Factor out sdp_stream_metadata definition

Signed-off-by: Kévin Commaille <zecakeh@tedomum.fr>

data/event-schemas/schema/core-event-schema/sdp_stream_metadata.yaml

@@ -0,0 +1,27 @@
+type: object
+x-addedInMatrixVersion: "1.10"
+description: |-
+  Metadata describing the [streams](/client-server-api/#streams) that will be
+  sent.
+  
+  This is a map of stream ID to metadata about the stream.
+additionalProperties:
+  type: object
+  title: StreamMetadata
+  description: Metadata describing a stream.
+  properties:
+    purpose:
+      type: string
+      enum:
+        - m.usermedia
+        - m.screenshare
+      description: |-
+        The purpose of the stream.
+
+        The possible values are:
+
+        * `m.usermedia` - stream that contains the webcam and/or microphone
+          tracks
+        * `m.screenshare` - stream with the screen-sharing tracks      
+  required:
+    - purpose

data/event-schemas/schema/m.call.answer.yaml

@@ -29,21 +29,7 @@
                     "required": ["type", "sdp"]
                 },
                 "sdp_stream_metadata": {
-                    "type": "object",
-                    "title": "SDP Stream Metadata",
-                    "x-addedInMatrixVersion": "1.7",
-                    "description": "Object describing the streams that will be sent",
-                    "additionalProperties": {
-                        "type": "object",
-                        "title": "Stream Metadata Block",
-                        "properties": {
-                            "purpose": {
-                              "type": "string",
-                              "enum": ["m.usermedia", "m.screenshare"]
-                            }
-                        },
-                        "required": ["purpose"]
-                    }
+                    "$ref": "core-event-schema/sdp_stream_metadata.yaml"
                 }
             },
             "required": ["answer"]

data/event-schemas/schema/m.call.invite.yaml

@@ -38,21 +38,7 @@
                     "x-addedInMatrixVersion": "1.7"
                 },
                 "sdp_stream_metadata": {
-                    "type": "object",
-                    "title": "SDP Stream Metadata",
-                    "x-addedInMatrixVersion": "1.7",
-                    "description": "Object describing the streams that will be sent",
-                    "additionalProperties": {
-                        "type": "object",
-                        "title": "Stream Metadata Block",
-                        "properties": {
-                            "purpose": {
-                              "type": "string",
-                              "enum": ["m.usermedia", "m.screenshare"]
-                            }
-                        },
-                        "required": ["purpose"]
-                    }
+                    "$ref": "core-event-schema/sdp_stream_metadata.yaml"
                 }
             },
             "required": ["offer", "lifetime"]

data/event-schemas/schema/m.call.negotiate.yaml

@@ -64,22 +64,7 @@ properties:
         description: The time in milliseconds that the negotiation is valid for.
           Once the negotiation age exceeds this value, clients should discard it.
       sdp_stream_metadata:
-        type: object
-        title: SDP Stream Metadata
-        x-addedInMatrixVersion: '1.7'
-        description: Object describing the streams that will be sent
-        additionalProperties:
-          type: object
-          title: Stream Metadata Block
-          properties:
-            purpose:
-              type: string
-              enum:
-              - m.usermedia
-              - m.screenshare
-    required:
-    - purpose
-
+        $ref: core-event-schema/sdp_stream_metadata.yaml
     required:
     - description
     - lifetime