Monday, 15 October 2012

More Kinovea Trials

I've spent a bit more time with Kinovea this evening and I think I've now pretty much got my head around the features I plan to use. I'm convinced that this freebie package will do what I want and is a far better option for me that spending a load of money on DartFish.  The package has it's limitations but in all honesty I think they are not truly package imitations but the result of me doing this on the cheap with a little webcam.

I think the disengagement of the tracking "lock" I've experienced is very much cadence related. Filming at 30fps the lock remains good up to about 65rpm and then starts to fail, even with markers. I think this is because the tracking uses colour AND object shape and as the cadence rises the apparent object (marker) shape changes from round to oval as a result of the pedal speed and tracking is lost.

I'm hoping that using the PS3 Eye, if I can get it going, will allow me to film at maybe 50fps (up to the USB2 data transfer limit anyway) which might allow me to use cadences of about 70-75, we'll see. The camera was only £15 so it's worth an experiment.

So, did some initial trial recordings of myself this evening, nothing serious, just experimental, here's the outcome:


  1. Hi Quentin.
    I've been using Kinovea with swim analysis. I had problems with processing speed, so upgraded to the beta version (0..1.9 off the top of my head). Its resolved the issues I was having, but I haven't done a lot with it. May be worth trying?

  2. Hi Ian, I'm using v0.8.19 which is the latest experimental version. The issue I have is I am certain related to video frame rate as I'm just using a webcam which will not record at a higher frame rate than 30fps. At areas of high movement speed (at the knee and ankle) this makes tracking difficult because the software relies on the shape of the tracked object not changing. Inevitably with a slower frame rate a fast moving object or maker will become distorted, a circle becomes an elongated oval and tracking will be lost. The other potential problem, depending on the video resolution being used, is that a higher frame rate coupled with a higher resolution (e.g.. HD) can generate a data stream which USB2 cannot deal with, this will result in dropped frames. There are answers to these problems but in a cheap (this has cost me nothing to do) and cheerful setup, which is all I need and is just something I'm looking at out of interest, there are always going to be compromises. As this stands I get live capture and can immediately see all the angles and things I want to refer to which is just grand. DartFish would have cost hundreds of pounds, I looked at the free trial download and it would not really have done what I want any better!