[libcamera-devel] [PATCH v3 02/12] libcamera: camera: Introduce SensorConfiguration

[Sakari Ailus]

Hi Laurent,

On Sun, Nov 10, 2024 at 09:05:03PM +0200, Laurent Pinchart wrote:
> On Sun, Nov 10, 2024 at 11:25:08AM +0000, Sakari Ailus wrote:
> > Hi Laurent, Jacopo,
> > 
> > Sorry for the late reply.
> > 
> > On Sun, Sep 17, 2023 at 06:45:55PM +0300, Laurent Pinchart wrote:
> > > > > > +		unsigned int xOddInc = 1;
> > > > > > +		unsigned int xEvenInc = 1;
> > > > > > +		unsigned int yOddInc = 1;
> > > > > > +		unsigned int yEvenInc = 1;
> > > > >
> > > > > What's the reason for exposing the odd and even increments separately,
> > > > > instead of a skipping factor ?
> > > > 
> > > > CCS expresses the two skipping factors separately. I agree there are
> > > > not many meaningful ways this two parameters can be combined, but if
> > > > one knows how a sensor work it might be more natural expressing them
> > > > in this way instead of simply saying x_skip = 2 ( == x_odd_inc=3,
> > > > x_even_inc=2)
> > > 
> > > Lots of sensors that support configuring skipping do no expose separate
> > > odd and even skipping increments. That's why I think a simpler parameter
> > > would be better.
> > > 
> > > Sakari, do you have an opinion on this ? Are there reasonable use cases
> > > for controlling the odd and even increments separately in a way that
> > > couldn't be expressed by a single skipping factor (for each direction) ?
> > 
> > Skipping (sub-sampling) is generally independent horizontally and
> > vertically, binning is not. On some sensors reasonable output sizes may be
> > impelemented a combination of the two.
> 
> There's no disagreement that horizontal and vertical factors need to be
> expressed independently. The question was about independent even and odd
> increments.

That's what I meant.

CCS separates odd and even increments but in practice the odd increment
should always be 1. I guess we could add support for these as well. I'd be
inclined to support sub-sampling using controls, separately for each
direction. 

-- 
Regards,

Sakari Ailus