1 Reply by Chas Tennis

(2 replies, posted in Ideas and feature requests)

I had practiced the serve for 35 years, but I did not know the correct main sub-motion.  Even the tennis research world did not know of the correct sub-motion - Internal Shoulder Rotation - until 1995!  (Elliott & Marshall publications). Now, 30 years later, most active tennis players still do not understand. I refer to this situation as the Tennis Serve Nuthouse.

On Talk Tennis forum, I have posted on tennis strokes and their sub-motions for years.  Still, it's a battle to get more posters to view high speed videos and observe things.

A thread on Talk Tennis forum, The Tennis Serve - What's True?
 The latest posts are on Forth & Back. 

In the past, if I suggested any video analysis, there were only a few serious readers that did it.  Most posters do YouTube single frame now, I guess.

I notice sub-motions better doing Forth & Back on Vimeo videos and I recall better what I have seen. Using only a one sentence instruction, anyone can be doing Forth & Back on Vimeo videos in a minute.  However, the available tennis stroke videos from Vimeo are limited. Mostly, I have found videos from my collection.

My goal is to find a very easy way for people to view the sub-motions of tennis strokes, with hardly any learning curve and aimed at a new crowd. The Vimeo videos for Forth &  Back have been very short videos of single tennis strokes. Longer videos may cause problems with dragging the time indicator. ?   

I thought of what Kinovea can do, so I posted on this forum. 

Also, there is a subject, new to me, that seems likely related to the serve, Spinal Engine Theory.  Coco Gauff's new serve coach, Gavin MacMillan, advocates Spinal Engine Theory for the tennis serve. Spinal Engine, unlike joint motions that bend more, does not show well in high speed videos because the spine bends are small and the players wear shirts.  Some next level observation techniques, Forth & Back or "time grab" or better, might help show Spinal Engine on shirtless servers.  Information on Spinal Engine is also in the tennis serve thread.

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2 Topic by Chas Tennis

(2 replies, posted in Ideas and feature requests)

Athletic motions can be divided into sub-motions that are useful for understanding and communication.

When viewing athletic motions, single frame advance is often used.  A problem with single frame advance is that the frames before  and after the viewed frame have to be remembered.  Things are missed.

The Forth & Back Video Display Technique is another approach that I think can work better if the viewer can control displaying the video.  I have found that some things are easier to notice and study using Forth & Back displaying. Spatial & temporal information are noticed better.  I study sub-motions with it.  A sub-motion is anything that is useful for understanding.

On forums it works smoothly with Vimeo videos.   A Kinovea video with a millisecond count down time scale is perfect for the fastest  athletic motions. 

Kinovea Analysis of a Kick Serve. Recorded at 240 fps. Use Forth & Back on it.
https://vimeo.com/196108282
Go full screen, start video then stop video, now drag the white time indicator Forth & Back, Forth & Back.....to display sub-motions of the tennis serve.  You can move the cursor up, out of the way, and it still controls the frame time displayed.

With the Kinovea millisecond count down timer, time lines for all joint motions, sub-motions, ball impacts, etc., can be observed and estimated from a single high speed video.

Could Forth & Back also be added as a capability of Kinovea for split screen display with millisecond time scale?

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3 Reply by Chas Tennis

(9 replies, posted in Cameras and hardware)

"Oh, I was looking more at connecting 2 cameras directly to my PC and record using Kinovea."

I should have realized your application.......  I don't know anything about triggering cameras.

I don't recall seeing any remote start capability in the manual.   It's strong feature is that it has a shutter speed down to 25 microseconds. Of course, with rolling shutter that exposure time is applied sequentially and results in small Jello Effect.

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4 Reply by Chas Tennis

(9 replies, posted in Cameras and hardware)

"I presume they connect to a PC via USB? What resolution and fps do you use them at? Will it work with Kinovea?"

I have a cable somewhere to connect but I remove the SD card and use the SD slot on the computer.  (I did not load the original Casio software on my present computer.)   

The video works well with Kinovea.  But saving the .MOV video file with available Kinovea video formats increases the file size of the video file more than I would have expected.

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5 Reply by Chas Tennis

(9 replies, posted in Cameras and hardware)

deepakvrao wrote:
Chas Tennis wrote:

I am out of date on the current cameras.

I recently (2021) purchased 2 used Casio Ex-FH100 cameras about ~$100 each.  Also a Casio Ex-F1 for ~$300. They worked. These cameras were very well designed for high speed video in about 2010.   They have low resolution but adequate resolution for analysis at 240 fps. The strong feature - usually hard to find - was the full manual exposure control with shutter speed down to 25 microseconds, 1/40,000 sec.  That shutter speed produces small motion blur for athletic speeds. It is also nice to deal with small video file sizes, although I like high resolution like everyone else.

I tested the camera for Jello Effect distortions and JE was not significant for tennis strokes.  In the past, high speed cameras bent golf clubs in swings due to Jello Effect.  For many years, some golfers and sales people did not understand that it was JE and thought the golf club actually was bending!

I posted here on general camera issues involving frame rates, shutter speed, motion blur, Jello Effects and athletic applications. There are videos. I posted on a Golf website some years ago.

You can get the user's manuals from the Casio Support web site.

Thanks. I presume those are rolling shutter cameras?

Casio FH100 is CMOS with rolling shutter.  They are widely used in golf.   Partly because of the small number of lines to be scanned in high speed video modes, the Jello Effect is small for athletic motions.  Search Casio FH100 golf swing Youtubes.

Here is a 900+ post thread on a golfing website about Casio cameras and their application for golf. 
https://forums.golfwrx.com/topic/329254 … d/page/29/

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6 Reply by Chas Tennis

(2 replies, posted in Cameras and hardware)

Sorry, I'm not familiar with GoPro settings. I'd expect the GoPro to have an automatic exposure control.  Get a user's manual from the GoPro Support website and take videos.  To reduce motion blur you will need a fast shutter speed.  That might be a problem indoors or under artificial lighting outdoors at night because the camera's automatic exposure control  might not select a fast enough shutter speed for small motion blur. 

Here is some information on light levels for outdoor tennis court lighting and outdoor sunlight, etc. 
https://tt.tennis-warehouse.com/index.p … t-16932668

I once found estimates that recommended indoor tennis court light levels should be about 1/80th/1.3% of outdoor direct sunlight (with sharp shadows).  Check my estimate and keep that very large difference in mind. 

You can take a camera with manual settings and photograph outdoor tennis and the indoor squash court.  Use the shutter speed settings to estimate the difference in light levels for similar exposures.

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7 Reply by Chas Tennis

(9 replies, posted in Cameras and hardware)

I am out of date on the current cameras.

I recently (2021) purchased 2 used Casio Ex-FH100 cameras about ~$100 each.  Also a Casio Ex-F1 for ~$300. They worked. These cameras were very well designed for high speed video in about 2010.   They have low resolution but adequate resolution for analysis at 240 fps. The strong feature - usually hard to find - was the full manual exposure control with shutter speed down to 25 microseconds, 1/40,000 sec.  That shutter speed produces small motion blur for athletic speeds. It is also nice to deal with small video file sizes, although I like high resolution like everyone else.

I tested the camera for Jello Effect distortions and JE was not significant for tennis strokes.  In the past, high speed cameras bent golf clubs in swings due to Jello Effect.  For many years, some golfers and sales people did not understand that it was JE and thought the golf club actually was bending!

I posted here on general camera issues involving frame rates, shutter speed, motion blur, Jello Effects and athletic applications. There are videos. I posted on a Golf website some years ago.

You can get the user's manuals from the Casio Support web site.

Go to forum: Cameras and hardware

8 Reply by Chas Tennis

(3 replies, posted in General)

Recently with 8.25, I expected to be saving the side-by-side videos.  I must have increased the size of my screen and did not notice that the icons in the bottom right were for the single video and not the side-by-side. Is there some way to color code or place to make fool proof?

I often increase the display size of videos especially for analyzing side-by-side videos where I don't have control of videoing.  Often to start, one image of a tennis server is large but the other is small. If I am placing, for example, the angle tool on the smaller image, the Kinovea video gets smaller when the angle tool is selected. It is too small to work with and I increase display magnification.  My screen is 17" so I guess others do the same.

I use the Kinovea magnification tool to good effect in the final videos but the added angle tool or texts, etc, don't appear in the  magnification box.  When it is done and full screen it seems to be pretty good but for placing the angle tool, lines, arrows, etc, on a small image, it's difficult.

A second off topic issue involves the forum.  When I try to go directly to the latest post by clicking on the date of the latest post, I don't get the post.  Instead, I get a REPLY BOX for it.  This has been the case for some time.

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9 Topic by Chas Tennis

(2 replies, posted in Ideas and feature requests)

My application is high speed video of tennis strokes.  (I have not used Version 8.26)

I use the countdown feature in Version 8.25 and it is great.  It is especially useful for side-by-side tennis stroke comparisons with setting "0" the time of racket to ball impact for each video.  The entire time line of the stroke motions is labeled.  This would apply to many sports: striking, throw release, kicking impact, etc.

But the countdown feature ends at 0 time.  It would be a big improvement if the countdown feature counted down to 0 displaying negative time and then counted past 0 displaying positive time. 

It would seem that this could be done all from frame "0" for side-by-side videos by coordinating the two videos on a single frame and using the frame rate data.   For side-by-side videos with identical frame rates probably only one time display is needed.

------------------------------------------------
There is also a procedure required to set up the countdown that might be more direct. I have difficulty remembering this procedure. Perhaps a maximum time could be set prior to frame "0".  Does it have to count from the first frame of the video "segment"? and not back from frame "0". Are the frames always counted for each segment video?

8.25 Procedure to set up countdown mode.  From 2016 Nov 28 post by Joan in Version 8.25 thread.

"Stopwatch in countdown mode within the segment prior to the synchronization point should work. However the countdown mode only works if the stopwatch has a well defined range, specified by start and end points.

I think in your case you want to do the following:

    Go to the begining of the segment.

    Add the stopwatch object on the first frame.

    Right click the stopwatch and choose "Start"

    Move forward in time up to the synchronization point (shortcut: F8).

    Right click the stopwatch and choose "Stop".

    Right click the stopwatch again and choose "Countdown"."

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10 Topic by Chas Tennis

(0 replies, posted in Cameras and hardware)

I do not have a smartphone with high speed video or understand any special issues using their high speed video files on Kinovea or elsewhere.

I would like to recommend that smartphones are usable directly from the smartphone or to have some idea of what is involved, such as converting to video files that are compatible with Kinovea. 

Any general information or personal experiences using specific smartphones would be very informative.

Another approach would be to download all the smartphone instructions and see what they have to say.  Too much...

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11 Reply by Chas Tennis

(7 replies, posted in General)

For a Kinovea side-by-side comparison there could be a total of 4 different frame rates for the 2 source videos:

1) video #1 - source frame rate
2) video #1 - recording frame rate
3) video #2 - source frame rate
4) video #2 - recording frame rate

Would frame rates of the two source videos be found in 'metadata' of the source videos?

Kinovea produces a video file with another frame rate.  How does Kinovea select a default frame rate?  Does the selected Kinovea default frame rate depend on the frame rate of which source video happens to be on the right or the left?

How can/should the user select a different frame rate than the Kinovea default frame rate?

If the user selects a Kinovea video frame rate that is accepted by, for example, Youtube or Vimeo, then if frames are still skipped it would probably be a video website issue. ?   

Are the source video frame rates (metadata) still in a side-by-side Kinovea video file? Could one of those source video frame rates somehow be mistaken for the Kinovea frame rate by a video hosting website?

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12 Reply by Chas Tennis

(7 replies, posted in General)

I only have glimmers of the philosophies used by camera manufacturers, video processing creators, video analysis program creators and video hosting websites when they select frame rates.
1) camera recording frame rates -  Casio or iPhone,etc...
2) in camera processed  video output files - Casio or iPhone
3) if used, video output file from video processing applications - ?
4) output files from video analysis applications - Kinovea
5) input files for video hosting websites - Vimeo, Youtube, etc
6) final video files, compressed, stored on video hosting websites - Vimeo, Youtube, etc

My older Casio Ex FH100 records at various high speed video frame rates and outputs an AVI video file that plays back at 30 fps.  30 fps is the frame rate I'd prefer to see at the video hosting website.  To fully use what Kinovea can do all frames should appear on the hosting website with single frame control.   

What's the difference between 29.97 fps and 30 fps?  Can that cause issues?   

I do not understand why to select one of the Kinovea video file formats - Matroska, MP4 or AVI - over another.

UPDATE - I've decided that I prefer the frame rate of the video file out of my camera, 30 fps. Also, 30 fps is accepted by Youtube, Vimeo and probably others?  Camera users have experience with the frame rates that their cameras produce.   Mine plays back at 30 fps so that my 240 fps recording is shown at slow motion speed, 1/8 X real time speed.  I guess 25 fps from other cameras and countries is similar. ?

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13 Reply by Chas Tennis

(44 replies, posted in General)

Chas Tennis wrote:

Kinovea Analyses on Vimeo

We often may want to communicate the Kinovea analyses videos using Youtube, Vimeo or other video web hosts.

This issue probably involves Vimeo website processing and I have not asked them yet. .......................................................................................
I have uploaded some videos on Vimeo.   The Kinovea analysis videos worked well on my computer. They were side-by-side videos, each video recorded at different frame rates, 240 & 30 fps often,  with magnification boxes and millisecond countdown time displays.  Very informative displays.
..........................................................................................................
2) often the Vimeo processed video would do single frame so that the faster video (say 240 fps) would advance 2 frames using the Vimeo process for single frame advance.

Vimeo single frame process - Hold down SHIFT KEY & use ARROW KEYS

This side-by-side video works well, magnification box is good, but the high speed video on the right advances 2 frame times each time the arrow is pressed. (8.4 milliseconds per Vimeo arrow press instead of 4.2 ms.) This video has very brief messages and is intended to stop on specific single frames when messages appear. Not a useful video for 30 fps playback.
[video]https://vimeo.com/203003367[/video]

I am so pleased with the great job that Kinovea does on these videos.  That Vimeo video is so near perfect except it advances 2 frames on Vimeo for every one frame advance key press.

I believe that I had set the video speed properly to 240 fps when making the Kinovea analysis video.
.................................................

I contacted Vimeo about the issue of skipping frames when uploading  Kinovea videos to Vimeo.  Here is their reply.

" The original video you uploaded to Vimeo is 100 fps, which exceeds our 60fps threshold. We reduce the frame rate for all videos exceeding 60fps during our conversion process. Frame drops can occur during our conversion process in this case.

My best recommendation is that you re-encode this video using our compression guidelines https://vimeo.com/help/compression. "

I reviewed many of my Kinovea analysis video files and found some 30 fps, some 100 fps and some not listed.  (I have used 8.15 and 8.25) I thought all Kinovea videos were 30 fps and did not realize that many Kinovea files were 100 fps.  Skipping frames on videos above 60 fps appears to be an issue when uploading 100 fps Kinovea analyses video files to Vimeo. 

When does Kinovea save videos as 30 fps and when at 100 fps?    Is there a way to control the playback video frame rate before saving the Kinovea analysis video file on Kinovea 8.25?

Is there a similar issue uploading 100 fps Kinovea videos to Youtube?

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14 Reply by Chas Tennis

(7 replies, posted in General)

Chas Tennis wrote:

Kinovea Analyses on Vimeo

We often may want to communicate the Kinovea analyses videos using Youtube, Vimeo or other video web hosts.

This issue probably involves Vimeo website processing and I have not asked them yet. .......................................................................................
I have uploaded some videos on Vimeo.   The Kinovea analysis videos worked well on my computer. They were side-by-side videos, each video recorded at different frame rates, 240 & 30 fps often,  with magnification boxes and millisecond countdown time displays.  Very informative displays.
..........................................................................................................
2) often the Vimeo processed video would do single frame so that the faster video (say 240 fps) would advance 2 frames using the Vimeo process for single frame advance.

Vimeo single frame process - Hold down SHIFT KEY & use ARROW KEYS

This side-by-side video works well, magnification box is good, but the high speed video on the right advances 2 frame times each time the arrow is pressed. (8.4 milliseconds per Vimeo arrow press instead of 4.2 ms.) This video has very brief messages and is intended to stop on specific single frames when messages appear. Not a useful video for 30 fps playback.
[video]https://vimeo.com/203003367[/video]

I am so pleased with the great job that Kinovea does on these videos.  That Vimeo video is so near perfect except it advances 2 frames on Vimeo for every one frame advance key press.

I believe that I had set the video speed properly to 240 fps when making the Kinovea analysis video.
.................................................

I contacted Vimeo about the issue of skipping frames when uploading  Kinovea videos to Vimeo.  Here is their reply.

" The original video you uploaded to Vimeo is 100 fps, which exceeds our 60fps threshold. We reduce the frame rate for all videos exceeding 60fps during our conversion process. Frame drops can occur during our conversion process in this case.

My best recommendation is that you re-encode this video using our compression guidelines https://vimeo.com/help/compression. "

I reviewed many of my Kinovea analysis video files and found some 30 fps, some 100 fps and some not listed.  (I have used 8.15 and 8.25) I thought all Kinovea videos were 30 fps and did not realize that many Kinovea files were 100 fps.  Skipping frames on videos above 60 fps appears to be an issue when uploading 100 fps Kinovea analyses video files to Vimeo. 

When does Kinovea save videos as 30 fps and when at 100 fps?    Is there a way to control the playback video frame rate before saving the Kinovea analysis video file on Kinovea 8.25?

Is there a similar issue uploading 100 fps Kinovea videos to Youtube?

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15 Reply by Chas Tennis

(7 replies, posted in General)

Problem Working in Kinovea 8.25


[video]https://vimeo.com/225430440[/video]
Go full screen.

Video intended for single frame viewing of frames with text.  "Serve 1", "Serve 2" and "Serve 3" were analyzed and have text and angle scale, etc.

At the very end of this video at 48 seconds, for only a few frames, there is a brief green text box. It starts with "Forearm".......

When I was in Kinovea and making the original analysis video,  whenever I would double click on this green box to edit it,  instead the small & distant text box across the bottom would open up to be edited.  Small box - "Single Frame Vimeo".....  It became difficult to get the large green box because the small box kept opening up.  I'm not sure how I was able to edit it, but maybe I had to move the green box to open it.

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