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0.9
git-svn-id: file:///home/ksmith/gitmigration/svn/xmpp/trunk@1387 4b5297f7-1745-476d-ba37-a9c6900126ab
This commit is contained in:
Peter Saint-Andre
parent
238265c362
commit
413cd96e89
94
xep-0180.xml
94
xep-0180.xml
@ -27,6 +27,12 @@
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<surname>Chen</surname>
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<email>Milton.Chen@vseelab.com</email>
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</author>
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<revision>
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<version>0.9</version>
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<date>2007-11-15</date>
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<initials>psa</initials>
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<remark><p>Editorial review and consistency check.</p></remark>
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</revision>
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<revision>
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<version>0.8</version>
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<date>2007-05-23</date>
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@ -83,13 +89,13 @@
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</revision>
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</header>
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<section1 topic='Introduction' anchor='intro'>
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<p>&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;).</p>
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<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>
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</section1>
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<section1 topic='Requirements' anchor='reqs'>
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<p>The Jingle content description format defined herein is designed to meet the following requirements:</p>
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<p>The Jingle application format defined herein is designed to meet the following requirements:</p>
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<ol>
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<li>Enable negotiation of parameters necessary for video exchange.</li>
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<li>Enable negotiation of parameters necessary for video chat.</li>
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<li>Map these parameters to the Session Description Protocol (SDP; see &rfc4566;) to enable interoperability.</li>
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<li>Define informational messages related to video chat.</li>
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</ol>
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@ -98,8 +104,8 @@
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<section1 topic='Jingle Conformance' anchor='conformance'>
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<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>
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<ol>
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<li><p>The content negotiation process is defined in the <link url='#negotiation'>Negotiating a Jingle Video Session</link> section of this document.</p></li>
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<li><p>The semantics of the &DESCRIPTION; element are defined in the <link url='#format'>Content Description Format</link> section of this document.</p></li>
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<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>
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<li><p>The semantics of the &DESCRIPTION; element are defined in the <link url='#format'>Application Format</link> section of this document.</p></li>
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<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>
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<li><p>A Jingle video session MUST use a lossy transport method such as &xep0177; or the "ice-udp" method specified in &xep0176;.</p></li>
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<li>
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@ -111,9 +117,9 @@
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</ol>
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</section1>
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<section1 topic='Content Description Format' anchor='format'>
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<p>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 <cite>RFC 4566</cite> 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 <cite>RFC 3550</cite>) 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 <cite>RFC 3551</cite> (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.</p>
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<example caption="Video Description Format"><![CDATA[
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<section1 topic='Application Format' anchor='format'>
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<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 'http://www.xmpp.org/extensions/xep-0180.html#ns' namespace &NSNOTE;. In the language of <cite>RFC 4566</cite> 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 <cite>RFC 3551</cite>.</p>
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<example caption="Video application format"><![CDATA[
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<description xmlns='http://www.xmpp.org/extensions/xep-0180.html#ns'>
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<payload-type id='96' name='theora' clockrate='90000' height='720' width='1280'>
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<parameter name='delivery-method' value='inline'/>
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@ -126,6 +132,7 @@
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</description>
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]]></example>
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<p>The &DESCRIPTION; element is intended to be a child of a &CONTENT; element as specified in <cite>XEP-0166</cite>.</p>
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<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>
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<p>The defined attributes of the &PAYLOADTYPE; element are as follows:</p>
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<table caption='Video Description Attributes'>
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<tr>
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@ -204,7 +211,7 @@
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<section1 topic='Negotiating a Jingle Video Session' anchor='negotiation'>
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<p>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):</p>
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<example caption="Initiation Example"><![CDATA[
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<example caption="Initiation"><![CDATA[
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<iq from='romeo@montague.net/orchard'
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to='juliet@capulet.com/balcony'
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id='jinglevideo1'
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@ -214,7 +221,7 @@
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initiator='romeo@montague.net/orchard'
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sid='v1d30k1ll3dth3r4d10st4r'>
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<content content='initiator' name='this-is-the-video-content' profile='RTP/AVP'>
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<description xmlns='http://www.xmpp.org/extensions/xep-0167.html#ns'>
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<description xmlns='http://www.xmpp.org/extensions/xep-0180.html#ns'>
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<payload-type id='96' name='theora' clockrate='90000' height='720' width='1280'>
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<parameter name='delivery-method' value='inline'/>
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<parameter name='configuration' value='somebase16string'/>
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@ -229,12 +236,12 @@
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</jingle>
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</iq>
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]]></example>
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<p>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 <cite>XEP-0166</cite>. 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/>:</p>
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<example caption="Receiver Does Not Support Codecs"><![CDATA[
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<p>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 <cite>XEP-0166</cite> 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/>:</p>
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<example caption="Receiver does not support any of the codecs"><![CDATA[
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<iq type='error'
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from='juliet@capulet.com/balcony'
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to='romeo@montague.net/orchard'
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id='jinglevideo1'>
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id='jingleaudio1'>
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<error type='cancel'>
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<not-acceptable xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'/>
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<unsupported-codecs xmlns='http://www.xmpp.org/extensions/xep-0180.html#ns-errors'/>
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@ -242,14 +249,14 @@
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</iq>
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]]></example>
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<p>If there is no error, the receiver provisionally accepts the session:</p>
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<example caption="Receiver Provisionally Accepts Session"><![CDATA[
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<example caption="Receiver provisionally accepts session"><![CDATA[
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<iq from='juliet@capulet.com/balcony'
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to='romeo@montague.net/orchard'
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id='jinglevideo1'
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type='result' />
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]]></example>
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<p>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.</p>
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<example caption="Receiver Accepts Content Type"><![CDATA[
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<p>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.</p>
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<example caption="Receiver accepts content type"><![CDATA[
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<iq from='juliet@capulet.com/balcony'
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to='romeo@montague.net/orchard'
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id='jinglevideo2'
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@ -259,7 +266,7 @@
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initiator='romeo@montague.net/orchard'
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sid='v1d30k1ll3dth3r4d10st4r'>
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<content content='initiator' name='this-is-the-video-content' profile='RTP/AVP'>
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<description xmlns='http://www.xmpp.org/extensions/xep-0167.html#ns'>
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<description xmlns='http://www.xmpp.org/extensions/xep-0180.html#ns'>
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<payload-type id='96' name='theora' height='720' width='1280'>
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<parameter name='delivery-method' value='inline'/>
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<parameter name='configuration' value='somebase16string'/>
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@ -274,14 +281,14 @@
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</iq>
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]]></example>
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<p>The initiator acknowledges the 'content-accept' with an empty IQ result:</p>
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<example caption="Initiator Acknowledges Modified Content Description"><![CDATA[
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<example caption="Initiator acknowledges modified application type"><![CDATA[
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<iq from='romeo@montegue.net/orchard'
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to='juliet@capulet.com/balcony'
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id='jinglevideo2'
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type='result'/>
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]]></example>
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<p>After successful transport negotiation (not shown here), the receiver then accepts the session:</p>
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<example caption="Receiver Definitively Accepts the Session"><![CDATA[
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<example caption="Receiver definitively accepts The session"><![CDATA[
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<iq type='set'
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from='juliet@capulet.com/balcony'
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to='romeo@montague.net/orchard'
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@ -292,7 +299,7 @@
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responder='juliet@capulet.com/balcony'
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sid='v1d30k1ll3dth3r4d10st4r'>
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<content creator='initiator' name='this-is-the-video-content' profile='RTP/AVP'>
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<description xmlns='http://www.xmpp.org/extensions/xep-0167.html#ns'/>
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<description xmlns='http://www.xmpp.org/extensions/xep-0180.html#ns'/>
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<transport xmlns='http://www.xmpp.org/extensions/xep-0176.html#ns-udp'>
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<candidate component='2'
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foundation='1'
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@ -311,12 +318,13 @@
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</iq>
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]]></example>
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<p>And the initiator acknowledges session acceptance:</p>
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<example caption="Initiator Acknowledges Session Acceptance"><![CDATA[
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<example caption="Initiator acknowledges session acceptance"><![CDATA[
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<iq from='romeo@montague.net/orchard'
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to='juliet@capulet.com/balcony'
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id='accept1'
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type='result' />
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]]></example>
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<p>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.</p>
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</section1>
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<section1 topic='Mapping to Session Description Protocol' anchor='sdp'>
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<code><![CDATA[
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m=<media> <port> <transport> <fmt list>
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]]></code>
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<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 transport method is negotiated via the Jingle negotiation (e.g., "RTP/AVP"), and the <fmt list> is the payload-type ID.</p>
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<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>
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<p>For example, consider the following static payload-type:</p>
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<example caption="Jingle Format for Static Payload-Type"><![CDATA[
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<example caption="Jingle format for static payload-type"><![CDATA[
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<payload-type id="28" name="nv"/>
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]]></example>
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<p>That Jingle-formatted information would be mapped to SDP as follows:</p>
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<example caption="SDP Mapping of Static Payload-Type"><![CDATA[
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<example caption="SDP mapping of static payload-type"><![CDATA[
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m=video 9000 RTP/AVP 28
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]]></example>
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<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>
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<p>For example, consider a VC-1 payload such as that described in &rfc4425;:</p>
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<example caption="Jingle Format for Dynamic Payload-Type"><![CDATA[
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<example caption="Jingle format for dynamic payload-type"><![CDATA[
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<payload-type id='98' name='vc1' height='288' width='352'/>
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]]></example>
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<p>That Jingle-formatted information would be mapped to SDP as follows:</p>
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<example caption="SDP Mapping of Dynamic Payload-Type"><![CDATA[
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<example caption="SDP mapping of dynamic payload-type"><![CDATA[
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m=video 49170 RTP/AVP 98
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a=rtpmap:98 vc1/90000
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a=fmtp:98 width=352;height=288;
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]]></example>
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<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>
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<example caption="Jingle Format for Dynamic Payload-Type With Parameters"><![CDATA[
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<example caption="Jingle format for dynamic payload-type with parameters"><![CDATA[
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<payload-type id='96' name='theora' height='720' width='1280'>
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<parameter name='delivery-method' value='inline'/>
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<parameter name='configuration' value='somebase16string'/>
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@ -353,7 +361,7 @@ a=fmtp:98 width=352;height=288;
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</payload-type>
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]]></example>
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<p>That Jingle-formatted information would be mapped to SDP as follows:</p>
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<example caption="SDP Mapping of Dynamic Payload-Type With Parameters"><![CDATA[
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<example caption="SDP mapping of dynamic payload-type with parameters"><![CDATA[
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m=video 49170 RTP/AVP 98
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a=rtpmap:96 theora/90000
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a=fmtp:96 sampling=YCbCr-4:2:2; width=1280; height=720;
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]]></example>
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</section1>
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<section1 topic='Error Handling' anchor='errors'>
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<p>The Jingle-Video-specific error conditions are as follows:</p>
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<table caption='Other Error Conditions'>
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<tr>
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<th>Jingle Video Condition</th>
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<th>XMPP Condition</th>
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<th>Description</th>
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</tr>
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<tr>
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<td><unsupported-codecs/></td>
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<td>¬acceptable;</td>
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<td>The recipient does not support any of the offered video encodings.</td>
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</tr>
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</table>
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</section1>
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<section1 topic='Determining Support' anchor='support'>
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<p>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;.</p>
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<example caption="Service Discovery Information Request"><![CDATA[
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<example caption="Service discovery information request"><![CDATA[
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<iq from='romeo@montague.net/orchard'
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id='disco1'
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to='juliet@capulet.com/balcony'
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<query xmlns='http://jabber.org/protocol/disco#info'/>
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</iq>
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]]></example>
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<example caption="Service Discovery Information Response"><![CDATA[
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<example caption="Service discovery information response"><![CDATA[
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<iq from='juliet@capulet.com/balcony'
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id='disco1'
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to='romeo@montague.net/orchard'
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<section2 topic='Protocol Namespaces' anchor='ns'>
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<p>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;.</p>
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</section2>
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<section2 topic='Jingle Content Description Formats' anchor='registrar-content'>
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<p>The XMPP Registrar shall include "video-rtp" in its registry of Jingle content description formats. The registry submission is as follows:</p>
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<section2 topic='Jingle Application Formats' anchor='registrar-content'>
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<p>The XMPP Registrar shall include "video-rtp" in its registry of Jingle application formats. The registry submission is as follows:</p>
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<code><![CDATA[
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<content>
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<application>
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<name>video-rtp</name>
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<desc>Jingle sessions that support video exchange via the Real-time Transport Protocol</desc>
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<transport>lossy</transport>
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<doc>XEP-0180</doc>
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</content>
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</application>
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]]></code>
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</section2>
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</section1>
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<section1 topic='XML Schemas' anchor='schema'>
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<section2 topic='Content Description Format' anchor='schema-content'>
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<section2 topic='Application Format' anchor='schema-content'>
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<code><![CDATA[
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<?xml version='1.0' encoding='UTF-8'?>
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