v4l2 very simple example [closed]

Question

I'm looking for a simple example for camera access in Linux using V4L2. Where I can find it? As simple, as possible.

Thanks,

Benbow

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.

Spikelet

Answer 2

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

Solana

This example works fine for me, but it's a little bit complex. I found this one credentiality2.blogspot.com/2010/04/v4l2-example.html but it doesn't work for me :( I get read error 22, Invalid argument – Benbow

The links are dead. I suppose that was this one, which works, but only outputs the image frames to stdout... – Abaca

Answer 3

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.

Dripping