found.
  You need FFmpeg. Get it at &lt;http://ffmpeg.org/&gt;
  </code></pre>
  
  <p>But FFMPEG is correctly installed, in fact executing <code>ffmpeg</code> it returns:</p>
  
  <pre><code>ffmpeg version 3.0.2 Copyright (c) 2000-2016 the FFmpeg developers
    built with gcc 4.8 (Ubuntu 4.8.4-2ubuntu1~14.04.1)
    configuration: 
    libavutil      55. 17.103 / 55. 17.103
    libavcodec     57. 24.102 / 57. 24.102
    libavformat    57. 25.100 / 57. 25.100
    libavdevice    57.  0.101 / 57.  0.101
    libavfilter     6. 31.100 /  6. 31.100
    libswscale      4.  0.100 /  4.  0.100
    libswresample   2.  0.101 /  2.  0.101
  Hyper fast Audio and Video encoder
  usage: ffmpeg [options] [[infile options] -i infile]... {[outfile options] outfile}...
  
  Use -h to get full help or, even better, run 'man ffmpeg'
  </code></pre>
  
  <p>Why this happens?</p>