title: ffmpeg concatenated file does not play as expected
body: <p>I am trying create a video by concatenating in this order:</p>
  
  <p><a href="http://s3.amazonaws.com/myh12/video1.mp4" rel="nofollow noreferrer"><code>video1.mp4</code></a> <strong>&amp;</strong>  <a href="http://s3.amazonaws.com/myh12/video_from_static_image.mp4" rel="nofollow noreferrer"><code>video_from_static_image.mp4</code></a> <strong>&amp;</strong> <a href="http://s3.amazonaws.com/myh12/video1.mp4" rel="nofollow noreferrer"><code>video1.mp4</code></a></p>
  
  <p><code>video1.mp4</code> is a simple video file. <code>video_from_static_image.mp4</code> was created from the <a href="http://s3.amazonaws.com/myh12/a.png" rel="nofollow noreferrer"><code>a.png</code></a> image like this:</p>
  
  <p><code>ffmpeg  -y -framerate 25 -f image2  -loop 1 -i a.png -c:v libx264 -profile:v main -pix_fmt yuv420p -t 2 -r 25  video_from_static_image.mp4
  </code></p>
  
  <p>I create the final concatenated file through this command:</p>
  
  <p><code>ffmpeg -y -f concat -safe 0 -i mylist.txt -c copy final_concat.mp4</code></p>
  
  <p>I get the following message during the concat process:</p>
  
  <p><code>[mp4 @ 0x7fee6b815e00] Non-monotonous DTS in output stream 0:0; previous: 120678, current: 65722; changing to 120679. This may result in incorrect timestamps in the output file.</code></p>
  
  <p>The complete output when running the above command is <a href="http://s3.amazonaws.com/myh12/finalout.txt" rel="nofollow noreferrer">here</a></p>
  
  <p>When I play <a href="http://s3.amazonaws.com/myh12/final_concat.mp4" rel="nofollow noreferrer"><code>final_concat.mp4</code></a> it has problems with video_from_static_image.mp4 and it seems to skip it (and other variations resulted in playing for a short while). I've tried a bunch of things, but I believe they all point to the DTS error above.</p>
  
  <p>BTW, all the video files are pretty small (&lt; 1MB). Here are details about the version I am using:</p>
  
  <p><code>$ ffmpeg -version
  ffmpeg version 3.3.4 Copyright (c) 2000-2017 the FFmpeg developers
  built with Apple LLVM version 7.3.0 (clang-703.0.31)
  configuration: --prefix=/usr/local/Cellar/ffmpeg/3.3.4 --enable-shared --enable-pthreads --enable-gpl --enable-version3 --enable-hardcoded-tables --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-libmp3lame --enable-libvpx --enable-libx264 --enable-libxvid --enable-opencl --enable-videotoolbox --disable-lzma --enable-vda
  libavutil      55. 58.100 / 55. 58.100
  libavcodec     57. 89.100 / 57. 89.100
  libavformat    57. 71.100 / 57. 71.100
  libavdevice    57.  6.100 / 57.  6.100
  libavfilter     6. 82.100 /  6. 82.100
  libavresample   3.  5.  0 /  3.  5.  0
  libswscale      4.  6.100 /  4.  6.100
  libswresample   2.  7.100 /  2.  7.100
  libpostproc    54.  5.100 / 54.  5.100
  </code></p>