From: Steinar H. Gunderson <sgunderson@bigfoot.com>
Date: Tue, 30 Oct 2018 08:01:41 +0000 (+0100)
Subject: Stop crushing blacks for full-range sources.
X-Git-Tag: 1.8.0~76^2~26
X-Git-Url: https://git.sesse.net/?p=nageru;a=commitdiff_plain;h=2aa8d36ac83790a9beb30a2d74c9101cbba39fa8

Stop crushing blacks for full-range sources.
---

diff --git a/ycbcr_converter.cpp b/ycbcr_converter.cpp
index 143c471..694ba97 100644
--- a/ycbcr_converter.cpp
+++ b/ycbcr_converter.cpp
@@ -39,7 +39,6 @@ YCbCrConverter::YCbCrConverter(YCbCrConverter::OutputMode output_mode, ResourceP
 	inout_format.gamma_curve = GAMMA_sRGB;
 
 	ycbcr_format.luma_coefficients = YCBCR_REC_709;
-	ycbcr_format.full_range = false;
 	ycbcr_format.num_levels = 256;
 	ycbcr_format.chroma_subsampling_x = 2;
 	ycbcr_format.chroma_subsampling_y = 1;
@@ -48,6 +47,18 @@ YCbCrConverter::YCbCrConverter(YCbCrConverter::OutputMode output_mode, ResourceP
 	ycbcr_format.cr_x_position = 0.0f;
 	ycbcr_format.cr_y_position = 0.5f;
 
+	// This is a hack. Even though we're sending MJPEG around, which is
+	// full-range, it's mostly transporting signals from limited-range
+	// sources with no conversion, so we ought to have had false here.
+	// However, in the off chance that we're actually getting real MJPEG,
+	// we don't want to crush its blacks (or whites) by clamping. All of
+	// our processing is fades, so if we're in limited-range input, we'll
+	// stay in limited-range output. (Fading between limited-range and
+	// full-range sources will be broken, of course.) There will be some
+	// slight confusion in the parts of the algorithms dealing with RGB,
+	// but they're small and we'll manage.
+	ycbcr_format.full_range = true;
+
 	YCbCrFormat ycbcr_output_format = ycbcr_format;
 	ycbcr_output_format.chroma_subsampling_x = 1;