title: ffmpeg to get screenshot
body: <p>I have a collections of videos, and I would like to get a screenshot from every on of them, and save them all in a folder.<br>
  I was told about ffmpeg, a Linux command. But the only extension I get is mpg, instead of .jpeg or .png. </p>
  
  <p>Anybody could tell me if it is possible to write something similar to:</p>
  
  <blockquote>
    <p>ffmpeg -i
    videoscambiados/"+filename+".flv
    img/"+filename+".png</p>
  </blockquote>
  
  <p>instead of this?</p>
  
  <blockquote>
    <p>ffmpeg -i
    videoscambiados/"+filename+".flv
    img/"+filename+".mpg</p>
  </blockquote>
  
  <p>This piece of code is got from a java program I made, and filename, of course, is the name of every videos I have in /videoscambiados and I would like to save the images in /img</p>
  
  <p>Thanks in advance!</p>