1 Topic by coachmattb

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I am an athletic coach that uses Kinovea with my students to enhance performance via video capture and review. (am using 8.15 w/ Win XP)  During a session with one of my students, I was making extensive use of the 2 capture screen capability to watch a movement via 2 angles being captured by 1) a camcorder with firewire connection and 2) a PS3Eye webcam utilizing USB. The student would perform 4 or 5 reps of the movement while watching himself on the capture screens. We would then stop and watch the recorded video. I noticed after about a half an hour of this that the live video capture was several seconds late with showing the movement on the screen. Also, when playing the later video back, it would change speeds (usually being too fast) when compared to real time. I have gone thru a few of the older posts on this subject and see others have had similar situations. My question is this:

what are the controlling factors in keeping the capture and subsequent playback as “fresh” (or real time) as possible?

Are there memory/space buffers that I can clear when I get into a session such as previously mentioned? If so, how would I do this? Also, I noticed that performance of both of the aforementioned recording devices was better when I had the camcorder as the first capture screen and the PS3Eye as the second capture screen.

Many thanks in advance for any feedback and many thanks to Joan for all the work done on a terrific product!

2 Reply by joan

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Thanks for the feedback, it's appreciated.
The issue with the file playing too fast has been addressed in version 0.8.16. Displaying the image and saving it to the file are now in two separate threads. Previously, the saving was done in the same thread, generally the time to process one captured image was longer than the capture interval.

Beware that 0.8.16 also has some regressions apparently (see announcement topic). I hope to get 0.8.17 out in the coming weeks.

3 Reply by coachmattb

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Thank you, Joan.

What do you think of my observation on how the capturing response seemed to slow down as I did more and more files? Outside of deleting previously created files, is there something with memory usage that might be slowing the software down? Are there temporary files being written somewher that I should delete?

4 Reply by joan

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I don't know… In any case there are no temporary files.
Next time you can check the memory consumption, maybe there was a memory leak. (If you can try with 0.8.16 it's better because if the leak is still there I'd like to know). If memory goes up and up, there is a leak. It can take a while until it builds up to get noticed.

Hopefully someone else will come with his/her experience of long capture sessions.

5 Reply by coachmattb

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How does the allocation of memory size in the Capture tab affect this? Since I do quite a bit of Capture, should I set this as high as possible?

6 Reply by joan (edited by joan 2012-02-09 22:28:40)

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It controls the buffer used in the context of delayed presentation. The higher the value, the more delay can be applied to the live stream.

edit: Dual capture in 0.8.16 and the current version seems very broken sad

7 Reply by coachmattb

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is dual capture better in 8.15 or 8.16?

8 Reply by joan

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From my limited experience with capture as a user, 0.8.16 works better for single screen capture, especially with regards to recording, but it has important issues for dual screen capture, even without recording (When I tried yesterday, it was constantly crashing).

I'm not really using this extensively myself so hopefully someone else can confirm.
I'm actually surprised there isn't more comments on these issues if it's been broken in the experimental release (~450 downloads).

9 Reply by coachmattb

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ok here's an observation from yesterday's dual capture session.

on the left capture screen i am using a ps3eye webcam. on the right, a generic webcam that came with the laptop which is configured as follows:

Windows XP pro
version 2002 service pack 3 (all updates applied)
Intel Core 2 Due
t7500@ 2.2 ghz
789 mhz 3.5 gb ram
500 gb hd  7200 rpm
430 gb free

first did side and front video shot and then synched the result and made composite to avi file. everything worked fine.

next, repeated and wrote to MKV files. on playback, the video on the right capture screen played back at very fast speed and came out that way in the synched composite video.

next repeated and wrote to MP4 files. same results as previous.

re did the 1st side by side capture to  avi files and this time, the right screen played back faster.

i notice that when recording, the fps number in the parenthesis for the webcam on the right screen, is not at the fps that the properties value shows for the particular device. in my opinion it appears that internal resources are dedicated to the left most screen and the second screen gets whatever the software can give it. (of course I am guessing.)

so, the first recording and composite generation work fine but subsequent redo (albeit to a different output file type) had speed up issues on playback.

10 Reply by joan

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Thanks.
Was this with 0.8.15 or 0.8.16 ?
I don't have as many crashes right now, I'll have to investigate later. Yes, the second screen will often be more jittery. However, in 0.8.16 it should not impact recording. (The streaming video may look jittery on screen, but the recorded file is smooth and at the right framerate).

11 Reply by coachmattb (edited by coachmattb 2012-02-11 00:52:36)

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hi joan.

this was with 8.15.

so do you think dual screen capture is better with 8.16?

12 Reply by joan

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coachmattb wrote:

so do you think dual screen capture is better with 8.16?

I think it's your job to tell me smile Because unlike me you use it in real scenario.
Note that it's possible to install both versions side by side by specifying a different installation directory during installation process.