how to capture odd/even fields

[Bernd Blessmann <bibi@xxxxxxxxx>]

Hi all,

I am using a 2.4.19-pre7 kernel patched with the v4l2 patches from
bytesex.org and a bttv-driver ver. 0.8.38.

I am trying to capture odd / even field (TOPFIELD / BOTFIELD)
according to the docs of the v4l2 api, but I am just getting
TOPFIELDS. I do the settings it like this:
...
 		vid_fmt.fmt.pix.flags = 0x00;
		//vid_fmt.fmt.pix.flags |= V4L2_FMT_FLAG_INTERLACED;
		vid_fmt.fmt.pix.flags |= V4L2_FMT_FLAG_TOPFIELD;
		vid_fmt.fmt.pix.flags |= V4L2_FMT_FLAG_BOTFIELD;

		vid_fmt.fmt.pix.width = 768;
		vid_fmt.fmt.pix.height = 288;
		vid_fmt.fmt.pix.depth = 8;
		vid_fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_GREY;

		if ( ioctl(fd, VIDIOC_S_FMT, &vid_fmt) == -1 ) {
			perror("VIDIOC_S_FMT");
			close(fd);
			exit(1);
		}
...

Is it at all possible with a cheap (e.g. TERRATEC VALUE) bttv card to
capture each field (german PAL -> 50 field/sec) ?

Any hints are welcome.

Greetings
  Bernd