Re: [FFmpeg-devel] [PATCH 2/6] avfilter/vf_setparams: allow setting chroma location

[Paul B Mahol <onemda@gmail.com>]

On Thu, Jul 4, 2024 at 1:54 PM Niklas Haas <ffmpeg@haasn.xyz> wrote:

> From: Niklas Haas <git@haasn.dev>
>
> Shockingly, there isn't currently _any_ filter for overriding this.
> ---
>  doc/filters.texi           | 17 +++++++++++++++++
>  libavfilter/vf_setparams.c | 19 ++++++++++++++++---
>  2 files changed, 33 insertions(+), 3 deletions(-)
>
> diff --git a/doc/filters.texi b/doc/filters.texi
> index c9c4f7cf6b..ca8f6e461a 100644
> --- a/doc/filters.texi
> +++ b/doc/filters.texi
> @@ -22073,6 +22073,23 @@ Keep the same colorspace property (default).
>  @item chroma-derived-c
>  @item ictcp
>  @end table
> +
> +@item chroma_location
> +Set the chroma sample location.
> +Available values are:
> +
> +@table @samp
> +@item auto
> +Keep the same chroma location (default).
> +
> +@item unspecified, unknown
> +@item left
> +@item center
> +@item topleft
> +@item top
> +@item bottomleft
> +@item bottom
> +@end table
>  @end table
>
>  @section sharpen_npp
> diff --git a/libavfilter/vf_setparams.c b/libavfilter/vf_setparams.c
> index b7da8eb54b..ba32a6699c 100644
> --- a/libavfilter/vf_setparams.c
> +++ b/libavfilter/vf_setparams.c
> @@ -41,6 +41,7 @@ typedef struct SetParamsContext {
>      int color_primaries;
>      int color_trc;
>      int colorspace;
> +    int chroma_location;
>  } SetParamsContext;
>
>  #define OFFSET(x) offsetof(SetParamsContext, x)
> @@ -119,6 +120,17 @@ static const AVOption setparams_options[] = {
>      {"chroma-derived-c",           NULL,  0, AV_OPT_TYPE_CONST,
> {.i64=AVCOL_SPC_CHROMA_DERIVED_CL}, INT_MIN, INT_MAX, FLAGS, .unit =
> "colorspace"},
>      {"ictcp",                      NULL,  0, AV_OPT_TYPE_CONST,
> {.i64=AVCOL_SPC_ICTCP},             INT_MIN, INT_MAX, FLAGS, .unit =
> "colorspace"},
>      {"ipt-c2",                     NULL,  0, AV_OPT_TYPE_CONST,
> {.i64=AVCOL_SPC_IPT_C2},            INT_MIN, INT_MAX, FLAGS, .unit =
> "colorspace"},
> +
> +    {"chroma_location", "select chroma sample location",
> OFFSET(chroma_location), AV_OPT_TYPE_INT, {.i64=-1}, -1, AVCHROMA_LOC_NB-1,
> FLAGS, .unit = "chroma_location"},
> +    {"auto", "keep the same chroma location",  0, AV_OPT_TYPE_CONST,
> {.i64=-1},                       INT_MIN, INT_MAX, FLAGS, .unit =
> "chroma_location"},
> +    {"unspecified",                      NULL, 0, AV_OPT_TYPE_CONST,
> {.i64=AVCHROMA_LOC_UNSPECIFIED}, INT_MIN, INT_MAX, FLAGS, .unit =
> "chroma_location"},
> +    {"unknown",                          NULL, 0, AV_OPT_TYPE_CONST,
> {.i64=AVCHROMA_LOC_UNSPECIFIED}, INT_MIN, INT_MAX, FLAGS, .unit =
> "chroma_location"},
> +    {"left",                             NULL, 0, AV_OPT_TYPE_CONST,
> {.i64=AVCHROMA_LOC_LEFT},        INT_MIN, INT_MAX, FLAGS, .unit =
> "chroma_location"},
> +    {"center",                           NULL, 0, AV_OPT_TYPE_CONST,
> {.i64=AVCHROMA_LOC_CENTER},      INT_MIN, INT_MAX, FLAGS, .unit =
> "chroma_location"},
> +    {"topleft",                          NULL, 0, AV_OPT_TYPE_CONST,
> {.i64=AVCHROMA_LOC_TOPLEFT},     INT_MIN, INT_MAX, FLAGS, .unit =
> "chroma_location"},
> +    {"top",                              NULL, 0, AV_OPT_TYPE_CONST,
> {.i64=AVCHROMA_LOC_TOP},         INT_MIN, INT_MAX, FLAGS, .unit =
> "chroma_location"},
> +    {"bottomleft",                       NULL, 0, AV_OPT_TYPE_CONST,
> {.i64=AVCHROMA_LOC_BOTTOMLEFT},  INT_MIN, INT_MAX, FLAGS, .unit =
> "chroma_location"},
> +    {"bottom",                           NULL, 0, AV_OPT_TYPE_CONST,
> {.i64=AVCHROMA_LOC_BOTTOM},      INT_MIN, INT_MAX, FLAGS, .unit =
> "chroma_location"},
>      {NULL}
>  };
>
>
Why TYPE_CONST options have this cargo cult INT_MIN, INT_MAX propagated
again? I do not remember ever writing such nonsense, at least I remove it
whenever I see it.




> @@ -174,17 +186,18 @@ FF_ENABLE_DEPRECATION_WARNINGS
>              frame->flags &= ~AV_FRAME_FLAG_TOP_FIELD_FIRST;
>      }
>
> -    /* set range */
> +    /* set straightforward parameters */
>      if (s->color_range >= 0)
>          frame->color_range = s->color_range;
> -
> -    /* set color prim, trc, space */
>      if (s->color_primaries >= 0)
>          frame->color_primaries = s->color_primaries;
>      if (s->color_trc >= 0)
>          frame->color_trc = s->color_trc;
>      if (s->colorspace >= 0)
>          frame->colorspace = s->colorspace;
> +    if (s->chroma_location >= 0)
> +        frame->chroma_location = s->chroma_location;
> +
>      return ff_filter_frame(ctx->outputs[0], frame);
>  }
>
> --
> 2.45.2
>
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