[vlc-devel] [PATCH] provide the display format from the demuxer to the vout to respect cropping

Steve Lhomme robux4 at videolabs.io
Mon Mar 9 18:44:19 CET 2015

On Mon, Mar 9, 2015 at 6:32 PM, Jean-Baptiste Kempf <jb at videolan.org> wrote:
> On 09 Mar, Steve Lhomme wrote :
>> And I explained each time why there is information missing at the vout
>> level.
> Can't we forward the info from the demux fmt to the codec step, and use
> those values, if the codec does not override them (aka, i_x, i_y = 0 ) ?

First of all, this is codec specific. Does libvpx support it ? libmpeg
? libjpeg ? Do they support offsets by 1 pixel or do they have to be
rounded ? Does it disable hardware acceleration and/or implies some
swscale down the data path ?

And what if the codec already overrides the display dimensions (which
is the case in #13982) ? Is it going to handle its own internal
preference or the one we try to force it to ?

That's a lot of uncertainty IMO. I don't know all the code enough. But
on the other hand I provide something that will work regardless of the
codec and vout used, for any size. Apart from Direct2D, all vout seem
to handle cropping properly and internally (no swscale).

I think the codec way could be done in addition, as an optimization.
Hopefully less pixels will be decoded and written to the vout.

> With my kindest regards,
> --
> Jean-Baptiste Kempf
> http://www.jbkempf.com/ - +33 672 704 734
> Sent from my Electronic Device
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