video: Add new APIs for HDR information representation

Introduce HDR signalling methods
* GstVideoMasteringDisplayInfo: Representing display color volume info.
  Defined by SMPTE ST 2086
* GstVideoContentLightLevel: Representing content light level specified in
  CEA-861.3, Appendix A.

Closes https://gitlab.freedesktop.org/gstreamer/gst-plugins-base/issues/400

docs/libs/gst-plugins-base-libs-sections.txt

@@ -3047,6 +3047,23 @@ GST_TYPE_VIDEO_MATRIX_MODE
 GST_TYPE_VIDEO_PRIMARIES_MODE
 GST_TYPE_VIDEO_DITHER_METHOD
 
+#video-hdr.h
+<SUBSECTION>
+GstVideoMasteringDisplayInfo
+GstVideoContentLightLevel
+gst_video_mastering_display_info_add_to_caps
+gst_video_mastering_display_info_from_caps
+gst_video_mastering_display_info_from_string
+gst_video_mastering_display_info_init
+gst_video_mastering_display_info_is_equal
+gst_video_mastering_display_info_is_valid
+gst_video_mastering_display_info_to_string
+gst_video_content_light_level_add_to_caps
+gst_video_content_light_level_from_caps
+gst_video_content_light_level_from_string
+gst_video_content_light_level_init
+gst_video_content_light_level_to_string
+
 #video-multiview.h
 <SUBSECTION>
 GstVideoMultiviewMode

gst-libs/gst/video/Makefile.am

@@ -5,7 +5,7 @@ include $(top_srcdir)/common/orc.mak
 glib_enum_headers = video.h video-format.h video-color.h video-info.h video-dither.h \
 			colorbalance.h navigation.h video-chroma.h video-tile.h video-converter.h \
 			video-resampler.h video-frame.h video-scaler.h video-anc.h \
-			video-overlay-composition.h
+			video-overlay-composition.h video-hdr.h
 glib_enum_define = GST_VIDEO
 glib_gen_prefix = gst_video
 glib_gen_basename = video
@@ -32,6 +32,7 @@ libgstvideo_@GST_API_VERSION@_la_SOURCES = \
 	video-color.c         	\
 	video-converter.c    	\
 	video-dither.c    	\
+	video-hdr.c         	\
 	video-info.c         	\
 	video-frame.c         	\
 	video-scaler.c          \
@@ -72,6 +73,7 @@ libgstvideo_@GST_API_VERSION@include_HEADERS = \
 	video-color.h         	\
 	video-converter.h      	\
 	video-dither.h      	\
+	video-hdr.h         	\
 	video-info.h         	\
 	video-frame.h         	\
 	video-scaler.h          \

gst-libs/gst/video/meson.build

@@ -24,6 +24,7 @@ video_sources = [
   'video-event.c',
   'video-format.c',
   'video-frame.c',
+  'video-hdr.c',
   'video-info.c',
   'video-multiview.c',
   'video-resampler.c',
@@ -57,6 +58,7 @@ video_headers = [
   'video-color.h',
   'video-converter.h',
   'video-dither.h',
+  'video-hdr.h',
   'video-info.h',
   'video-frame.h',
   'video-prelude.h',