[FFmpeg-devel] [PATCH 1/2] avfilter/vf_zscale: add slice threading

[Hendrik Leppkes]

On Fri, May 31, 2019 at 5:32 PM Paul B Mahol <onemda at gmail.com> wrote:
>
> On 5/31/19, Lynne <dev at lynne.ee> wrote:
> >
> >
> >
> > May 31, 2019, 2:33 PM by onemda at gmail.com:
> >
> >> On 5/31/19, Lynne <dev at lynne.ee> wrote:
> >>
> >>>
> >>>
> >>>
> >>> May 31, 2019, 2:16 PM by onemda at gmail.com:
> >>>
> >>>> On 5/31/19, Lynne <dev at lynne.ee> wrote:
> >>>>
> >>>>> May 31, 2019, 11:45 AM by onemda at gmail.com <mailto:onemda at gmail.com>:
> >>>>>
> >>>>>> Signed-off-by: Paul B Mahol <> onemda at gmail.com
> >>>>>> <mailto:onemda at gmail.com>>
> >>>>>> >
> >>>>>> ---
> >>>>>> libavfilter/vf_zscale.c | 335 +++++++++++++++++++++++++---------------
> >>>>>> 1 file changed, 214 insertions(+), 121 deletions(-)
> >>>>>>
> >>>>>
> >>>>> This will create discontinuities between each slice.
> >>>>>
> >>>>
> >>>> Have you actually tried it?
> >>>>
> >>>> I had and its just fine.
> >>>>
> >>>
> >>> Bitexact results with non-nearest scaling? Should be even worse with
> >>> anything better than bilinear.
> >>>
> >>
> >> Results are always bitexact. It just not bitexact with single
> >> threading and differences are irrelevant.
> >>
> >
> > Number of threads should not have any impact at all on quality ever.
>
> Agreed. And it doesn't have any such impact.
>

If there is a difference between 1 thread (single threaded), and many
threads, then there is an impact, and thats not good. Don't downplay
it for your convenience.

- Hendrik