3 files changed, 125 insertions, 0 deletions
diff --git a/src/gstreamer/gstlibcamera-utils.cpp b/src/gstreamer/gstlibcamera-utils.cpp
new file mode 100644
index 00000000..386ec364
--- /dev/null
+++ b/src/gstreamer/gstlibcamera-utils.cpp
@@ -0,0 +1,105 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2020, Collabora Ltd.
+ *     Author: Nicolas Dufresne <nicolas.dufresne@collabora.com>
+ *
+ * gstlibcamera-utils.c - GStreamer libcamera Utility Function
+ */
+
+#include "gstlibcamera-utils.h"
+
+#include <linux/drm_fourcc.h>
+
+using namespace libcamera;
+
+static struct {
+	GstVideoFormat gst_format;
+	guint drm_fourcc;
+} format_map[] = {
+	{ GST_VIDEO_FORMAT_ENCODED, DRM_FORMAT_MJPEG },
+	{ GST_VIDEO_FORMAT_RGB, DRM_FORMAT_BGR888 },
+	{ GST_VIDEO_FORMAT_BGR, DRM_FORMAT_RGB888 },
+	{ GST_VIDEO_FORMAT_ARGB, DRM_FORMAT_BGRA8888 },
+	{ GST_VIDEO_FORMAT_NV12, DRM_FORMAT_NV12 },
+	{ GST_VIDEO_FORMAT_NV21, DRM_FORMAT_NV21 },
+	{ GST_VIDEO_FORMAT_NV16, DRM_FORMAT_NV16 },
+	{ GST_VIDEO_FORMAT_NV61, DRM_FORMAT_NV61 },
+	{ GST_VIDEO_FORMAT_NV24, DRM_FORMAT_NV24 },
+	{ GST_VIDEO_FORMAT_UYVY, DRM_FORMAT_UYVY },
+	{ GST_VIDEO_FORMAT_VYUY, DRM_FORMAT_VYUY },
+	{ GST_VIDEO_FORMAT_YUY2, DRM_FORMAT_YUYV },
+	{ GST_VIDEO_FORMAT_YVYU, DRM_FORMAT_YVYU },
+	/* \todo NV42 is used in libcamera but is not mapped in GStreamer yet. */
+};
+
+static GstVideoFormat
+drm_to_gst_format(guint drm_fourcc)
+{
+	for (const auto &item : format_map) {
+		if (item.drm_fourcc == drm_fourcc)
+			return item.gst_format;
+	}
+	return GST_VIDEO_FORMAT_UNKNOWN;
+}
+
+static GstStructure *
+bare_structure_from_fourcc(guint fourcc)
+{
+	GstVideoFormat gst_format = drm_to_gst_format(fourcc);
+
+	if (gst_format == GST_VIDEO_FORMAT_UNKNOWN)
+		return nullptr;
+
+	if (gst_format != GST_VIDEO_FORMAT_ENCODED)
+		return gst_structure_new("video/x-raw", "format", G_TYPE_STRING,
+					 gst_video_format_to_string(gst_format), nullptr);
+
+	switch (fourcc) {
+	case DRM_FORMAT_MJPEG:
+		return gst_structure_new_empty("image/jpeg");
+	default:
+		return nullptr;
+	}
+}
+
+GstCaps *
+gst_libcamera_stream_formats_to_caps(const StreamFormats &formats)
+{
+	GstCaps *caps = gst_caps_new_empty();
+
+	for (unsigned int fourcc : formats.pixelformats()) {
+		g_autoptr(GstStructure) bare_s = bare_structure_from_fourcc(fourcc);
+
+		if (!bare_s) {
+			GST_WARNING("Unsupported DRM format %" GST_FOURCC_FORMAT,
+				    GST_FOURCC_ARGS(fourcc));
+			continue;
+		}
+
+		for (const Size &size : formats.sizes(fourcc)) {
+			GstStructure *s = gst_structure_copy(bare_s);
+			gst_structure_set(s,
+					  "width", G_TYPE_INT, size.width,
+					  "height", G_TYPE_INT, size.height,
+					  nullptr);
+			gst_caps_append_structure(caps, s);
+		}
+
+		const SizeRange &range = formats.range(fourcc);
+		if (range.hStep && range.vStep) {
+			GstStructure *s = gst_structure_copy(bare_s);
+			GValue val = G_VALUE_INIT;
+
+			g_value_init(&val, GST_TYPE_INT_RANGE);
+			gst_value_set_int_range_step(&val, range.min.width, range.max.width, range.hStep);
+			gst_structure_set_value(s, "width", &val);
+			gst_value_set_int_range_step(&val, range.min.height, range.max.height, range.vStep);
+			gst_structure_set_value(s, "height", &val);
+			g_value_unset(&val);
+
+			gst_caps_append_structure(caps, s);
+		}
+	}
+
+	return caps;
+}
diff --git a/src/gstreamer/gstlibcamera-utils.h b/src/gstreamer/gstlibcamera-utils.h
new file mode 100644
index 00000000..2e4e3042
--- /dev/null
+++ b/src/gstreamer/gstlibcamera-utils.h
@@ -0,0 +1,19 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2020, Collabora Ltd.
+ *     Author: Nicolas Dufresne <nicolas.dufresne@collabora.com>
+ *
+ * gstlibcamera-utils.h - GStreamer libcamera Utility Functions
+ */
+
+#ifndef __GST_LIBCAMERA_UTILS_H__
+#define __GST_LIBCAMERA_UTILS_H__
+
+#include <gst/gst.h>
+#include <gst/video/video.h>
+
+#include <libcamera/stream.h>
+
+GstCaps *gst_libcamera_stream_formats_to_caps(const libcamera::StreamFormats &formats);
+
+#endif /* __GST_LIBCAMERA_UTILS_H__ */
diff --git a/src/gstreamer/meson.build b/src/gstreamer/meson.build
index 490e030e..9b11a46f 100644
--- a/src/gstreamer/meson.build
+++ b/src/gstreamer/meson.build
@@ -1,4 +1,5 @@
 libcamera_gst_sources = [
+    'gstlibcamera-utils.cpp',
     'gstlibcamera.c',
     'gstlibcamerasrc.cpp',
 ]