Jpunt

We're on the startingpoint of a new project and I'm orientating about how to get this to work. The idea is to have 3 (web)cams, randomly switch between them and use it in a video-montage/layering. Is this possible to switch between usb-ports from inside Max? Is this possible at all? Where should I start looking for info?

multiple-cameras-2

Quote: Jpunt wrote on Wed, 04 February 2009 14:02

----------------------------------------------------

> We're on the startingpoint of a new project and I'm orientating about how to get this to work. The idea is to have 3 (web)cams, randomly switch between them and use it in a video-montage/layering. Is this possible to switch between usb-ports from inside Max? Is this possible at all? Where should I start looking for info? 

I'd be very curious if you can get this to work. Look into the jit.qt.grab or jit.dx.grab (Windows) and see whether you can have three of these objects running simultaneously for the three different inputs. I seem to remember seeing "a grabber component is already open" and it not working, but my setup was different...

If it does work, you wouldn't have to switch USB ports or anything at all. Instead use switches and gates in Max to only grab the one you want at the time, or modify the rate you grab each to conserve processing (three cameras is considerable grab-itude). Don't use more resolution than you need (or that the cameras can provide) since that really gobbles up the CPU, and keep the aspect ratios the same if you scale up or down. Maybe scale a 640 x 480 down to 320 x 240, this would help a lot. For a montage-type effect, you might do well with grabbing frames from certain cameras infrequently rather than constantly, which will free up processing for effects etc.

Another option is to use one jit.qt.grab and switch between inputs, which requires a "close", select the new camera, then "open", which can be done but it takes a few seconds. This may not be a problem for a montage, as you could grab whatever frames you want into a jit.matrixset before closing one camera, then use these stored frames to mix with input from the next one---look into jit.xfade for simple fading, or you can use the video as GL textures on videoplanes that can move around, etc.

Quote: Jpunt wrote on Wed, 04 February 2009 14:02
----------------------------------------------------
> Hey everyone,
>
> We're on the startingpoint of a new project and I'm orientating about how to get this to work. The idea is to have 3 (web)cams, randomly switch between them and use it in a video-montage/layering. Is this possible to switch between usb-ports from inside Max? Is this possible at all? Where should I start looking for info? 
>
> Thanks in advance!
> J.
----------------------------------------------------

If it does work, you wouldn't have to switch USB ports or anything at all. Instead use switches and gates in Max to only grab the one you want at the time, or modify the rate you grab each to conserve processing (three cameras is considerable grab-itude). Don't use more resolution than you need (or that the cameras can provide) since that really gobbles up the CPU, and keep the aspect ratios the same if you scale up or down. Maybe scale a 640 x 480 down to 320 x 240, this would help a lot. For a montage-type effect, you might do well with grabbing frames from certain cameras infrequently rather than constantly, which will free up processing for effects etc. 

use a separate jit.dx.grab object for each digitizer, and route the 

On Feb 4, 2009, at 9:34 PM, Seejay James wrote:

> Quote: Jpunt wrote on Wed, 04 February 2009 14:02

> ----------------------------------------------------

>> We're on the startingpoint of a new project and I'm orientating 

>> about how to get this to work. The idea is to have 3 (web)cams, 

>> randomly switch between them and use it in a video-montage/ 

>> layering. Is this possible to switch between usb-ports from inside 

>> Max? Is this possible at all? Where should I start looking for info?

> I'd be very curious if you can get this to work. Look into the 

> jit.qt.grab or jit.dx.grab (Windows) and see whether you can have 

> three of these objects running simultaneously for the three 

> different inputs. I seem to remember seeing "a grabber component is 

> already open" and it not working, but my setup was different...

> If it does work, you wouldn't have to switch USB ports or anything 

> at all. Instead use switches and gates in Max to only grab the one 

> you want at the time, or modify the rate you grab each to conserve 

> processing (three cameras is considerable grab-itude). Don't use 

> more resolution than you need (or that the cameras can provide) 

> since that really gobbles up the CPU, and keep the aspect ratios the 

> same if you scale up or down. Maybe scale a 640 x 480 down to 320 x 

> 240, this would help a lot. For a montage-type effect, you might do 

> well with grabbing frames from certain cameras infrequently rather 

> than constantly, which will free up processing for effects etc.

> Another option is to use one jit.qt.grab and switch between inputs, 

> which requires a "close", select the new camera, then "open", which 

> can be done but it takes a few seconds. This may not be a problem 

> for a montage, as you could grab whatever frames you want into a 

> jit.matrixset before closing one camera, then use these stored 

> frames to mix with input from the next one---look into jit.xfade for 

> simple fading, or you can use the video as GL textures on 

> Interactive Media :: Concepts | Creation | Learning

use a separate jit.dx.grab object for each digitizer, and route the  
bangs to random ones.

>
> Quote: Jpunt wrote on Wed, 04 February 2009 14:02
> ----------------------------------------------------
>> Hey everyone,
>>
>> We're on the startingpoint of a new project and I'm orientating  
>> about how to get this to work. The idea is to have 3 (web)cams,  
>> randomly switch between them and use it in a video-montage/ 
>> layering. Is this possible to switch between usb-ports from inside  
>> Max? Is this possible at all? Where should I start looking for info?
>>
>> Thanks in advance!
>> J.
> ----------------------------------------------------
>
> I'd be very curious if you can get this to work. Look into the  
> jit.qt.grab or jit.dx.grab (Windows) and see whether you can have  
> three of these objects running simultaneously for the three  
> different inputs. I seem to remember seeing "a grabber component is  
> already open" and it not working, but my setup was different...
>
> If it does work, you wouldn't have to switch USB ports or anything  
> at all. Instead use switches and gates in Max to only grab the one  
> you want at the time, or modify the rate you grab each to conserve  
> processing (three cameras is considerable grab-itude). Don't use  
> more resolution than you need (or that the cameras can provide)  
> since that really gobbles up the CPU, and keep the aspect ratios the  
> same if you scale up or down. Maybe scale a 640 x 480 down to 320 x  
> 240, this would help a lot. For a montage-type effect, you might do  
> well with grabbing frames from certain cameras infrequently rather  
> than constantly, which will free up processing for effects etc.
>
> Another option is to use one jit.qt.grab and switch between inputs,  
> which requires a "close", select the new camera, then "open", which  
> can be done but it takes a few seconds. This may not be a problem  
> for a montage, as you could grab whatever frames you want into a  
> jit.matrixset before closing one camera, then use these stored  
> frames to mix with input from the next one---look into jit.xfade for  
> simple fading, or you can use the video as GL textures on  
> videoplanes that can move around, etc.
>
> Sounds like a cool project!
>
>
> --
> Interactive Media :: Concepts | Creation | Learning
> http://www.third-space-mind.com/


The project is now officially started and I hope I've managed some extra cams by next week. The single webcam (build in isight in my macbookpro) is working, which wasn't such a big operation. I'll keep you posted on this!

Ok, thanks for the replys! 
The project is now officially started and I hope I've managed some extra cams by next week. The single webcam (build in isight in my macbookpro) is working, which wasn't such a big operation. I'll keep you posted on this!

Little update about this.. it doesn't seem to be rocket science! :)

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Multiple cameras?