[libcamera-devel] [PATCH v1 1/5] gstreamer: Convert form colorspace to colorimetry.

[Rishikesh Donadkar]

Libcamera StreamConfiguration class has colorSpace attribute, which
holds the colorspace that is being applied to the camera after the
validation of the camera configuration.

Map between the libcamera colorspace and GStreamer colorimetry and find
the closest colorimetry corresponding to the colorspace in stream
configuration.

Signed-off-by: Rishikesh Donadkar <rishikeshdonadkar at gmail.com>
---
 src/gstreamer/gstlibcamera-utils.cpp | 71 ++++++++++++++++++++++++++++
 1 file changed, 71 insertions(+)

diff --git a/src/gstreamer/gstlibcamera-utils.cpp b/src/gstreamer/gstlibcamera-utils.cpp
index 3f242286..20c39919 100644
--- a/src/gstreamer/gstlibcamera-utils.cpp
+++ b/src/gstreamer/gstlibcamera-utils.cpp
@@ -45,6 +45,34 @@ static struct {
 	/* \todo NV42 is used in libcamera but is not mapped in GStreamer yet. */
 };
 
+static const std::vector<std::pair<ColorSpace, std::string>> ColorSpaceTocolorimetry = {
+	{ ColorSpace::Srgb, GST_VIDEO_COLORIMETRY_SRGB },
+	{ ColorSpace::Rec709, GST_VIDEO_COLORIMETRY_BT709 },
+	{ ColorSpace::Rec2020, GST_VIDEO_COLORIMETRY_BT2020 },
+};
+
+static const std::map<ColorSpace::Primaries, GstVideoColorPrimaries> ToGstVideoColorPrimaries = {
+	{ ColorSpace::Primaries::Smpte170m, GST_VIDEO_COLOR_PRIMARIES_SMPTE170M },
+	{ ColorSpace::Primaries::Rec709, GST_VIDEO_COLOR_PRIMARIES_BT709 },
+	{ ColorSpace::Primaries::Rec2020, GST_VIDEO_COLOR_PRIMARIES_BT2020 },
+};
+
+static const std::map<ColorSpace::TransferFunction, GstVideoTransferFunction> ToGstVideoTransferFunction = {
+	{ ColorSpace::TransferFunction::Srgb, GST_VIDEO_TRANSFER_SRGB },
+	{ ColorSpace::TransferFunction::Rec709, GST_VIDEO_TRANSFER_BT709 },
+};
+
+static const std::map<ColorSpace::YcbcrEncoding, GstVideoColorMatrix> ToGstVideoColorMatrix = {
+	{ ColorSpace::YcbcrEncoding::Rec601, GST_VIDEO_COLOR_MATRIX_BT601 },
+	{ ColorSpace::YcbcrEncoding::Rec709, GST_VIDEO_COLOR_MATRIX_BT709 },
+	{ ColorSpace::YcbcrEncoding::Rec2020, GST_VIDEO_COLOR_MATRIX_BT2020 },
+};
+
+static const std::map<ColorSpace::Range, GstVideoColorRange> ToGstVideoColorRange = {
+	{ ColorSpace::Range::Full, GST_VIDEO_COLOR_RANGE_0_255 },
+	{ ColorSpace::Range::Limited, GST_VIDEO_COLOR_RANGE_16_235 },
+};
+
 static GstVideoFormat
 pixel_format_to_gst_format(const PixelFormat &format)
 {
@@ -87,6 +115,49 @@ bare_structure_from_format(const PixelFormat &format)
 	}
 }
 
+static const gchar *
+colorimerty_from_colorspace(std::optional<ColorSpace> colorSpace)
+{
+	const gchar *colorimetry_str;
+	GstVideoColorimetry colorimetry;
+
+	auto iterColorimetry = std::find_if(ColorSpaceTocolorimetry.begin(), ColorSpaceTocolorimetry.end(),
+					    [&colorSpace](const auto &item) {
+						    return colorSpace == item.first;
+					    });
+	if (iterColorimetry != ColorSpaceTocolorimetry.end()) {
+		colorimetry_str = (gchar *)iterColorimetry->second.c_str();
+		return colorimetry_str;
+	}
+
+	auto iterPrimaries = ToGstVideoColorPrimaries.find(colorSpace->primaries);
+	if (iterPrimaries != ToGstVideoColorPrimaries.end())
+		colorimetry.primaries = iterPrimaries->second;
+	else
+		colorimetry.primaries = GST_VIDEO_COLOR_PRIMARIES_UNKNOWN;
+
+	auto iterTransferFunction = ToGstVideoTransferFunction.find(colorSpace->transferFunction);
+	if (iterTransferFunction != ToGstVideoTransferFunction.end())
+		colorimetry.transfer = iterTransferFunction->second;
+	else
+		colorimetry.transfer = GST_VIDEO_TRANSFER_UNKNOWN;
+
+	auto iterYcbcrEncoding = ToGstVideoColorMatrix.find(colorSpace->ycbcrEncoding);
+	if (iterYcbcrEncoding != ToGstVideoColorMatrix.end())
+		colorimetry.matrix = iterYcbcrEncoding->second;
+	else
+		colorimetry.matrix = GST_VIDEO_COLOR_MATRIX_UNKNOWN;
+
+	auto iterRange = ToGstVideoColorRange.find(colorSpace->range);
+	if (iterRange != ToGstVideoColorRange.end())
+		colorimetry.range = iterRange->second;
+	else
+		colorimetry.range = GST_VIDEO_COLOR_RANGE_UNKNOWN;
+
+	colorimetry_str = gst_video_colorimetry_to_string(&colorimetry);
+	return colorimetry_str;
+}
+
 GstCaps *
 gst_libcamera_stream_formats_to_caps(const StreamFormats &formats)
 {
-- 
2.25.1