Merge pull request #313 from w3c/issue-223-codec-switching

Address remote playback issues.

index.bs

@@ -1114,8 +1114,6 @@ particular URL or set of URLs, the controller may send a
 :: A list of [=media resources=], the same as specified in the
     [=remote-playback-start-request=] message.  Must not be empty.
 
-Issue(146): Remote Playback HTTP headers.
-
 : headers
 :: headers that the receiver should use to fetch the
     urls.  For example,
@@ -1173,12 +1171,13 @@ values:
 Note: A version 4 (pseudorandom) [=UUID=] is recommended as it meets the
 requirements for a remote-playback-id.
 
-: sources
+: sources (optional)
 :: The [=media resources=] that the controller has selected for playback
     on the receiver.  Each source must include a <{source/src|source URL}>
-    and should include an <{source/type|extended MIME type}>.
-
-Issue(265): Should media resource URLs be optional?
+    and should include an <{source/type|extended MIME type}> when available
+    for the [=media resource=].  If `sources` is missing or empty, the
+    `remoting` field must be populated, as the controller will use a
+    streaming session to send encoded media.
 
 : text-track-urls
 :: URLs of text tracks associated with the [=media resources=].
@@ -1194,6 +1193,7 @@ Issue(265): Should media resource URLs be optional?
 : remoting (optional)
 :: Parameters for starting a streaming session associated with this
     remote playback.  If not included, no streaming session is started.
+    Required when `sources` is missing or empty.
 
 When the receiver receives a [=remote-playback-start-request=] message, it should
 send back a [=remote-playback-start-response=] message.  It should do so quickly,
@@ -1342,13 +1342,12 @@ present control value indicates the change defined below. These controls
 intentionally mirror settable attributes and methods of the
 {{HTMLMediaElement}}.
 
-: source-url
-:: Change the [=media resource=] URL. See
+: source
+:: Change the [=media resource=]. See
     {{HTMLMediaElement/src|HTMLMediaElement.src}}
     for more details. Must not be used in the initial controls of the
-    [=remote-playback-start-request=] message (which already contains a list of URLs).
-
-Issue(223): Codec switching when remoting.
+    [=remote-playback-start-request=] message (which already contains a
+    [=media resource=]).
 
 : preload
 :: Set how aggressively to preload media. See
@@ -1473,8 +1472,8 @@ changed.
     The default is empty (support for nothing)
     for the initial state in the [=remote-playback-start-response=] message.
 
-: source-url
-:: The current [=media resource=] URL. See
+: source
+:: The current [=media resource=]. See
     {{HTMLMediaElement/currentSrc|HTMLMediaElement.currentSrc}}.
     Must be present in the initial state in the [=remote-playback-start-response=] message
     so the controller knows what [=media resource=] was selected for playback.
@@ -1996,6 +1995,11 @@ a [=streaming-session-modify-request=], it should send back a
 application of the new request from the
 [=streaming-session-modify-request=] was successful.
 
+NOTE: If the sender wishes to send an encoding other than the one selected by
+the receiver in a [=streaming-session-start-response=] or
+[=streaming-session-modify-request=], it must terminate the current session
+and start a new session.
+
 Finally, the sender may terminate the streaming session by sending
 a [=streaming-session-terminate-request=] command.  When the receiver
 receives the [=streaming-session-terminate-request=], it should send back

messages_appendix.cddl

@@ -266,7 +266,7 @@ remote-playback-availability-event = {
 remote-playback-start-request = {
   request
   1: remote-playback-id ; remote-playback-id
-  2: [* remote-playback-source] ; sources
+  ? 2: [* remote-playback-source] ; sources
   ? 3: [* text] ; text-track-urls
   ? 4: [* http-header] ; headers
   ? 5: remote-playback-controls ; controls
@@ -337,7 +337,7 @@ remote-playback-state-event = {
 remote-playback-id = uint
 
 remote-playback-controls = {
-  ? 1: text ; source-url
+  ? 1: remote-playback-source ; source
   ? 2: &(none, metadata, auto) ; preload
   ? 3: bool ; loop
   ? 4: bool ; paused
@@ -360,7 +360,7 @@ remote-playback-state = {
          added-text-track:
          bool,
          added-cues: bool) ; supports
-  ? 2: text ; source-url
+  ? 2: remote-playback-source ; source
   ? 3: &(
     empty: 0
     idle: 1