title: avconv: make a video from a subset on images
body: <p>I am trying to make a bunch of png's into a video using avconv, the png's are numbered like <code>filename_&lt;number&gt;</code> so I usually just use the command: </p>
  
  <p><code>avconv -r 10 -i filename_%d.png -b:v 1000k test.mp4</code></p>
  
  <p>I now want to make a video from a subset of the files <code>filename_8</code> - <code>filename_50</code> lets say, so I've copied these files into a new directory and tried the same command but now I get the error:</p>
  
  <pre><code>filename_%d.png: No such file or directory
  </code></pre>
  
  <p>I assume this is because the numbering doesn't start from 1? </p>
  
  <p>How can I achieve this?</p>