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Jingle Video Content Description Format This document defines a content description format for Jingle video sessions. &LEGALNOTICE; 0180 Experimental Standards Track Standards Council XMPP Core XEP-0166 TO BE ASSIGNED &stpeter; Milton Chen Milton.Chen@vseelab.com 0.4 2006-12-21 psa

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

 0.3 2006-08-23 psa

Modified namespace to track XEP-0166.

 0.2 2006-07-12 psa

Updated to use content type instead of media type.

 0.1 2006-03-23 psa/mc

Initial version.

 0.0.1 2006-03-20 psa/mc

First draft.

&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.

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

  1. Enable negotiation of parameters necessary for video exchange.
  2. Map these parameters to Session Description Protocol (SDP; see &rfc4566;) to enable interoperability.
  3. Define informational messages related to video exchange chat.

A Jingle video session is described by one or more encodings contained within a wrapper &DESCRIPTION; element. In the language of RFC 4566 these encodings are payload-types; therefore, each <payload-type/> child element specifies an encoding that can be used for the video stream. Such encodings are often used in the context of the Real-time Transfer Protocol (RTP; see &rfc3550;) 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 96), although other encodings are allowed (these "dynamic" types use payload IDs 97 to 127) in accordance with the dynamic assignment rules described in Section 3 of RFC 3551. The &PAYLOADTYPE; element's 'id' attribute is REQUIRED and its 'name' attribute is RECOMMENDED. The encodings SHOULD be provided in order of preference.

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

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

Attribute Description Datatype/Units
channels The number of channels (e.g., 2 for stereoscopic video) positiveInteger (defaults to 1)
height The vertical extent of the displayed video, in pixels positiveInteger
id A unique identifier for the payload type positiveInteger
layer The relationship of a layer to the "bottom" of the stack, where 0 = bottom (the first layer) nonNegativeInteger
name A name for the payload type string
transparent Whether or not a layer is transparent boolean
width The horizontal extent of the displayed video, in pixels positiveInteger
x The horizontal starting point of a tile, in pixels from the origin point positiveInteger
y The vertical starting point of a tile, in pixels from the origin point positiveInteger

To follow.

If an entity supports the Jingle video content description format, it MUST advertise that fact by returning a feature of "http://www.xmpp.org/extensions/xep-0166.html#ns/description/video" in response to &xep0030; information requests.

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Informational messages may be sent by either party within the context of Jingle to communicate the status of a Jingle video session, device, or principal. The informational message MUST be an IQ-set containing a &JINGLE; element of type "content-info", where the informational message is a payload element qualified by the 'http://www.xmpp.org/extensions/xep-0166.html#ns/info/video' namespace. No payload elements have yet been defined, but will be specified in a future version of this document.

Support for the Theora codec See <http://www.theora.org/>. is RECOMMENDED.

The description of a format for video sessions introduces no known security vulnerabilities.

This document requires no interaction with &IANA;.

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-info"; upon advancement of this specification, the ®ISTRAR; shall issue permanent namespaces in accordance with the process defined in Section 4 of &xep0053;.

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

video Jingle sessions that support video exchanges XEP-0180 ]]> ]]>

To follow.