FPS = Frames per second
We can find a lot of slow motion captures on on sprinting … When you see a 100m race on TV it always have a re-play in slow motion.
Lots of people are uploading videos on Youtube etc.
Thats great! Especially for nerds like myself that like to analyze contact times etc.
But to the problem: How do you determine the original frame rate?
For convenience I always use 100 fps for my own capture so that I know one frame equals one millisecond.
When I find a clip with unknown frame rate I can often find the results of the race somewhere, so I can get the original fsp though some number crunching.
Ex: A race that took 9.85 seconds with X FPS converted to 25 fps (standard for video), in 40.55 seconds.
40.55 / 9.85 = 4,12 (times slower)
4,12 * 25 = 103 (the original frame rate was 103 fps)
So if contact time for a particular athlete in the race was 12 frames, that means his/her contact time is 12/103 seconds.
Often though, the video does not cover the entire race, and only show a section, for example 40m to finish. If I’m lucky I can see the 60m /80 line or markings for hurdles. Then I can roughly estimate the current speed to get the FPS.
Does anyone have other methods, tips and tricks? Anything that I can look for, like someone in the crowd dropping something (timing the drop, knowing the gravity), camera flashes, some biomechanic movement, etc that has a known and somewhat accurate timing.