Calculating pitch speeds from video

[robinh]

I don't have a radar gun and DD has never had a gun put on her pitches. I wanted a baseline speed as we start this off season so that we can measure her progress. So I had the idea that I could calculate it from video. I know the frame rate of my camera (30 frames per second) and can use software to click through the video one frame at a time to count how many frames elapse through any sequence. Then we measured exactly how far from where DD released the ball (six o clock position) to where I was catching it. (I made sure to be consistent with where I held my glove.) I set up the camera on a tripod far enough away to film the entire pitch and had her pitch 30 or so pitches.

Using this method I found her pitch speed to range 43 mph to 48 mph. This seems reasonable to me, she's 14 but pitches on the slow side for her age, the reason we are working on speed this off season.

Here's the details of what I did:

I came up with this formula and plugged it into a spreadsheet. Speed in Feet/Second = Distance in Feet/(Elapsed Frames/Video Frame Rate in frames per second.) Speed in MPH = Speed in FPS * 0.681818181818182, so that is added to the formula to convert the result to MPH.

This formula obviously calculates the average speed over the entire flight of the ball, so I did a little research and found that a softball loses 1 mph for every seven feet it travels. I added a line to the spreadsheet that uses that to calculate the speed at the release (Average speed in MPH + ((distance in feet /7)/2) = speed at beginning of flight.)

I loaded the video on my PC and counted frames pitch by pitch. I have Adobe Premiere which makes it easy to count frames, but you can do it in Quicktime or Windows Media Player, and probably most video players.

I found I could even count fractions of frames, it was obvious when the ball only traveled half the distance in the final frame that it had been traveling in previous frames. I rounded to the nearest half frame, I figure that's plenty precise enough for my purposes.

The spreadsheet allows me to enter any distance and frame rate, then it's very simple to plug in the frame count of a pitch and see the average and top speed for the pitch

Any flaws in my logic or formulas here?

I apparently can't attach the spreadsheet here, but I will be happy to email if anyone wants to try it or check my math. (request it at robin@robinhickman.com)

 

[roscoe545]

Sounds easy!! With simple formula's like this, why would anyone ever buy a gun?
Awesome work robinh!!

 

[Amy in AZ.]

Robin, I don't know any math, but as a pitching instructor, the range between 43mph and 48mph is a big jump. That could well be 6 months worth of work. So, if you want a true reading, I would go to an indoor facility and ask them to gun your DD. The results will be 2 fold, as you can then tell how close you formula came to being right. Let us know. I always like to learn.

 

[GOINGDEEP]

I came up with this formula and plugged it into a spreadsheet. Speed in Feet/Second = Distance in Feet/(Elapsed Frames/Video Frame Rate in frames per second.) Speed in MPH = Speed in FPS * 0.681818181818182, so that is added to the formula to convert the result to MPH.

Here's my formula. Plug my keys into the ignition and drive to the sporting goods store. Speed in MPH = 40 average. Park/walk inside and factor distance in feet = 300 feet round trip. Convert my $100 bill into a Bushnell radar gun. Problem solved.

Seriously I do like your presentation and ideas. Not sure if I would want to go through all that work when a gun will give you instant information for many years to come.

 

[robinh]

Seriously I do like your presentation and ideas. Not sure if I would want to go through all that work when a gun will give you instant information for many years to come.

I actually do plan to buy a radar gun in the next couple of months, but once this idea occurred to me I had to see if I could make it work.

 

[robinh]

Robin, I don't know any math, but as a pitching instructor, the range between 43mph and 48mph is a big jump. That could well be 6 months worth of work. So, if you want a true reading, I would go to an indoor facility and ask them to gun your DD. The results will be 2 fold, as you can then tell how close you formula came to being right. Let us know. I always like to learn.

I thought the same thing, but the 43 reading was only one pitch out of the set, most pitches were around 45. And the pitches that were coming in at 48 she was throwing a peel drop as opposed to a fastball. not sure what that means, but I've noticed her peel drop is always faster. We don't have any pitching facilities here, but I think the high school has a Jugs gun, if so I'll see if we get a reading on it for a comparison. School doesn't start for over a week though, so that will be a bit.

 

[GunnerShotgun]

Be sure to add 10 MPH if you live in Texas.

 

[robinh]

Be sure to add 10 MPH if you live in Texas.

Right, forgot to put that in the formula.

 

[chinamigarden]

Here's my formula. Plug my keys into the ignition and drive to the sporting goods store. Speed in MPH = 40 average. Park/walk inside and factor distance in feet = 300 feet round trip. Convert my $100 bill into a Bushnell radar gun. Problem solved.

Seriously I do like your presentation and ideas. Not sure if I would want to go through all that work when a gun will give you instant information for many years to come.

Because this way you can also look on youtube and figure out on other's videos that the actual pitch speed is 38MPH and grandpa is moving the radar gun towards the pitch at 13 MPH so the combined speed on the gun reads 51.

 

[Angus T]

I bought the gun...then my daughter went to tryouts for a few teams. My gun said 46-47mph, their guns said 50-51...I like my gun better. Now my daughter converts my gun speed to their gun speed for the "true reading". My response to her, "throw me a drop, inside corner, and don't make me move my mitt".