Video Playback with Stimulus Presentation App

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charles.gaona
Posts: 2
Joined: 05 Jan 2011, 12:08

Video Playback with Stimulus Presentation App

Post by charles.gaona » 05 Jan 2011, 12:17

I would like to synchronize video clips with the Stimulus Presentation Application. Any suggestions on the most straightforward approach to doing so?
Thanks for your help,
Charlie

gschalk
Posts: 615
Joined: 28 Jan 2003, 12:37

videos

Post by gschalk » 06 Jan 2011, 12:56

Charlie,

This depends on the nature of the videos. If the videos are short, simply break them into individual images, and show the images with an appropriate system update speed (e.g., 30 times/second). This works fine for several small clips, but clearly not when you would show several minutes, etc.

If you would like to show longer clips, you would need to write a BCI2000 Application module, or perhaps an extension to StimulusPresentation, that can show videos. This updated module could stick the current video frame into a state variable. Please let us know if you need details regarding necessary software modifications.

Thanks,
Gerv

charles.gaona
Posts: 2
Joined: 05 Jan 2011, 12:08

Post subject: videos

Post by charles.gaona » 06 Jan 2011, 13:14

Thanks Gerv,
We need to synch audio and video. I'm not familiar with the video playback libraries available, I would need some pointers here. I've also seen that the BCPy2000 platform supports vision egg. Are you familiar with anyone using it to do video playback?
Best,
Charlie

jhill
Posts: 31
Joined: 17 Nov 2009, 15:15

Post by jhill » 06 Jan 2011, 23:00

Hi Charlie,

BCPy2000 is, by default, based on VisionEgg. I have seen VisionEgg do movies: that seems to be well-supported feature in principle, although I have never tried it within BCPy2000. I have slight misgivings based on the multithreaded way BCPy2000 Applications work, but it's definitely worth a try.

If I remember correctly, VisionEgg does movies via Quicktime. If so, you'll almost certainly have to download and install the Quicktime runtime for Windows. Then, it might work out-of-the-box for you (try it first: without launching BC{I,Py}2000, just use Python directly to run the appropriate script from the "demo" subdirectory of the VisionEgg source download). Or it might not: I have a vague memory from two years ago that Quicktime support wasn't enabled by default in VisionEgg's Windows build. If this is still the case, you might have to get more technical, and compile VisionEgg from source after installing the appropriate Quicktime SDK files: IIRC this is explained in the VisionEgg sources.

If it's necessary, you can find some notes on compiling Python modules under Windows here.

Hope this helps,

jez

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