AVT Working Group Rocky Wang Internet Draft Ying Zhang Intended status: Standards Track Huawei Technologies Expires: July 24, 2008 January 24, 2008 Media Type Registration of GSM-HR payload Format draft-rocky-avt-rtp-gsm-hr-00.txt Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html This Internet-Draft will expire on July 24, 2008. Copyright Notice Copyright (c) The IETF Turst (2008). Abstract This document registers a media type for the Real-time Transport protocol (RTP) payload format, which is used for the Group Special Mobile half-rate speech transcoding. Rocky Expires July 24, 2008 [Page 1] Internet-Draft Media Type Registration of GSM-HR January 2008 Table of Contents Abstract........................................................1 1. Introduction.................................................2 1.1. Terminology.............................................2 2. Registration of Media Type audio/GSM-HR......................2 3. Mapping MIME Parameters into SDP.............................4 4. Security Considerations......................................4 5. IANA Considerations..........................................4 6. References...................................................5 6.1. Normative References....................................5 Author's Addresses..............................................5 Full Copyright Statement........................................5 Intellectual Property Statement.................................6 Acknowledgment..................................................6 1. Introduction Global System for Mobile Communication (GSM) network has been widely deployed in the last several years to provide mobile communication services. GSM half rate codec (GSM-HR) is one of the compressed audio codecs which are used for the basic speech service in the GSM mobile networks. GSM-HR denotes GSM 06.20 half-rate speech transcoding, specified in ETS 300 969 which is available from ETSI at the address given in RFC 3551 [1] Section 4.5.8. This codec has a frame length of 112 bits. For transmission in RTP, each codec frame is packed into a 14 octet(112 bit). The packing is specified in ETSI Technical Specification TS 101 318. This document registers a media type for the Real-time Transport protocol (RTP) payload format for the GSM-HR codec to enabling the use of the codec in the Voice over IP (VoIP) application. 1.1. Terminology The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC-2119 [2]. 2. Registration of Media Type audio/GSM-HR Type name: audio Subtype name: GSM-HR Rocky Expires July 24, 2008 [Page 2] Internet-Draft Media Type Registration of GSM-HR January 2008 Required parameters: none Optional parameters: ptime: the recommended length of time (in milliseconds) represented by the media in a packet and the default value is 20 milliseconds. See Section 6 of RFC 4566 [3]. Encoding considerations: This media type is framed binary data (see Section 4.8 in RFC4288 [4]). Security consideration: This media type does not carry active content. It does transfer compressed data. See Section 4. Interoperability considerations: none Published specification: RFC XXXX Applications that use this media type: Audio and video streaming and conferencing tools Additional information: none Person & email address to contact for further information: Rocky Wang Intended usage: COMMON Restrictions on usage: This media type depends on RTP framing, and hence is only defined for transfer via RTP (RFC 3550 [5]). Transfer within other framing protocols is not defined at this time. Author: Rocky Wang Change controller: IETF Audio/Video Transport working group delegated from the IESG. Rocky Expires July 24, 2008 [Page 3] Internet-Draft Media Type Registration of GSM-HR January 2008 3. Mapping MIME Parameters into SDP The information carried in the MIME media type specification has a specific mapping to fields in the Session Description Protocol (SDP) [3], which is commonly used to describe RTP sessions. When SDP is used to specify sessions employing the compact bundled format for GSM half-rate speech, the mapping is as follows: The MIME type ("audio") goes in SDP "m=" as the media name. The MIME subtype ("GSM-HR") goes in SDP "a=rtpmap" as the encoding name and the sampling rate for the GSM-HR codec is 8 KHz. The optional parameters "ptime" goes in the SDP "a=ptime" attributes, respectively. The payload type payload type value for GSM-HR is created dynamically and is used in the PT field of the RTP data header. 4. Security Considerations RTP packets using the GSM-HR payload format are subject to the security considerations discussed in the RTP specification [5]. A potential denial-of-service threat exists for data encodings using compression techniques that have non-uniform receiver-end computational load. The attacker can inject pathological datagrams into the stream which are complex to decode and cause the receiver to be overloaded. However, this encoding does not exhibit anysignificant non-uniformity. As with any IP-based protocol, in some circumstances a receiver may be overloaded simply by the receipt of too many packets, either desired or undesired. Network-layer authentication MAY be used to discard packets from undesired sources, but the processing cost of the authentication itself may be too high. 5. IANA Considerations It is requested that one new media subtype (audio/GSM-HR) is registered by IANA. For details, see Section 2. Rocky Expires July 24, 2008 [Page 4] Internet-Draft Media Type Registration of GSM-HR January 2008 6. References 6.1. Normative References [1] Schulzrinne, H. and S. Casner, "RTP Profile for Audio and Video Conferences with Minimal Control", RFC 3551, July 2003. [2] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [3] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session Description Protocol", RFC 4566, July 2006. [4] Freed, N. and J. Klensin, "Media Type Specifications and Registration Procedures", BCP 13, RFC 4288, December 2005. [5] Schulzrinne, H., Casner, S., Frederick, R. and V. Jacobson, "RTP: A Transport Protocol for Real-Time Applications", RFC 3550, July 2003. Author's Addresses Rocky Wang Huawei Technologies Huawei Industrial Base, Bantian Longgang Shenzhen, Guangdong Province 518129, P.R.China Email: Ying Zhang Huawei Technologies Huawei Industrial Base, Bantian Longgang Shenzhen, Guangdong Province 518129, P.R.China Email: Full Copyright Statement Copyright (C) The IETF Trust (2008). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. Rocky Expires July 24, 2008 [Page 5] Internet-Draft Media Type Registration of GSM-HR January 2008 This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 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The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society. Rocky Expires July 24, 2008 [Page 6]