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I am using a high-speed camera recording at 250 frames per second. OpenSHAPA is very suited to my needs, except that the time counter (and corresponding onset and offset times) are currently not able to be adjusted to my particular capture rate. What this means is that I cannot view my data in OpenSHAPA in real time. It also means that when I print my data, I will need to convert the onset and offset times to real times.

My request is that there be an option for users to choose the time counter you currently use or a frame counter (i.e., a counter that increments from Frame 1 to Frame x). The ideal solution would be for users like me to be able to enter the frame rate so that the time counter accurately depicts the passage of time in the video. For 250 fps, the counter would increment in 4 ms intervals (rather than the 33 ms intervals for standard video).

I am willing to provide funds to make this functionality possible.

asked 22 Sep '11, 15:52

Clinton's gravatar image

accept rate: 36%

Karen has passed on short samples of your video (very impressive stuff), and have noticed that while the camera captures at 250 frames per second (fps) the video files are stored at 15fps for files like “... ringlamp 15 fps.avi” and actually 60 fps for files like “… ringlamp 40fps.avi”.

So that I can better understand your work-flow, what is the processing pathway used when moving data from the camera into video files. Does the camera create them itself (customised with various settings), or do you use another piece of software to create the video files from a custom camera format?

However, as you pointed out there is still a problem - since the the video file is actually telling a bit of a lie to OpenSHAPA -- it isn’t really a 15fps data source, but actually a 250fps data source!

At the moment, you can workaround this problem: Code and work with your data at 15fps, however you will be creating cells that are not in real time, but actually about 16.67 (250/15) times longer than real time. To compensate for this, after you have completed your coding, and looking to aggregate your results for publication, you can write a small script that takes all the timestamps in your OpenSHAPA spreadsheet and divide them by 16.67 to turn them into real times.

However, the above workaround is a bit clunky, and we have been designing a much better solution to this and few other “wibbley wobbly timey wimey” issues. So to allow for people as yourself to say “Hey this video is actually 16.67 times longer than real time”, we want to allow people to “stretch” and “squeeze” tracks in the data controller. You could grab the end of a track and pull it in, so say - well this video doesn’t actually run for a whole 16 seconds, but only a second. It is going to be a very powerful feature that will allow people to address all sorts of clock skew issues, and more importantly help mix and match data from all kinds of different sources... Naturally we welcome all support in making OpenSHAPA better, and you can email Karen or developers at openshapa to work out ways we can speed up improvements made in this area.

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answered 22 Sep '11, 15:53

Clinton's gravatar image

accept rate: 36%

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question asked: 22 Sep '11, 15:52

question was seen: 6,569 times

last updated: 22 Sep '11, 15:53

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