[libcamera-devel] [PATCH v2 1/4] gstreamer: convert from libcamera colorspace toGStreamer 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 the libcamera colorspace to GStreamer colorimetry and find
the colorimetry corresponding to the colorspace that is being applied to
the camera. This colorimetry if found will be pushed in the caps.

Signed-off-by: Rishikesh Donadkar <rishikeshdonadkar at gmail.com>
---
 src/gstreamer/gstlibcamera-utils.cpp | 32 ++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/src/gstreamer/gstlibcamera-utils.cpp b/src/gstreamer/gstlibcamera-utils.cpp
index c97c0d43..60ac8c8e 100644
--- a/src/gstreamer/gstlibcamera-utils.cpp
+++ b/src/gstreamer/gstlibcamera-utils.cpp
@@ -45,6 +45,12 @@ 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 GstVideoFormat
 pixel_format_to_gst_format(const PixelFormat &format)
 {
@@ -87,6 +93,32 @@ bare_structure_from_format(const PixelFormat &format)
 	}
 }
 
+static gchar *
+colorimerty_from_colorspace(std::optional<ColorSpace> colorSpace)
+{
+	gchar *colorimetry_str = nullptr;
+	gchar *colorimetry_found = nullptr;
+	GstVideoColorimetry colorimetry;
+	gboolean isColorimetryValid;
+
+	auto iterColorimetry = std::find_if(ColorSpaceTocolorimetry.begin(), ColorSpaceTocolorimetry.end(),
+					    [&colorSpace](const auto &item) {
+						    return colorSpace == item.first;
+					    });
+	if (iterColorimetry != ColorSpaceTocolorimetry.end()) {
+		colorimetry_found = (gchar *)iterColorimetry->second.c_str();
+		isColorimetryValid = gst_video_colorimetry_from_string(&colorimetry, colorimetry_found);
+	}
+	if (isColorimetryValid) {
+		colorimetry_str = gst_video_colorimetry_to_string(&colorimetry);
+		return colorimetry_str;
+	} else {
+		g_free(colorimetry_found);
+		g_free(colorimetry_str);
+		return nullptr;
+	}
+}
+
 GstCaps *
 gst_libcamera_stream_formats_to_caps(const StreamFormats &formats)
 {
-- 
2.25.1