<?xml version='1.0' encoding='UTF-8'?> <!DOCTYPE xep SYSTEM 'xep.dtd' [ <!ENTITY % ents SYSTEM 'xep.ent'> %ents; ]> <?xml-stylesheet type='text/xsl' href='xep.xsl'?> <xep> <header> <title>Jingle Video via RTP</title> <abstract> Note: This specification has been retracted in favor of XEP-0167, which now consolidates both audio and video chat via RTP and therefore contains the content originally published in this specification; please refer to XEP-0167 for the most up-to-date definition of XMPP video chat. This specification defines a Jingle application type for negotiating a video chat or other video session. The application type uses the Real-time Transport Protocol (RTP) for the underlying media exchange and provides a straightforward mapping to Session Description Protocol (SDP) for interworking with SIP media endpoints. </abstract> &LEGALNOTICE; <number>0180</number> <status>Retracted</status> <type>Standards Track</type> <sig>Standards</sig> <approver>Council</approver> <dependencies> <spec>XMPP Core</spec> <spec>XEP-0166</spec> </dependencies> <supersedes/> <supersededby> <spec>XEP-0167</spec> </supersededby> <shortname>NOT_YET_ASSIGNED</shortname> &stpeter; <author> <firstname>Milton</firstname> <surname>Chen</surname> <email>Milton.Chen@vseelab.com</email> </author> <revision> <version>0.13</version> <date>2008-06-04</date> <initials>psa</initials> <remark><p>Retracted in favor of XEP-0167, which now consolidates both audio and video chat via RTP and therefore contains the content originally published in this specification.</p></remark> </revision> <revision> <version>0.12</version> <date>2008-05-28</date> <initials>psa</initials> <remark><p>Specified default value for profile attribute; clarified relationship to SDP offer-answer model; moved some attributes from payload-type element to optional parameter elements.</p></remark> </revision> <revision> <version>0.11</version> <date>2008-02-28</date> <initials>psa</initials> <remark><p>Moved profile attribute from XEP-0166 to this specification.</p></remark> </revision> <revision> <version>0.10</version> <date>2007-11-27</date> <initials>psa</initials> <remark><p>Further editorial review.</p></remark> </revision> <revision> <version>0.9</version> <date>2007-11-15</date> <initials>psa</initials> <remark><p>Editorial review and consistency check.</p></remark> </revision> <revision> <version>0.8</version> <date>2007-05-23</date> <initials>psa</initials> <remark><p>Corrected examples to use video codecs; added clockrate attribute.</p></remark> </revision> <revision> <version>0.7</version> <date>2007-05-23</date> <initials>psa</initials> <remark><p>More completely specified how to include SDP parameters and codec-specific parameters (same approach as in XEP-0167); added and corrected Theora examples.</p></remark> </revision> <revision> <version>0.6</version> <date>2007-04-17</date> <initials>psa</initials> <remark><p>Specified Jingle conformance, including the need to use a lossy transport and the process of sending and receiving video content.</p></remark> </revision> <revision> <version>0.5</version> <date>2007-03-23</date> <initials>psa</initials> <remark><p>Added negotiation flow and SDP mapping; renamed to mention RTP as the associated transport; corrected negotiation flow to be consistent with SIP/SDP (each party specifies a list of the payload types it can receive); added profile attribute to content element in order to specify RTP profile in use.</p></remark> </revision> <revision> <version>0.4</version> <date>2006-12-21</date> <initials>psa</initials> <remark><p>Modified spec to use provisional namespace before advancement to Draft (per XEP-0053).</p></remark> </revision> <revision> <version>0.3</version> <date>2006-08-23</date> <initials>psa</initials> <remark><p>Modified namespace to track XEP-0166.</p></remark> </revision> <revision> <version>0.2</version> <date>2006-07-12</date> <initials>psa</initials> <remark><p>Updated to use content type instead of media type.</p></remark> </revision> <revision> <version>0.1</version> <date>2006-03-23</date> <initials>psa/mc</initials> <remark><p>Initial version.</p></remark> </revision> <revision> <version>0.0.1</version> <date>2006-03-20</date> <initials>psa/mc</initials> <remark><p>First draft.</p></remark> </revision> </header> <section1 topic='Introduction' anchor='intro'> <p class='box'><em>Note: This specification has been retracted in favor of &xep0167;, which now consolidates both audio and video chat via RTP and therefore contains the content originally published in this specification; please refer to XEP-0167 for the most up-to-date definition of XMPP video chat.</em></p> <p>&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;).</p> </section1> <section1 topic='Requirements' anchor='reqs'> <p>The Jingle application format defined herein is designed to meet the following requirements:</p> <ol> <li>Enable negotiation of parameters necessary for video chat.</li> <li>Map these parameters to the Session Description Protocol (SDP; see &rfc4566;) to enable interoperability.</li> <li>Define informational messages related to video chat.</li> </ol> </section1> <section1 topic='Jingle Conformance' anchor='conformance'> <p>In accordance with Section 8 of <cite>XEP-0166</cite>, this document specifies the following information related to the Jingle Video via RTP application type:</p> <ol> <li><p>The application format negotiation process is defined in the <link url='#negotiation'>Negotiating a Jingle Video Session</link> section of this document.</p></li> <li><p>The semantics of the &DESCRIPTION; element are defined in the <link url='#format'>Application Format</link> section of this document.</p></li> <li><p>A mapping of Jingle semantics to the Session Description Protocol is provided in the <link url='#sdp'>Mapping to Session Description Protocol</link> section of this document.</p></li> <li><p>A Jingle video session SHOULD use a lossy transport method such as &xep0177; or the "ice-udp" method specified in &xep0176;.</p></li> <li> <p>Content is to be sent and received as follows:</p> <ul> <li><p>Outbound video content shall be encoded into RTP packets and each packet shall be sent individually over the transport. Each inbound packet received over the transport is an RTP packet.</p></li> </ul> </li> </ol> </section1> <section1 topic='Application Format' anchor='format'> <p>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 'urn:xmpp:tmp:jingle:apps:video-rtp' namespace &NSNOTE;. In the language of <cite>RFC 4566</cite> each encoding is a payload-type; therefore, each <payload-type/> element specifies an encoding that can be used for the audio stream, as illustrated in the following example.</p> <example caption="Video description format"><![CDATA[ <description xmlns='urn:xmpp:tmp:jingle:apps:video-rtp'> <payload-type id='96' name='theora' clockrate='90000'> <parameter name='height' value='720'/> <parameter name='width' value='1280'/> <parameter name='delivery-method' value='inline'/> <parameter name='configuration' value='somebase16string'/> <parameter name='sampling' value='YCbCr-4:2:2'/> </payload-type> <payload-type id='28' name='nv' clockrate='90000'/> <payload-type id='25' name='CelB' clockrate='90000'/> <payload-type id='32' name='MPV' clockrate='90000'/> </description> ]]></example> <p>The &DESCRIPTION; element is intended to be a child of a &CONTENT; element as specified in <cite>XEP-0166</cite>.</p> <p>The &DESCRIPTION; element SHOULD possess a 'profile' attribute that specifies the profile of RTP in use as would be encapsulated in SDP (e.g., "RTP/AVP" or "UDP/TLS/RTP/SAVP"). If not included, the default value of "RTP/AVP" MUST be assumed.</p> <p>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.).</p> <p>The allowable attributes of the &PAYLOADTYPE; element are as follows:</p> <table caption='Payload-Type Attributes'> <tr> <th>Attribute</th> <th>Description</th> <th>Datatype/Units</th> <th>Inclusion</th> </tr> <tr> <td>channels</td> <td>The number of channels (e.g., 2 for stereoscopic video)</td> <td>positiveInteger (defaults to 1)</td> <td>OPTIONAL</td> </tr> <tr> <td>clockrate</td> <td>The sampling frequency in Hertz</td> <td>positiveInteger</td> <td>RECOMMENDED</td> </tr> <tr> <td>id</td> <td>A unique identifier for the payload type</td> <td>positiveInteger</td> <td>REQUIRED</td> </tr> <tr> <td>name</td> <td>A name for the payload type</td> <td>string</td> <td>RECOMMENDED for static payload types, REQUIRED for dynamic payload types</td> </tr> </table> <p>In Jingle Video, the 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 <cite>RFC 3551</cite>. The payload IDs are represented in the 'id' attribute.</p> <p>Each <payload-type/> element MAY contain one or more child elements that specify particular parameters related to the payload. For example, as described in &rtptheora;, the "configuration", "configuration-uri", "delivery-method", "height", "sampling", and "width" parameters may be specified in relation to usage of the Theora <note>See <<link url='http://www.theora.org/'>http://www.theora.org/</link>>.</note> codec. Where such parameters are encoded via the "fmtp" SDP attribute, they shall be represented in Jingle via the following format:</p> <code><![CDATA[ <parameter name='foo' value='bar'/> ]]></code> <p>Note: The parameter names are effectively guaranteed to be unique, since &IANA; maintains a registry of SDP parameters (see <<link url='http://www.iana.org/assignments/sdp-parameters'>http://www.iana.org/assignments/sdp-parameters</link>>).</p> </section1> <section1 topic='Negotiating a Jingle Video Session' anchor='negotiation'> <p>When the initiator sends a session-initiate stanza to the responder, the &DESCRIPTION; element includes all of the payload types that the initiator can send and/or receive for Jingle video, each one encapsulated in a separate &PAYLOADTYPE; element (the rules specified in &rfc3264; SHOULD be followed regarding inclusion of payload types).</p> <example caption="Initiation"><![CDATA[ <iq from='romeo@montague.net/orchard' to='juliet@capulet.com/balcony' id='jinglevideo1' type='set'> <jingle xmlns='urn:xmpp:tmp:jingle'> action='session-initiate' initiator='romeo@montague.net/orchard' sid='v1d30k1ll3dth3r4d10st4r'> <content content='initiator' name='this-is-the-video-content'> <description xmlns='urn:xmpp:tmp:jingle:apps:video-rtp' profile='RTP/AVP'> <payload-type id='96' name='theora' clockrate='90000'> <parameter name='height' value='720'/> <parameter name='width' value='1280'/> <parameter name='delivery-method' value='inline'/> <parameter name='configuration' value='somebase16string'/> <parameter name='sampling' value='YCbCr-4:2:2'/> </payload-type> <payload-type id='28' name='nv' clockrate='90000'/> <payload-type id='25' name='CelB' clockrate='90000'/> <payload-type id='32' name='MPV' clockrate='90000'/> </description> <transport xmlns='urn:xmpp:tmp:jingle:transports:ice-tcp'/> </content> </jingle> </iq> ]]></example> <p>Upon receiving the session-initiate stanza, the responder determines whether it can proceed with the negotiation. The general Jingle error cases are specified in <cite>XEP-0166</cite> and illustrated &xep0167;. In addition, the responder 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/>:</p> <example caption="Responder does not support any of the codecs"><![CDATA[ <iq from='juliet@capulet.com/balcony' id='jingleaudio1' to='romeo@montague.net/orchard' type='error'> <error type='cancel'> <not-acceptable xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'/> <unsupported-codecs xmlns='urn:xmpp:tmp:jingle:apps:video:errors'/> </error> </iq> ]]></example> <p>If there is no error, the responder acknowledges the session initiation request:</p> <example caption="Responder acknowledges session-initiate request"><![CDATA[ <iq from='juliet@capulet.com/balcony' id='jinglevideo1' to='romeo@montague.net/orchard' type='result' /> ]]></example> <p>If the responder wishes to accept the content definition, it MUST send a content-accept action to the initiator, which SHOULD include a list of the payload types that it can send and/or receive. The list that the responder 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 responder's preferences, with the most-preferred types first.</p> <example caption="Responder accepts content type"><![CDATA[ <iq from='juliet@capulet.com/balcony' to='romeo@montague.net/orchard' id='jinglevideo2' type='set'> <jingle xmlns='urn:xmpp:tmp:jingle'> action='content-accept' initiator='romeo@montague.net/orchard' sid='v1d30k1ll3dth3r4d10st4r'> <content content='initiator' name='this-is-the-video-content'> <description xmlns='urn:xmpp:tmp:jingle:apps:video-rtp' profile='RTP/AVP'> <payload-type id='96' name='theora' clockrate='90000'> <parameter name='height' value='720'/> <parameter name='width' value='1280'/> <parameter name='delivery-method' value='inline'/> <parameter name='configuration' value='somebase16string'/> <parameter name='sampling' value='YCbCr-4:2:2'/> </payload-type> <payload-type id='32' name='MPV' clockrate='90000'/> <payload-type id='33' name='MP2T' clockrate='90000'/> </description> <transport xmlns='urn:xmpp:tmp:jingle:transports:ice-tcp'/> </content> </jingle> </iq> ]]></example> <p>The initiator acknowledges the 'content-accept' with an empty IQ result:</p> <example caption="Initiator acknowledges modified application type"><![CDATA[ <iq from='romeo@montegue.net/orchard' to='juliet@capulet.com/balcony' id='jinglevideo2' type='result'/> ]]></example> <p>After successful transport negotiation (for the ICE-UDP method, see <cite>XEP-0176</cite>), the responder then accepts the session:</p> <example caption="Responder definitively accepts the session"><![CDATA[ <iq from='juliet@capulet.com/balcony' id='accept1' to='romeo@montague.net/orchard' type='set'> <jingle xmlns='urn:xmpp:tmp:jingle' action='session-accept' initiator='romeo@montague.net/orchard' responder='juliet@capulet.com/balcony' sid='v1d30k1ll3dth3r4d10st4r'> <content content='initiator' name='this-is-the-video-content'> <description xmlns='urn:xmpp:tmp:jingle:apps:video-rtp' profile='RTP/AVP'> <payload-type id='96' name='theora' clockrate='90000'> <parameter name='height' value='720'/> <parameter name='width' value='1280'/> <parameter name='delivery-method' value='inline'/> <parameter name='configuration' value='somebase16string'/> <parameter name='sampling' value='YCbCr-4:2:2'/> </payload-type> <payload-type id='32' name='MPV' clockrate='90000'/> <payload-type id='33' name='MP2T' clockrate='90000'/> </description> <transport xmlns='urn:xmpp:tmp:jingle:transports:ice-tcp'> <candidate component='1' foundation='1' generation='0' ip='192.0.2.3' network='1' port='45664' priority='1694498815' protocol='udp' pwd='asd88fgpdd777uzjYhagZg' rel-addr='10.0.1.1' rel-port='8998' rem-addr='192.0.2.1' rem-port='3478' type='srflx' ufrag='8hhy'/> </transport> </content> </jingle> </iq> ]]></example> <p>And the initiator acknowledges session acceptance:</p> <example caption="Initiator acknowledges session acceptance"><![CDATA[ <iq from='romeo@montague.net/orchard' to='juliet@capulet.com/balcony' id='accept1' type='result' /> ]]></example> <p>Note: For more examples, see <cite>XEP-0167</cite>.</p> </section1> <section1 topic='Mapping to Session Description Protocol' anchor='sdp'> <p>The SDP media type for Jingle Video via RTP is "video" (see Section 8.2.1 of <cite>RFC 4566</cite>).</p> <p>If the payload type is static (payload-type IDs 0 through 95 inclusive), it MUST be mapped to a media field defined in <cite>RFC 4566</cite>. The generic format for the media field is as follows:</p> <code><![CDATA[ m=<media> <port> <transport> <fmt list> ]]></code> <p>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.</p> <p>For example, consider the following static payload-type:</p> <example caption="Jingle format for static payload-type"><![CDATA[ <payload-type id="28" name="nv"/> ]]></example> <p>That Jingle-formatted information would be mapped to SDP as follows:</p> <example caption="SDP mapping of static payload-type"><![CDATA[ m=video 9000 RTP/AVP 28 ]]></example> <p>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".</p> <p>For example, consider a VC-1 payload such as that described in &rfc4425;:</p> <example caption="Jingle format for dynamic payload-type"><![CDATA[ <payload-type id='98' name='vc1'/> ]]></example> <p>That Jingle-formatted information would be mapped to SDP as follows:</p> <example caption="SDP mapping of dynamic payload-type"><![CDATA[ m=video 49170 RTP/AVP 98 a=rtpmap:98 vc1/90000 ]]></example> <p>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.</p> <example caption="Jingle format for dynamic payload-type with parameters"><![CDATA[ <payload-type id='96' name='theora' clockrate='90000'> <parameter name='height' value='720'/> <parameter name='width' value='1280'/> <parameter name='delivery-method' value='inline'/> <parameter name='configuration' value='somebase16string'/> <parameter name='sampling' value='YCbCr-4:2:2'/> </payload-type> ]]></example> <p>That Jingle-formatted information would be mapped to SDP as follows:</p> <example caption="SDP mapping of dynamic payload-type with parameters"><![CDATA[ m=video 49170 RTP/AVP 98 a=rtpmap:96 theora/90000 a=fmtp:96 sampling=YCbCr-4:2:2; width=1280; height=720; delivery-method=inline; configuration=somebase16string; ]]></example> </section1> <section1 topic='Error Handling' anchor='errors'> <p>The Jingle-Video-specific error conditions are as follows:</p> <table caption='Other Error Conditions'> <tr> <th>Jingle Video Condition</th> <th>XMPP Condition</th> <th>Description</th> </tr> <tr> <td><unsupported-codecs/></td> <td>¬acceptable;</td> <td>The recipient does not support any of the offered video encodings.</td> </tr> </table> </section1> <section1 topic='Determining Support' anchor='support'> <p>If an entity supports Jingle video exchanges via RTP, it MUST advertise that fact by returning a feature of "urn:xmpp:tmp:jingle:apps:video" in response to &xep0030; information requests &NSNOTE;.</p> <example caption="Service discovery information request"><![CDATA[ <iq from='romeo@montague.net/orchard' id='disco1' to='juliet@capulet.com/balcony' type='get'> <query xmlns='http://jabber.org/protocol/disco#info'/> </iq> ]]></example> <example caption="Service discovery information response"><![CDATA[ <iq from='juliet@capulet.com/balcony' id='disco1' to='romeo@montague.net/orchard' type='result'> <query xmlns='http://jabber.org/protocol/disco#info'> ... <feature var='urn:xmpp:tmp:jingle'/> <feature var='urn:xmpp:tmp:jingle:apps:video-rtp'/> ... </query> </iq> ]]></example> <p>Naturally, support may also be discovered via the dynamic, presence-based profile of service discovery defined in &xep0115;.</p> </section1> <section1 topic='Informational Messages' anchor='info'> <p>Informational messages may be sent by either party within the context of Jingle to communicate the status of a Jingle video session, device, or principal. The informational message MUST be an IQ-set containing a &JINGLE; element of type "session-info". No informational message payload elements have yet been defined for Jingle Video via RTP, but they may be specified in a future version of this document.</p> </section1> <section1 topic='Implementation Notes' anchor='impl'> <section2 topic='Codecs' anchor='impl-codecs'> <p>Support for the Theora codec is RECOMMENDED.</p> </section2> </section1> <section1 topic='Security Considerations' anchor='security'> <p>In order to secure the data stream, implementations SHOULD use encryption methods appropriate to the transport method and media being exchanged; for example, in the case of UDP, that would include Datagram Transport Layer Security (DTLS) as specified in &rfc4347;. &sdpdtls; defines such methods for the Session Description Protocol; the relevant RTP profile (e.g., "UDP/TLS/RTP/SAVP" for transporting the RTP stream over DTLS with UDP) shall be specified as the value of the &CONTENT; element's 'profile' attribute.</p> </section1> <section1 topic='IANA Considerations' anchor='iana'> <p>This document requires no interaction with &IANA;.</p> </section1> <section1 topic='XMPP Registrar Considerations' anchor='registrar'> <section2 topic='Protocol Namespaces' anchor='ns'> <p>Until this specification advances to a status of Draft, its associated namespaces shall be:</p> <ul> <li>urn:xmpp:tmp:jingle:apps:video</li> <li>urn:xmpp:tmp:jingle:apps:video:errors</li> </ul> <p>Upon advancement of this specification, the ®ISTRAR; shall issue permanent namespaces in accordance with the process defined in Section 4 of &xep0053;.</p> <p>The following namespaces are requested, and are thought to be unique per the XMPP Registrar's requirements:</p> <ul> <li>urn:xmpp:jingle:app:video-rtp</li> <li>urn:xmpp:jingle:app:video-rtp:errors</li> </ul> </section2> <section2 topic='Jingle Application Formats' anchor='registrar-content'> <p>The XMPP Registrar shall include "video-rtp" in its registry of Jingle application formats. The registry submission is as follows:</p> <code><![CDATA[ <application> <name>video-rtp</name> <desc>Jingle sessions that support video exchange via the Real-time Transport Protocol</desc> <transport>lossy</transport> <doc>XEP-0180</doc> </application> ]]></code> </section2> </section1> <section1 topic='XML Schemas' anchor='schema'> <section2 topic='Application Format' anchor='schema-content'> <code><![CDATA[ <?xml version='1.0' encoding='UTF-8'?> <xs:schema xmlns:xs='http://www.w3.org/2001/XMLSchema' targetNamespace='urn:xmpp:tmp:jingle:apps:video-rtp' xmlns='urn:xmpp:tmp:jingle:apps:video-rtp' elementFormDefault='qualified'> <xs:element name='description'> <xs:complexType> <xs:sequence> <xs:element ref='payload-type' minOccurs='0' maxOccurs='unbounded'/> </xs:sequence> <xs:attribute name='profile' use='required' type='xs:string' default='RTP/AVP'/> </xs:complexType> </xs:element> <xs:element name='payload-type'> <xs:complexType> <xs:sequence minOccurs='0' maxOccurs='unbounded'> <xs:element ref='parameter'/> </xs:sequence> <xs:attribute name='channels' type='xs:integer' use='optional' default='1'/> <xs:attribute name='clockrate' type='xs:short' use='optional'/> <xs:attribute name='id' type='xs:unsignedByte' use='required'/> <xs:attribute name='name' type='xs:string' use='optional'/> </xs:complexType> </xs:element> <xs:element name='parameter'> <xs:complexType> <xs:simpleContent> <xs:extension base='empty'> <xs:attribute name='name' type='xs:string' use='required'/> <xs:attribute name='value' type='xs:string' use='required'/> </xs:extension> </xs:simpleContent> </xs:complexType> </xs:element> <xs:simpleType name='empty'> <xs:restriction base='xs:string'> <xs:enumeration value=''/> </xs:restriction> </xs:simpleType> </xs:schema> ]]></code> </section2> <section2 topic='Errors' anchor='schema-errors'> <code><![CDATA[ <?xml version='1.0' encoding='UTF-8'?> <xs:schema xmlns:xs='http://www.w3.org/2001/XMLSchema' targetNamespace='urn:xmpp:tmp:jingle:apps:video:errors' xmlns='urn:xmpp:tmp:jingle:apps:video:errors' elementFormDefault='qualified'> <xs:element name='unsupported-codecs' type='empty'/> <xs:simpleType name='empty'> <xs:restriction base='xs:string'> <xs:enumeration value=''/> </xs:restriction> </xs:simpleType> </xs:schema> ]]></code> </section2> </section1> </xep>