title: ffmpeg concat: "Unsafe file name"
body: <p>Trying to convert a bunch of mts-files into a big mp4-file:</p>
  
  <pre><code>stephan@rechenmonster:/mnt/backupsystem/archive2/Videos/20151222/PRIVATE/AVCHD/BDMV$ ~/bin/ffmpeg-git-20160817-64bit-static/ffmpeg -v info -f concat -i &lt;(find STREAM -name '*' -printf "file '$PWD/%p'\n") -deinterlace -r 25 -s hd720 -c:v libx264 -crf 23 -acodec copy -strict -2 ~/tmp/Videos/20151222.mp4
  ffmpeg version N-81364-gf85842b-static http://johnvansickle.com/ffmpeg/  Copyright (c) 2000-2016 the FFmpeg developers
    built with gcc 5.4.1 (Debian 5.4.1-1) 20160803
    configuration: --enable-gpl --enable-version3 --enable-static --disable-debug --enable-libmp3lame --enable-libx264 --enable-libx265 --enable-libwebp --enable-libspeex --enable-libvorbis --enable-libvpx --enable-libfreetype --enable-fontconfig --enable-libxvid --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libtheora --enable-libvo-amrwbenc --enable-gray --enable-libopenjpeg --enable-libopus --enable-libass --enable-gnutls --enable-libvidstab --enable-libsoxr --enable-frei0r --enable-libfribidi --disable-indev=sndio --disable-outdev=sndio --enable-librtmp --enable-libmfx --enable-libzimg --cc=gcc-5
    libavutil      55. 28.100 / 55. 28.100
    libavcodec     57. 53.100 / 57. 53.100
    libavformat    57. 46.101 / 57. 46.101
    libavdevice    57.  0.102 / 57.  0.102
    libavfilter     6. 51.100 /  6. 51.100
    libswscale      4.  1.100 /  4.  1.100
    libswresample   2.  1.100 /  2.  1.100
    libpostproc    54.  0.100 / 54.  0.100
  [concat @ 0x56054a0] Unsafe file name '/mnt/backupsystem/archive2/Videos/20151222/PRIVATE/AVCHD/BDMV/STREAM'
  /dev/fd/63: Operation not permitted
  </code></pre>
  
  <p>Any ideas what goes wrong here? What does the term "unsafe file" mean in this context?</p>