Merge pull request #300 from w3c/issue-194-hdr

Add transfer-functions and hdr-metadata to video-capabilities.

index.bs

@@ -1702,15 +1702,34 @@ following additional fields:
     display could return this value as 1.6 to indicate its preferred content
     scaling. Default is none.
 
-Issue(194): Expose capabilities for decoding HDR transfer functions and metadata formats.
-
 : color-gamuts (optional)
 :: An optional field indicating what color spaces can be decoded and rendered by
     the media receiver.  The media sender may use these values to determine how
     to encode video. Valid values correspond to [[MEDIA-CAPABILITIES#colorgamut|ColorGamut]]
     in the [[!MEDIA-CAPABILITIES|Media Capabilities]] API.  The default value is
     a list with the single entry "srgb".
 
+: hdr-formats (optional)
+:: An optional field indicating what HDR transfer functions and metadata formats
+    can be decoded and rendered by the media receiver.  Each `video-hdr-format`
+    consists of two fields, `transfer-function` and `hdr-metadata`.
+
+    The `transfer-function` field must be a valid
+    [[MEDIA-CAPABILITIES#transferfunction|TransferFunction]]
+    and the `hdr-metadata` field must be a valid
+    [[MEDIA-CAPABILITIES#hdrmetadatatype|HdrMetadataType]], both defined in the
+    [[!MEDIA-CAPABILITIES|Media Capabilities]] API.
+
+    If a `video-hdr-format` is provided with a `transfer-function` but no
+    `hdr-metadata`, then the media receiver can render the `transfer-function`
+    without any associated metadata.  (This is the case, for example, with the
+    "hlg" `transfer-function`.)
+
+    The media receiver should ignore duplicate entries in `hdr-formats.`
+    If no `hdr-formats` are listed, then the media reciever cannot decode any
+    HDR formats.
+
+
 : native-resolutions (optional)
 :: An optional field indicating what video-resolutions the media receiver supports and
     considers to be "native," meaning that scaling is not required.

messages_appendix.cddl

@@ -553,6 +553,11 @@ video-resolution = {
   1: uint ; width
 }
 
+video-hdr-format = {
+  0: transfer-function ; string
+  1: ? hdr-metadata ; string
+}
+
 receive-video-capability = {
   0: format ; codec
   ? 1: video-resolution ; max-resolution
@@ -564,6 +569,7 @@ receive-video-capability = {
   ? 7: [* video-resolution] ; native-resolutions
   ? 8: bool ; supports-scaling
   ? 9: bool ; supports-rotation
+  ? 10: [* video-hdr-format] ; hdr-formats
 }
 
 receive-data-capability = {