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

[From: Qole]

Hey Simon,

The other option, for the interim until the Camera Secrets Are Unveiled, is
to get the user to tell your app where to look for new pictures (internal or
external memory), then tell the user to take a picture using the camera app,
and press OK when they're done. Show them the last picture taken and say,
"is this it?" and if they say yes, go ahead and do your thing...

It's an ugly hack, but what can you do?

Other than wait for the Summit, that is.

On Tue, Sep 22, 2009 at 4:49 AM, Mohammed Hassan <
mohammed.2.hassan at nokia.com> wrote:

> 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
>
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