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Topic: Video power... (Read 478 times) |
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megamu
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Video power...
« on: Aug 7th, 2003, 9:20am » |
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I'm a few weeks away from starting a project through school utilizing HCI and Computer "Vision." I really like the P5 software (I've used it for 2d work in the not to distant past).
I just need to know if P5 is going to be fast enough to support my project: 20-30fps it needs to take a shot from a webcam (or other video source) transform the image, manipulate the image, and then display it to screen (800x600 most likely).
Will P5 be fast enough to support my project? or should I start shopping for Director?
Thanks
-Lee
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toxi
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Re: Video power...
« Reply #1 on: Aug 7th, 2003, 8:59pm » |
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to be honest i don't think either (P5 or director) will be fast enough to do this @ 20fps+
at 800x600 you deal with an awful lot of data:
each frame is 800*600*4 bytes = 1.875MB
at 20fps this means you have to process and move at least 36.6MB per second.
IMHO the only feasible tool for this is C/C++ on a VERY fast machine...
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http://toxi.co.uk/
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benelek
 
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Re: Video power...
« Reply #2 on: Aug 8th, 2003, 9:03am » |
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that's assuming you're working with an 800x600 image from the webcam - you could work with a smaller image and blow it up a bit. depending on what you're trying to do, it may not be necessary to have such a large pixel-by-pixel manipulation on your hands. what kind of idea are you trying out?
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megamu
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Re: Video power...
« Reply #3 on: Aug 10th, 2003, 8:00pm » |
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well, I became very intrigued by Zack Simpson's http://www.mine-control.com/ Which is a few years old to date. While my project is quite different, the techincal core concepts are more or less the same: reading dark or light spots from an image and using it as imput towards the program.
I would like the output to be highquality and realtime. realtime is more important than quality though.
The machine I would be running isn't too quick. Maybe a 1ghz P3. Hopefully I'll be getting a new laptop with some heavyduty power soon.
-Lee
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benelek
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Re: Video power...
« Reply #5 on: Aug 11th, 2003, 7:48am » |
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yeah, i remember seeing this stuff a while ago. it's excelent work, and i wonder if they had to resort to using a quasi-godlike computer behind the scenes (to make it realtime and of such high quality).
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toxi
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Re: Video power...
« Reply #6 on: Aug 11th, 2003, 10:11am » |
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okay, now that we know what you're trying to do (  )... it's a bit different than from what i gathered from your original message.
in the mine-control demos the output is not strictly based on the input. the input is merely used to get the shadow parts of an image and this image can be much lower res (even 320x240 should be sufficient). it is also not fed back into the output. so in that case you have quite a different situation as you drastically cut down the amount of process data. and you could even use hardware acceleration (openGL/directX) to display your 2d/3d stuff. this would help performance even more, but depends on your plans. if you're going to use 2d graphics, i would possibly stick with processing, simply for the better pixel controls, freedom. for anything 3d based, at this point in time, i'd only recommend director with josh nimoy's webcam xtra for that job. however you'll need to work with a smaller source image, because director's pixel commands are slooow...
to summarize, i'd start playing around with both to see the basic performance. to give you a little headstart with the director side, charles forman has done a mind-control type thingy last year.
my 2p
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http://toxi.co.uk/
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trip
 
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Re: Video power...
« Reply #7 on: Aug 22nd, 2003, 7:42am » |
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from what I understand, the mine-control peeps come from video game programming... imho the best coders are game coders. as far as Charles Forman's (setpixel.com) stuff, he did it in Director with Danny Rozen's Track Them Colors Xtra. I can tell you that TTC is a bit on the slow side (especially on the PC) if you want to manipulate the video pixels. You can tell that there is some lag in Forman's installation. Some of the stuff I was doing in Director with TTC (simple realtime video image manipulation) is MUCH faster in P5. Still, there is no way that it runs at full rez and frames.
c
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Cameron Owen
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Re: Video power...
« Reply #8 on: Dec 14th, 2003, 4:26pm » |
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Just thought I'd jump in and risk dragging this up from the dead in case anyone else swings by with a similar question.
Director and the TTC xtra are very slow for this kind of thing. I built something very similar to Shadow Garden recently (exhibited it at SOOB, www.straightoutofbrisbane.com earlier this month). I built it in director, which wasn't hard, as the TTC threshold filter simplifies most of the dirty work but to get it running at around 30 fps I had to cut the video resolution down to 160x120. This was running on a P4 1.6 Ghz with 512 RAM, (My AMD XP 2000+ was a little faster, but not by much) although even at that resolution it'll work quite well as the shadows are blurry anyways which means you have a fuzzy area in which to trigger collisions and it'll still appear to be accurate, which I believe is the real ket to this kind of work. Most people were shocked when I told them how low the input resolution was. The final image output was at 640x480 -- but if you're projecting than anything more than 640x480 is kinda overkill anyways.
I honestly don't know how Charles got his running smoothly with a video resolution of 320x240, that quite literally halved my frame rate. Maybe he had a much faster computer than I did.
On a whole it only took a couple of weeks to build, then a further two months re-coding here and there to try and squeeze every ounce of speed out of it. I found Proce55or because I was searching for a better solution to these kind of applications. Doing this in Director was a big headache so I'd advise that you avoid that route if you can.
Oh and when you're using live Digital Video, there will always be some lag in the input regardless of what language you use to build the application, even the 'sand' videos of the mine-control work show some lag in this area.
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