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Maximum run time for the camera / lags on rpi2

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Hi, i am trying to turn my camera into a motion detecting security camera, may i know what is the theoretical and actually camera uptime 

at the same time, i followed the tutorial and run  on rpi2 on Raspbian jessie

"guvcview -ao none -f YUYV -x 640x360"
which gave me some error, I saw someone posting to use "guvcview -a none -f YUYV -x 640x360" which did work for me, but the video turns out to be pretty laggy any idea why? 
asked Apr 19 in Hardware Questions by zacwy (180 points)

1 Answer

+1 vote
Best answer

There is no maximum uptime that we know of. We have JeVois cameras running here for weeks, stable and no memory leaks (i.e., the amount of free memory returned when you type info in a serial terminal connected to JeVois is roughly constant. It varies a bit from moment to moment, as images do get allocated and then de-allocated, but there is no overall slow trend towards less free memory). Also, even under constant load, the CPU frequency remains at 1.34GHz thanks to the fan.

If you run jevois-daemon in valgrind, it will detect a bunch of memory leaks inside OpenCV, but those appear to not be growing over time, and probably are resources that are allocated once at start time and then do not get properly freed (as opposed to resources that would be allocated and leaked on every video frame).

Now for the RPi2 performance: Yes, the pi is a bit slow at displaying video. The best use of JeVois with rpi is to capture the video (e.g., using opencv), then process it further, then control the motors of a robot, etc and never display anything. That is a true "machine vision" application, as opposed to something that relies on a visual display and a human to finish the vision job by looking at the display. Nevertheless, make sure that:

- you add a heatsink and fan to your pi, then check the CPU frequency at which it is running. Without heatsink and fan, it will quickly overheat and slow down to avoid burning away. The rpi is not a thermally stable solution out of the box. You need to add cooling to it.

- make sure you give the rpi enough power, on mine (which is a RPi3), you see a little yellow lightning bolt in the top right of the screen when the power is too weak, and the CPU frequency get cut in half when that happens. Connect it to a USB charger rated for 2A or such.

- try lower video resolutions, how about YUYV 64x192 @ 25fps, does that work ok for you?

answered Apr 24 by JeVois (8,720 points)
selected Apr 25 by zacwy