From: The IESG To: IETF-Announce Message-Id: Date: Mon, 30 Oct 2006 18:02:51 -0500 Cc: mmusic chair , Internet Architecture Board , RFC Editor Subject: Protocol Action: 'The SDP (Session Description Protocol) Content Attribute' to Proposed Standard The IESG has approved the following document: - 'The SDP (Session Description Protocol) Content Attribute ' as a Proposed Standard This document is the product of the Multiparty Multimedia Session Control Working Group. The IESG contact persons are Cullen Jennings and Jon Peterson. A URL of this Internet-Draft is: http://www.ietf.org/internet-drafts/draft-ietf-mmusic-sdp-media-content-06.txt Technical Summary This document defines a new Session Description Protocol (SDP) media-level attribute, 'content'. The 'content' attribute defines the content of the media stream in more detailed level than the media description line. The sender of an SDP session description can attach the 'content' attribute to one or more media streams. The receiving application can then treat each media stream differently (e.g., show it on a big screen or small screen) based on its content. Working Group Summary The draft is a product of the MMUSIC working group. Protocol Quality The draft received thorough review by Tom Taylor. The draft was brought to the attention of the ietf-types list, which raised no concerns. Note to RFC Editor OLD The 'content' attribute contains a token, which MAY be attached to a media stream by a sending application. An application MAY attach a content attribute to any media stream it describes. That attribute contains one or more tokens describing the content of the transmitted media stream to the receiving application. NEW The 'content' attribute contains one or more tokens, which MAY be attached to a media stream by a sending application. An application MAY attach a content attribute to any media stream it describes. OLD: Since the 'content' attribute does not have to be understood, an SDP answer MAY contain 'content' attributes even if none were present in the offer. Similarly, the answer MAY contain no 'content' attributes even if they were present in the offer. Furthermore, the values of 'content' attributes does not need to match in an offer and an answer. NEW: The 'content' attribute describes the data the application generating the SDP session description intends to send over a particular media stream. The 'content' values for both directions of a media stream do not need to be the same. Therefore, an SDP answer MAY contain 'content' attributes even if none were present in the offer. Similarly, the answer MAY contain no 'content' attributes even if they were present in the offer. Furthermore, the values of 'content' attributes does not need to match in an offer and an answer. OLD: All these values can be used with any media type. The application can make decisions on how to handle a single media stream based on both the media type and the value of the 'content' attribute. Therefore the situation where one value of 'content' attribute occurs more than once in a single session descriptor is not problematic. NEW: All these values can be used with any media type. We chose not to restrict each value to a particular set of media types in order not to prevent applications from using innovative combinations of a given value with different media types. The application can make decisions on how to handle a single media stream based on both the media type and the value of the 'content' attribute. If the application does not implement any special logic for the handling of a given media type and 'content' value combination, it applies the application's default handling for the media type. Note that the same 'content' attribute value can occur more than once in a single session description.