title: Join video in FFmpeg have problem More than 1000 frames duplicated
body: <p>Hello I have this FFMPEG code</p>
  
  <pre><code>ffmpeg -i video1.mp4 -i video2.mp4 -i video3.mp4 -filter_complex 
  "[0:v]scale=1280x720,setsar=1[v0];
  [1:v]scale=1280x720,setsar=1[v1];
  [2:v]scale=1280x720,setsar=1[v2]; 
  [v0][0:a][v1][1:a][v2][2:a]concat=n=3:v=1:a=1" output.mp4
  </code></pre>
  
  <p>But I exec it it give back me this Warring Message:</p>
  
  <blockquote>
    <p>More than 1000 frames duplicated</p>
  </blockquote>
  
  <p>How can I solve it? Plesase help me. Thanks!</p>