title: After merge videos, the duration is too long - ffmpeg
body: <p>I have file txt with content</p>
  
  <pre><code>file intro.mp4
  file video.mp4
  file outtro.mp4
  </code></pre>
  
  <p>with duration by <code>10s</code>, <code>178s</code>, <code>13s</code>.</p>
  
  <p>I use ffmpeg to merge 3 files into one with below command:</p>
  
  <pre><code>ffmpeg -f concat -i "file.txt" -vcodec copy -acodec copy "endfile.mp4"
  </code></pre>
  
  <p>The duration of <code>endfile.mp4</code> is longer <code>11</code> mins (<code>660s</code>).</p>
  
  <p>I have a question that <code>which params of video affect to merge?</code> And <code>which common params to merge another videos?</code></p>
  
  <p>My English really too bad. Sorry for it :)<br>
  Good working this week!</p>
  
  <p><code>P/S</code> Details infor of files:<br></p>
  
  <p><code>intro.mp4</code>:</p>
  
  <pre><code>ffprobe version N-82885-g6d09d6e Copyright (c) 2007-2016 the FFmpeg developers&lt;br&gt;
      built with gcc 4.4.7 (GCC) 20120313 (Red Hat 4.4.7-17)&lt;br&gt;
      configuration: --prefix=/root/ffmpeg_build --extra-cflags=-I/root/ffmpeg_build/include --extra-ldflags='-L/root/ffmpeg_build/lib -ldl' --&lt;br&gt;bindir=/root/bin --pkg-config-flags=--static --enable-gpl --enable-nonfree --enable-libfdk_aac --enable-libfreetype --enable-libmp3lame&lt;br&gt; --enable-libopus --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libx265&lt;br&gt;
      libavutil      55. 43.100 / 55. 43.100&lt;br&gt;
      libavcodec     57. 68.100 / 57. 68.100&lt;br&gt;
      libavformat    57. 61.100 / 57. 61.100&lt;br&gt;
      libavdevice    57.  2.100 / 57.  2.100&lt;br&gt;
      libavfilter     6. 68.100 /  6. 68.100&lt;br&gt;
      libswscale      4.  3.101 /  4.  3.101&lt;br&gt;
      libswresample   2.  4.100 /  2.  4.100&lt;br&gt;
      libpostproc    54.  2.100 / 54.  2.100&lt;br&gt;
    Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/path/to/intro.mp4':&lt;br&gt;
      Metadata:&lt;br&gt;
      major_brand     : isom&lt;br&gt;
      minor_version   : 512&lt;br&gt;
      compatible_brands: isomiso2avc1mp41&lt;br&gt;
      encoder         : Lavf56.23.100&lt;br&gt;
    Duration: 00:00:10.08, start: -0.013061, bitrate: 701 kb/s&lt;br&gt;
      Stream #0:0(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 128 kb/s (default)&lt;br&gt;
      Metadata:&lt;br&gt;
      handler_name    : SoundHandler&lt;br&gt;
      Stream #0:1(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1920x1080, 853 kb/s, 24 fps, 24 tbr, 12288 tbn, 48 tbc (default)&lt;br&gt;
    Metadata:&lt;br&gt;
      handler_name    : VideoHandler&lt;br&gt;
  </code></pre>
  
  <p><code>outtro.mp4</code>:</p>
  
  <pre><code>ffprobe version N-82885-g6d09d6e Copyright (c) 2007-2016 the FFmpeg developers&lt;br&gt;
      built with gcc 4.4.7 (GCC) 20120313 (Red Hat 4.4.7-17)&lt;br&gt;
      configuration: --prefix=/root/ffmpeg_build --extra-cflags=-I/root/ffmpeg_build/include --extra-ldflags='-L/root/ffmpeg_build/lib -ldl' --&lt;br&gt;bindir=/root/bin --pkg-config-flags=--static --enable-gpl --enable-nonfree --enable-libfdk_aac --enable-libfreetype --enable-libmp3lame&lt;br&gt; --enable-libopus --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libx265&lt;br&gt;
      libavutil      55. 43.100 / 55. 43.100&lt;br&gt;
      libavcodec     57. 68.100 / 57. 68.100&lt;br&gt;
      libavformat    57. 61.100 / 57. 61.100&lt;br&gt;
      libavdevice    57.  2.100 / 57.  2.100&lt;br&gt;
      libavfilter     6. 68.100 /  6. 68.100&lt;br&gt;
      libswscale      4.  3.101 /  4.  3.101&lt;br&gt;
      libswresample   2.  4.100 /  2.  4.100&lt;br&gt;
      libpostproc    54.  2.100 / 54.  2.100&lt;br&gt;
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/path/to/outtro.mp4':&lt;br&gt;
  Metadata:&lt;br&gt;
      major_brand     : isom&lt;br&gt;
      minor_version   : 512&lt;br&gt;
      compatible_brands: isomiso2avc1mp41&lt;br&gt;
      encoder         : Lavf56.23.100&lt;br&gt;
  Duration: 00:00:13.08, start: -0.013061, bitrate: 481 kb/s&lt;br&gt;
  Stream #0:0(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 128 kb/s (default)&lt;br&gt;
  Metadata:&lt;br&gt;
      handler_name    : SoundHandler&lt;br&gt;
  Stream #0:1(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1920x1080, 392 kb/s, 24 fps, 24 tbr, 12288 tbn, 48 tbc (default)&lt;br&gt;
  Metadata:&lt;br&gt;
      handler_name    : VideoHandler&lt;br&gt;
  </code></pre>
  
  <p><code>video.mp4</code></p>
  
  <pre><code>ffprobe version N-82885-g6d09d6e Copyright (c) 2007-2016 the FFmpeg developers&lt;br&gt;
      built with gcc 4.4.7 (GCC) 20120313 (Red Hat 4.4.7-17)&lt;br&gt;
      configuration: --prefix=/root/ffmpeg_build --extra-cflags=-I/root/ffmpeg_build/include --extra-ldflags='-L/root/ffmpeg_build/lib -ldl' --&lt;br&gt;bindir=/root/bin --pkg-config-flags=--static --enable-gpl --enable-nonfree --enable-libfdk_aac --enable-libfreetype --enable-libmp3lame&lt;br&gt; --enable-libopus --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libx265&lt;br&gt;
      libavutil      55. 43.100 / 55. 43.100&lt;br&gt;&lt;br&gt;
      libavcodec     57. 68.100 / 57. 68.100&lt;br&gt;&lt;br&gt;
      libavformat    57. 61.100 / 57. 61.100&lt;br&gt;&lt;br&gt;
      libavdevice    57.  2.100 / 57.  2.100&lt;br&gt;&lt;br&gt;
      libavfilter     6. 68.100 /  6. 68.100&lt;br&gt;&lt;br&gt;
      libswscale      4.  3.101 /  4.  3.101&lt;br&gt;&lt;br&gt;
      libswresample   2.  4.100 /  2.  4.100&lt;br&gt;&lt;br&gt;
      libpostproc    54.  2.100 / 54.  2.100&lt;br&gt;&lt;br&gt;
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'path/to/video.mp4':&lt;br&gt;
      Metadata:&lt;br&gt;
          major_brand     : isom&lt;br&gt;
          minor_version   : 512&lt;br&gt;
          compatible_brands: isomiso2avc1mp41&lt;br&gt;
          encoder         : Lavf57.61.100&lt;br&gt;
      Duration: 00:02:58.38, start: 0.000000, bitrate: 922 kb/s&lt;br&gt;
          Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1280x720 [SAR 1:1 DAR 16:9], 782 kb/s, 29.97 fps, 29.97 tbr, 30k &lt;br&gt;tbn, 59.94 tbc (default)&lt;br&gt;
          Metadata:&lt;br&gt;
              handler_name    : VideoHandler&lt;br&gt;
          Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 130 kb/s (default)&lt;br&gt;
          Metadata:&lt;br&gt;
              handler_name    : SoundHandler&lt;br&gt;
  </code></pre>