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

[Vittorio Giovara]

On 3/20/18, Michael Niedermayer <michael at niedermayer.cc
<http://ffmpeg.org/mailman/listinfo/ffmpeg-devel>> wrote:
>* Signed-off-by: Michael Niedermayer <michael at niedermayer.cc <http://ffmpeg.org/mailman/listinfo/ffmpeg-devel>>
*>* ---
*>*  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
*

shouldn't color_range be always set to FULL when outputting RGB? This would
simplify conversions towards YUV (which assumes UNSPEC == LIMITED) and
something that other libraries already assume (ie zimg).
-- 
Vittorio