Re: [FFmpeg-devel] [PATCH 4/8] lavfi/vf_vpp_qsv: add vpp_preinit callback

["Xiang, Haihao" <haihao.xiang-at-intel.com@ffmpeg.org>]

On Do, 2023-01-12 at 05:11 +0100, Andreas Rheinhardt wrote:
> Xiang, Haihao:
> > From: Haihao Xiang <haihao.xiang@intel.com>
> > 
> > Set the expected default value for options in this callback, hence we
> > have the right values even if these options are not included in the
> > option arrray.
> > 
> > This is in preparation for reusing the code for other QSV filters.
> > 
> > Signed-off-by: Haihao Xiang <haihao.xiang@intel.com>
> > ---
> >  libavfilter/vf_vpp_qsv.c | 14 ++++++++++++++
> >  1 file changed, 14 insertions(+)
> > 
> > diff --git a/libavfilter/vf_vpp_qsv.c b/libavfilter/vf_vpp_qsv.c
> > index cf11cd7fdc..2a7b06fa33 100644
> > --- a/libavfilter/vf_vpp_qsv.c
> > +++ b/libavfilter/vf_vpp_qsv.c
> > @@ -259,6 +259,19 @@ release:
> >      return ret;
> >  }
> >  
> > +static av_cold int vpp_preinit(AVFilterContext *ctx)
> > +{
> > +    VPPContext  *vpp  = ctx->priv;
> > +    /* For AV_OPT_TYPE_STRING options, NULL is handled in other way so
> > +     * we needn't set default value here
> > +     */
> > +    vpp->saturation= 1.0;
> > +    vpp->contrast = 1.0;
> > +    vpp->transpose = -1;
> > +
> > +    return 0;
> > +}
> > +
> >  static av_cold int vpp_init(AVFilterContext *ctx)
> >  {
> >      VPPContext  *vpp  = ctx->priv;
> > @@ -683,6 +696,7 @@ const AVFilter ff_vf_vpp_qsv = {
> >      .name          = "vpp_qsv",
> >      .description   = NULL_IF_CONFIG_SMALL("Quick Sync Video VPP."),
> >      .priv_size     = sizeof(VPPContext),
> > +    .preinit       = vpp_preinit,
> >      .init          = vpp_init,
> >      .uninit        = vpp_uninit,
> >      FILTER_INPUTS(vpp_inputs),
> 
> I do not get the point of this at all: None of these options are of type
> AV_OPT_TYPE_STRING. You are merely setting the default values that
> av_opt_set_defaults() would set lateron anyway.

> 
> I also fail to see how this would facilitate reusing this code for other
> QSV filters.

Actually this is a part of an old patchset, see 
https://patchwork.ffmpeg.org/project/ffmpeg/list/?series=4467, I want to use use
functions and data structures defined in vf_vpp_qsv.c and qsvvpp.c to implement
scale_qsv and deinterlace_qsv filters, hence we may remove vf_scale_qsv.c and
vf_deinterlace_qsv.c 

E.g.
saturation option is used in vpp_qsv filter but not in other qsv filters, so
av_opt_set_defaults() works for saturation in vpp_qsv filter but not for other
filters, we need to set a default value to vpp->saturation for other filters,
otherwise vpp->saturation is 0 for other other filters. 
 
Thanks
Haihao


> 
> - Andreas
> 
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