ffprobe -v error -count_frames -select_streams v:0 -show_entries stream=nb_read_frames -of default=nokey=1:noprint_wrappers=1 \
input.mkv https://stackoverflow.com/questions/2017843/fetch-frame-count-with-ffmpeg
input.mkv
https://stackoverflow.com/questions/2017843/fetch-frame-count-with-ffmpeg