How many Webcams can be captured simultaneously?
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Hi,
for a new project I need to capture 80 (!) Webcams simultaneously. Not a video, just one single picture of each Webcam at the same time.
If I have enough (active) hubs to connect all those webcams to my Mac, can the mac handle that many cams? (Resolution ~10 MegaPixels)
I know how to capture a Webcam via QuickTimeSDK, so that's no problem... but 80..?! Is that possible?
Or would I need to split the cams over 3 or 4 Macs and synchronize them?
Aya~_______________________________________________
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Isn't USB limited to 63 devices per controller?
-Daniel
On Apr 13, 2010, at 4:59 AM, Aya Koshigaya wrote:
> Hi,
>
> for a new project I need to capture 80 (!) Webcams simultaneously. Not a video, just one single picture of each Webcam at the same time.
>
> If I have enough (active) hubs to connect all those webcams to my Mac, can the mac handle that many cams? (Resolution ~10 MegaPixels)
>
> I know how to capture a Webcam via QuickTimeSDK, so that's no problem... but 80..?! Is that possible?
> Or would I need to split the cams over 3 or 4 Macs and synchronize them?
>
> Aya~_______________________________________________
> MacOSX-dev mailing list
> <MacOSX-dev...>
> http://www.omnigroup.com/mailman/listinfo/macosx-dev
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I believe it is 127 devices per controller, including hubs (7-bit address with one reserved address). Investigate the star topology in the USB 2 spec, which will make getting this many devices on one network a little difficult, but you might have more than one USB controller in the computer.
I think bandwidth is divided among devices, so your capture rate for this many 10MP cameras may be slow?
-Owen
On Apr 13, 2010, at 1:53 PM, Daniel DeCovnick wrote:
> Isn't USB limited to 63 devices per controller?
>
> -Daniel
>
> On Apr 13, 2010, at 4:59 AM, Aya Koshigaya wrote:
>
>> Hi,
>>
>> for a new project I need to capture 80 (!) Webcams simultaneously. Not a video, just one single picture of each Webcam at the same time.
>>
>> If I have enough (active) hubs to connect all those webcams to my Mac, can the mac handle that many cams? (Resolution ~10 MegaPixels)
>>
>> I know how to capture a Webcam via QuickTimeSDK, so that's no problem... but 80..?! Is that possible?
>> Or would I need to split the cams over 3 or 4 Macs and synchronize them?
>>
>> Aya~_______________________________________________
>> MacOSX-dev mailing list
>> <MacOSX-dev...>
>> http://www.omnigroup.com/mailman/listinfo/macosx-dev
>
> _______________________________________________
> MacOSX-dev mailing list
> <MacOSX-dev...>
> http://www.omnigroup.com/mailman/listinfo/macosx-dev
-
I don't know about the limits imposed by the OS, but I'm curious how you are planning to distribute these cameras. Are these all at a single location looking in different directions? Or are these scattered throughout an area?
USB has a pretty limited maximum distance that you can run the cables. That may be more of a limitation than just how many your OS can handle.
USB 2.0 can have cables up to 5 meters. There is also a maximum of 5 hubs in series. That gives you a theoretical maximum run length of 30 meters from the computer. You would need optical or CAT5 extenders if you wanted to go longer than that.
-Chris -
6 bits, 7 bits, what's one bit between friends? :p
On Apr 13, 2010, at 11:59 AM, Owen Imholte wrote:
> I believe it is 127 devices per controller, including hubs (7-bit address with one reserved address). Investigate the star topology in the USB 2 spec, which will make getting this many devices on one network a little difficult, but you might have more than one USB controller in the computer.
>
> I think bandwidth is divided among devices, so your capture rate for this many 10MP cameras may be slow?
>
Yes, it is, but I think he was saying that it's 10 MP total, not per camera. There will be a fair amount of overhead just from bus mastering at that number of devices though.
-Daniel
