Convert AVI to MP4
  ----------------------------
  ffmpeg -i input.avi -c:v libx264 -crf 19 -preset slow -c:a libvo_aacenc -b:a 192k -ac 2 out.mp4

  Convert MP4 to GIF
  ---------------------------
  mkdir frames
  ffmpeg -i video.mp4  -r 5 'frames/frame-%03d.jpg'
  cd frames
  convert -delay 20 -loop 0 -layers Optimize *.jpg myimage.gif