On Friday 02 September 2005 07:51, Luc Saillard wrote:
> On Thu, Sep 01, 2005 at 02:01:42PM +0100, Alistair John Strachan wrote:
> > Hi Luc, list,
> >
> > Here is a patch which implements setting various previously unsettable
> > controls via the v4l2 interface. We need these controls to be exported to
> > userspace so that we can flexibly change the camera settings for
> > scientific imaging purposes.
> >
> > Please review these changes and let me know if there's any problems. I've
> > verified it doesn't break xawtv, at the very least, and for our purposes
> > these controls work perfectly.
>
> I've look the patch, and i'll made a new snapshots this week-end. Thanks
> for your works.
No problem. It's my intention to patch through the rest of the controls once I
can verify they work semantically correctly.
>
> > After making these changes, it's obvious to me that maybe the internal
> > pwc-ctrl functions shouldn't really be implemented as taking a 16bit
> > value, only to downshift them to the range the camera supports (generally
> > 8bit or 7bit, sometimes even 5bit values). Currently almost all the v4l2
> > controls shift up to the 16bit value only to be shifted back internally..
> > also I can't find anywhere whether the v4l2 control range values are
> > enforced by the driver, or whether there's a standard for ranges (I've
> > used 0-255, but I've read elsewhere that other v4l2 devices use 0-100).
>
> Because we keep the v4l1 api that want a value between 1-65535. So perhaps
> i'll change all the function to accept the right range, and when we change
> value using v4l1 or setpwc, shift the value at this moment.
Thanks. I would suggest always taking an 8bit argument, then shift left for
the v4l1 controls (indicating to the developer that there is a loss of
precision), and the v4l2 controls can map right through (or be scaled from
0-100, whichever is preferable).
>
> > In other news, having looked at the PDF specification for the chip on the
> > camera we're using (the PCVC740), I can't see how their register
> > descriptions If anybody has the documentation from which this driver was
> > written, I'd happily validate it and check whether these issues actually
> > exist.
>
> Is it possible to get this documentation ? for now i've nothing :(
Find the documentation for (at least) the 740K attached. I had a brief look
last week, but I couldn't see how the register offsets matched with what was
in the driver. At the very least, some of the commands seem to be out of
order versus this spec.
--
Cheers,
Alistair.
'No sense being pessimistic, it probably wouldn't work anyway.'
Third year Computer Science undergraduate.
1F2 55 South Clerk Street, Edinburgh, UK.
SAA8116_3.pdf
Description: Adobe PDF document
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