Network Working Group S. Ahmadi
Request for Comments: 4424 February 2006
Updates: 4348
Category: Standards Track
Network Working Group S. Ahmadi
Request for Comments: 4424 February 2006
Updates: 4348
Category: Standards Track
Real-Time Transport Protocol (RTP) Payload Format for the Variable-Rate Multimode Wideband (VMR-WB) Extension Audio Codec
用于可变速率多模宽带（VMR-WB）扩展音频编解码器的实时传输协议（RTP）有效载荷格式
Status of This Memo
关于下段备忘
This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited.
本文件规定了互联网社区的互联网标准跟踪协议，并要求进行讨论和提出改进建议。有关本协议的标准化状态和状态，请参考当前版本的“互联网官方协议标准”（STD 1）。本备忘录的分发不受限制。
Copyright Notice
版权公告
Copyright (C) The Internet Society (2006).
版权所有（C）互联网协会（2006年）。
Abstract
摘要
This document is an addendum to RFC 4348, which specifies the RTP payload format for the Variable-Rate Multimode Wideband (VMR-WB) speech codec. This document specifies some updates in RFC 4348 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 4348.
本文件是RFC 4348的附录，其中规定了可变速率多模宽带（VMR-WB）语音编解码器的RTP有效载荷格式。本文件规定了RFC 4348中的一些更新，以支持VMR-WB标准的新运行模式（即VMR-WB模式4）。这些更新不会影响RFC 4348中已经指定的VMR-WB的现有模式。
The payload formats and their associated parameters, as well as all provisions, restrictions, use cases, features, etc., that are specified in RFC 4348 are applicable to the new operating mode with no exception.
RFC 4348中规定的有效载荷格式及其相关参数以及所有规定、限制、用例、特征等均适用于新的运行模式，无例外。
Table of Contents
目录
1. Introduction ....................................................2
2. Conventions and Acronyms ........................................2
3. The Variable-Rate Multimode Wideband (VMR-WB) Extension .........2
4. The Necessary Updates in RFC 4348 ...............................4
5. Security Considerations .........................................6
6. Public Specification ............................................6
7. IANA Considerations .............................................7
8. References ......................................................7
8.1. Normative References .......................................7
8.2. Informative References .....................................7
1. Introduction ....................................................2
2. Conventions and Acronyms ........................................2
3. The Variable-Rate Multimode Wideband (VMR-WB) Extension .........2
4. The Necessary Updates in RFC 4348 ...............................4
5. Security Considerations .........................................6
6. Public Specification ............................................6
7. IANA Considerations .............................................7
8. References ......................................................7
8.1. Normative References .......................................7
8.2. Informative References .....................................7
This document is an addendum to RFC 4348 [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 (VMR-WB mode 4), although operating at a lower data rate, has similar characteristics and functionalities compared to the existing modes of VMR-WB already included in RFC 4348 (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 4348 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.
本文件是RFC 4348[2]的附录，包含支持3GPP2 VMR-WB标准[1]新操作模式的必要更新。VMR-WB标准的新模式（VMR-WB模式4）虽然以较低的数据速率运行，但与RFC 4348中已包含的现有VMR-WB模式相比，具有类似的特征和功能（例如，可变比特率、窄带/宽带输入/输出语音/音频处理能力、连续和不连续传输等）因此，RFC 4348中规定的所有规定和限制适用于VMR-WB标准的所有模式，包括本文件中规定的新模式。因此，无需新媒体类型注册。
The VMR-WB file format 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.
[1,4]中规定了在存储模式应用程序中传输VMR-WB语音数据的VMR-WB文件格式，并包括对新操作模式的支持。
The following sections provide the necessary updates to RFC 4348 to enable support of VMR-WB mode 4.
以下各节提供了对RFC 4348的必要更新，以支持VMR-WB模式4。
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 [3].
本文件中的关键词“必须”、“不得”、“要求”、“应”、“不应”、“应”、“不应”、“建议”、“可”和“可选”应按照RFC 2119[3]中所述进行解释。
The following acronyms are used in this document:
本文件中使用了以下首字母缩略词：
3GPP2 - Third Generation Partnership Project 2 CDMA - Code Division Multiple Access VMR-WB - Variable-Rate Multimode Wideband CMR - Codec Mode Request DTX - Discontinuous Transmission RTP - Real-Time Transport Protocol MIME - Multipurpose Internet Mail Extensions
3GPP2-第三代合作伙伴项目2 CDMA-码分多址VMR-WB-可变速率多模宽带CMR-编解码器模式请求DTX-不连续传输RTP-实时传输协议MIME-多用途互联网邮件扩展
VMR-WB is the wideband speech-coding standard developed by the 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 trade-off 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
VMR-WB是由第三代合作伙伴项目2（3GPP2）开发的宽带语音编码标准，用于在3G CDMA蜂窝系统中对多媒体业务中的宽带/窄带语音内容进行编码/解码[1]。VMR-WB是一种源代码控制的可变速率多模宽带语音编解码器。它有许多操作模式，每种模式都是语音质量和平均数据速率之间的折衷。VMR-WB中的运行模式（如表2所示）是根据网络的流量状况和所需的质量选择的
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.
提供服务。根据输入语音的瞬时特性以及网络运营商施加的最大和最小速率限制，以符合CDMA2000系统的允许速率（如表1和表3所示）对语音帧进行编码，从而获得每种模式下的期望平均数据速率（ADR）。
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].
VMR-WB编解码器的功能通过添加以较低平均数据速率运行的新模式得到扩展，从而提高了IP和非IP网络中的系统容量[1]。
As a result of this extension, certain reserved table entries in RFC 4348 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 4348 [2]. Note that the existing table entries of RFC 4348 remain unchanged (e.g., frame types) and the original modes of VMR-WB are not affected by these updates.
作为此扩展的结果，RFC 4348中的某些保留表条目用于包括对新操作模式的支持。VMR-WB模式4符合RFC 4348[2]中规定的所有适用规定和限制。请注意，RFC 4348的现有表格条目保持不变（例如，帧类型），VMR-WB的原始模式不受这些更新的影响。
The existing flexibility in RFC 4348 for future extensions allows the addition of the new mode without any impact on the interoperability with earlier implementations of RFC 4348.
RFC 4348中针对未来扩展的现有灵活性允许添加新模式，而不会影响与RFC 4348早期实现的互操作性。
The following sections provide the necessary updates that are required to be made in RFC 4348.
以下章节提供了RFC 4348中需要进行的必要更新。
The provisions and considerations for implementation, congestion control, and security remain identical to those specified in RFC 4348.
实施、拥塞控制和安全方面的规定和注意事项与RFC 4348中规定的相同。
Table 1 of RFC 4348 is updated as follows:
RFC 4348的表1更新如下：
+---------------------------+-----------------+---------------+
| 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 |
+---------------------------+-----------------+---------------+
+---------------------------+-----------------+---------------+
| 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
表1:CDMA2000系统允许的帧类型及其相关编码速率
Note that the new permissible rates correspond to CDMA2000 rate-set I and have been added to the table.
请注意，新的允许速率对应于CDMA2000速率集I，并已添加到表中。
Table 2 of RFC 4348 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].
RFC 4348的表2更新如下，包括VMR-WB模式4和VMR-WB模式4，最大半速率类似于修订后的VMR-WB规范[1]第2.4节中所述。
+-------+----------------------------------------------------------+
| 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) |
+-------+----------------------------------------------------------+
+-------+----------------------------------------------------------+
| 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
表2：有效CMR值及其相关VMR-WB操作模式列表
Note that CMR values 7 and 8 replace the reserved values in Table 2 of RFC 4348.
注意，CMR值7和8替换RFC 4348表2中的保留值。
Table 3 of RFC 4348 is updated as follows to include new frame types (FTs) associated with VMR-WB mode 4.
RFC 4348的表3更新如下，以包括与VMR-WB模式4相关的新帧类型（FTs）。
Note that the sizes of the frames are unique and different, allowing for the use of header-free payload format for all modes of operations [2].
请注意，帧的大小是唯一和不同的，允许对所有操作模式使用无报头有效负载格式[2]。
+----+--------------------------------------------+-----------------+
| 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 |
+----+--------------------------------------------+-----------------+
+----+--------------------------------------------+-----------------+
| 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
表3：用于实时传输的VMR-WB有效负载帧类型
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 4348 and there are no changes in the existing entries of Table 3 of RFC 4348.
请注意，与VMR-WB模式4关联的新FT类型将替换RFC 4348表3中的保留条目7、8和10，并且RFC 4348表3中的现有条目没有变化。
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 4348 [2].
“模式集”MIME参数值4的定义表明支持并使用VMR-WB模式4。请注意，IP终端通过RFC 4348[2]第9.3节中提供的报价/应答模型协商并同意主动操作模式。
Same as RFC 4348.
与RFC 4348相同。
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 4348.
包括新模式的VMR-WB语音编解码器在以下3GPP2规范C.S0052-A版本1.0中指定。RFC 4348中规定了传输方法。
This document updates the media type registered in [2]. IANA has added this document as reference to that media type registration and has modified the optional parameter mode-set in the registration. Section 9.1 of RFC 4348 [2] reads:
本文档更新[2]中注册的媒体类型。IANA已添加此文档作为该媒体类型注册的参考，并修改了注册中设置的可选参数模式。RFC 4348[2]第9.1节内容如下：
Currently, this list includes modes 0, 1, 2, and 3 [1], but MAY be extended in the future. If such mode-set is specified during session initiation, the encoder MUST NOT use modes outside of the subset. If not present, all operating modes in the set 0 to 3 are allowed for the session.
目前，该列表包括模式0、1、2和3[1]，但将来可能会扩展。如果在会话启动期间指定了此类模式集，编码器不得使用子集之外的模式。如果不存在，则会话允许设置为0到3的所有操作模式。
IANA will change "modes 0, 1, 2 and 3 [1]" to "modes 0, 1, 2, 3, and 4 [1] [2]", and change "modes in the set 0 to 3" to "modes in the set 0 to 4". [1] will be the IANA's reference to the original VMR-WB document (3GPP2 C.S0052-A v1.0) and [2] will be IANA's reference to this document (RFC 4424).
IANA将“模式0、1、2和3[1]”更改为“模式0、1、2、3和4[1][2]”，并将“集合0到3中的模式”更改为“集合0到4中的模式”。[1] IANA将参考原始VMR-WB文件（3GPP2 C.S0052-A v1.0），而[2]将是IANA参考本文件（RFC 4424）。
[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, http://www.3gpp2.org/.
[1] 3GPP2 C.S0052-A v1.0“用于扩频系统的源控可变速率多模宽带语音编解码器（VMR-WB）服务选项62和63”，《3GPP2技术规范》，2005年4月，http://www.3gpp2.org/.
[2] Ahmadi, S., "Real-Time Transport Protocol (RTP) Payload Format for the Variable-Rate Multimode Wideband (VMR-WB) Audio Codec", RFC 4348, January 2006.
[2] Ahmadi，S.，“变速率多模宽带（VMR-WB）音频编解码器的实时传输协议（RTP）有效载荷格式”，RFC 4348，2006年1月。
[3] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997.
[3] Bradner，S.，“RFC中用于表示需求水平的关键词”，BCP 14，RFC 2119，1997年3月。
[4] 3GPP2 C.S0050-A v1.0 "3GPP2 File Formats for Multimedia Services", 3GPP2 Technical Specification, October 2005, http://www.3gpp2.org/.
[4] 3GPP2 C.S0050-A v1.0“多媒体服务的3GPP2文件格式”，3GPP2技术规范，2005年10月，http://www.3gpp2.org/.
Author's Address
作者地址
Dr. Sassan Ahmadi
萨桑·艾哈迈迪博士
EMail: sassan.ahmadi@ieee.org
EMail: sassan.ahmadi@ieee.org
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