Getting the Most Out of Your Video

[diredesire]

Lots of threads have been popping up recently about videos, calculating speeds, and other related topics. I'm going to (for now) sticky a thread where you can post links and other resources for how to get the most out of your video...

Thanks to user Mike Cottrill for suggesting this thread, and the first link of the sticky:

http://tt.tennis-warehouse.com/showthread.php?t=99228
"Calculating Serve Speed from a digital Video"

Please help out by adding more links!

[MasturB]

If you want to check your speed, use a free program like Windows Movie Maker, pause it at the point of contact and fastforward it by frame.

It's automatically set to 30 FPS (I think)

[Mike Cottrill]

Looking for consumer Camcorder for sports? Sony DCR-DVD505 Smooth Slow Recording 240fps

Looking for a consumer Camcorder for sports? As of 10-3-2006, Sony has a selection of camcorders that can record short clips at 240fps. Great for analyzing strokes and for calculating serve speeds.
Sony:
“Smooth Slow Recording
By increasing the record rate from 60 fields per second (fps) to 240 fps for 3 seconds allowing you to capture 3 seconds of fast motion and play the video back in 12 seconds. This is great for analyzing a golf swing or a viewing a bird in flight”
At times in normal mode, it appears that the camera playbacks 30 or 60fps. Most likely just an interlacing adjustment the camera does with on board processing.

I personally have this one:


3 seconds if enough time to capture the serve motion and the ball reaching the fence if serve is at least in the upper 80’s. Resolution in smooth slow recording mode is far less than in normal mode, but still very useful for analyzing sport strokes. Nice camera for every day recording as well.

Here is a link to the selection of camcorders:
http://www.sonystyle.com/is-bin/INTE....com/index.php


Examples and editing to come soon.

[onehandbh]

Unfortunately I "upgraded" to windows moviemaker2. It added editing
features but reduced fps down to about 14 or 15. Anybody know how
to get back this feature?

[maverick1]

Originally Posted by onehandbh

Unfortunately I "upgraded" to windows moviemaker2. It added editing
features but reduced fps down to about 14 or 15. Anybody know how
to get back this feature?

I am pretty sure it depends on what format you choose when capturing.
The default format is a highly compressed one. If you choose DV-AVI, it will take up a lot of space but it will preserve all the information that is on the tape.

There are intermediate formats that compress and still keep 30 fps.

[maverick1]

Onehandbh,
You seem to be right that Windows movie maker displays about 15 fps in its preview window, even if you capture DV-AVI.

But the captured file does contain 30 fps. You can use a 3rd party player that shows frame-by-frame.

For example, Elecard. A 21-day trial version is free(http://www.elecard.com/download/index.php)
To see frame by frame, you have to pause and hit the arrow keys. BUT there is a setting that controls how much each arrow key advances to film. Make sure you set it to 1 frame.

[onehandbh]

hey maverick1,

Thanks for the tip on elecard. It's a nice, simple video player.
Not sure if I totally understand the whole frame counting
thing. Here's a video of my old service motion.
how many frames would this be? (and speed?)


http://media.putfile.com/old-service-motion

[maverick1]

Originally Posted by onehandbh

hey maverick1,

Thanks for the tip on elecard. It's a nice, simple video player.
Not sure if I totally understand the whole frame counting
thing. Here's a video of my old service motion.
how many frames would this be? (and speed?)

http://media.putfile.com/old-service-motion

Onehandbh,

Putfile doesn't allow me to step through the video.

The serve seems to have nice form and speed, but I am not experienced enough to judge speed from watching.

If you are computer-savvy enough to download Elecard and take a look, I am sure you can do the rest.
Open up the captured file(should be a large one, 1 Gigabyte for every 2 minutes) in Elecard, pause it before you are about to hit the serve.
(I don't have this software at work, so this is from memory)
There should be something at the bottom of the Elecard controls window to click, that expands the window to display more controls. One of the controls is for how much the video advances every time you press the left/right arrow keys. Set it to the minimum(1 frame or 1/30th of a second).

Then press Right Arrow until you reach a frame where you have just hit the ball. (It is likely that the you won't catch the exact instant of contact, and ball is already on its way. In this case, just use your judgment to estimate a half or 1/3rd frame or whatever)
Then keep pressing the Right arrow key until the ball lands on the court, and of course count the number of times you had to press the key, and let me know.
Please try it and if you still have trouble I will do my best. It would be a pity to give up now after you have done 95% of the work.
You can send me an email by clicking on my alias on the left.

[onehandbh]

Okay.

I get 13 frames: if I don't count the frame at the moment of contact w/racket
and click until it hits the court.(and including that frame where the ball
hits the court) Is that right? According to the calculator (for 30 fps)
the serve would be 111 mph.

If count the frame at the moment of contact then 14 frames would come
out to 103mph.

[maverick1]

Originally Posted by onehandbh

Okay.

I get 13 frames: if I don't count the frame at the moment of contact w/racket
and click until it hits the court.(and including that frame where the ball
hits the court) Is that right? According to the calculator (for 30 fps)
the serve would be 111 mph.

If count the frame at the moment of contact then 14 frames would come
out to 103mph.

It sounds right that you should NOT count the frame at contact.
Congratulations, that is very fast.
Make sure you account for the distance correctly. It is 60 feet you strike the ball directly above the baseline and it lands on the service line, down the middle.

[onehandbh]

maverick1,

Do you happen to know which web/video hosting sites allow you
to step through video frame by frame (and preserve the original 30fps rate)?

[maverick1]

Originally Posted by onehandbh

maverick1,

Do you happen to know which web/video hosting sites allow you
to step through video frame by frame (and preserve the original 30fps rate)?

I haven't found any. Not youtube nor google.

You can try the filesharing sites like putfile.com. You can edit in Windows movie maker and produce a 0.5 second to 1 second video with 15 to 30 frames. Even at high resolution, it should be a pretty small file. You can upload to one of these sites. Users will still need something like Elecard to step through it.

[onehandbh]

Here's an example on how to use maverick1's serve
speed calculator (using my one of my serves). (with lots of
help from maverick1!) Hope it helps others how to use his
calculator.

Video was recorded at 30 frames / second (29.97). I used
the elecard video player on my computer that maverick1
suggested. Here is a frame by frame jpeg captured from
the video using elecard:



1) Calculate the distance the serve travels (and adjustments):
60.0 feet (distance to T)
+ 0.5 feet (for additional distance from striking ball 8+
feet above the court. I am 5' 11 3/4")
+ 0.5 feet (my serve was in the middle of the box)
- 1.0 feet (distance inside the service line the serve landed)
- 1.5 feet (distance from baseline at contact point.
I land inside the court)
= 58.5 feet traveled by ball.

2) Calculate total number of frames (time) the ball is in the
air.

a) Frame 1 appears closest to the point of contact.
According to maverick1, if you look carefully you'll
realize that it is actually just before contact. The main
clue is that arm is not vertical yet - it is leaning back.
Also, the ball is still in the same focus and is not
blurry or squashed from the contact yet. (looks the
same as frame 0)

b) In frame 14, it appears that the ball has struck the
court and in frame 15 it is clearly bouncing back up.

c) 14 - 1 = 13 frames. Then subract 0.5 frames since
frame 1 is just before contact.
So we have 12.5 frames.

3) Plugging 58.5 feet and 12.5 frames into maverick1's
calculator (http://mavericks.cc/tennis/serve_speed.html)
I get:
112.32 mph.

It seems like a bunch of steps but once you actually get down
to doing it it isn't hard and is actually kind of fun. Another
thing that maverick1 pointed out was that the racquet
travels about 90 degrees from from 0 to frame 1 and that
shows the racquet head speed.

[drakulie]

One hand, are you sure the way you are calculating is correct? I ask because this photo, along with the video were provided to mav and mike when they were working on their formulas. They used it to see the accuracy of their formula compared to the radar gun I used in the video. The ball landed just inside the baseline up the T-it almost landed on the line. (60 feet). The radar in the video shows 101 mph, and using the calculator I got 103+. However, doing it the way you are I would get a speed of 115.7 MPH. That just doesn't sound accurate to me. That is a difference of 14 mph between the formula and the radar. It would mean the original videos I posted were between 118-122 MPH, which I know can not be possible.

http://www.youtube.com/watch?v=5EJe64Ky7rE

[maverick1]

Originally Posted by drakulie

One hand, are you sure the way you are calculating is correct? I ask because this photo, along with the video were provided to mav and mike when they were working on their formulas. They used it to see the accuracy of their formula compared to the radar gun I used in the video. The ball landed just inside the baseline up the T-it almost landed on the line. (60 feet). The radar in the video shows 101 mph, and using the calculator I got 103+. However, doing it the way you are I would get a speed of 115.7 MPH. That just doesn't sound accurate to me. That is a difference of 14 mph between the formula and the radar. It would mean the original videos I posted were between 118-122 MPH, which I know can not be possible.

Drakulie, What do you think he is doing differently from you?
The distance estimates seem reasonable. As far as frames go, I thought 12.5 was a good estimate and I suggested it to him, but now I think it may be closer to 13.

Onehandbh has numbered his frames from 0, but since the 0th frame is well before contact, I think your sequence and his sequence can be compared very nicely.

I think in frame 1, his wrist is still cocked back so it is some distance from contact. So I thought it was reasonable to assume contact happened at frame 1.5. But considering how much the racket moved between frame 0 and frame 1, contact probably happened at frame 1.1 or 1.2. Since the ball seems to be touching the floor in frame 14, the net number of frames is 12.8 or 12.9

In your frame sequence, your first frame is closer to contact than onehandbh's "frame 1" because your racket has passed vertical.

The ball is touching the court at frame 14 for both you. So I would say your serve took about 0.1 frames longer but it landed closer to the service line. I don't want to speculate on which serve was faster.

[drakulie]

Mav, the reason I asked was because the following confused me:

"c) 14 - 1 = 13 frames. Then subract 0.5 frames since
frame 1 is just before contact.
So we have 12.5 frames."

14 - 1? then another .5 was subtracted. I still don't get it.

Wouldn't it be: 14 - .5 frames = 13.5? Where did he loose another whole frame?

On mine, there are 14 exact frames between the very first frame and when the ball strikes (forget about the last two frames). On mine, I have not yet made contact with the ball (almost there), on frame 1, although it is extremely close. On his # "1" frame, contact has been made as you can see the ball blurred.

So I was curious how he lost 1.5 frames, even if he had not made contact on frame 1, and both of our serves, as you said landed on frame 14.

[maverick1]

Originally Posted by drakulie

Mav, the reason I asked was because the following confused me:

"c) 14 - 1 = 13 frames. Then subract 0.5 frames since
frame 1 is just before contact.
So we have 12.5 frames."

14 - 1? then another .5 was subtracted. I still don't get it.

Wouldn't it be: 14 - .5 frames = 13.5? Where did he loose another whole frame?

On mine, there are 14 exact frames between the very first frame and when the ball strikes (forget about the last two frames). On mine, I have not yet made contact with the ball (almost there), on frame 1, although it is extremely close. On his # "1" frame, contact has been made as you can see the ball blurred.

So I was curious how he lost 1.5 frames, even if he had not made contact on frame 1, and both of our serves, as you said landed on frame 14.

May be it will easier to see if we count in miliseconds.

The interval between frames is a little greater than 33 milliSeconds.
Let us say the 1st frame is taken at time 0, the second would be at time 1x33 milliseconds, the 3rd would be at 2x33 milliseconds...the 14th frame at 13x33 = 429 = milliseconds.

If contact between racket and ball happened half way between the first and second frame, that means contact happened at time 16.5 millisecs. If the ball hit the court in the 14th frame, that corresponds to a time of 430 millisec. So the time of travel is 429 - 16.5 = 412.5 milliseconds
412.5 / 33 = 12.5 frames.

The 0.5 frame may be too much of a deduction and should be .1 or .2, but that is a different issue.

By the exact same process as above, your serve comes out to 13 frames.

It may be confusing because he has included an extra frame at the beginning that you don't have. If you count from his second frame(labeled "1") and your first frame, it is exactly the same number of frames to bounce.

[onehandbh]

drakulie,

Basically, just count then number of frames (from but excluding
frame at point of contact w/racquet) up to and including
the frame where the ball strikes the court.
On both of our videos that comes out to 13 frames.
But frame 1 of my video is slightly prior to contact verses
your frame 1. Hence maverick1 suggested I subtract 0.5.
(but corrected to 0.1 or 0.2 now).

There are other variables involved like height of contact point,
forward lean of body, depth of actual serve, and location in
the service box so it's hard to say which serve traveled faster
despite mine taking less time to reach the court.

[drakulie]

Originally Posted by maverick1

By the exact same process as above, your serve comes out to 13 frames.

How?

In my first frame I haven't made contact and his first frame labeled "1" he hasn't made contact; and both of our serves make contact with the ground on frame 14.

How do you calculate "13" for mine, and 12.5 for his?

This does not make sense.

In addition, 13 frames for mine would mean my serve was actually 111 mph. A difference of 10 mph from the radar, which is a lot.

Originally Posted by maverick1

It may be confusing because he has included an extra frame at the beginning that you don't have.

I'm aware of that, and did not take that frame into consideration.

Originally Posted by maverick1

If you count from his second frame(labeled "1") and your first frame, it is exactly the same number of frames to bounce.

Exactly. So how do you conclude 12.5 frames for him and 13 for mine. Even if I am little closer to contact on frame 1.

Sorry for the confusion mav, but this makes no sense.

[drakulie]

Originally Posted by onehandbh

drakulie,

Basically, just count then number of frames (from but excluding
frame at point of contact w/racquet) up to and including
the frame where the ball strikes the court.
On both of our videos that comes out to 13 frames.

OK, so far we are on the same page.

Originally Posted by onehandbh

But frame 1 of my video is slightly prior to contact verses your frame 1. Hence maverick1 suggested I subtract 0.5.
(but corrected to 0.1 or 0.2 now).

Actually, I haven't made contact on my frame 1 either. Here is where the confusion begins.

Going by how you are doing it, that would mean I should put 12.5 in the calculator as well. Which would come out to 115 mph serve. That is a difference of 14 mph between the radar and the formula. This is a huge difference.

Even if I go to 13 frames (saying I am closer to contact than you on frame 1) I get 111 mph. A difference of 9 mph between formula and radar which is still a huge difference.

By the way, I'm not concerned about who's serve is faster, rather more concerned about the accuracy of the formula.

PS: forgot to mention in my first post, you have a real nice service motion