gstreamer: Provide colorimetry <> ColorSpace mappings

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

Read the colorimetry field from caps into the stream configuration.
After stream validation, the sensor supported colorimetry will
be retrieved and the caps will be updated accordingly.

Colorimetry support for gstlibcamera currently undertakes only one
argument. Multiple colorimetry support shall be introduced in
subsequent commits.

Signed-off-by: Rishikesh Donadkar <rishikeshdonadkar@gmail.com>
Signed-off-by: Umang Jain <umang.jain@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Umang Jain <umang.jain@ideasonboard.com>
Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>

1 files changed, 169 insertions, 0 deletions

diff --git a/src/gstreamer/gstlibcamera-utils.cpp b/src/gstreamer/gstlibcamera-utils.cpp
index 5a21a391..4df5dd6c 100644
--- a/src/gstreamer/gstlibcamera-utils.cpp
+++ b/src/gstreamer/gstlibcamera-utils.cpp
@@ -57,6 +57,152 @@ 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 std::optional<ColorSpace>
+colorspace_from_colorimetry(const GstVideoColorimetry &colorimetry)
+{
+	std::optional<ColorSpace> colorspace = ColorSpace::Raw;
+
+	switch (colorimetry.primaries) {
+	case GST_VIDEO_COLOR_PRIMARIES_UNKNOWN:
+		/* Unknown primaries map to raw colorspace in gstreamer */
+		return ColorSpace::Raw;
+	case GST_VIDEO_COLOR_PRIMARIES_SMPTE170M:
+		colorspace->primaries = ColorSpace::Primaries::Smpte170m;
+		break;
+	case GST_VIDEO_COLOR_PRIMARIES_BT709:
+		colorspace->primaries = ColorSpace::Primaries::Rec709;
+		break;
+	case GST_VIDEO_COLOR_PRIMARIES_BT2020:
+		colorspace->primaries = ColorSpace::Primaries::Rec2020;
+		break;
+	default:
+		GST_WARNING("Colorimetry primaries %d not mapped in gstlibcamera",
+			    colorimetry.primaries);
+		return std::nullopt;
+	}
+
+	switch (colorimetry.transfer) {
+	/* Transfer function mappings inspired from v4l2src plugin */
+	case GST_VIDEO_TRANSFER_GAMMA18:
+	case GST_VIDEO_TRANSFER_GAMMA20:
+	case GST_VIDEO_TRANSFER_GAMMA22:
+	case GST_VIDEO_TRANSFER_GAMMA28:
+		GST_WARNING("GAMMA 18, 20, 22, 28 transfer functions not supported");
+	/* fallthrough */
+	case GST_VIDEO_TRANSFER_GAMMA10:
+		colorspace->transferFunction = ColorSpace::TransferFunction::Linear;
+		break;
+	case GST_VIDEO_TRANSFER_SRGB:
+		colorspace->transferFunction = ColorSpace::TransferFunction::Srgb;
+		break;
+	case GST_VIDEO_TRANSFER_BT601:
+	case GST_VIDEO_TRANSFER_BT2020_12:
+	case GST_VIDEO_TRANSFER_BT2020_10:
+	case GST_VIDEO_TRANSFER_BT709:
+		colorspace->transferFunction = ColorSpace::TransferFunction::Rec709;
+		break;
+	default:
+		GST_WARNING("Colorimetry transfer function %d not mapped in gstlibcamera",
+			    colorimetry.transfer);
+		return std::nullopt;
+	}
+
+	switch (colorimetry.matrix) {
+	case GST_VIDEO_COLOR_MATRIX_RGB:
+		colorspace->ycbcrEncoding = ColorSpace::YcbcrEncoding::None;
+		break;
+	/* FCC is about the same as BT601 with less digit */
+	case GST_VIDEO_COLOR_MATRIX_FCC:
+	case GST_VIDEO_COLOR_MATRIX_BT601:
+		colorspace->ycbcrEncoding = ColorSpace::YcbcrEncoding::Rec601;
+		break;
+	case GST_VIDEO_COLOR_MATRIX_BT709:
+		colorspace->ycbcrEncoding = ColorSpace::YcbcrEncoding::Rec709;
+		break;
+	case GST_VIDEO_COLOR_MATRIX_BT2020:
+		colorspace->ycbcrEncoding = ColorSpace::YcbcrEncoding::Rec2020;
+		break;
+	default:
+		GST_WARNING("Colorimetry matrix %d not mapped in gstlibcamera",
+			    colorimetry.matrix);
+		return std::nullopt;
+	}
+
+	switch (colorimetry.range) {
+	case GST_VIDEO_COLOR_RANGE_0_255:
+		colorspace->range = ColorSpace::Range::Full;
+		break;
+	case GST_VIDEO_COLOR_RANGE_16_235:
+		colorspace->range = ColorSpace::Range::Limited;
+		break;
+	default:
+		GST_WARNING("Colorimetry range %d not mapped in gstlibcamera",
+			    colorimetry.range);
+		return std::nullopt;
+	}
+
+	return colorspace;
+}
+
 static GstVideoFormat
 pixel_format_to_gst_format(const PixelFormat &format)
 {
@@ -151,6 +297,18 @@ 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;
@@ -234,6 +392,17 @@ gst_libcamera_configure_stream_from_caps(StreamConfiguration &stream_cfg,
 	gst_structure_get_int(s, "height", &height);
 	stream_cfg.size.width = width;
 	stream_cfg.size.height = height;
+
+	/* Configure colorimetry */
+	if (gst_structure_has_field(s, "colorimetry")) {
+		const gchar *colorimetry_str = gst_structure_get_string(s, "colorimetry");
+		GstVideoColorimetry colorimetry;
+
+		if (!gst_video_colorimetry_from_string(&colorimetry, colorimetry_str))
+			g_critical("Invalid colorimetry %s", colorimetry_str);
+
+		stream_cfg.colorSpace = colorspace_from_colorimetry(colorimetry);
+	}
 }
 
 #if !GST_CHECK_VERSION(1, 17, 1)