diff --git a/xep-0180.xml b/xep-0180.xml index e72149d9..35868319 100644 --- a/xep-0180.xml +++ b/xep-0180.xml @@ -27,6 +27,12 @@ Chen Milton.Chen@vseelab.com + + 0.9 + 2007-11-15 + psa +

Editorial review and consistency check.

 + 0.8 2007-05-23 @@ -83,13 +89,13 @@ -

&xep0166; can be used to initiate and negotiate a wide range of peer-to-peer sessions. One session type of interest is video exchange. This document specifies a format for describing Jingle video sessions, where the media exchange occurs using the Real-time Transport Protocol (see &rfc3550;).

+

&xep0166; can be used to initiate and negotiate a wide range of peer-to-peer sessions. One session type of interest is video chat. This document specifies a format for describing Jingle video sessions, where the media exchange occurs using the Real-time Transport Protocol (see &rfc3550;).

 -

The Jingle content description format defined herein is designed to meet the following requirements:

+

The Jingle application format defined herein is designed to meet the following requirements:

    -
  1. Enable negotiation of parameters necessary for video exchange.
    2. +
  2. Enable negotiation of parameters necessary for video chat.
  3. Map these parameters to the Session Description Protocol (SDP; see &rfc4566;) to enable interoperability.
  4. Define informational messages related to video chat.
@@ -98,8 +104,8 @@

In accordance with Section 8 of XEP-0166, this document specifies the following information related to the Jingle Video via RTP application type:

    -

  1. The content negotiation process is defined in the Negotiating a Jingle Video Session section of this document.

    2. -

  2. The semantics of the &DESCRIPTION; element are defined in the Content Description Format section of this document.

    3. +

  3. The application format negotiation process is defined in the Negotiating a Jingle Video Session section of this document.

    4. +

  4. The semantics of the &DESCRIPTION; element are defined in the Application Format section of this document.

  5. A mapping of Jingle semantics to the Session Description Protocol is provided in the Mapping to Session Description Protocol section of this document.

  6. A Jingle video session MUST use a lossy transport method such as &xep0177; or the "ice-udp" method specified in &xep0176;.

  7. @@ -111,9 +117,9 @@
- -

A Jingle video session is described by one or more encodings contained within a wrapper &DESCRIPTION; element qualified by the 'http://www.xmpp.org/extensions/xep-0180.html#ns' namespace &NSNOTE;. In the language of RFC 4566 these encodings are payload-types; therefore, each <payload-type/> child element specifies an encoding that can be used for the video stream. Such encodings are often used in the context of the Real-time Transfer Protocol (RTP; see RFC 3550) but may be used in other contexts as well. The most common encodings for the Audio/Video Profile (AVP) of RTP are listed in &rfc3551; (these "static" types are reserved from payload ID 0 through payload ID 95), although other encodings are allowed in accordance with the dynamic assignment rules described in Section 3 of RFC 3551 (these "dynamic" types use payload IDs 96 to 127). The &PAYLOADTYPE; element's 'id' attribute is REQUIRED and its 'name' attribute is RECOMMENDED. The encodings SHOULD be provided in order of preference.

- +

A Jingle video session is described by a content type that contains one application format and one transport method. The application format consists of one or more encodings contained within a wrapper &DESCRIPTION; element qualified by the 'http://www.xmpp.org/extensions/xep-0180.html#ns' namespace &NSNOTE;. In the language of RFC 4566 these encodings are payload-types; therefore, each <payload-type/> child element specifies an encoding that can be used for the video stream. In Jingle Video, these encodings are used in the context of RTP. The most common encodings for the Audio/Video Profile (AVP) of RTP are listed in &rfc3551; (these "static" types are reserved from payload ID 0 through payload ID 95), although other encodings are allowed (these "dynamic" types use payload IDs 96 to 127) in accordance with the dynamic assignment rules described in Section 3 of RFC 3551.

+ @@ -126,6 +132,7 @@ ]]>

The &DESCRIPTION; element is intended to be a child of a &CONTENT; element as specified in XEP-0166.

+

The encodings SHOULD be provided in order of preference by placing the most-preferred &PAYLOADTYPE; element as the first child of the &DESCRIPTION; element (etc.).

The defined attributes of the &PAYLOADTYPE; element are as follows:

@@ -204,7 +211,7 @@

When the initiator sends a session-initiate stanza to the receiver, the &DESCRIPTION; element includes all of the payload types that the initiator can receive for Jingle video (each one encapsulated in a separate &PAYLOADTYPE; element):

- - + @@ -229,12 +236,12 @@ ]]> -

Upon receiving the session-initiate stanza, the receiver determines whether it can provisionally accept the session and proceed with the negotiation. The general Jingle error cases are specified in XEP-0166. In addition, the receiver must determine if it supports any of the payload types advertised by the initiator; if it does not, it MUST reject the session by sending a ¬acceptable; error, which SHOULD include a Jingle-specific error condition of <unsupported-codecs/>:

- Upon receiving the session-initiate stanza, the receiver determines whether it can provisionally accept the session and proceed with the negotiation. The general Jingle error cases are specified in XEP-0166 and illustrated &xep0167;. In addition, the receiver must determine if it supports any of the payload types advertised by the initiator; if it supports none of the offered payload types, it must reject the session by returning a ¬acceptable; error with a Jingle-Video-specific condition of <unsupported-codecs/>:

+ + id='jingleaudio1'> @@ -242,14 +249,14 @@ ]]>

If there is no error, the receiver provisionally accepts the session:

- ]]> -

The receiver then should send a list of the payload types that it can receive via a Jingle "content-accept" (or "session-accept") action. The list that the receiver sends MAY include any payload types (not a subset of the payload types sent by the initiator) but SHOULD retain the ID numbers and order specified by the initiator.

- The receiver then should send a list of the payload types that it can receive via a Jingle "content-accept" (or "session-accept") action. The list that the receiver sends MAY include any payload types (not a subset of the payload types sent by the initiator) but SHOULD retain the ID numbers specified by the initiator. The order of the &PAYLOADTYPE; elements indicates the receiver's preferences, with the most-preferred types first.

+ - + @@ -274,14 +281,14 @@ ]]>

The initiator acknowledges the 'content-accept' with an empty IQ result:

- ]]>

After successful transport negotiation (not shown here), the receiver then accepts the session:

- - + ]]>

And the initiator acknowledges session acceptance:

- ]]> +

Note: Because a "session-accept" action implicitly indicates acceptance of the application format (i.e., "content-accept"), it is not necessary to send a separate "content-accept" action. This flow is shown for completeness only.

 @@ -324,28 +332,28 @@ ]]> -

In the context of Jingle video sessions, the <media> is "video", the <port> is the preferred port for such communications (which may be determined dynamically), the <transport> is whatever transport method is negotiated via the Jingle negotiation (e.g., "RTP/AVP"), and the <fmt list> is the payload-type ID.

+

In the context of Jingle video sessions, the <media> is "video", the <port> is the preferred port for such communications (which may be determined dynamically), the <transport> is whatever profile is negotiated via the 'profile' attribute of the &CONTENT; element in the Jingle negotiation (e.g., "RTP/AVT"), and the <fmt list> is the payload-type ID.

For example, consider the following static payload-type:

- ]]>

That Jingle-formatted information would be mapped to SDP as follows:

-

If the payload type is dynamic (payload-type IDs 96 through 127 inclusive), it SHOULD be mapped to an SDP media field plus an SDP attribute field named "rtpmap".

For example, consider a VC-1 payload such as that described in &rfc4425;:

- ]]>

That Jingle-formatted information would be mapped to SDP as follows:

-

As noted, if additional parameters are to be specified, they shall be represented as attributes of the <payload-type/> element or its child <parameter/> element, as in the following example.

- @@ -353,7 +361,7 @@ a=fmtp:98 width=352;height=288; ]]>

That Jingle-formatted information would be mapped to SDP as follows:

- + +

The Jingle-Video-specific error conditions are as follows:

+
+ + + + + + + + + + +
Jingle Video ConditionXMPP ConditionDescription
<unsupported-codecs/>¬acceptable;The recipient does not support any of the offered video encodings.
+ +

If an entity supports Jingle video exchanges via RTP, it MUST advertise that fact by returning a feature of "http://www.xmpp.org/extensions/xep-0180.html#ns" in response to &xep0030; information requests &NSNOTE;.

- ]]> -

Until this specification advances to a status of Draft, its associated namespaces shall be "http://www.xmpp.org/extensions/xep-0180.html#ns" and "http://www.xmpp.org/extensions/xep-0180.html#ns-errors"; upon advancement of this specification, the ®ISTRAR; shall issue permanent namespaces in accordance with the process defined in Section 4 of &xep0053;.

- -

The XMPP Registrar shall include "video-rtp" in its registry of Jingle content description formats. The registry submission is as follows:

+ +

The XMPP Registrar shall include "video-rtp" in its registry of Jingle application formats. The registry submission is as follows:

+ video-rtp Jingle sessions that support video exchange via the Real-time Transport Protocol lossy XEP-0180 - + ]]> - +