Код:

	{
		v4l2_requestbuffers reqbuf = {};
		//memset (&reqbuf, 0, sizeof (reqbuf));
		reqbuf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
		reqbuf.memory = V4L2_MEMORY_USERPTR;

		_logged(ioctl(_hvideo, VIDIOC_REQBUFS, &reqbuf), "request buffers");
	
		v4l2_buffer buffer = {};
//		memset (&map_buffer, 0, sizeof (map_buffer));
		buffer.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
		buffer.memory = V4L2_MEMORY_USERPTR;
		buffer.m.userptr = reinterpret_cast<long unsigned>(&frame_buffer[0]);
		buffer.length	= frame_buffer.size()*4;

		_logged(ioctl(_hvideo, VIDIOC_STREAMON, &reqbuf), "start stream");

		_logged(ioctl(_hvideo, VIDIOC_QBUF, &buffer), "queue buffer");
		
		sleep(10);
		//copy(frame_buffer.begin(), frame_buffer.end(), ostream_iterator<long,char>(cout, ", "));

		_logged(ioctl(_hvideo, VIDIOC_DQBUF, &buffer), "dequeue buffer");

		_logged(ioctl(_hvideo, VIDIOC_STREAMOFF, &reqbuf), "stop stream");

	}