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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