[libcamera-devel] [PATCH 3/3] gstreamer: Provide colorimetry <> libcamera::ColorSpace mappings

Umang Jain umang.jain at ideasonboard.com
Sun Jul 24 16:43:55 CEST 2022


From: Rishikesh Donadkar <rishikeshdonadkar at gmail.com>

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 gstlibcamerasrc currently undertakes only one
argument. Multiple colorimetry support shall be introduced in
subsequent commits.

Signed-off-by: Rishikesh Donadkar <rishikeshdonadkar at gmail.com>
Signed-off-by: Umang Jain <umang.jain at ideasonboard.com>
---
 src/gstreamer/gstlibcamera-utils.cpp | 175 +++++++++++++++++++++++++++
 1 file changed, 175 insertions(+)

diff --git a/src/gstreamer/gstlibcamera-utils.cpp b/src/gstreamer/gstlibcamera-utils.cpp
index c97c0d43..fb4f0e5c 100644
--- a/src/gstreamer/gstlibcamera-utils.cpp
+++ b/src/gstreamer/gstlibcamera-utils.cpp
@@ -45,6 +45,157 @@ 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::Rec709:
+		colorimetry.primaries = GST_VIDEO_COLOR_PRIMARIES_BT709;
+		break;
+	case ColorSpace::Primaries::Rec2020:
+		colorimetry.primaries = GST_VIDEO_COLOR_PRIMARIES_BT2020;
+		break;
+	case ColorSpace::Primaries::Smpte170m:
+		colorimetry.primaries = GST_VIDEO_COLOR_PRIMARIES_SMPTE170M;
+		break;
+	default:
+		GST_WARNING("ColorSpace primaries not mapped in GstLibcameraSrc");
+		colorimetry.primaries = GST_VIDEO_COLOR_PRIMARIES_UNKNOWN;
+	}
+
+	switch (colorSpace.transferFunction) {
+	case ColorSpace::TransferFunction::Rec709:
+		colorimetry.transfer = GST_VIDEO_TRANSFER_BT709;
+		break;
+	case ColorSpace::TransferFunction::Srgb:
+		colorimetry.transfer = GST_VIDEO_TRANSFER_SRGB;
+		break;
+	case ColorSpace::TransferFunction::Linear:
+		colorimetry.transfer = GST_VIDEO_TRANSFER_GAMMA10;
+		break;
+	default:
+		GST_WARNING("ColorSpace transfer function not mapped in GstLibcameraSrc");
+		colorimetry.transfer = GST_VIDEO_TRANSFER_UNKNOWN;
+	}
+
+	switch (colorSpace.ycbcrEncoding) {
+	case ColorSpace::YcbcrEncoding::Rec709:
+		colorimetry.matrix = GST_VIDEO_COLOR_MATRIX_BT709;
+		break;
+	case ColorSpace::YcbcrEncoding::Rec2020:
+		colorimetry.matrix = GST_VIDEO_COLOR_MATRIX_BT2020;
+		break;
+	case ColorSpace::YcbcrEncoding::Rec601:
+		colorimetry.matrix = GST_VIDEO_COLOR_MATRIX_BT601;
+		break;
+	default:
+		GST_WARNING("Colorspace YcbcrEncoding not mapped in GstLibcameraSrc");
+		colorimetry.matrix = GST_VIDEO_COLOR_MATRIX_UNKNOWN;
+	}
+
+	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;
+	default:
+		GST_WARNING("Colorspace range not mapped in GstLibcameraSrc");
+		colorimetry.range = GST_VIDEO_COLOR_RANGE_UNKNOWN;
+	}
+
+	return colorimetry;
+}
+
+static std::optional<ColorSpace>
+colorspace_from_colorimetry(GstVideoColorimetry *colorimetry)
+{
+	std::optional<ColorSpace> colorspace = ColorSpace::Default;
+
+	switch (colorimetry->primaries) {
+	case GST_VIDEO_COLOR_PRIMARIES_BT709:
+		colorspace->primaries = ColorSpace::Primaries::Rec709;
+		break;
+	case GST_VIDEO_COLOR_PRIMARIES_BT2020:
+		colorspace->primaries = ColorSpace::Primaries::Rec2020;
+		break;
+	case GST_VIDEO_COLOR_PRIMARIES_SMPTE170M:
+		colorspace->primaries = ColorSpace::Primaries::Smpte170m;
+		break;
+	case GST_VIDEO_COLOR_PRIMARIES_UNKNOWN:
+		colorspace->primaries = ColorSpace::Primaries::Default;
+		break;
+	default:
+		GST_WARNING("Unknown primaries in colorimetry %d", colorimetry->primaries);
+	}
+
+	switch (colorimetry->transfer) {
+	/* Tranfer 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_BT601:
+	case GST_VIDEO_TRANSFER_BT2020_12:
+	case GST_VIDEO_TRANSFER_BT2020_10:
+	case GST_VIDEO_TRANSFER_BT709:
+		colorspace->transferFunction = ColorSpace::TransferFunction::Rec709;
+		break;
+	case GST_VIDEO_TRANSFER_SRGB:
+		colorspace->transferFunction = ColorSpace::TransferFunction::Srgb;
+		break;
+	case GST_VIDEO_TRANSFER_UNKNOWN:
+		colorspace->transferFunction = ColorSpace::TransferFunction::Default;
+		break;
+	default:
+		GST_WARNING("Unknown colorimetry transfer %d", colorimetry->transfer);
+	}
+
+	switch (colorimetry->matrix) {
+	/* 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;
+	case GST_VIDEO_COLOR_MATRIX_RGB:
+	case GST_VIDEO_COLOR_MATRIX_UNKNOWN:
+		colorspace->ycbcrEncoding = ColorSpace::YcbcrEncoding::Default;
+		break;
+	default:
+		GST_WARNING("Unknown colorimetry matrix %d", colorimetry->matrix);
+	}
+
+	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;
+	case GST_VIDEO_COLOR_RANGE_UNKNOWN:
+		colorspace->range = ColorSpace::Range::Default;
+		break;
+	default:
+		GST_WARNING("Unknown range in colorimetry %d", colorimetry->range);
+	}
+
+	return colorspace;
+}
+
 static GstVideoFormat
 pixel_format_to_gst_format(const PixelFormat &format)
 {
@@ -139,6 +290,17 @@ 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 != nullptr)
+			gst_structure_set(s, "colorimetry", G_TYPE_STRING, colorimetry_str, nullptr);
+		else
+			g_warning("libcamera::ColorSpace found but GstVideoColorimetry unknown");
+	}
+
 	gst_caps_append_structure(caps, s);
 
 	return caps;
@@ -222,6 +384,19 @@ 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_caps = gst_structure_get_string(s, "colorimetry");
+		GstVideoColorimetry colorimetry;
+
+		if(gst_video_colorimetry_from_string(&colorimetry, colorimetry_caps)) {
+			std::optional<ColorSpace> colorSpace = colorspace_from_colorimetry(&colorimetry);
+			stream_cfg.colorSpace = colorSpace;
+		} else {
+			g_print("Invalid colorimetry %s", colorimetry_caps);
+		}
+	}
 }
 
 #if !GST_CHECK_VERSION(1, 17, 1)
-- 
2.31.1



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