ffmpegでサムネイル抽出

Extracting a single frame

ffmpeg -i yosemiteA.mp4 -ss 00:00:18.123 -f image2 -vframes 1 yosemite.png

Periodic thumbnails

ffmpeg -i yosemiteA.mp4 -f image2 -vf fps=fps=1/10 ythumb%3d.png

i-frame thumbnails

ffmpeg -i yosemiteA.mp4 -f image2 -vf "select='eq(pict_type,PICT_TYPE_I)'" -vsync vfr yi%03d.png

Capturing scene change

ffmpeg -i yosemiteA.mp4 -vf  "select=gt(scene\,0.5), scale=640:360" -vsync vfr yosemiteThumb%03d.png