title: How to concatenate flv file into one?
body: <p>There is a file named  input.txt  </p>
  
  <pre class="lang-sh prettyprint-override"><code>file '/home/1.flv'
  file '/home/2.flv'
  </code></pre>
  
  <p>I can use the command to Concatenate  1.flv and 2.flv into a mp4 file.  </p>
  
  <pre class="lang-sh prettyprint-override"><code># there are two files in output.mp4
  ffmpeg -f concat -i input.txt -c copy output.mp4
  </code></pre>
  
  <p>When i use  the following command   </p>
  
  <pre class="lang-sh prettyprint-override"><code>ffmpeg -i "concat:1.flv|2.flv" -c copy output.mp4
  </code></pre>
  
  <p>I found the there is only one file <code>1.flv</code> in the <code>output.mp4</code>, why?</p>