Re: [PATCH v7 2/9] media: vivid: Convert to v4l2_ext_pix_format

From: Nicolas Dufresne
Date: Fri Aug 04 2023 - 16:19:25 EST


Le vendredi 28 juillet 2023 à 16:22 +0900, Tomasz Figa a écrit :
> > For MPLANE, where backward compatibility was built into libv4l2 LD_PRELOAD
> > wrapper,
>
> Could you refresh my memory on what kind of backwards compatibility we
> had in libv4l2? Was that to make it possible to use new MPLANE-only
> drivers with old applications?

https://git.linuxtv.org/v4l-utils.git/tree/lib/libv4l-mplane

It does some "magic" trick due to some of the new fields not guarantied to be
zero, translate the type, the capabilities. Strangely it does not filter the
pixel formats. I suspect it assumes legacy application won't know about the new
one and will just ignore/not use them.

Nicolas