[FFmpeg-devel] [PATCH] avcodec/hevcdsp: Offset ff_hevc_.pel_filters to simplify addressing

[Nuo Mi]

On Mon, Feb 12, 2024 at 5:48 AM Christophe Gisquet <
christophe.gisquet at gmail.com> wrote:

> Le dim. 11 févr. 2024 à 12:37, Nuo Mi <nuomi2021 at gmail.com> a écrit :
> > > -DECLARE_ALIGNED(16, const int8_t, ff_hevc_qpel_filters)[3][16] = {
> > > +DECLARE_ALIGNED(16, const int8_t, ff_hevc_qpel_filters)[4][16] = {
> > >
> > Do you know why this is [4][16]? [4][8] should suffice.
>
> Probably so that all coefficient banks are aligned. Another use for it
> is you can directly use the address in some instruction instead of
> using/wasting a reg for holding the data.
>

Hi Christophe,
Thank you for the explanation.
However, epel (chroma) did not adhere to this. X86 doesn't require this
either since VVC didn't do it.
It's a bit odd that only some architectures and luma need this
I'll revisit this when I determine which architecture needs it and leave a
comment in the code accordingly.

>
> --
> Christophe Gisquet
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