(ffmpeg-utils)2.5. Syntax | Video rate

doc

Video rate

Official documentation says:

Specify the frame rate of a video, expressed as the number of frames generated per second. It has to be a string in the format frame_rate_num/frame_rate_den, an integer number, a float number or a valid video frame rate abbreviation.

video frame rate abbreviations:

abbr	frame_rate_num/frame_rate_den	approx.
ntsc	30000/1001	29.97
qntsc	30000/1001	29.97
sntsc	30000/1001	29.97
pal	25/1	25.00
qpal	25/1	25.00
spal	25/1	25.00
film	24/1	24.00
ntsc-film	24000/1001	23.98

[me@host: ~]$ # followings will have the same result.
[me@host: ~]$ ffplay video.mkv -vf framerate=ntsc-film
[me@host: ~]$ ffplay video.mkv -vf framerate=24/1
[me@host: ~]$ ffplay video.mkv -vf framerate=24.0

[me@host: ~]$ # extract a frame from video
[me@host: ~]$ ffmpeg -y -ss 5 -i video.mkv -r 1/1 -t 1 video_5s.png
[me@host: ~]$ # extract multiple frames from video
[me@host: ~]$ ffmpeg -y -i video.mkv -r 1/3 -t 6 'video_5s_%d.png'