From: Niklas Haas <g...@haasn.dev>
YUV->YUV conversions should preserve input range, if the output range is
unspecified. Ensures full-range YUV input comes out as full-range YUV
output by default, even through YUV->YUV pixel format conversions.
---
libavfilter/vf_scale.c | 23 +++++++++++++++++++++++
1 file changed, 23 insertions(+)
diff --git a/libavfilter/vf_scale.c b/libavfilter/vf_scale.c
index 3d58de0494..cde6f52169 100644
--- a/libavfilter/vf_scale.c
+++ b/libavfilter/vf_scale.c
@@ -687,6 +687,27 @@ static int scale_field(ScaleContext *scale, AVFrame *dst,
AVFrame *src,
return 0;
}
+static int is_regular_yuv(enum AVPixelFormat fmt)
+{
+ const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(fmt);
+ if (desc->flags & (AV_PIX_FMT_FLAG_RGB | AV_PIX_FMT_FLAG_PAL))
+ return 0;
+ if (desc->name && av_strstart(desc->name, "xyz", NULL))
+ return 0;
+ if (desc->nb_components < 3)
+ return 0; /* grayscale is forced full range inside libswscale */
+ switch (fmt) {
+ case AV_PIX_FMT_YUVJ420P:
+ case AV_PIX_FMT_YUVJ422P:
+ case AV_PIX_FMT_YUVJ444P:
+ case AV_PIX_FMT_YUVJ440P:
+ case AV_PIX_FMT_YUVJ411P:
+ return 0;
+ default:
+ return 1;
+ }
+}
+
static int scale_frame(AVFilterLink *link, AVFrame *in, AVFrame **frame_out)
{
AVFilterContext *ctx = link->dst;
@@ -794,6 +815,8 @@ scale:
in_full = in->color_range == AVCOL_RANGE_JPEG;
if (scale->out_range != AVCOL_RANGE_UNSPECIFIED)
out_full = scale->out_range == AVCOL_RANGE_JPEG;
+ else if (is_regular_yuv(in->format) && is_regular_yuv(outlink->format))
+ out_full = in_full; /* preserve pixel range by default */
if (in->width == outlink->w &&
in->height == outlink->h &&
--
2.42.0
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