On Sat, Jul 6, 2024 at 6:42 PM Michael Niedermayer
<mich...@niedermayer.cc> wrote:
>
> On Sat, Jul 06, 2024 at 02:11:30AM +0200, Hendrik Leppkes wrote:
> > On Fri, Jul 5, 2024 at 11:34 PM Michael Niedermayer
> > <mich...@niedermayer.cc> wrote:
> > > > /**
> > > > * The exact interpretation of these quality presets depends on the
> > > > backend
> > > > * used, but the backend-invariant common settings are derived as
> > > > follows:
> > > > */
> > > > enum AVScaleQuality {
> > > > AV_SCALE_ULTRAFAST = 1, /* no dither, nearest+nearest */
> > > > AV_SCALE_SUPERFAST = 2, /* no dither, bilinear+nearest */
> > > > AV_SCALE_VERYFAST = 3, /* no dither, bilinear+bilinear */
> > > > AV_SCALE_FASTER = 4, /* bayer dither, bilinear+bilinear */
> > > > AV_SCALE_FAST = 5, /* bayer dither, bicubic+bilinear */
> > > > AV_SCALE_MEDIUM = 6, /* bayer dither, bicubic+bicubic */
> > > > AV_SCALE_SLOW = 7, /* bayer dither, lanczos+bicubic */
> > > > AV_SCALE_SLOWER = 8, /* full dither, lanczos+bicubic */
> > > > AV_SCALE_VERYSLOW = 9, /* full dither, lanczos+lanczos */
> > > > AV_SCALE_PLACEBO = 10, /* full dither, lanczos+lanczos */
> > >
> > > I dont think its a good idea to hardcode dither and the "FIR" filter to
> > > the quality level in the API
> > >
> >
> > The entire point of presets is to have them provide a predefined set
> > of parameters, easy for users to pick one value, rather than a bunch.
> > And what a preset actually means should be documented.
> > How do you define "presets" if they don't hardcode a list of choices
> > for all the relevant options?
> >
> > Advanced settings exist for a user to select any particular detail, if
> > they so desire.
>
> The problem is if new features are added and you have a hardcoded list in
> the API what each quality corresponds to change it you have to bump major
>
> also, do we really have or want to have optimized nearest neighbor scaler
> code ?
> If not the AV_SCALE_ULTRAFAST could be slower than AV_SCALE_VERYFAST
> simply because it now "has to" do something we actually have not optimized
>
So.. you object to the comments that explain what it does?
Someone that uses presets will never have a guarantee to the selected
algorithms and options, if thats your desire - set what you want. That
doesn't mean you can't inform users what they are at this time. Its a
comment indicating a behavior, we don't make any stability guarantees
about that, and no API linkage occurs.
- Hendrik
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