===== ffmpeg video to frames =====

all frames:
  - <code>ffmpeg -i "x.mp4" '%04d.png'</code>
  - (delete .mp4 file, sort frames)

1/1:
  - <code>ffmpeg -i "x.mp4" -filter:v fps=fps=1/1 %04d.jpg</code>

1/2:
  - <code>ffmpeg -i "x.mp4" -filter:v fps=fps=1/2 %04d.jpg</code>