XEP-0167: Jingle RTP Sessions

1. Introduction¶

Jingle (XEP-0166) [1] can be used to initiate and negotiate a wide range of peer-to-peer sessions. One session type of interest is media such as voice or video. This document specifies an application format for negotiating Jingle media sessions, where the media is exchanged over the Realtime Transport Protocol (RTP; see RFC 3550 [2]).

2. Requirements¶

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

1. Enable negotiation of parameters necessary for media sessions using the Realtime Transport Protocol (RTP).
2. Map these parameters to Session Description Protocol (SDP; see RFC 4566 [3]) to enable interoperability.
3. Define informational messages related to typical RTP uses such as audio chat and video chat (e.g., ringing, on hold, on mute).

3. Jingle Conformance¶

In accordance with Section 10 of XEP-0166, this document specifies the following information related to the Jingle RTP application type:

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

2. The semantics of the <description/> element are defined in the Application Format section of this document.

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

4. A Jingle RTP session SHOULD use a datagram transport method (e.g. Jingle Raw UDP Transport Method (XEP-0177) [4] or the "ice-udp" method specified in Jingle ICE-UDP Transport Method (XEP-0176) [5]), but MAY use a streaming transport if the end-to-end link has minimal latency and the media negotiated is not unduly heavy (e.g., it might be possible to use a streaming transport for audio, but not for video).

5. Jingle RTP supports two components: one for RTP itself and one for the Real Time Control Protocol (RTCP). The component numbered "1" MUST be associated with RTP and the component numbered "2" MUST be associated with RTCP. Even if an implementation does not support RTCP, it MUST accept Jingle content types that include component "2" by mirroring the second component in its replies (however, it would simply ignore the RTCP-related data during the RTP session).

6. Content is to be sent and received as follows:

   • For datagram transports, outbound 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.

   • For streaming transports, outbound content shall be encoded into RTP packets, framed in accordance with RFC 4571 [6], and sent in succession over the transport. Incoming data received over the transport shall be processed as a stream of RTP packets, where each RTP packet boundary marks the location of the next packet.

4. Application Format¶

A Jingle RTP session is described by a content type that contains one application format and one transport method. Each <content/> element defines a single RTP session. A Jingle negotiation MAY result in the establishment of multiple RTP sessions (e.g., one for audio and one for video). An application SHOULD consider all of the RTP sessions that are established via the same Jingle negotiation to be synchronized for purposes of streaming, playback, recording, etc.

RTP as defined in RFC 3550 is used in the context of various "profiles" that are defined by other specifications. Jingle RTP treats RTP profiles as follows:

1. By default the RTP profile in Jingle RTP MUST be considered "RTP/AVP" as defined in RFC 3551 [7].
2. If the session initiation request contains an <encryption/> element to specify use of SRTP as described under Negotiation of SRTP, then the RTP profile MUST instead be considered "RTP/SAVP" as defined in RFC 3711 [8].
3. Future versions of this specification might define how to use other RTP profiles, such as "RTP/AVPF" and "RTP/SAVPF" as defined in RFC 4585 [9] and RFC 5124 [10] respectively.

The application format consists of one or more encodings contained within a wrapper <description/> element qualified by the 'urn:xmpp:jingle:apps:rtp:1' namespace (see Namespace Versioning regarding the possibility of incrementing the version number). In the language of RFC 4566 each encoding is a payload-type; therefore, each <payload-type/> element specifies an encoding that can be used for the RTP stream, as illustrated in the following example.

    <description xmlns='urn:xmpp:jingle:apps:rtp:1' media='audio'>
      <payload-type id='96' name='speex' clockrate='16000'/>
      <payload-type id='97' name='speex' clockrate='8000'/>
      <payload-type id='18' name='G729'/>
      <payload-type id='103' name='L16' clockrate='16000' channels='2'/>
      <payload-type id='98' name='x-ISAC' clockrate='8000'/>
      <payload-type id='102' name='iLBC'/>
      <payload-type id='4' name='G723'/>
      <payload-type id='0' name='PCMU' clockrate='16000'/>
      <payload-type id='8' name='PCMA'/>
      <payload-type id='13' name='CN'/>
    </description>

The <description/> element is intended to be a child of a Jingle <content/> element as specified in XEP-0166.

The <description/> element MUST possess a 'media' attribute that specifies the media type, such as "audio" or "video", where the media type SHOULD be as registered at IANA MIME Media Types Registry [11].

The <description/> element MAY possess a 'ssrc' attribute that specifies the 32-bit synchronization source for this media stream, as defined in RFC 3550.

After inclusion of one or more <payload-type/> child elements, the <description/> element MAY also contain a <bandwidth/> element that specifies the allowable or preferred bandwidth for use by this application type. The 'type' attribute of the <bandwidth/> element SHOULD be a value for the SDP "bwtype" parameter as listed in the IANA Session Description Protocol Parameters Registry [12]. For RTP sessions, often the <bandwidth/> element will specify the "session bandwidth" as described in Section 6.2 of RFC 3550, measured in kilobits per second as described in Section 5.2 of RFC 4566.

The encodings SHOULD be provided in order of preference by placing the most-preferred payload type as the first <payload-type/> child of the <description/> element and the least-preferred payload type as the last child.

The attributes of the <payload-type/> element are as follows:

In Jingle RTP, the encodings are used in the context of RTP. The most common encodings for the Audio/Video Profile (AVP) of RTP are listed in RFC 3551 (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. The payload IDs are represented in the 'id' attribute.

Each <payload-type/> element MAY contain one or more child elements that specify particular parameters related to the payload. For example, as described in RFC 5574 [13], the "cng", "mode", and "vbr" parameters can be specified in relation to usage of the Speex [14] codec. Where such parameters are encoded via the "fmtp" SDP attribute, they shall be represented in Jingle via the following format:

<parameter name='foo' value='bar'/>

The order of parameter elements MUST be ignored.

Parameter names MUST be treated as case-sensitive.

Note: Parameter names are effectively guaranteed to be unique, since the Internet Assigned Numbers Authority (IANA) [15] maintains a registry of SDP parameters (see <http://www.iana.org/assignments/sdp-parameters>).

5. Negotiating a Jingle RTP Session¶

In general, the process for negotiating a Jingle RTP session is as follows:

Initiator                    Responder
  |                             |
  |   session-initiate          |
  |---------------------------->|
  |   ack                       |
  |<----------------------------|
  |   session-accept            |
  |<----------------------------|
  |   ack                       |
  |---------------------------->|
  |   [optional further         |
  |    negotiation]             |
  |<--------------------------->|
  |   AUDIO (RTP)               |
  |<===========================>|
  |                             |

When the initiator sends a session-initiate message to the responder, the <description/> element includes all of the payload types that the initiator can send and/or receive for Jingle RTP, each one encapsulated in a separate <payload-type/> element (the rules specified in RFC 3264 [16] SHOULD be followed regarding inclusion of payload types).

<iq from='romeo@montague.lit/orchard'
    id='ih28sx61'
    to='juliet@capulet.lit/balcony'
    type='set'>
  <jingle xmlns='urn:xmpp:jingle:1'
          action='session-initiate'
          initiator='romeo@montague.lit/orchard'
          sid='a73sjjvkla37jfea'>
    <content creator='initiator' name='voice'>
      <description xmlns='urn:xmpp:jingle:apps:rtp:1' media='audio'>
        <payload-type id='96' name='speex' clockrate='16000'/>
        <payload-type id='97' name='speex' clockrate='8000'/>
        <payload-type id='18' name='G729'/>
        <payload-type id='0' name='PCMU'/>
        <payload-type id='103' name='L16' clockrate='16000' channels='2'/>
        <payload-type id='98' name='x-ISAC' clockrate='8000'/>
      </description>
      <transport xmlns='urn:xmpp:jingle:transports:ice-udp:1'
                 pwd='asd88fgpdd777uzjYhagZg'
                 ufrag='8hhy'>
        <candidate component='1'
                   foundation='1'
                   generation='0'
                   id='el0747fg11'
                   ip='10.0.1.1'
                   network='1'
                   port='8998'
                   priority='2130706431'
                   protocol='udp'
                   type='host'/>
        <candidate component='1'
                   foundation='2'
                   generation='0'
                   id='y3s2b30v3r'
                   ip='192.0.2.3'
                   network='1'
                   port='45664'
                   priority='1694498815'
                   protocol='udp'
                   rel-addr='10.0.1.1'
                   rel-port='8998'
                   type='srflx'/>
      </transport>
    </content>
  </jingle>
</iq>

Upon receiving the session-initiate stanza, the responder determines whether it can proceed with the negotiation. The general Jingle error cases are specified in XEP-0166 and illustrated in the Scenarios section of this document.

If there is no immediate error, the responder acknowledges the session initiation request.

<iq from='juliet@capulet.lit/balcony'
    id='ih28sx61'
    to='romeo@montague.lit/orchard'
    type='result'/>

Depending on user preferences or client configuration, a user agent controlled by a human user might need to wait for the user to affirm a desire to proceed with the session before continuing. When the user agent has received such affirmation (or if the user agent can automatically proceed for any reason, e.g. because no human intervention is expected or because a human user has configured the user agent to automatically accept sessions with a given entity), it returns a Jingle session-accept message. The session-accept message SHOULD include a subset of the payload types sent by the initiator, i.e., a list of the offered payload types that the responder can send and/or receive. The list that the responder sends SHOULD retain the ID numbers specified by the initiator. The order of the <payload-type/> elements indicates the responder's preferences, with the most-preferred type first.

In the following example, we imagine that the responder supports Speex at a clockrate of 8000 but not 16000, G729, and PCMA but not PMCU. Therefore the responder returns only two payload types (since PCMA was not offered).

<iq from='juliet@capulet.lit/balcony'
    id='i91fs6d5'
    to='romeo@montague.lit/orchard'
    type='set'>
  <jingle xmlns='urn:xmpp:jingle:1'
          action='session-accept'
          initiator='romeo@montague.lit/orchard'
          responder='juliet@capulet.lit/balcony'
          sid='a73sjjvkla37jfea'>
    <content creator='initiator' name='voice'>
      <description xmlns='urn:xmpp:jingle:apps:rtp:1' media='audio'>
        <payload-type id='97' name='speex' clockrate='8000'/>
        <payload-type id='18' name='G729'/>
      </description>
      <transport xmlns='urn:xmpp:jingle:transports:ice-udp:1'
                 pwd='YH75Fviy6338Vbrhrlp8Yh'
                 ufrag='9uB6'>
        <candidate component='1'
                   foundation='1'
                   generation='0'
                   id='or2ii2syr1'
                   ip='192.0.2.1'
                   network='0'
                   port='3478'
                   priority='2130706431'
                   protocol='udp'
                   type='host'/>
      </transport>
    </content>
  </jingle>
</iq>

If the responder supports none of the payload-types offered by the initiator, the responder SHOULD terminate the session and include a Jingle reason of <failed-application/>.

If the responder accepts the session, the initiator acknowledges the session-accept message:

<iq from='romeo@montague.lit/orchard'
    id='i91fs6d5'
    to='juliet@capulet.lit/balcony'
    type='result'/>

The initiator and responder would then attempt to establish connectivity for the data channel, Once they do, they would exchange media using any of the codecs that meet the following criteria:

• If the value of the 'senders' attribute is "initiator" then the initiator MAY use any codec that it can send and the responder can receive.
• If the value of the 'senders' attribute is "responder" then the responder MAY use any codec that it can send and the initiator can receive.
• If the value of the 'senders' attribute is "both" then the parties MAY use any codec that both parties can send and receive.

6. Mapping to Session Description Protocol¶

The SDP media type for Jingle RTP is "audio" (see Section 8.2.1 of RFC 4566) for audio media, "video" (see Section 8.2.1 of RFC 4566) for video media, etc. The media type is reflected in the Jingle 'media' attribute.

The Jingle <bandwidth/> element SHALL be mapped to an SDP b= line; in particular, the value of the 'type' attribute SHALL be mapped to the SDP <bwtype> parameter and the XML character data of the Jingle <bandwidth/> element SHALL be mapped to the SDP <bandwidth> parameter.

If the payload type is static (payload-type IDs 0 through 95 inclusive), it MUST be mapped to an m= line as defined in RFC 4566. The generic format for this line is as follows:

m=<media> <port> <transport> <fmt list>

The SDP <media> parameter is "audio" or "video" or some other media type as specified by the Jingle 'media' attribute, the <port> parameter is the preferred port for such communications (which might be determined dynamically), the <transport> parameter corresponds to the RTP profile as described under Application Format, and the <fmt list> parameter is the payload-type ID.

For example, consider the following static payload-type:

<description xmlns='urn:xmpp:jingle:apps:rtp:1' media='audio'>
  <payload-type id="13" name="CN"/>
</description>

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

m=audio 9999 RTP/AVP 13

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 payload of 16-bit linear-encoded stereo audio sampled at 16KHz associated with dynamic payload-type 96:

<description xmlns='urn:xmpp:jingle:apps:rtp:1' media='audio'>
  <payload-type id='96' name='speex' clockrate='16000'/>
</description>

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

m=audio 9999 RTP/AVP 96
a=rtpmap:96 speex/16000

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

<description xmlns='urn:xmpp:jingle:apps:rtp:1' media='audio'>
  <payload-type id='96' name='speex' clockrate='16000' ptime='40'>
    <parameter name='vbr' value='on'/>
    <parameter name='cng' value='on'/>
  </payload-type>
</description>

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

m=audio 9999 RTP/AVP 96
a=rtpmap:96 speex/16000
a=ptime:40
a=fmtp:96 vbr=on;cng=on

The formatting is similar for video parameters, as shown in the following example.

<description xmlns='urn:xmpp:jingle:apps:rtp:1' media='video'>
  <payload-type id='98' name='theora' clockrate='90000'>
    <parameter name='height' value='600'/>
    <parameter name='width' value='800'/>
    <parameter name='delivery-method' value='inline'/>
    <parameter name='configuration' value='somebase16string'/>
    <parameter name='sampling' value='YCbCr-4:2:2'/>
  </payload-type>
</description>

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

m=video 49170 RTP/AVP 98
a=rtpmap:98 theora/90000
a=fmtp:98 sampling=YCbCr-4:2:2; width=800; height=600;
delivery-method=inline; configuration=somebase16string;

7. Negotiation of SRTP¶

RFC 3711 [8] defines the Secure Real-time Transport Protocol, and RFC 4568 [17] defines the SDP "crypto" attribute for signalling and negotiating the use of SRTP in the context of offer-answer protocols such as SIP. To enable the use of SRTP and gatewaying to non-XMPP technologies that make use of the "crypto" SDP attribute, we define a corresponding <crypto/> element qualified by the 'urn:xmpp:jingle:apps:rtp:1' namespace.

If the initiator wishes to use SRTP, the session-initiate stanza shall include an <encryption/> element, which MUST contain at least one <crypto/> element and MAY include multiple instances of the <crypto/> element. The <encryption/> element MUST be a child of the <description/> element. If the initiator requires the session to be encrypted, the <encryption/> element MUST include a 'required' attribute whose logical value is TRUE and whose lexical value is "true" or "1" [18], where this attribute defaults to a logical value of FALSE (i.e., a lexical value of "false" or "0").

The <crypto/> element is defined as empty (i.e., not containing any child elements); the XML attributes of the <crypto/> element are as follows:

• crypto-suite -- this maps to the SDP "crypto-suite" parameter and has the same semantics (i.e., it is an identifier that describes the encryption and authentication algorithms).
• key-params -- this maps to the SDP "key-params" parameter and has the same semantics (i.e., it provides one or more sets of keying material for the crypto-suite in question).
• session-params -- this maps to the SDP "session-params" parameter and has the same semantics (i.e., it provides transport-specific parameters for SRTP negotiation).
• tag -- this maps to the SDP "tag" parameter and has the same semantics (i.e., it is a decimal number used as an identifier for a particular crypto element).

An example follows.

<encryption xmlns='urn:xmpp:jingle:apps:rtp:1'
            required='1'>
  <crypto
      crypto-suite='AES_CM_128_HMAC_SHA1_80'
      key-params='inline:WVNfX19zZW1jdGwgKCkgewkyMjA7fQp9CnVubGVz|2^20|1:32'
      session-params='KDR=1 UNENCRYPTED_SRTCP'
      tag='1'/>
</encryption>

The mapping of that data to SDP is as follows.

    a=crypto:1 AES_CM_128_HMAC_SHA1_80
    inline:WVNfX19zZW1jdGwgKCkgewkyMjA7fQp9CnVubGVz|2^20|1:32
    KDR=1 UNENCRYPTED_SRTCP

When the responder receives a session-initiate message containing an <encryption/> element, the responder MUST do one of the following:

1. Attempt to proceed with an encrypted session by including the acceptable credentials (i.e., the relevant <crypto/> element) in its session-accept message.
2. Attempt to proceed with an unencrypted session by not including any <crypto/> element in its session-accept message (it is up to the initiator to reject this attempt if desired).
3. Reject the initiator's offer by sending a session-terminate message with a Jingle reason of <security-error/> (typically with an RTP-specific condition of <invalid-crypto/>).

Which of these the responder does is a matter of personal security policies or client configuration.

<iq from='juliet@capulet.lit/balcony'
    id='nv71c396'
    to='romeo@montague.lit/orchard'
    type='set'>
  <jingle xmlns='urn:xmpp:jingle:1'
          action='session-terminate'
          initiator='romeo@montague.lit/orchard'
          sid='a73sjjvkla37jfea'>
    <reason>
      <security-error/>
      <invalid-crypto xmlns='urn:xmpp:jingle:apps:rtp:errors:1'/>
    </reason>
  </jingle>
</iq>

If the responder requires encryption but the initiator did not include an <encryption/> element in its offer, the responder MUST reject the offer by sending a session-terminate message with a Jingle reason of <security-error/> and an RTP-specific condition of <crypto-required/>.

<iq from='juliet@capulet.lit/balcony'
    id='nv71c396'
    to='romeo@montague.lit/orchard'
    type='set'>
  <jingle xmlns='urn:xmpp:jingle:1'
          action='session-terminate'
          initiator='romeo@montague.lit/orchard'
          sid='a73sjjvkla37jfea'>
    <reason>
      <security-error/>
      <crypto-required xmlns='urn:xmpp:jingle:apps:rtp:errors:1'/>
    </reason>
  </jingle>
</iq>

If the initiator requires encryption but the responder does not include an <encryption/> element in its session acceptance, the initiator MUST terminate the session with a Jingle reason of <security-error/> and an RTP-specific condition of <crypto-required/>.

<iq from='romeo@montague.lit/orchard'
    id='ik3hs615'
    to='juliet@capulet.lit/balcony'
    type='set'>
  <jingle xmlns='urn:xmpp:jingle:1'
          action='session-terminate'
          initiator='romeo@montague.lit/orchard'
          sid='a73sjjvkla37jfea'>
    <reason>
      <security-error/>
      <crypto-required xmlns='urn:xmpp:jingle:apps:rtp:errors:1'/>
    </reason>
  </jingle>
</iq>

8. Informational Messages¶

Informational messages can be sent by either party within the context of Jingle to communicate the status of a Jingle RTP session, device, or principal. The informational message MUST be an IQ-set containing a <jingle/> element of type "session-info", where the informational message is a payload element qualified by the 'urn:xmpp:jingle:apps:rtp:info:1' namespace. The following payload elements are defined. [19]

Note: Because an informational message is sent in an IQ-set, the receiving party MUST return either an IQ-result or an IQ-error (normally an IQ-result simply to acknowledge receipt).

<iq from='juliet@capulet.lit/balcony'
    id='yh3gr714'
    to='romeo@montague.lit/orchard'
    type='set'>
  <jingle xmlns='urn:xmpp:jingle:1'
          action='session-info'
          initiator='romeo@montague.lit/orchard'
          sid='a73sjjvkla37jfea'>
    <active xmlns='urn:xmpp:jingle:apps:rtp:info:1'/>
  </jingle>
</iq>

<iq from='juliet@capulet.lit/balcony'
    id='xv39z423'
    to='romeo@montague.lit/orchard'
    type='set'>
  <jingle xmlns='urn:xmpp:jingle:1'
          action='session-info'
          initiator='romeo@montague.lit/orchard'
          sid='a73sjjvkla37jfea'>
    <hold xmlns='urn:xmpp:jingle:apps:rtp:info:1'/>
  </jingle>
</iq>

<iq from='juliet@capulet.lit/balcony'
    id='br81gd63'
    to='romeo@montague.lit/orchard'
    type='set'>
  <jingle xmlns='urn:xmpp:jingle:1'
          action='session-info'
          initiator='romeo@montague.lit/orchard'
          sid='a73sjjvkla37jfea'>
    <unhold xmlns='urn:xmpp:jingle:apps:rtp:info:1'/>
  </jingle>
</iq>

<iq from='juliet@capulet.lit/balcony'
    id='hg4891f5'
    to='romeo@montague.lit/orchard'
    type='set'>
  <jingle xmlns='urn:xmpp:jingle:1'
          action='session-info'
          initiator='romeo@montague.lit/orchard'
          sid='a73sjjvkla37jfea'>
    <mute xmlns='urn:xmpp:jingle:apps:rtp:info:1'
          creator='responder'
          name='voice'/>
  </jingle>
</iq>

<iq from='juliet@capulet.lit/balcony'
    id='ms91g47c'
    to='romeo@montague.lit/orchard'
    type='set'>
  <jingle xmlns='urn:xmpp:jingle:1'
          action='session-info'
          initiator='romeo@montague.lit/orchard'
          sid='a73sjjvkla37jfea'>
    <unmute xmlns='urn:xmpp:jingle:apps:rtp:info:1'
            creator='responder'
            name='voice'/>
  </jingle>
</iq>

<iq from='juliet@capulet.lit/balcony'
    id='tgr515bt'
    to='romeo@montague.lit/orchard'
    type='set'>
  <jingle xmlns='urn:xmpp:jingle:1'
          action='session-info'
          initiator='romeo@montague.lit/orchard'
          sid='a73sjjvkla37jfea'>
    <ringing xmlns='urn:xmpp:jingle:apps:rtp:info:1'/>
  </jingle>
</iq>

9. Exchanging Application Parameters¶

Before or during an RTP session, either party can share suggested application parameters with the other party by sending a Jingle stanza with an action of "description-info". The stanza shall contain only a <description/> element, which specifies suggested parameters for a given application type (e.g., a change to the height and width for display of a video stream). An example follows.

<iq from='romeo@montague.lit/orchard'
    id='pq6x5v37'
    to='juliet@capulet.lit/balcony'
    type='set'>
  <jingle xmlns='urn:xmpp:jingle:1'
          action='description-info'
          initiator='romeo@montague.lit/orchard'
          sid='a73sjjvkla37jfea'>
    <content creator='initiator' name='webcam'>
      <description xmlns='urn:xmpp:jingle:apps:rtp:1' media='video'>
        <payload-type id='98' name='theora' clockrate='90000'>
          <parameter name='height' value='768'/>
          <parameter name='width' value='1024'/>
        </payload-type>
      </description>
    </content>
  </jingle>
</iq>

The description-info message SHOULD include only the modified codecs, not the complete set of codecs (if those codecs have not changed). Their order is NOT meaningful. Furthermore, the data provided is purely advisory; the session SHOULD NOT fail if the receiving party cannot adjust its parameters accordingly.

10. Determining Support¶

To advertise its support for Jingle RTP Sessions and specific media types for RTP, when replying to Service Discovery (XEP-0030) [20] information requests an entity MUST return the following features:

• URNs for any version of this protocol that the entity supports -- e.g., "urn:xmpp:jingle:apps:rtp:1" for this version and "urn:xmpp:jingle:apps:rtp:0" for the previous version (see Namespace Versioning regarding the possibility of incrementing the version number)
• URNs for all of the media types that the entity supports -- e.g., "urn:xmpp:jingle:apps:rtp:audio" for RTP audio and "urn:xmpp:jingle:apps:rtp:video" for RTP video [21]

An example follows.

<iq from='romeo@montague.lit/orchard'
    id='bh3vd715'
    to='juliet@capulet.lit/balcony'
    type='get'>
  <query xmlns='http://jabber.org/protocol/disco#info'/>
</iq>

<iq from='juliet@capulet.lit/balcony'
    id='bh3vd715'
    to='romeo@montague.lit/orchard'
    type='result'>
  <query xmlns='http://jabber.org/protocol/disco#info'>
    <feature var='urn:xmpp:jingle:1'/>
    <feature var='urn:xmpp:jingle:apps:rtp:0'/>
    <feature var='urn:xmpp:jingle:apps:rtp:1'/>
    <feature var='urn:xmpp:jingle:apps:rtp:audio'/>
    <feature var='urn:xmpp:jingle:apps:rtp:video'/>
  </query>
</iq>

In order for an application to determine whether an entity supports this protocol, where possible it SHOULD use the dynamic, presence-based profile of service discovery defined in Entity Capabilities (XEP-0115) [22]. However, if an application has not received entity capabilities information from an entity, it SHOULD use explicit service discovery instead.

11. Scenarios¶

The following sections show a number of Jingle RTP scenarios, roughly in order of increasing complexity.

Romeo                         Juliet
  |                             |
  |  session-initiate           |
  |---------------------------->|
  |  ack                        |
  |<----------------------------|
  |  terminate                  |
  |  (reason = busy)            |
  |<----------------------------|
  |  ack                        |
  |---------------------------->|
  |                             |

<iq from='romeo@montague.lit/orchard'
    id='rg6s5134'
    to='juliet@capulet.lit/balcony'
    type='set'>
  <jingle xmlns='urn:xmpp:jingle:1'
          action='session-initiate'
          initiator='romeo@montague.lit/orchard'
          sid='a73sjjvkla37jfea'>
    <content creator='initiator' name='voice'>
      <description xmlns='urn:xmpp:jingle:apps:rtp:1' media='audio'>
        <payload-type id='96' name='speex' clockrate='16000'/>
        <payload-type id='97' name='speex' clockrate='8000'/>
        <payload-type id='18' name='G729'/>
        <payload-type id='103' name='L16' clockrate='16000' channels='2'/>
        <payload-type id='98' name='x-ISAC' clockrate='8000'/>
      </description>
      <transport xmlns='urn:xmpp:jingle:transports:ice-udp:1'
                 pwd='asd88fgpdd777uzjYhagZg'
                 ufrag='8hhy'>
        <candidate component='1'
                   foundation='1'
                   generation='0'
                   id='el0747fg11'
                   ip='10.0.1.1'
                   network='1'
                   port='8998'
                   priority='2130706431'
                   protocol='udp'
                   type='host'/>
        <candidate component='1'
                   foundation='2'
                   generation='0'
                   id='y3s2b30v3r'
                   ip='192.0.2.3'
                   network='1'
                   port='45664'
                   priority='1694498815'
                   protocol='udp'
                   rel-addr='10.0.1.1'
                   rel-port='8998'
                   type='srflx'/>
      </transport>
    </content>
  </jingle>
</iq>

<iq from='juliet@capulet.lit/balcony'
    id='rg6s5134'
    to='romeo@montague.lit/orchard'
    type='result'/>

<iq from='juliet@capulet.lit/balcony'
    id='ch3vs61d'
    to='romeo@montague.lit/orchard'
    type='set'>
  <jingle xmlns='urn:xmpp:jingle:1'
          action='session-terminate'
          initiator='romeo@montague.lit/orchard'
          sid='a73sjjvkla37jfea'>
    <reason>
      <busy/>
    </reason>
  </jingle>
</iq>

<iq from='romeo@montague.lit/orchard'
    id='ch3vs61d'
    to='juliet@capulet.lit/balcony'
    type='result'/>

Romeo                         Juliet
  |                             |
  |  session-initiate           |
  |---------------------------->|
  |  ack                        |
  |<----------------------------|
  |  session-info (ringing)     |
  |<----------------------------|
  |  ack                        |
  |---------------------------->|
  |  session-accept             |
  |<----------------------------|
  |  ack                        |
  |---------------------------->|
  |  [optional transport and    |
  |   application negotiation]  |
  |<--------------------------->|
  |  STUN connectivity checks   |
  |<===========================>|
  |  AUDIO (RTP)                |
  |<===========================>|
  |  session-terminate          |
  |<----------------------------|
  |  ack                        |
  |---------------------------->|
  |                             |

<iq from='romeo@montague.lit/orchard'
    id='ds9864v6'
    to='juliet@capulet.lit/balcony'
    type='set'>
  <jingle xmlns='urn:xmpp:jingle:1'
          action='session-initiate'
          initiator='romeo@montague.lit/orchard'
          sid='a73sjjvkla37jfea'>
    <content creator='initiator' name='voice'>
      <description xmlns='urn:xmpp:jingle:apps:rtp:1' media='audio'>
        <payload-type id='96' name='speex' clockrate='16000'/>
        <payload-type id='97' name='speex' clockrate='8000'/>
        <payload-type id='18' name='G729'/>
        <payload-type id='103' name='L16' clockrate='16000' channels='2'/>
        <payload-type id='98' name='x-ISAC' clockrate='8000'/>
      </description>
      <transport xmlns='urn:xmpp:jingle:transports:ice-udp:1'
                 pwd='asd88fgpdd777uzjYhagZg'
                 ufrag='8hhy'>
        <candidate component='1'
                   foundation='1'
                   generation='0'
                   id='el0747fg11'
                   ip='10.0.1.1'
                   network='1'
                   port='8998'
                   priority='2130706431'
                   protocol='udp'
                   type='host'/>
        <candidate component='1'
                   foundation='2'
                   generation='0'
                   id='y3s2b30v3r'
                   ip='192.0.2.3'
                   network='1'
                   port='45664'
                   priority='1694498815'
                   protocol='udp'
                   rel-addr='10.0.1.1'
                   rel-port='8998'
                   type='srflx'/>
      </transport>
    </content>
  </jingle>
</iq>

<iq from='juliet@capulet.lit/balcony'
    id='ds9864v6'
    to='romeo@montague.lit/orchard'
    type='result'/>

<iq from='juliet@capulet.lit/balcony'
    id='ed81vd64'
    to='romeo@montague.lit/orchard'
    type='set'>
  <jingle xmlns='urn:xmpp:jingle:1'
          action='session-info'
          initiator='romeo@montague.lit/orchard'
          sid='a73sjjvkla37jfea'>
    <ringing xmlns='urn:xmpp:jingle:apps:rtp:info:1'/>
  </jingle>
</iq>

<iq from='romeo@montague.lit/orchard'
    id='ed81vd64'
    to='juliet@capulet.lit/balcony'
    type='result'/>

<iq from='juliet@capulet.lit/balcony'
    id='lj3bf87g'
    to='romeo@montague.lit/orchard'
    type='set'>
  <jingle xmlns='urn:xmpp:jingle:1'
          action='session-accept'
          initiator='romeo@montague.lit/orchard'
          responder='juliet@capulet.lit/balcony'
          sid='a73sjjvkla37jfea'>
    <content creator='initiator' name='voice'>
      <description xmlns='urn:xmpp:jingle:apps:rtp:1' media='audio'>
        <payload-type id='97' name='speex' clockrate='8000'/>
        <payload-type id='18' name='G729'/>
      </description>
      <transport xmlns='urn:xmpp:jingle:transports:ice-udp:1'
                 pwd='YH75Fviy6338Vbrhrlp8Yh'
                 ufrag='9uB6'>
        <candidate component='1'
                   foundation='1'
                   generation='0'
                   id='or2ii2syr1'
                   ip='192.0.2.1'
                   network='0'
                   port='3478'
                   priority='2130706431'
                   protocol='udp'
                   type='host'/>
      </transport>
    </content>
  </jingle>
</iq>

<iq from='romeo@montague.lit/orchard'
    id='lj3bf87g'
    to='juliet@capulet.lit/balcony'
    type='result'/>

<iq from='juliet@capulet.lit/balcony'
    id='wps8b597'
    to='romeo@montague.lit/orchard'
    type='set'>
  <jingle xmlns='urn:xmpp:jingle:1'
          action='session-terminate'
          initiator='romeo@montague.lit/orchard'
          sid='a73sjjvkla37jfea'>
    <reason>
      <success/>
      <text>Sorry, gotta go!</text>
    </reason>
  </jingle>
</iq>

<iq from='romeo@montague.lit/orchard'
    id='wps8b597'
    to='juliet@capulet.lit/balcony'
    type='result'/>

Romeo                         Juliet
  |                             |
  |  session-initiate           |
  |  (with keying material)     |
  |---------------------------->|
  |  ack                        |
  |<----------------------------|
  |  session-info (ringing)     |
  |<----------------------------|
  |  ack                        |
  |---------------------------->|
  |  session-accept             |
  |<----------------------------|
  |  ack                        |
  |---------------------------->|
  |  [optional transport and    |
  |   application negotiation]  |
  |<--------------------------->|
  |  STUN connectivity checks   |
  |<===========================>|
  |  AUDIO (RTP)                |
  |<===========================>|
  |  session-terminate          |
  |<----------------------------|
  |  ack                        |
  |---------------------------->|
  |                             |

<iq from='romeo@montague.lit/orchard'
    id='vy3g641x'
    to='juliet@capulet.lit/balcony'
    type='set'>
  <jingle xmlns='urn:xmpp:jingle:1'
          action='session-initiate'
          initiator='romeo@montague.lit/orchard'
          sid='a73sjjvkla37jfea'>
    <content creator='initiator' name='voice'>
      <description xmlns='urn:xmpp:jingle:apps:rtp:1' media='audio'>
        <payload-type id='96' name='speex' clockrate='16000'/>
        <payload-type id='97' name='speex' clockrate='8000'/>
        <payload-type id='18' name='G729'/>
        <payload-type id='103' name='L16' clockrate='16000' channels='2'/>
        <payload-type id='98' name='x-ISAC' clockrate='8000'/>
        <encryption required='1'>
          <crypto
              crypto-suite='AES_CM_128_HMAC_SHA1_80'
              key-params='inline:WVNfX19zZW1jdGwgKCkgewkyMjA7fQp9CnVubGVz|2^20|1:32'
              session-params='KDR=1 UNENCRYPTED_SRTCP'
              tag='1'/>
        </encryption>
      </description>
      <transport xmlns='urn:xmpp:jingle:transports:ice-udp:1'
                 pwd='asd88fgpdd777uzjYhagZg'
                 ufrag='8hhy'>
        <candidate component='1'
                   foundation='1'
                   generation='0'
                   id='el0747fg11'
                   ip='10.0.1.1'
                   network='1'
                   port='8998'
                   priority='2130706431'
                   protocol='udp'
                   type='host'/>
        <candidate component='1'
                   foundation='2'
                   generation='0'
                   id='y3s2b30v3r'
                   ip='192.0.2.3'
                   network='1'
                   port='45664'
                   priority='1694498815'
                   protocol='udp'
                   rel-addr='10.0.1.1'
                   rel-port='8998'
                   type='srflx'/>
      </transport>
    </content>
  </jingle>
</iq>

<iq from='juliet@capulet.lit/balcony'
    id='vy3g641x'
    to='romeo@montague.lit/orchard'
    type='result'/>

<iq from='juliet@capulet.lit/balcony'
    id='z2d85b6l'
    to='romeo@montague.lit/orchard'
    type='set'>
  <jingle xmlns='urn:xmpp:jingle:1'
          action='session-info'
          initiator='romeo@montague.lit/orchard'
          sid='a73sjjvkla37jfea'>
    <ringing xmlns='urn:xmpp:jingle:apps:rtp:info:1'/>
  </jingle>
</iq>

<iq from='romeo@montague.lit/orchard'
    id='z2d85b6l'
    to='juliet@capulet.lit/balcony'
    type='result'/>

<iq from='juliet@capulet.lit/balcony'
    id='ywf364b1'
    to='romeo@montague.lit/orchard'
    type='set'>
  <jingle xmlns='urn:xmpp:jingle:1'
          action='session-accept'
          initiator='romeo@montague.lit/orchard'
          responder='juliet@capulet.lit/balcony'
          sid='a73sjjvkla37jfea'>
    <content creator='initiator' name='voice'>
      <description xmlns='urn:xmpp:jingle:apps:rtp:1' media='audio'>
        <payload-type id='97' name='speex' clockrate='8000'/>
        <payload-type id='18' name='G729'/>
        <encryption>
          <crypto
              crypto-suite='AES_CM_128_HMAC_SHA1_80'
              key-params='inline:PS1uQCVeeCFCanVmcjkpPywjNWhcYD0mXXtxaVBR|2^20|1:32'
              session-params='KDR=1;UNENCRYPTED_SRTCP'
              tag='1'/>
        </encryption>
      </description>
      <transport xmlns='urn:xmpp:jingle:transports:ice-udp:1'
                 pwd='YH75Fviy6338Vbrhrlp8Yh'
                 ufrag='9uB6'>
        <candidate component='1'
                   foundation='1'
                   generation='0'
                   id='or2ii2syr1'
                   ip='192.0.2.1'
                   network='0'
                   port='3478'
                   priority='2130706431'
                   protocol='udp'
                   type='host'/>
      </transport>
    </content>
  </jingle>
</iq>

<iq from='romeo@montague.lit/orchard'
    id='ywf364b1'
    to='juliet@capulet.lit/balcony'
    type='result'/>

<iq from='juliet@capulet.lit/balcony'
    id='ws71bf94'
    to='romeo@montague.lit/orchard'
    type='set'>
  <jingle xmlns='urn:xmpp:jingle:1'
          action='session-terminate'
          initiator='romeo@montague.lit/orchard'
          sid='a73sjjvkla37jfea'>
    <reason>
      <success/>
      <text>Sorry, gotta go!</text>
    </reason>
  </jingle>
</iq>

<iq from='romeo@montague.lit/orchard'
    id='ws71bf94'
    to='juliet@capulet.lit/balcony'
    type='result'/>

Romeo                         Juliet
  |                             |
  |  session-initiate           |
  |---------------------------->|
  |  ack                        |
  |<----------------------------|
  |  session-info (ringing)     |
  |<----------------------------|
  |  ack                        |
  |---------------------------->|
  |  session-accept             |
  |<----------------------------|
  |  ack                        |
  |---------------------------->|
  |  [optional transport and    |
  |   application negotiation]  |
  |<--------------------------->|
  |  STUN connectivity checks   |
  |<===========================>|
  |  AUDIO (RTP)                |
  |<===========================>|
  |  content-add for video      |
  |---------------------------->|
  |  ack                        |
  |<----------------------------|
  |  content-modify for video   |
  |<----------------------------|
  |  ack                        |
  |---------------------------->|
  |  content-accept for video   |
  |<----------------------------|
  |  ack                        |
  |---------------------------->|
  |  [optional transport and    |
  |   application negotiation]  |
  |<--------------------------->|
  |  STUN connectivity checks   |
  |<===========================>|
  |  AUDIO + VIDEO (RTP)        |
  |<===========================>|
  |  content-modify for video   |
  |<----------------------------|
  |  ack                        |
  |---------------------------->|
  |  session-terminate          |
  |<----------------------------|
  |  ack                        |
  |---------------------------->|
  |                             |

<iq from='romeo@montague.lit/orchard'
    id='sf93gv76'
    to='juliet@capulet.lit/balcony'
    type='set'>
  <jingle xmlns='urn:xmpp:jingle:1'
          action='session-initiate'
          initiator='romeo@montague.lit/orchard'
          sid='a73sjjvkla37jfea'>
    <content creator='initiator' name='voice'>
      <description xmlns='urn:xmpp:jingle:apps:rtp:1' media='audio'>
        <payload-type id='96' name='speex' clockrate='16000'/>
        <payload-type id='97' name='speex' clockrate='8000'/>
        <payload-type id='18' name='G729'/>
        <payload-type id='103' name='L16' clockrate='16000' channels='2'/>
        <payload-type id='98' name='x-ISAC' clockrate='8000'/>
      </description>
      <transport xmlns='urn:xmpp:jingle:transports:ice-udp:1'
                 pwd='asd88fgpdd777uzjYhagZg'
                 ufrag='8hhy'>
        <candidate component='1'
                   foundation='1'
                   generation='0'
                   id='el0747fg11'
                   ip='10.0.1.1'
                   network='1'
                   port='8998'
                   priority='2130706431'
                   protocol='udp'
                   type='host'/>
        <candidate component='1'
                   foundation='2'
                   generation='0'
                   id='y3s2b30v3r'
                   ip='192.0.2.3'
                   network='1'
                   port='45664'
                   priority='1694498815'
                   protocol='udp'
                   rel-addr='10.0.1.1'
                   rel-port='8998'
                   type='srflx'/>
      </transport>
    </content>
  </jingle>
</iq>

<iq from='juliet@capulet.lit/balcony'
    id='sf93gv76'
    to='romeo@montague.lit/orchard'
    type='result'/>

<iq from='juliet@capulet.lit/balcony'
    id='nf91g647'
    to='romeo@montague.lit/orchard'
    type='set'>
  <jingle xmlns='urn:xmpp:jingle:1'
          action='session-info'
          initiator='romeo@montague.lit/orchard'
          sid='a73sjjvkla37jfea'>
    <ringing xmlns='urn:xmpp:jingle:apps:rtp:info:1'/>
  </jingle>
</iq>

<iq from='romeo@montague.lit/orchard'
    id='nf91g647'
    to='juliet@capulet.lit/balcony'
    type='result'/>

<iq from='juliet@capulet.lit/balcony'
    id='pr93b5ga'
    to='romeo@montague.lit/orchard'
    type='set'>
  <jingle xmlns='urn:xmpp:jingle:1'
          action='session-accept'
          initiator='romeo@montague.lit/orchard'
          responder='juliet@capulet.lit/balcony'
          sid='a73sjjvkla37jfea'>
    <content creator='initiator' name='voice'>
      <description xmlns='urn:xmpp:jingle:apps:rtp:1' media='audio'>
        <payload-type id='97' name='speex' clockrate='8000'/>
        <payload-type id='18' name='G729'/>
      </description>
      <transport xmlns='urn:xmpp:jingle:transports:ice-udp:1'>
        <candidate component='1'
                   foundation='1'
                   generation='0'
                   id='or2ii2syr1'
                   ip='192.0.2.1'
                   network='0'
                   port='3478'
                   priority='2130706431'
                   protocol='udp'
                   type='host'/>
      </transport>
    </content>
  </jingle>
</iq>

<iq from='romeo@montague.lit/orchard'
    id='pr93b5ga'
    to='juliet@capulet.lit/balcony'
    type='result'/>

<iq from='romeo@montague.lit/orchard'
    id='ij6s4198'
    to='juliet@capulet.lit/balcony'
    type='set'>
  <jingle xmlns='urn:xmpp:jingle:1'
          action='content-add'
          initiator='romeo@montague.lit/orchard'
          sid='a73sjjvkla37jfea'>
    <content creator='initiator' name='webcam'>
      <description xmlns='urn:xmpp:jingle:apps:rtp:1' media='video'>
        <payload-type id='98' name='theora' clockrate='90000'>
          <parameter name='height' value='600'/>
          <parameter name='width' value='800'/>
          <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'/>
        <bandwidth type='AS'>128</bandwidth>
      </description>
      <transport xmlns='urn:xmpp:jingle:transports:ice-udp:0'/>
    </content>
  </jingle>
</iq>

<iq from='juliet@capulet.lit/balcony'
    id='ij6s4198'
    to='romeo@montague.lit/orchard'
    type='result'/>

<iq from='juliet@capulet.lit/balcony'
    id='rh49l1k4'
    to='romeo@montague.lit/orchard'
    type='set'>
  <jingle xmlns='urn:xmpp:jingle:1'
          action='content-modify'
          initiator='romeo@montague.lit/orchard'
          sid='a73sjjvkla37jfea'>
    <content creator='initiator' name='webcam' senders='initiator'/>
  </jingle>
</iq>

<iq from='romeo@montague.lit/orchard'
    id='rh49l1k4'
    to='juliet@capulet.lit/balcony'
    type='result'/>

<iq from='juliet@montague.lit/balcony'
    id='vx2s91a6'
    to='romeo@montague.lit/orchard'
    type='set'>
  <jingle xmlns='urn:xmpp:jingle:1'
          action='content-reject'
          initiator='romeo@montague.lit/orchard'
          sid='a73sjjvkla37jfea'>
    <content creator='initiator' name='webcam'>
      <description xmlns='urn:xmpp:jingle:apps:rtp:1' media='video'>
        <payload-type id='101' name='H263-1998' clockrate='90000'/>
        <payload-type id='102' name='H263-2000' clockrate='90000'/>
      </description>
      <transport xmlns='urn:xmpp:jingle:transports:ice-udp:0'/>
    </content>
    <reason>
      <failed-application/>
    </reason>
  </jingle>
</iq>

<iq from='juliet@capulet.lit/balcony'
    id='ih481v7s'
    to='romeo@montague.lit/orchard'
    type='set'>
  <jingle xmlns='urn:xmpp:jingle:1'
          action='content-accept'
          initiator='romeo@montague.lit/orchard'
          sid='a73sjjvkla37jfea'>
    <content creator='initiator' name='webcam'>
      <description xmlns='urn:xmpp:jingle:apps:rtp:1' media='video'>
        <payload-type id='98' name='theora' clockrate='90000'>
          <parameter name='height' value='600'/>
          <parameter name='width' value='800'/>
          <parameter name='delivery-method' value='inline'/>
          <parameter name='configuration' value='somebase16string'/>
          <parameter name='sampling' value='YCbCr-4:2:2'/>
        </payload-type>
        <bandwidth type='AS'>128</bandwidth>
      </description>
      <transport xmlns='urn:xmpp:jingle:transports:ice-udp:0'/>
    </content>
  </jingle>
</iq>

<iq from='romeo@montague.lit/orchard'
    id='ih481v7s'
    to='juliet@capulet.lit/balcony'
    type='result'/>

<iq from='juliet@capulet.lit/balcony'
    id='di492bf8'
    to='romeo@montague.lit/orchard'
    type='set'>
  <jingle xmlns='urn:xmpp:jingle:1'
          action='content-modify'
          initiator='romeo@montague.lit/orchard'
          sid='a73sjjvkla37jfea'>
    <content creator='initiator' name='webcam' senders='both'/>
  </jingle>
</iq>

<iq from='romeo@montague.lit/orchard'
    id='di492bf8'
    to='juliet@capulet.lit/balcony'
    type='result'/>

<iq from='romeo@montague.lit/orchard'
    id='xu3bg810'
    to='juliet@capulet.lit/balcony'
    type='set'>
  <jingle xmlns='urn:xmpp:jingle:1'
          action='description-info'
          initiator='romeo@montague.lit/orchard'
          sid='a73sjjvkla37jfea'>
    <content creator='initiator' name='webcam'>
      <description xmlns='urn:xmpp:jingle:apps:rtp:1' media='video'>
        <payload-type id='98' name='theora' clockrate='90000'>
          <parameter name='height' value='768'/>
          <parameter name='width' value='1024'/>
          <parameter name='delivery-method' value='inline'/>
          <parameter name='configuration' value='somebase16string'/>
          <parameter name='sampling' value='YCbCr-4:2:2'/>
        </payload-type>
        <bandwidth type='AS'>128</bandwidth>
      </description>
    </content>
  </jingle>
</iq>

<iq from='juliet@capulet.lit/balcony'
    id='xu3bg810'
    to='romeo@montague.lit/orchard'
    type='result'/>

<iq from='romeo@montague.lit/orchard'
    id='fl2v387j'
    to='juliet@capulet.lit/balcony'
    type='set'>
  <jingle xmlns='urn:xmpp:jingle:1'
          action='session-terminate'
          initiator='romeo@montague.lit/orchard'
          sid='a73sjjvkla37jfea'>
    <reason>
      <success/>
      <text>I&apos;m outta here!</text>
    </reason>
  </jingle>
</iq>

<iq from='juliet@capulet.lit/balcony'
    id='fl2v387j'
    to='romeo@montague.lit/orchard'
    type='result'/>

12. Implementation Notes¶

13. Security Considerations¶

In order to secure the data stream, implementations SHOULD use encryption methods appropriate to the RTP data transport. It is RECOMMENDED to use SRTP as defined in the Negotiation of SRTP section of this document. The SRTP keying material SHOULD (1) be tied to a separate, secure connection such as provided by DTLS (RFC 4347 [25]) where the keys are established as described in DTLS-SRTP [26] and/or (2) protected by sending the Jingle signalling over a secure channel that protects the confidentiality and integrity of the SRTP-related signalling data.

While it is also possible to use native RTP methods, such as RFC 6189 [27] as described in Use of ZRTP in Jingle RTP Sessions (XEP-0262) [28], this specification does not actively encourage or discourage the use of such methods.

14. IANA Considerations¶

This document requires no interaction with the Internet Assigned Numbers Authority (IANA) [15].

15. XMPP Registrar Considerations¶

<var>
  <name>urn:xmpp:jingle:apps:rtp:audio</name>
  <desc>Signals support for audio sessions via RTP</desc>
  <doc>XEP-0167</doc>
</var>
<var>
  <name>urn:xmpp:jingle:apps:rtp:video</name>
  <desc>Signals support for video sessions via RTP</desc>
  <doc>XEP-0167</doc>
</var>

<application>
  <name>rtp</name>
  <desc>
    Jingle sessions that support media exchange
    via the Real-time Transport Protocol.
  </desc>
  <transport>datagram</transport>
  <doc>XEP-0167</doc>
</application>

16. XML Schemas¶

<?xml version='1.0' encoding='UTF-8'?>

<xs:schema
    xmlns:xs='http://www.w3.org/2001/XMLSchema'
    targetNamespace='urn:xmpp:jingle:apps:rtp:1'
    xmlns='urn:xmpp:jingle:apps:rtp:1'
    elementFormDefault='qualified'>

  <xs:annotation>
    <xs:documentation>
      The protocol documented by this schema is defined in
      XEP-0167: http://www.xmpp.org/extensions/xep-0167.html
    </xs:documentation>
  </xs:annotation>

  <xs:element name='description'>
    <xs:complexType>
      <xs:sequence>
        <xs:element name='payload-type'
                    type='payloadElementType'
                    minOccurs='0'
                    maxOccurs='unbounded'/>
        <xs:element name='encryption'
                    type='encryptionElementType'
                    minOccurs='0'
                    maxOccurs='1'/>
        <xs:element name='bandwidth'
                    type='bandwidthElementType'
                    minOccurs='0'
                    maxOccurs='1'/>
      </xs:sequence>
      <xs:attribute name='media'
                    type='xs:NCName'
                    use='required'/>
      <xs:attribute name='ssrc'
                    type='xs:string'
                    use='optional'/>
    </xs:complexType>
  </xs:element>

  <xs:complexType name='bandwidthElementType'>
    <xs:simpleContent>
      <xs:extension base='xs:string'>
        <xs:attribute name='type'
                      type='xs:string'
                      use='required'/>
      </xs:extension>
    </xs:simpleContent>
  </xs:complexType>

  <xs:complexType name='cryptoElementType'>
    <xs:simpleContent>
      <xs:extension base='empty'>
        <xs:attribute name='crypto-suite' type='xs:NCName' use='required'/>
        <xs:attribute name='key-params' type='xs:string' use='required'/>
        <xs:attribute name='session-params' type='xs:string' use='optional'/>
        <xs:attribute name='tag' type='xs:string' use='required'/>
      </xs:extension>
    </xs:simpleContent>
  </xs:complexType>

  <xs:complexType name='encryptionElementType'>
    <xs:sequence>
      <xs:element name='crypto'
                  type='cryptoElementType'
                  minOccurs='0'
                  maxOccurs='unbounded'/>
    </xs:sequence>
  </xs:complexType>

  <xs:complexType name='payloadElementType'>
    <xs:sequence>
      <xs:element name='parameter'
                  type='parameterElementType'
                  minOccurs='0'
                  maxOccurs='unbounded'/>
    </xs:sequence>
    <xs:attribute name='channels'
                  type='xs:unsignedByte'
                  use='optional'
                  default='1'/>
    <xs:attribute name='clockrate' type='xs:unsignedInt' use='optional'/>
    <xs:attribute name='id' type='xs:unsignedByte' use='required'/>
    <xs:attribute name='maxptime' type='xs:unsignedInt' use='optional'/>
    <xs:attribute name='name' type='xs:string' use='optional'/>
    <xs:attribute name='ptime' type='xs:unsignedInt' use='optional'/>
  </xs:complexType>

  <xs:complexType name='parameterElementType'>
    <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:simpleType name='empty'>
    <xs:restriction base='xs:string'>
      <xs:enumeration value=''/>
    </xs:restriction>
  </xs:simpleType>

</xs:schema>

<?xml version='1.0' encoding='UTF-8'?>

<xs:schema
    xmlns:xs='http://www.w3.org/2001/XMLSchema'
    targetNamespace='urn:xmpp:jingle:apps:rtp:errors:1'
    xmlns='urn:xmpp:jingle:apps:rtp:errors:1'
    elementFormDefault='qualified'>

  <xs:annotation>
    <xs:documentation>
      The protocol documented by this schema is defined in
      XEP-0167: http://www.xmpp.org/extensions/xep-0167.html
    </xs:documentation>
  </xs:annotation>

  <xs:element name='crypto-required' type='empty'/>

  <xs:element name='invalid-crypto' type='empty'/>

  <xs:simpleType name='empty'>
    <xs:restriction base='xs:string'>
      <xs:enumeration value=''/>
    </xs:restriction>
  </xs:simpleType>

</xs:schema>

<?xml version='1.0' encoding='UTF-8'?>

<xs:schema
    xmlns:xs='http://www.w3.org/2001/XMLSchema'
    targetNamespace='urn:xmpp:jingle:apps:rtp:info:1'
    xmlns='urn:xmpp:jingle:apps:rtp:info:1'
    elementFormDefault='qualified'>

  <xs:annotation>
    <xs:documentation>
      The protocol documented by this schema is defined in
      XEP-0167: http://www.xmpp.org/extensions/xep-0167.html
    </xs:documentation>
  </xs:annotation>

  <xs:element name='active' type='empty'/>

  <xs:element name='hold' type='empty'/>

  <xs:element name='mute' type='mutingElementType'/>

  <xs:element name='ringing' type='empty'/>

  <xs:element name='unhold' type='empty'/>

  <xs:element name='unmute' type='mutingElementType'/>

  <xs:complexType name='mutingElementType'>
    <xs:simpleContent>
      <xs:extension base='empty'>
        <xs:attribute name='creator' use='required'>
          <xs:simpleType>
            <xs:restriction base='xs:NCName'>
              <xs:enumeration value='initiator'/>
              <xs:enumeration value='responder'/>
            </xs:restriction>
          </xs:simpleType>
        </xs:attribute>
        <xs:attribute name='name'
                      type='xs:string'
                      use='required'/>
      </xs:extension>
    </xs:simpleContent>
  </xs:complexType>

  <xs:simpleType name='empty'>
    <xs:restriction base='xs:string'>
      <xs:enumeration value=''/>
    </xs:restriction>
  </xs:simpleType>

</xs:schema>

17. Acknowledgements¶

Thanks to Milton Chen, Paul Chitescu, Olivier Crête, Tim Julien, Steffen Larsen, Jeff Muller, Mike Ruprecht, Sjoerd Simons, Will Thompson, Justin Uberti, Unnikrishnan Vikrama Panicker, Paul Witty, and Konstantin Kozlov for their feedback.

Appendices

Appendix A: Document Information¶

Series

XEP

Number

0167

Publisher

XMPP Standards Foundation

Status

Draft

Type

Standards Track

Version

1.1.2

Last Updated

2020-03-19

Approving Body

XMPP Council

Dependencies

XMPP Core, XEP-0166, RFC 3550, RFC 3551, RFC 3711

Supersedes

None

Superseded By

None

Short Name

jingle-rtp

Schema

XML Schema for the 'jingle:apps:rtp' namespace: <http://xmpp.org/schemas/jingle-apps-rtp.xsd>

XML Schema for the 'jingle:apps:rtp:errors' namespace: <http://xmpp.org/schemas/jingle-apps-rtp-errors.xsd>

XML Schema for the 'jingle:apps:rtp:info' namespace: <http://xmpp.org/schemas/jingle-apps-rtp-info.xsd>

Source Control

HTML

This document in other formats: XML  PDF

Appendix B: Author Information¶

Scott Ludwig

Email

scottlu@google.com

JabberID

scottlu@google.com

Peter Saint-Andre

Email

xsf@stpeter.im

JabberID

peter@jabber.org

URI

http://stpeter.im/

Sean Egan

Email

seanegan@google.com

JabberID

seanegan@google.com

Robert McQueen

Email

robert.mcqueen@collabora.co.uk

JabberID

robert.mcqueen@collabora.co.uk

Diana Cionoiu

Email

diana@null.ro

JabberID

l-fy@jabber.null.ro

Appendix C: Legal Notices¶

Appendix D: Relation to XMPP¶

The Extensible Messaging and Presence Protocol (XMPP) is defined in the XMPP Core (RFC 6120) and XMPP IM (RFC 6121) specifications contributed by the XMPP Standards Foundation to the Internet Standards Process, which is managed by the Internet Engineering Task Force in accordance with RFC 2026. Any protocol defined in this document has been developed outside the Internet Standards Process and is to be understood as an extension to XMPP rather than as an evolution, development, or modification of XMPP itself.

Appendix E: Discussion Venue¶

There exists a special venue for discussion related to the technology described in this document: the <jingle@xmpp.org> mailing list.

The primary venue for discussion of XMPP Extension Protocols is the <standards@xmpp.org> discussion list.

Discussion on other xmpp.org discussion lists might also be appropriate; see <http://xmpp.org/about/discuss.shtml> for a complete list.

Given that this XMPP Extension Protocol normatively references IETF technologies, discussion on the <xsf-ietf@xmpp.org> list might also be appropriate.

Errata can be sent to <editor@xmpp.org>.

Appendix F: Requirements Conformance¶

The following requirements keywords as used in this document are to be interpreted as described in RFC 2119: "MUST", "SHALL", "REQUIRED"; "MUST NOT", "SHALL NOT"; "SHOULD", "RECOMMENDED"; "SHOULD NOT", "NOT RECOMMENDED"; "MAY", "OPTIONAL".

Appendix G: Notes¶

Appendix H: Revision History¶

Note: Older versions of this specification might be available at http://xmpp.org/extensions/attic/

1. Version 1.1.2 (2020-03-19)¶

   Add missing namespace in an example.

   egp
2. Version 1.1.1 (2016-07-08)¶

   Fix typos (PMCA to PCMA).

   XEP Editor: ssw
3. Version 1.1 (2009-12-23)¶

   Added creator attribute to mute and unmute elements so that these events can be correlated with a particular content type; clarified use of the reason element in cases other than termination; defined handling of content-add when none of the offered payload-types are supported, where the signalling uses a content-reject message with a Jingle reason of <failed-application/> and a list of the supported codecs; clarified that the RTP profile is RTP/AVP by default, that the profile is RTP/SAVP if security preconditions are present, and that additional profiles such as RTP/AVPF and RTP/SAVPF might be supported in a future version of this specification.

   psa
4. Version 1.0 (2009-06-10)¶

   Per a vote of the XMPP Council, advanced specification from Experimental to Draft.

   psa
5. Version 0.31 (2009-05-19)¶

   Moved early media scenario to separate specification; clarified text regarding multiple components and handling of encryption element; corrected syntax and handling of active element.

   psa
6. Version 0.30 (2009-04-08)¶

   Further adjusted session flows for two scenarios scenario; added unhold and unmute messages.

   psa
7. Version 0.29 (2009-03-20)¶

   Simplified session flow for audio/video scenario; clarified handling of hold messages.

   psa
8. Version 0.28 (2009-03-11)¶

   Moved codec recommendations to a separate specification; harmonized session flows with XEP-0166; modified flow for combined audio/video scenario to use content-modify with senders attribute set to none for media pause and set to both for media resumption; clarified handling of description-info message.

   psa
9. Version 0.27 (2009-02-17)¶

   Added ssrc attribute to description element; clarified handling with streaming transports; in accordance with list consensus, moved zrtp-hash to a separate specification; updated examples to reflect changes to XEP-0176.

   psa
10. Version 0.26 (2009-02-16)¶

    Clarified service discovery features; added support for zrtp-hash in the signalling channel.

    psa
11. Version 0.25 (2008-12-19)¶
    • Refactored encryption syntax.
    • Because the modified encryption syntax is not backwards-compatible, incremented protocol version from 0 to 1 and changed namespace from urn:xmpp:jingle:apps:rtp:zero to urn:xmpp:jingle:apps:rtp:1.
    • Added optional bandwidth element.
    • Added example of description-info action for modifying application parameters.
    • Corrected the schemas.
    psa
12. Version 0.24 (2008-09-25)¶
    • Defined handling of early media, including mappings to RFC 3959 and RFC 3960 using the newly-defined 'disposition' attribute for the <content/> element in XEP-0166.
    • Clarified handling of SRTP negotiation.
    • More fully specified invalid-crypto error condition.
    • Changed DTMF text to prefer native RTP methods and not recommend sending of DTMF in the XMPP signalling channel, per XEP-0181.
    • Modified namespaces to incorporate namespace versioning.
    • Cleaned up XML schemas.
    psa/dc
13. Version 0.23 (2008-07-31)¶

    Removed profile attribute; modified secure session establishment to align with SRTP usage.

    ram/psa
14. Version 0.22 (2008-06-09)¶

    Added name attribute to active element to mirror usage for mute element; clarified meaning of session in the context of this specification; recommended that all sessions established via the same Jingle negotiation should be treated as synchronized.

    psa
15. Version 0.21 (2008-06-09)¶

    Added name attribute to mute element for more precise handling of informational messages.

    psa
16. Version 0.20 (2008-06-04)¶

    In accordance with list consensus, generalized to cover all RTP media, not just audio; corrected text regarding payload types sent by responder in order to match SDP approach.

    psa
17. Version 0.19 (2008-05-28)¶

    Specified default value for profile attribute; clarified relationship to SDP offer-answer model.

    psa
18. Version 0.18 (2008-05-28)¶

    Removed content-replace from ICE-UDP examples per XEP-0176.

    psa
19. Version 0.17 (2008-02-29)¶

    Corrected use of content-replace action per XEP-0166.

    psa
20. Version 0.16 (2008-02-28)¶

    Moved profile attribute from XEP-0166 to this specification.

    psa
21. Version 0.15 (2008-01-11)¶

    Removed content-accept after content-remove per XEP-0166.

    psa
22. Version 0.14 (2008-01-03)¶

    Modified examples to track changes to XEP-0176.

    psa
23. Version 0.13 (2007-12-06)¶

    To track changes to XEP-0166, modified busy scenario and removed unsupported-codecs error.

    psa
24. Version 0.12 (2007-11-27)¶

    Further editorial review.

    psa
25. Version 0.11 (2007-11-15)¶

    Editorial review and consistency check; moved voice chat scenarios from XEP-0166 to this specification.

    psa
26. Version 0.10 (2007-11-13)¶

    Removed info message for busy since it is now a Jingle-specific error condition defined in XEP-0166; defined info message for active.

    psa
27. Version 0.9 (2007-04-17)¶

    Specified Jingle conformance, including the preference for datagram transports over streaming transports and the process of sending and receiving audio content over each transport type.

    psa
28. Version 0.8 (2007-03-23)¶

    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.

    psa/ram
29. Version 0.7 (2006-12-21)¶

    Modified spec to use provisional namespace before advancement to Draft (per XEP-0053).

    psa
30. Version 0.6 (2006-10-31)¶

    Specified how to include SDP parameters and codec-specific parameters; clarified negotiation process; added Speex examples; removed queued info message.

    psa/se
31. Version 0.5 (2006-08-23)¶

    Modified namespace to track XEP-0166.

    psa
32. Version 0.4 (2006-07-12)¶

    Specified when to play received audio (early media); specified that DTMF must use in-band signalling (XEP-0181).

    se/psa
33. Version 0.3 (2006-03-20)¶

    Defined info messages for hold and mute.

    psa
34. Version 0.2 (2006-02-13)¶

    Defined info message for busy; added info message examples; recommended use of Speex; updated schema and XMPP Registrar considerations.

    psa
35. Version 0.1 (2005-12-15)¶

    Initial version.

    psa
36. Version 0.0.3 (2005-12-05)¶

    Described service discovery usage; defined initial informational messages.

    psa
37. Version 0.0.2 (2005-10-27)¶

    Added SDP mapping, security considerations, IANA considerations, XMPP Registrar considerations, and XML schema.

    psa
38. Version 0.0.1 (2005-10-21)¶

    First draft.

    psa/sl

END