cat /home/ec2-user/FILES/*.jpg* | /home/ec2-user/ffmpeg/ffmpeg -f image2pipe -i /dev/stdin /home/ec2-user/OUT.MP4

ffmpeg version N-45884-g92a0a6bea-static https://johnvansickle.com/ffmpeg/  Copyright (c) 2000-2018 the FFmpeg developers
  built with gcc 6.3.0 (Debian 6.3.0-18+deb9u1) 20170516
  configuration: --enable-gpl --enable-version3 --enable-static --disable-debug --disable-ffplay --disable-indev=sndio --disable-outdev=sn
dio --cc=gcc-6 --enable-fontconfig --enable-frei0r --enable-gnutls --enable-gray --enable-libaom --enable-libfribidi --enable-libass --ena
ble-libvmaf --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-l
ibrubberband --enable-libsoxr --enable-libspeex --enable-libvorbis --enable-libopus --enable-libtheora --enable-libvidstab --enable-libvo-
amrwbenc --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzimg
  libavutil      56. 17.100 / 56. 17.100
  libavcodec     58. 19.100 / 58. 19.100
  libavformat    58. 13.100 / 58. 13.100
  libavdevice    58.  4.100 / 58.  4.100
  libavfilter     7. 20.100 /  7. 20.100
  libswscale      5.  2.100 /  5.  2.100
  libswresample   3.  2.100 /  3.  2.100
  libpostproc    55.  2.100 / 55.  2.100
[image2pipe @ 0x4f45bc0] Could not find codec parameters for stream 0 (Video: none, none): unknown codec
Consider increasing the value for the 'analyzeduration' and 'probesize' options
Input #0, image2pipe, from '/dev/stdin':
  Duration: N/A, bitrate: N/A
    Stream #0:0: Video: none, none, 25 tbr, 25 tbn, 25 tbc
Output #0, mp4, to '/home/ec2-user/OUT.MP4':
Output file #0 does not contain any stream