Now, this is for standard 30 (or 29.9) FPS video only. Not 24, not 15, or 10 fps on cellphones obviously. You can check by looking at video file properties.
I start counting when the ball starts it’s path. first frame is when forearm drops after releasing (ideal first frame is when forearm has separated 2-3 feet from the ball) and last frame is when the glove closes and you can’t see white color of the ball. This may take longer than actual distance, but its easier to be more consistent this way.
I don’t count videos where the ball goes very low and on the outside or almost hits the ground, as that adds about 1 extra frame. Also, if I can’t find a clean release point frame, I’ll look for the next throw.
I guesstimate this is accurate within 3mph, not much more than that.
75 mph fastball takes 17 frames, so does neftali feliz’ 80 mph curveball.
80 = ~16 frames
85mph changeup takes ~15.5 to the glove.
86mph = more than 15 frames, probably 15.3 or something like that.
88 mph = exactly 15 frames.
By watching bullpen videos, kids who throw 91 mph are usually ~14.5 (estimate) frames, depending on location (so is lincecum’s 90 mph).
Lincecum’s 92-94 mph fastball takes exactly 14 frames to catcher’s glove (so does Cliff Lee’s and anybody else’s 93- 94mph ).
Brian wilson’s 96 mph = ~13.5 frames
Daniel bard’s 100 mph is < 13 frames.
Joba chamberlain’s 101 mph is about 12.5 frames
I looked at chapman’s 105 mph from several video sources on youtube and it seems to be exactly 12 frames.
For the bat to make contact/foul @96, 12, @ 93 mph takes ~12.5 frames. 13 @ high 80’s.