Re: RFC> multi-crop (was: Multiple Rectangle cropping)

[Sylwester Nawrocki <sylvester.nawrocki@gmail.com>]

On 09/05/2013 11:10 PM, Ricardo Ribalda Delgado wrote:
> Hello

Hi,

>   I am working porting a industrial camera driver to v4l. So far I have
> been able to describe most of the old functionality with v4l
> equivalents. The only thing that I am missing is multi cropping.
>
> The sensor (both a cmosis and a ccd chips) supports skipping lines
> from up to 8 regions. This increases the readout speed up to 50%,
> which is critical for the application.
>
> Unfortunately I have no way to describe multiple cropping areas in
> v4l. I am thinking about creating a new API/extending and old one for
> this.
>
> Any suggestion before I start? Have you faced also this problem? How
> did you solve it?

A similar issue has been raised during discussions on the camera auto
focus rectangle selection API. While defining need selection targets [1]
it was also proposed to convert one of the struct v4l2_selection reserved
fields into an index field, which would indicate one rectangle of some
set of rectangles supported by a driver. Then there could be a v4l2
bitmask control to determine which rectangles are currently valid/in use.

Would something like this be relevant to your problem ?

> I am planning to go to the Edinburgh mini summit, maybe we could add
> this to the agenda (if you consider that it is worth the time, of
> course)

It definitely sounds like a good topic to discuss at the mini summit,
unless it gets resolved until then. ;-)

[1] http://www.spinics.net/lists/linux-media/msg64499.html

--
Regards,
Sylwester