title: How can I concatenate two mp3 files with different bit rates
body: <p>I have FFmpeg installed on my linux web server.  When I execute the following code, I have intermittent results.  </p>
  
  <p>I think I have figured out that the MP3s do not compile when they have different bitrates.  </p>
  
  <pre><code>exec ('cat '. $pair['source_file'] . ' ' . $pair['translated_word_file'] . '&gt;' . $temp_mp3);
  </code></pre>
  
  <p>I might have found some articles online that reference taking them apart and then bundling them back together at a consistent bitrates.  </p>
  
  <p>I have confirmed that this won't really work with basic "cat" function and that "sox" can be used IF they have the same sample rate.  </p>
  
  <p>The issue now becomes "What is the best way to get them to the same sample rate?"</p>