Thanks Nate! likewise, I will see if this helps and let you guys know! -Geoff
On 10/5/07, Nathanael Galpin <[EMAIL PROTECTED]> wrote: > > Hey Geoff, > > > > This is a great file to start with. In fact it's what I used first. Couple > things make it a bit tricky. One is that he's using switch statements to > separate different ways to read from the cameras, so you'll want to note > which method you're using, (should be MMAP). > > > > The line where he actually captures a frame is in the read_frame function. > > > > > (-1 == xioctl (fd, VIDIOC_DQBUF, &buf)) > > > > This blocks until it's able to deque a frame from the camera (unless you > specify non-blocking when you open the cam file, in which case it returns -1 > when it can't immediately deque a frame). You can get at the raw frame data > through the buf struct. > > > > A little farther down, he re-enques the buffer after he's finished with > with this line: > > > > (-1 == xioctl (fd, VIDIOC_QBUF, &buf)) > > > > You can read through the V4L2 spec a bit at bytesex.org to check out the > parameters of the buf struct. > > > > If you want to display this data, a quick way to do it would be to pull > the Y values from the buffer and use these to write a grayscale image to the > screen. I used a Qt picture object when I first started doing this, and that > actually worked quite well. > > > > Hope that helps, and good luck! > > > > > > -- Nathanael > > > ------------------------------ > > *From:* [EMAIL PROTECTED] [mailto: > [EMAIL PROTECTED] *On Behalf Of *Geoffrey Plitt > *Sent:* Thursday, October 04, 2007 9:18 PM > > hey christopher. this file looks promising, but it doesn't do anything > with the frames. i compiled/ran and it just prints dots, you have to take as > faith that it's capturing - it doesn't output or save the frames. in fact, i > can't tell exactly where in the code it actually grabs a frame and has > access to the frame's pixel buffer. any clues? > -geoff > > On 10/4/07, *Christopher HORLER* <[EMAIL PROTECTED]> wrote: > > http://v4l2spec.bytesex.org/v4l2spec/capture.c > > > >
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