[FFmpeg-devel] [PATCH] avfilter/vf_scale: Do not set YUV color range for RGB formats

[Paul B Mahol]

On 3/20/18, Michael Niedermayer <michael at niedermayer.cc> wrote:
> Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
> ---
>  libavfilter/vf_scale.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/libavfilter/vf_scale.c b/libavfilter/vf_scale.c
> index 9f45032e85..2f6fa4791d 100644
> --- a/libavfilter/vf_scale.c
> +++ b/libavfilter/vf_scale.c
> @@ -407,6 +407,7 @@ static int filter_frame(AVFilterLink *link, AVFrame *in)
>      AVFilterLink *outlink = link->dst->outputs[0];
>      AVFrame *out;
>      const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(link->format);
> +    const AVPixFmtDescriptor *out_desc =
> av_pix_fmt_desc_get(outlink->format);
>      char buf[32];
>      int in_range;
>
> @@ -497,7 +498,11 @@ static int filter_frame(AVFilterLink *link, AVFrame
> *in)
>                                       table, out_full,
>                                       brightness, contrast, saturation);
>
> -        out->color_range = out_full ? AVCOL_RANGE_JPEG : AVCOL_RANGE_MPEG;
> +        // color_range describes YUV, it is undefined for RGB
> +        if ((out_desc->flags & AV_PIX_FMT_FLAG_RGB) &&
> out_desc->nb_components != 1) {
> +            out->color_range = AVCOL_RANGE_UNSPECIFIED;
> +        } else
> +            out->color_range = out_full ? AVCOL_RANGE_JPEG :
> AVCOL_RANGE_MPEG;
>      }
>
>      av_reduce(&out->sample_aspect_ratio.num, &out->sample_aspect_ratio.den,
> --
> 2.16.2
>
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>

This is not optimal, as full color_range should remain full when not changed.