Audio Video Transport WG Sassan Ahmadi INTERNET-DRAFT Expires: April 19, 2006 October 19, 2005 Real-Time Transport Protocol (RTP) Payload Format for the Variable-Rate Multimode Wideband (VMR-WB) Extension Audio Codec 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/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html This document is a submission of the IETF AVT WG. Comments should be directed to the AVT WG mailing list, avt@ietf.org. Abstract This document is an addendum to RFC xxxx, which specifies the RTP payload format for the Variable-Rate Multimode Wideband (VMR-WB) speech codec. This document specifies some updates in RFC xxxx to enable support for the new operating mode of VMR-WB standard (i.e., VMR-WB mode 4). These updates do not affect the existing modes of VMR-WB already specified in RFC xxxx. The payload formats and their associated parameters, as well as all provisions, restrictions, use cases, features, etc. that are specified in RFC xxxx are applicable to the new operating mode with no exception. Sassan Ahmadi Standards Track [page 1] INTERNET-DRAFT VMR-WB Extension RTP Payload Format October 2005 Table of Contents 1.Introduction.................................................2 2.Conventions and Acronyms.....................................2 3.The Variable-Rate Multimode Wideband (VMR-WB) Extension......3 4.The Necessary Updates in RFC xxxx............................3 5.Security Considerations......................................5 6.Public Specification.........................................5 7.IANA Considerations..........................................5 References.....................................................5 Normative References........................................5 Informative References......................................6 Author's Address...............................................6 IPR Notice.....................................................6 Copyright Notice...............................................7 1. Introduction This document is an addendum to RFC xxxx [2] and contains the necessary updates for the support of the new operating mode of 3GPP2 VMR-WB standard [1]. The new mode of VMR-WB standard; i.e., VMR-WB mode 4, while operating at a lower data rate, has similar characteristics and functionalities compared to the existing modes of VMR-WB already included in RFC xxxx (e.g., variable bit rate, narrowband/wideband input/output speech/audio processing capability, continuous and discontinuous transmission, etc.). Therefore, all provisions and restrictions specified in RFC xxxx are applicable to all modes of the VMR-WB standard including the new mode, which is specified in this document. As a result, no new media type registration is required. The VMR-WB file format; i.e., for transport of VMR-WB speech data in storage mode applications, is specified in [1,4] and includes support for the new mode of operation. The following sections provide the necessary updates to RFC xxxx to enable support of VMR-WB mode 4. 2. Conventions and Acronyms 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 RFC2119 [3]. The following acronyms are used in this document: 3GPP2 - The Third Generation Partnership Project 2 CDMA - Code Division Multiple Access VMR-WB - Variable-Rate Multimode Wideband Codec CMR - Codec Mode Request DTX - Discontinuous Transmission Sassan Ahmadi Standards Track [page 2] INTERNET-DRAFT VMR-WB Extension RTP Payload Format October 2005 RTP - Real-Time Transport Protocol MIME - Multipurpose Internet Mail Extension 3. The Variable-Rate Multimode Wideband (VMR-WB) Extension VMR-WB is the wideband speech-coding standard developed by Third Generation Partnership Project 2 (3GPP2) for encoding/decoding wideband/narrowband speech content in multimedia services in 3G CDMA cellular systems [1]. VMR-WB is a source-controlled variable-rate multimode wideband speech codec. It has a number of operating modes, where each mode is a tradeoff between voice quality and average data rate. The operating mode in VMR-WB (as shown in Table 2) is chosen based on the traffic condition of the network and the desired quality of service. The desired average data rate (ADR) in each mode is obtained by encoding speech frames at permissible rates (as shown in Tables 1 and 3) compliant with cdma2000 system depending on the instantaneous characteristics of input speech and the maximum and minimum rate constraints imposed by the network operator. The capabilities of the VMR-WB codec were extended through the addition of a new mode operating at lower average data rates, resulting in improved system capacity in IP and non-IP networks [1]. As a result of this extension, certain reserved table entries in RFC xxxx are used to include support for the new operating mode. VMR-WB mode 4 is compliant with all applicable provisions and restrictions specified in RFC xxxx [2]. Note that the existing table entries of RFC xxxx remain unchanged (e.g., frame types, etc.) and the original modes of VMR-WB are not affected by these updates. The existing flexibility in RFC xxxx for future extensions allows the addition of the new mode without any impact on the interoperability with earlier implementations of RFC xxxx. The following sections provide the necessary updates that are required to be made in RFC xxxx. The provisions and considerations for implementation, congestion control, and security remain identical to those specified in RFC xxxx. 4. The Necessary Updates in RFC xxxx Table 1 of RFC xxxx is updated as follows: Sassan Ahmadi Standards Track [page 3] INTERNET-DRAFT VMR-WB Extension RTP Payload Format October 2005 +---------------------------+-----------------+---------------+ | Frame Type | Bits per Packet | Encoding Rate | | | (Frame Size) | (kbps) | +---------------------------+-----------------+---------------+ | Full-Rate | 266 | 13.3 | | Full-Rate | 171 | 8.55 | | Half-Rate | 124 | 7.2 | | Half-Rate | 80 | 4.0 | | Quarter-Rate | 54 | 2.7 | | Quarter-Rate | 40 | 2.0 | | Eighth-Rate | 20 | 1.0 | | Eighth-Rate | 16 | 0.8 | | Blank | 0 | - | | Erasure | 0 | - | | Full-Rate with Bit Errors | 171 | 8.55 | +---------------------------+-----------------+---------------+ Table 1: cdma2000 system permissible frame types and their associated encoding rates Note that the new permissible rates correspond to cdma2000 rate-set I have been added to the table. Table 2 of RFC xxxx is updated as follows to include VMR-WB mode 4 and VMR-WB mode 4 with maximum half-rate similar to that described in Section 2.4 of the revised VMR-WB specification [1]. +-------+----------------------------------------------------------+ | CMR | VMR-WB Operating Modes | +-------+----------------------------------------------------------+ | 0 | VMR-WB mode 3 (AMR-WB interoperable mode at 6.60 kbps) | | 1 | VMR-WB mode 3 (AMR-WB interoperable mode at 8.85 kbps) | | 2 | VMR-WB mode 3 (AMR-WB interoperable mode at 12.65 kbps) | | 3 | VMR-WB mode 2 | | 4 | VMR-WB mode 1 | | 5 | VMR-WB mode 0 | | 6 | VMR-WB mode 2 with maximum half-rate encoding | | 7 | VMR-WB mode 4 | | 8 | VMR-WB mode 4 with maximum half-rate encoding | | 9-14 | (reserved) | | 15 | No Preference (no mode request is present) | +-------+----------------------------------------------------------+ Table 2: List of valid CMR values and their associated VMR-WB operating modes. Note that CMR values 7 and 8 replace the reserved values in Table 2 of RFC xxxx. Table 3 of RFC xxxx is updated as follows to include new frame types (FT) associated with VMR-WB mode 4. Note that the size of the frames are unique and different, allowing for the use of header-free payload format for all modes of operations [2]. Sassan Ahmadi Standards Track [page 4] INTERNET-DRAFT VMR-WB Extension RTP Payload Format October 2005 +----+--------------------------------------------+-------------------+ | FT | Encoding Rate | Frame Size (Bits) | +----+--------------------------------------------+-------------------+ | 0 | Interoperable Full-Rate (AMR-WB 6.60 kbps) | 132 | | 1 | Interoperable Full-Rate (AMR-WB 8.85 kbps) | 177 | | 2 | Interoperable Full-Rate (AMR-WB 12.65 kbps)| 253 | | 3 | Full-Rate 13.3 kbps | 266 | | 4 | Half-Rate 6.2 kbps | 124 | | 5 | Quarter-Rate 2.7 kbps | 54 | | 6 | Eighth-Rate 1.0 kbps | 20 | | 7 | Full-Rate 8.55 kbps | 171 | | 8 | Half-Rate 4.0 kbps | 80 | | 9 | CNG (AMR-WB SID) | 35 | | 10 | Eighth-Rate 0.8 kbps | 16 | | 11 | (reserved) | - | | 12 | (reserved) | - | | 13 | (reserved) | - | | 14 | Erasure (AMR-WB SPEECH_LOST) | 0 | | 15 | Blank (AMR-WB NO_DATA) | 0 | +----+--------------------------------------------+-------------------+ Table 3:VMR-WB payload frame types for real-time transport Note that the new FT types associated with VMR-WB mode 4 replace the reserved entries 7, 8, and 10 in Table 3 of RFC xxxx and there are no changes in the existing entries of Table 3 of RFC xxxx. The 'mode-set' MIME parameter value 4 is defined to indicate that VMR-WB mode 4 is supported and used. Note that the active modes of operation are negotiated and agreed by the IP terminals through the offer-answer model provided in Section 9.3 of RFC xxxx [2]. 5. Security Considerations Same as RFC xxxx 6. Public specification The VMR-WB speech codec including the new mode is specified in following 3GPP2 specification C.S0052-A version 1.0. Transfer methods are specified in RFC xxxx. 7. IANA Considerations None References Normative References Sassan Ahmadi Standards Track [page 5] INTERNET-DRAFT VMR-WB Extension RTP Payload Format October 2005 [1] 3GPP2 C.S0052-A v1.0 "Source-Controlled Variable-Rate Multimode Wideband Speech Codec (VMR-WB) Service Options 62 and 63 for Spread Spectrum Systems", 3GPP2 Technical Specification, April 2005. [2] S. Ahmadi, "Real-Time Transport Protocol (RTP) Payload Formats for the Variable-Rate Multimode Wideband (VMR-WB) Audio Codec", RFC xxxx, Internet Engineering Task Force, October 2005. [3] S. Bradner, "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, Internet Engineering Task Force, March 1997. Informative References [4] 3GPP2 C.S0050-A v1.0 "3GPP2 File Formats for Multimedia Services", 3GPP2 Technical Specification, October 2005. Any 3GPP2 document can be downloaded from the 3GPP2 web server, "http://www.3gpp2.org/", see specifications. Author's Address Dr. Sassan Ahmadi Email: sassan.ahmadi@ieee.org This Internet-Draft expires in six months from October 19, 2005. RFC Editor Considerations The RFC editor is requested to replace all occurrences of xxxx with the RFC number that reference [2] will receive. 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