If you bypass OpenCV and capture directly like we did, you should test to see if you can capture successfully in YUYV format. OpenCV can convert YUYV to a Mat with less than 3% cpu use. If you capture in MJPEG, you will see cpu use of 90% or more to convert the image to a Mat. This isn't so bad on the Wandboard because it only consumes one core, but can be intense on the single core BBB. I can tell you from testing with the Wandboard Quad, it can push 30 fps in YUYV over USB. However, it is only possible to stream from one camera at 30 fps in YUYV. In short it is a tradeoff. You can either saturate the USB and save processing or save bandwidth and increase processing. Something to consider depending on your needs.
On Thu, Jan 30, 2014 at 12:53 PM, Michael Darling <[email protected]>wrote: > Okay, so the problem you're having has to do with bugs in OpenCV, itself. > Unfortunately, the capture methods in OpenCV do not set the camera > properties correctly for video4linux devices. In other words, you may > write the line of code to set the frame rate to 30 fps, but the camera > isn't actually getting the instruction to change the frame rate. > > The fix Matthew and I have used is to just use our own video4linux capture > code. You might be able to modify the OpenCV source code, but the capture > code is difficult to follow since there are so many layers of abstraction. > (There are a lot of wrapper classes used to handle v4l2 devices, v4l1 > devices, Mac, Windows so that the programmer doesn't have to handle each > camera differently depending on his/her system.) > > Hope that explains some things for you :) > - Mike > > -- > For more options, visit http://beagleboard.org/discuss > --- > You received this message because you are subscribed to a topic in the > Google Groups "BeagleBoard" group. > To unsubscribe from this topic, visit > https://groups.google.com/d/topic/beagleboard/G5Xs2JuwD_4/unsubscribe. > To unsubscribe from this group and all its topics, send an email to > [email protected]. > For more options, visit https://groups.google.com/groups/opt_out. > -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/groups/opt_out.
