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What are advantages of cameras dedicated for Raspberry Pi (I mean those connected via dedicated camera connector and tape) above those usb webcams ?

Is it just economy advantage (better value for price) ? Or maybe just more compact and lighter ? (what may make a difference e.g. when camera handled by robotic arm)

Or does it also have some (non-negligible) performance/technical advantages? e.g. framerate not possible to achieve via usb webcam, or less cpu overhead ? Therefore, are such advantages non-negligible only for video or also in same cases of capturing still photo pictures ? (I guess might be transfer rate/cpu overhead, maybe power consumption?)

Update: as we know, usb cameras as well as those dedicated for raspberry camera connector vary greatly in features and quality.

Therefore, please consider this question focused and narrowed to interfaces:

  • Are there some inherently advantages of 15-pin MIPI camera interface (CSI) connector cameras above usb webcams, because of Raspberry Pi camera interface?

I imagine that it might has something to do that it might omit usb bridge, or protocol might be more lightweight, giving less cpu overhead or latency, but really it's my guess, I have no clue if effects are not negligible, and I have trouble to find out from schematics: https://www.raspberrypi.org/documentation/hardware/raspberrypi/schematics/README.md

  • Trying to answer this for all USB webcams isn't really feasible - there are some really really nice, expensive, USB cameras with gigantic feature sets, and there are some that are cheap and truly miserably awful. If you could narrow your question to specify, for example, a specific USB camera with features equivalent to those found in the Pi cameras, it would be straightforward to answer. – goobering May 28 '16 at 20:18
  • Thanks! Added Update, that with respect to variety of cameras, focus of question is if MIPI / CSI interface gives some non-negligable advantages about USB ? (Maybe power consumption?) – Grzegorz Wierzowiecki May 28 '16 at 20:54
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    One thing would be that it doesn't occupy bandwidth on the USB/ethernet bus, which I think e.g. 1080p @ 30 fps is non-negligible. You're on to that in the last paragraph and it's not a direct answer to your core question, which I think is more about the relationship of that connector to the GPU -- I don't know if the CSI camera ultimately places less load on the CPU and I could hypothesize it being more (i.e., disadvantageous), so...hopefully someone with better facts comes along. – goldilocks May 28 '16 at 21:47
  • I really like @goldilocks your thought ! AFAIK Ethernet on raspberry goes via onboard USB Hub, (I don't know about wifi), if so, then depending on destination of given pictures/video (uploaded to NAS via ethernet/wifi? or dumped to attached usb drive) might get tights when sharing together bandwidth with webcam! (Still, some concrete numbers and schematics would make desired answer concrete to this question :) ) – Grzegorz Wierzowiecki May 28 '16 at 22:02
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As suggested by Goldilocks, a USB Webcam will run through the CPU, whereas the dedicated port does not. Raspberry Pi Essentials, page 42

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