[vlc-devel] [PATCH v3] picture: align pictures on 64 bytes

[Steve Lhomme]

On 12/11/2018 11:59, Rémi Denis-Courmont wrote:
> As far as I am concerned, the picture buffer could and maybe should be 
> page-aligned anyway. The real question is what the plane and scan line 
> alignment should be, which this patch leaves entirely open.

picture_Allocate() is called after picture_Setup() which aligns lines to 
at least 32 bytes. Then the amount of lines is also made a multiple of 
16. So all the planes are always aligned to 512 bytes.

>
> Le 12 novembre 2018 11:48:25 GMT+02:00, Francois Cartegnie 
> <fcvlcdev at free.fr> a écrit :
>
>     Le 12/11/2018 à 09:39, Steve Lhomme a écrit :
>
>         Code relying on AVX-2 (like dav1d) cannot work without an
>         alignment of 32 bytes at least. Even avcodec has a requirement
>         of 64 (likely to get at least 32 on all planes). So it's
>         probably time to upgrade. picture_Setup ensures a horizontal
>         alignment to 32 bytes and a vertical to 16 bytes. So for all
>         buffers allocated by the core, we have a size multiple of 512
>         bytes. 
>
>
>     Didn't we had an issue with some codec*filter*idontremember and anything
>
>         16 ? 
>
>
> -- 
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> excuser ma brièveté.
>
>
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