v4l2 very simple example [closed]

Answer 1

Try the uvccapture code here -> http://staticwave.ca/source/uvccapture/ It is very small yet very concrete example which makes use of all the V4l2 concepts (open,set format, allocate memory, Request Buffer, Dqbuffer and Query-buffer - all intems of ioclts).

uvcgrab() function is the one to look for which makes use of Dqbuffer and Query-buffer.

ioctl (vd->fd, VIDIOC_DQBUF, &vd->buf);

ioctl (vd->fd, VIDIOC_QBUF, &vd->buf)

While Studying it you can keep looking for the ioctl definition in this link which will ease your understanding.

Answer 2

I would advice also trying out v4l-utils.

http://linuxtv.org/downloads/v4l-utils/

It has some easy to use API calls to v4l devices and there is a qt based example in the source to build a custom interface for video devices.

Answer 3

In the API specification, there is an example, also downloadable as a C file