[libcamera-devel] [PATCH v2 1/2] gstreamer: Provide ColorSpace => colorimetry mappings

[Rishikesh Donadkar]

Provide libcamera::ColorSpace => colorimetry mappings via:
- GstVideoColorimetry colorimetry_from_colorspace(colorspace);

Read the ColorSpace from the StreamConfiguration, convert it to
colorimetry and update the colorimetry into the caps.

This patch handles colorimetry in libcamera->GStreamer direction.
Colorimetry support form GStreamer->libcamera direction is provided
the next patch.

Signed-off-by: Rishikesh Donadkar <rishikeshdonadkar at gmail.com>
Signed-off-by: Umang Jain <umang.jain at ideasonboard.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 c97c0d43..dbb47c5a 100644
--- a/src/gstreamer/gstlibcamera-utils.cpp
+++ b/src/gstreamer/gstlibcamera-utils.cpp
@@ -45,6 +45,65 @@ static struct {
 	/* \todo NV42 is used in libcamera but is not mapped in GStreamer yet. */
 };
 
+static GstVideoColorimetry
+colorimetry_from_colorspace(const ColorSpace &colorSpace)
+{
+	GstVideoColorimetry colorimetry;
+
+	switch (colorSpace.primaries) {
+	case ColorSpace::Primaries::Raw:
+		colorimetry.primaries = GST_VIDEO_COLOR_PRIMARIES_UNKNOWN;
+		break;
+	case ColorSpace::Primaries::Smpte170m:
+		colorimetry.primaries = GST_VIDEO_COLOR_PRIMARIES_SMPTE170M;
+		break;
+	case ColorSpace::Primaries::Rec709:
+		colorimetry.primaries = GST_VIDEO_COLOR_PRIMARIES_BT709;
+		break;
+	case ColorSpace::Primaries::Rec2020:
+		colorimetry.primaries = GST_VIDEO_COLOR_PRIMARIES_BT2020;
+		break;
+	}
+
+	switch (colorSpace.transferFunction) {
+	case ColorSpace::TransferFunction::Linear:
+		colorimetry.transfer = GST_VIDEO_TRANSFER_GAMMA10;
+		break;
+	case ColorSpace::TransferFunction::Srgb:
+		colorimetry.transfer = GST_VIDEO_TRANSFER_SRGB;
+		break;
+	case ColorSpace::TransferFunction::Rec709:
+		colorimetry.transfer = GST_VIDEO_TRANSFER_BT709;
+		break;
+	}
+
+	switch (colorSpace.ycbcrEncoding) {
+	case ColorSpace::YcbcrEncoding::None:
+		colorimetry.matrix = GST_VIDEO_COLOR_MATRIX_RGB;
+		break;
+	case ColorSpace::YcbcrEncoding::Rec601:
+		colorimetry.matrix = GST_VIDEO_COLOR_MATRIX_BT601;
+		break;
+	case ColorSpace::YcbcrEncoding::Rec709:
+		colorimetry.matrix = GST_VIDEO_COLOR_MATRIX_BT709;
+		break;
+	case ColorSpace::YcbcrEncoding::Rec2020:
+		colorimetry.matrix = GST_VIDEO_COLOR_MATRIX_BT2020;
+		break;
+	}
+
+	switch (colorSpace.range) {
+	case ColorSpace::Range::Full:
+		colorimetry.range = GST_VIDEO_COLOR_RANGE_0_255;
+		break;
+	case ColorSpace::Range::Limited:
+		colorimetry.range = GST_VIDEO_COLOR_RANGE_16_235;
+		break;
+	}
+
+	return colorimetry;
+}
+
 static GstVideoFormat
 pixel_format_to_gst_format(const PixelFormat &format)
 {
@@ -139,6 +198,18 @@ gst_libcamera_stream_configuration_to_caps(const StreamConfiguration &stream_cfg
 			  "width", G_TYPE_INT, stream_cfg.size.width,
 			  "height", G_TYPE_INT, stream_cfg.size.height,
 			  nullptr);
+
+	if (stream_cfg.colorSpace) {
+		GstVideoColorimetry colorimetry = colorimetry_from_colorspace(stream_cfg.colorSpace.value());
+		gchar *colorimetry_str = gst_video_colorimetry_to_string(&colorimetry);
+
+		if (colorimetry_str)
+			gst_structure_set(s, "colorimetry", G_TYPE_STRING, colorimetry_str, nullptr);
+		else
+			g_error("Got invalid colorimetry from ColorSpace: %s",
+				ColorSpace::toString(stream_cfg.colorSpace).c_str());
+	}
+
 	gst_caps_append_structure(caps, s);
 
 	return caps;
-- 
2.25.1