title: Unable to add silence to end of mp3 using cat
body: <p>I have a mp3 file with silence, s.mp3, which I'm trying to add to the end of an mp3 using:</p>
  
  <pre><code>cat file1.mp3 s.mp3 &gt; file1.mp3 
  </code></pre>
  
  <p>This worked fine for some mp3 files I downloaded from the net but not the files I created myself using lame.</p>
  
  <p>I'm on mac os x.</p>
  
  <p>Since I'm making the mp3 files myself with lame maybe I can do something that will allow then to work with cat.</p>
  
  <p>How might I establish the problem?</p>