[FFmpeg-devel] [PATCH v06 4/5] hwdownload detile framebuffer, if requested by user

C Hanish Menon hanishkvc at gmail.com
Sun Jul 5 23:46:38 EEST 2020


Hi Lynne,

On Sun, 5 Jul, 2020, 00:59 Lynne, <dev at lynne.ee> wrote:

> Jul 4, 2020, 14:17 by hanishkvc at gmail.com:
>
> > Added logic to support detiling of framebuffer.
> >
> > By default this is disabled. Only if requested by the user, the
> > logic will be triggered.
> >
> > It uses the fbtile helper routines to do the detiling. Currently
> > 32bit RGB pixel format based framebuffers are supported.
> >
> > If the underlying hardware context provides linear layouts, then
> > nothing is done. Only if the underlying hardware context generates
> > tiled layout, then user can use this to detile, where possible.
> >
> > ./ffmpeg -f kmsgrab -i - -vf hwdownload=1,format=bgr0 out.mp4
> >
>
> Not acceptable for the reasons stated in the hwcontext patch.
> Besides, allowing users to detile non-tiled images is a really, _really_
> bad idea.
>

As already responded, in case of the hwcontext patch, I take care of
avoiding the frame copy, so that it's efficient, where possible.

While this patch is different, as mentioned in this patch note. The idea
here is to provide a fall back option for detiling such that it's
independent of the underlying hwcontext, in case if such a situation arises
in future.

And Or Parallely it allows the user to force a detile, if they so desire
explicitly. As this is not automatic, but has to be triggered by the user,
It doesn't add any overhead by default, but gives the flexibility in case
the user so desires.

I do understand that there is a fundamental difference of opinion wrt
whether to give this additional flexibility to user or not between my
thinking and yours. I wanted to just show that it can be done in a simple
and relatively clean way without overhead, when not desired.

However It's finally your+any additional ffmpeg teams call.



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