Re: S_FMT vs. CROP vs...

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On Wed, 7 Jan 2009 10:14:31 +0100 (CET)
Guennadi Liakhovetski <g.liakhovetski@xxxxxx> wrote:

> Hi all
> 
> I have been guessing around these operations for a while now, and 
> eventually have decided to ask.
> 
> My current understanding is, that S_FMT in terms of window geometry should 
> (ideally) set user window sizes, while the view area should preferably be 
> kept maximum, i.e., it should scale, if supported.

Yes. However, if you cannot scale to that resolution, you should return -EINVAL.

> For example on mt9t031 
> binning and skipping are used for that. Whereas CROP uses the current 
> scaling configuration and selects a sub-window, so, once you've done S_FMT 
> to 320x240, a crop request for 640x480 might well fail.

I also understand this way. You cannot crop with a resolution bigger than what
you've selected.

> For this you have 
> to issue a S_FMT, i.e., change scaling. Or would one have to re-scale 
> transparently?
> 
> Is this interpretation correct? It seems to reflect the API as documented 
> on http://v4l2spec.bytesex.org/spec/book1.htm correctly.
> 
> If it is correct, then what should CROP_CAP return as maximum supported 
> window sizes? Should it return them according to the current scaling or 
> according to scale 1?

I understand that it should return against the current scaling.

Cheers,
Mauro
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