[maemo-developers] N900 camera control - focus movement, white balance, auto-focus calcs, etc.

[From: Mohammed Hassan]

On Tue, 2009-09-22 at 11:50 +0200, ext Simon Pickering wrote:
> Hello everyone,
> 
> I'm looking into how to use the camera on the N900 when it is released,
> I would like to be able to write some code in Python if at all possible,
> but I guess I can move my app back to C if needs must.
> 
> Anyway, the camera will need to be focused, so I have been trawling
> through the kernel code and gstreamer source to try and work out how to
> do this, but I thought I may as well just ask as it may save me some
> time.
> 
> I see there are ioctls for the ad5820 focus piezo controller which could
> be used (though I've not looked to see if there's a dev entry for that
> device yet), and Qole pointed out that the /dev/video0 device reports
> that it has v4l2 extended controls, including the ability to move the
> focus (though no mention of autofocus there afaict).
> 
> I understand I should be able to adjust the focus through a gstreamer
> element such as camerabin or the photography interfaces, but ideally I'd
> like to do this from Python. Is v4l2camsrc linked to these btw?
> 
> The other option (which means I don't have to wrap one of the gstreamer
> elements for Python) is to use the v4l2 extended control command ioctls
> directly on the /dev/video0 device. I'm assuming that should be possible
> anyway, certainly the Python part looks pretty straight forward (see
> e.g. FMRadio.py).
> 
> While we're on the subject, I see some header files for what I presume
> is a Ti binary blob named isp_*.h. isp_af.h contains header information
> for autofocus functionality afaict. Is this functionality exposed to
> userspace anywhere?
> 
> Looking through the package list, I came across a libgdigicam, might
> this be involved...?
> 
> Anyway I'm going to keep experimenting with the above, but thought I'd
> see if anyone else has any bright ideas.

Hi Simon,

I'd rather hold on for a while. I guess that more information will be
available at Summit's timeframe.

Cheers,
 
-- 
Maemo Software
Nokia Devices