title: FFMPEG - concat demuxer with duration filter issue
body: <p>I am trying to generate video from images using <strong>ffmpeg concat demuxer</strong>.I am creating a text file with image file path. Since images can be of different duration, i am using <strong>duration</strong> filter to specify the duration of each image. Sample text file is like :</p>
  
  <blockquote>
    <p>file 1.jpg</p>
    
    <p>duration 3</p>
    
    <p>file 2.jpg</p>
    
    <p>duration 3</p>
    
    <p>file 3.jpg</p>
    
    <p>duration 5</p>
  </blockquote>
  
  <p>1.jpg and 2.jpg both are displayed for specified 3 sec each but 3.jpg comes for just 2 seconds.</p>
  
  <p>FFMPEG command:</p>
  
  <blockquote>
    <p>ffmpeg -f concat -i D:/textfile.txt  -y -r 10 -crf 22 -threads 2 -preset veryfast D:/video.mp4</p>
  </blockquote>