title: ffmpeg leaves audio gap when concatening videos
body: <p>I am trying to cut a video in 2 parts then reassembling with ffmpeg but the final output has a small audio glitch right where the segments meet. I am using the following command to split the video 1.mp4 in 2 parts:</p>
  
  <blockquote>
    <p>ffmpeg -i 1.mp4 -ss 00:00:00 -t 00:00:02 -async 1 1-1.mp4</p>
  </blockquote>
  
  <p>and</p>
  
  <blockquote>
    <p>ffmpeg -i 1.mp4 -ss 00:00:02 -t 00:00:02 -async 1 1-2.mp4</p>
  </blockquote>
  
  <p>Once I have the 2 parts I am concatening them back together with:</p>
  
  <blockquote>
    <p>ffmpeg -f concat -i files.txt -c copy output.mp4</p>
  </blockquote>
  
  <p>files.txt is correctly listing both files. Can anyone point me to where the problem might be?</p>
  
  <p>Thanks</p>