Internet Engineering Task Force (IETF) M. Westerlund
Request for Comments: 6064 P. Frojdh
Category: Informational Ericsson
ISSN: 2070-1721 January 2011
Internet Engineering Task Force (IETF) M. Westerlund
Request for Comments: 6064 P. Frojdh
Category: Informational Ericsson
ISSN: 2070-1721 January 2011
SDP and RTSP Extensions Defined for 3GPP Packet-Switched Streaming Service and Multimedia Broadcast/Multicast Service
为3GPP分组交换流媒体服务和多媒体广播/多播服务定义的SDP和RTSP扩展
Abstract
摘要
The Packet-switched Streaming Service (PSS) and the Multimedia Broadcast/Multicast Service (MBMS) defined by 3GPP use the Session Description Protocol (SDP) and Real Time Streaming Protocol (RTSP) with some extensions. This document provides information about these extensions and registers the RTSP and SDP extensions with IANA.
3GPP定义的分组交换流媒体服务（PSS）和多媒体广播/多播服务（MBMS）使用会话描述协议（SDP）和实时流媒体协议（RTSP），并进行了一些扩展。本文档提供有关这些扩展的信息，并向IANA注册RTSP和SDP扩展。
Status of This Memo
关于下段备忘
This document is not an Internet Standards Track specification; it is published for informational purposes.
本文件不是互联网标准跟踪规范；它是为了提供信息而发布的。
This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Not all documents approved by the IESG are a candidate for any level of Internet Standard; see Section 2 of RFC 5741.
本文件是互联网工程任务组（IETF）的产品。它代表了IETF社区的共识。它已经接受了公众审查，并已被互联网工程指导小组（IESG）批准出版。并非IESG批准的所有文件都适用于任何级别的互联网标准；见RFC 5741第2节。
Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at http://www.rfc-editor.org/info/rfc6064.
有关本文件当前状态、任何勘误表以及如何提供反馈的信息，请访问http://www.rfc-editor.org/info/rfc6064.
Copyright Notice
版权公告
Copyright (c) 2011 IETF Trust and the persons identified as the document authors. All rights reserved.
版权所有（c）2011 IETF信托基金和确定为文件作者的人员。版权所有。
This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.
本文件受BCP 78和IETF信托有关IETF文件的法律规定的约束(http://trustee.ietf.org/license-info)自本文件出版之日起生效。请仔细阅读这些文件，因为它们描述了您对本文件的权利和限制。从本文件中提取的代码组件必须包括信托法律条款第4.e节中所述的简化BSD许可证文本，并提供简化BSD许可证中所述的无担保。
Table of Contents
目录
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 4
2. Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Applicability Statement . . . . . . . . . . . . . . . . . . . 5
4. PSS SDP Extensions . . . . . . . . . . . . . . . . . . . . . . 5
4.1. Video Buffering Attributes . . . . . . . . . . . . . . . . 5
4.2. Video Frame Size Attribute . . . . . . . . . . . . . . . . 6
4.3. Integrity-Protection Configuration Attributes . . . . . . 6
4.4. The Alternative Attributes . . . . . . . . . . . . . . . . 7
4.5. Adaptation Attribute . . . . . . . . . . . . . . . . . . . 7
4.6. Quality of Experience Attribute . . . . . . . . . . . . . 7
4.7. Asset Information Attribute . . . . . . . . . . . . . . . 8
5. MBMS SDP Extensions . . . . . . . . . . . . . . . . . . . . . 8
5.1. MBMS Bearer Mode Declaration Attribute . . . . . . . . . . 8
5.2. FEC Flow ID Attribute . . . . . . . . . . . . . . . . . . 8
5.3. MBMS Repair Attribute . . . . . . . . . . . . . . . . . . 8
5.4. SDP Protocol Identifiers for FEC . . . . . . . . . . . . . 8
5.4.1. RTP Protocol Identifiers . . . . . . . . . . . . . . . 9
5.4.2. FEC Repair Data Identifier . . . . . . . . . . . . . . 9
5.5. Video Buffering Attribute . . . . . . . . . . . . . . . . 9
6. SDP Offer/Answer Consideration . . . . . . . . . . . . . . . . 9
7. PSS RTSP Extensions . . . . . . . . . . . . . . . . . . . . . 10
7.1. 3GPP-Link-Char Header . . . . . . . . . . . . . . . . . . 10
7.2. 3GPP-Adaptation Header . . . . . . . . . . . . . . . . . . 10
7.3. 3GPP-QoE-Metrics Header . . . . . . . . . . . . . . . . . 10
7.4. 3GPP-QoE-Feedback Header . . . . . . . . . . . . . . . . . 11
7.5. Video Buffer Headers . . . . . . . . . . . . . . . . . . . 11
7.6. Integrity Protection . . . . . . . . . . . . . . . . . . . 11
7.7. RTSP URI Extension . . . . . . . . . . . . . . . . . . . . 11
7.8. Fast Start-Up and Content Switching . . . . . . . . . . . 12
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
8.1. SDP Registrations . . . . . . . . . . . . . . . . . . . . 12
8.2. RTSP Registrations . . . . . . . . . . . . . . . . . . . . 17
9. Security Considerations . . . . . . . . . . . . . . . . . . . 20
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 20
10.1. Normative References . . . . . . . . . . . . . . . . . . . 20
10.2. Informative References . . . . . . . . . . . . . . . . . . 21
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 4
2. Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Applicability Statement . . . . . . . . . . . . . . . . . . . 5
4. PSS SDP Extensions . . . . . . . . . . . . . . . . . . . . . . 5
4.1. Video Buffering Attributes . . . . . . . . . . . . . . . . 5
4.2. Video Frame Size Attribute . . . . . . . . . . . . . . . . 6
4.3. Integrity-Protection Configuration Attributes . . . . . . 6
4.4. The Alternative Attributes . . . . . . . . . . . . . . . . 7
4.5. Adaptation Attribute . . . . . . . . . . . . . . . . . . . 7
4.6. Quality of Experience Attribute . . . . . . . . . . . . . 7
4.7. Asset Information Attribute . . . . . . . . . . . . . . . 8
5. MBMS SDP Extensions . . . . . . . . . . . . . . . . . . . . . 8
5.1. MBMS Bearer Mode Declaration Attribute . . . . . . . . . . 8
5.2. FEC Flow ID Attribute . . . . . . . . . . . . . . . . . . 8
5.3. MBMS Repair Attribute . . . . . . . . . . . . . . . . . . 8
5.4. SDP Protocol Identifiers for FEC . . . . . . . . . . . . . 8
5.4.1. RTP Protocol Identifiers . . . . . . . . . . . . . . . 9
5.4.2. FEC Repair Data Identifier . . . . . . . . . . . . . . 9
5.5. Video Buffering Attribute . . . . . . . . . . . . . . . . 9
6. SDP Offer/Answer Consideration . . . . . . . . . . . . . . . . 9
7. PSS RTSP Extensions . . . . . . . . . . . . . . . . . . . . . 10
7.1. 3GPP-Link-Char Header . . . . . . . . . . . . . . . . . . 10
7.2. 3GPP-Adaptation Header . . . . . . . . . . . . . . . . . . 10
7.3. 3GPP-QoE-Metrics Header . . . . . . . . . . . . . . . . . 10
7.4. 3GPP-QoE-Feedback Header . . . . . . . . . . . . . . . . . 11
7.5. Video Buffer Headers . . . . . . . . . . . . . . . . . . . 11
7.6. Integrity Protection . . . . . . . . . . . . . . . . . . . 11
7.7. RTSP URI Extension . . . . . . . . . . . . . . . . . . . . 11
7.8. Fast Start-Up and Content Switching . . . . . . . . . . . 12
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
8.1. SDP Registrations . . . . . . . . . . . . . . . . . . . . 12
8.2. RTSP Registrations . . . . . . . . . . . . . . . . . . . . 17
9. Security Considerations . . . . . . . . . . . . . . . . . . . 20
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 20
10.1. Normative References . . . . . . . . . . . . . . . . . . . 20
10.2. Informative References . . . . . . . . . . . . . . . . . . 21
3GPP has specified the Packet-switched Streaming Service (PSS) that uses both RTSP [RFC2326] and SDP [RFC4566]. The service is specified in technical specifications TS 26.233 [PSS-233] and TS 26.234 [PSS-234] in Release 4 and subsequent releases. The basic service defined in Release 4 is enhanced in Release 5 with capability exchange, and in Release 6 with a number of features, such as adaptation, digital rights management (DRM), progressive download, as well as a streaming server file format defined in [PSS-3GP]. Fast start-up and content switching are addressed in Release 7.
3GPP已指定同时使用RTSP[RFC2326]和SDP[rfc456]的分组交换流媒体服务（PSS）。技术规范TS 26.233[PSS-233]和TS 26.234[PSS-234]在版本4和后续版本中规定了该服务。第4版中定义的基本服务在第5版中通过功能交换得到增强，在第6版中通过一系列功能得到增强，如自适应、数字版权管理（DRM）、渐进下载以及[PSS-3GP]中定义的流媒体服务器文件格式。快速启动和内容切换在第7版中有介绍。
3GPP has also specified the Multimedia Broadcast/Multicast Service (MBMS) that uses SDP. The IP-layer protocols used by this service are specified in technical specification TS 26.346 Release 6 [MBMS]. Release 7 extends the MBMS User Service to also work with unicast bearers for interactive and streaming traffic classes.
3GPP还指定了使用SDP的多媒体广播/多播服务（MBMS）。技术规范TS 26.346第6版[MBMS]中规定了此服务使用的IP层协议。第7版扩展了MBMS用户服务，使其也可以与用于交互式和流式流量类的单播承载器一起工作。
In the process of defining these services, there has occasionally been a need to extend both SDP and RTSP functionalities. These extensions have mostly been in the form of SDP attributes and RTSP headers and option tags. 3GPP uses the name "feature tags" (like RTSP 2.0 for what RTSP 1.0 calls "option tags"); "option tag" is the name that will be used in this document. The purpose of this informational document is to register these SDP and RTSP extensions, in order to avoid future conflicts, and also to raise the awareness of their existence within IETF.
在定义这些服务的过程中，有时需要扩展SDP和RTSP功能。这些扩展大多以SDP属性、RTSP头和选项标记的形式出现。3GPP使用名称“功能标签”（如RTSP 1.0称之为“选项标签”的RTSP 2.0）；“选项标签”是将在本文档中使用的名称。本信息性文档的目的是注册这些SDP和RTSP扩展，以避免将来的冲突，并提高IETF中存在这些扩展的意识。
In Section 5.4, this document defines three SDP protocol identifiers used in MBMS to enable the usage of block-based FEC. The SDP protocol identifiers require an RFC to be defined and registered. As this is an RFC from the IETF stream, any semantic change will require a new IETF-approved RFC. The other SDP and RTSP extensions registered by this document are not normatively defined in this document. Instead, the normative definitions are referenced by the registrations. 3GPP can update the normative definition in future versions of their specifications. However, to ensure that such a change is visible in the IETF, at minimum, IANA should be notified and the reference to the 3GPP specification updated, and preferably an updated version of this RFC published.
在第5.4节中，本文件定义了MBMS中使用的三个SDP协议标识符，以便能够使用基于块的FEC。SDP协议标识符要求定义和注册RFC。由于这是来自IETF流的RFC，任何语义更改都需要新的IETF批准的RFC。本文件注册的其他SDP和RTSP扩展未在本文件中进行规范性定义。相反，注册引用了规范性定义。3GPP可以在其规范的未来版本中更新规范定义。然而，为了确保这种变更在IETF中可见，至少应通知IANA，并更新对3GPP规范的引用，最好发布本RFC的更新版本。
The document begins with two sections presenting the SDP extensions for PSS and MBMS, respectively. They are followed by a section noting that offer/answer considerations are not applicable here. The subsequent section presents the extensions of RTSP for PSS. The IANA registration of SDP attributes and protocol identifiers is given in
本文档从两个部分开始，分别介绍PSS和MBMS的SDP扩展。随后是一节，指出此处不适用报价/应答考虑。下一节介绍了PSS的RTSP扩展。中给出了SDP属性和协议标识符的IANA注册
Section 8.1, and the RTSP headers and option tags in Section 8.2. For normative descriptions of all SDP and RTSP extensions, we refer to TS 26.234 [PSS-234] and TS 26.346 [MBMS].
第8.1节以及第8.2节中的RTSP标题和选项标签。有关所有SDP和RTSP扩展的规范性说明，请参阅TS 26.234[PSS-234]和TS 26.346[MBMS]。
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 [RFC2119].
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[RFC2119]中所述进行解释。
3GP: 3GPP file format, a multimedia file format based on the ISO base media file format, existing in different profiles intended for multimedia messages, direct playback on clients, progressive download, usage on servers to deliver on-demand multimedia sessions in PSS, or servers sending MBMS sessions.
3GP:3GPP文件格式，一种基于ISO基本媒体文件格式的多媒体文件格式，存在于不同的配置文件中，用于彩信、在客户端直接播放、渐进下载、在服务器上使用以在PSS中提供按需多媒体会话，或发送MBMS会话的服务器。
3GPP: Third Generation Partnership Project; see http://www.3gpp.org for more information about this organization.
3GPP：第三代合作项目；看见http://www.3gpp.org 有关此组织的详细信息。
FEC: Forward Error Correction
前向纠错
MBMS: Multimedia Broadcast/Multicast Service, a service defined by 3GPP that utilizes broadcast or multicast technology in combination with unicast for delivery of a wide range of content to mobile terminals.
MBMS：多媒体广播/多播服务，由3GPP定义的一种服务，利用广播或多播技术与单播相结合，向移动终端传送广泛的内容。
PSS: Packet-switched Streaming Service, a unicast-based streaming service for delivery of on-demand or live streaming multimedia content to mobile terminals.
PSS：分组交换流媒体服务，一种基于单播的流媒体服务，用于向移动终端交付点播或直播流媒体内容。
RTSP: Real Time Streaming Protocol; see [RFC2326].
RTSP：实时流协议；见[RFC2326]。
SDP: Session Description Protocol; see [RFC4566].
会话描述协议；见[RFC4566]。
SRTP: Secure Real-time Transport Protocol; see [RFC3711].
SRTP：安全实时传输协议；参见[RFC3711]。
QoE: Quality of Experience, the quality level of the user experience of a service. In PSS, this is estimated by a combination of application-level metrics.
QoE：体验的质量，服务的用户体验的质量水平。在PSS中，这是通过应用程序级指标的组合来估计的。
QoS: Quality of Service, the quality (properties) that the network provides toward the upper-layer service.
QoS：服务质量，网络向上层服务提供的质量（属性）。
This document describes 3GPP-defined extensions to SDP [RFC4566] and RTSP [RFC2326] and registers attributes that are normatively defined in 3GPP technical specifications 26.234, 26.244, and 26.346, up to the referenced versions of the respective documents.
本文档描述了对SDP[RFC4566]和RTSP[RFC2326]的3GPP定义的扩展，并注册了3GPP技术规范26.234、26.244和26.346中规范定义的属性，直至相应文档的参考版本。
The SDP and RTSP extensions have only been defined for usage with the 3GPP service in mind. The applicability for usage outside of these services has not been considered nor addressed. Usage of these attributes in other contexts may require further definitions or clarifications. For example, all SDP attributes lack offer/answer usage rules [RFC3264], which currently makes it impossible to use them with offer/answer. Please note that change control of these SDP and RTSP extensions belongs to 3GPP.
SDP和RTSP扩展仅针对3GPP服务的使用而定义。在这些服务之外使用的适用性尚未得到考虑或解决。在其他上下文中使用这些属性可能需要进一步的定义或澄清。例如，所有SDP属性都缺少提供/应答使用规则[RFC3264]，这使得目前无法将它们与提供/应答一起使用。请注意，这些SDP和RTSP扩展的更改控制权属于3GPP。
The PSS specification [PSS-234] defines a number of different SDP attributes for different purposes. They are listed below, grouped by their purpose. The text is intentionally not specific enough to allow implementation from this document. The normative definition is in the 3GPP technical specification cited.
PSS规范[PSS-234]为不同目的定义了许多不同的SDP属性。它们列在下面，按用途分组。该文本故意不够具体，不允许从本文件中实施。规范性定义在引用的3GPP技术规范中。
The following attributes are used to provide parameters for the video buffer model provided in Annex G and Section 5.3.3.2 of [PSS-234]. The attributes were defined in Release 5 as "X-" attributes and, at the time, were not considered for registration. In hindsight, however, they should not have been "X-" attributes, and they should have been registered, as the registration rules of SDP [RFC4566] point out. Changing their names today is impossible due to the deployed base of millions of mobile handsets supporting PSS, and therefore they are registered in their current form.
以下属性用于为附录G和[PSS-234]第5.3.3.2节中提供的视频缓冲区模型提供参数。在第5版中，这些属性被定义为“X-”属性，并且当时没有考虑注册。然而，事后看来，它们不应该是“X-”属性，它们应该被注册，正如SDP[RFC4566]的注册规则所指出的那样。由于部署了数百万支持PSS的手机，因此现在不可能更改它们的名称，因此它们是以当前的形式注册的。
All attributes are defined at media level.
所有属性都是在媒体级别定义的。
o The "a=X-predecbufsize" attribute provides the size of the pre-decoder buffer in bytes.
o “a=X-predecbufsize”属性以字节为单位提供预解码器缓冲区的大小。
o The "a=X-initpredecbufperiod" attribute provides the time during which a receiver should initially buffer, in 90 kHz ticks, before starting to consume the data in the buffer in order to ensure that underflow does not occur, assuming correct data delivery.
o “a=X-initpredecbufperiod”属性提供了接收机在开始使用缓冲区中的数据之前，以90 kHz为单位进行初始缓冲的时间，以确保在假设正确数据传递的情况下不会发生下溢。
o The "a=X-initpostdecbufperiod" attribute provides the initial buffering period, in 90 kHz ticks, for the post-decoder buffer present in H.263 and MPEG-4 Visual.
o “a=X-initpostdecbufperiod”属性为H.263和MPEG-4 Visual中存在的后解码器缓冲区提供初始缓冲期（以90 kHz为单位）。
o The "a=X-decbyterate" attribute indicates the maximum peak byte-decoding rate used in the verification of the Annex G buffer model expressed in bytes per second.
o “a=X-decbytate”属性表示附录G缓冲区模型验证中使用的最大峰值字节解码速率，以字节/秒表示。
o The "a=3gpp-videopostdecbufsize" attribute is used to indicate the value used in determining the H.264 video post-decoder buffer size.
o “a＝3gpp videopostdecbufsize”属性用于指示用于确定H.264视频后期解码器缓冲区大小的值。
Note that complete descriptions of these attributes can be found in Section 5.3.3.2 of [PSS-234].
请注意，这些属性的完整描述可在[PSS-234]第5.3.3.2节中找到。
This media-level attribute provides the receiver with the largest picture size that a specific H.263 payload type will carry within the session. The attribute has the following form (see Section 5.3.3.2 of [PSS-234]):
此媒体级别属性为接收器提供特定H.263有效负载类型将在会话中携带的最大图片大小。该属性具有以下形式（见[PSS-234]第5.3.3.2节）：
"a=framesize:<payload type number> <width>-<height>"
"a=framesize:<payload type number> <width>-<height>"
These attributes are all used to configure the integrity-protection mechanism defined in Annex K (Sections K.2.2.1, K.2.2.2, and K.2.2.3) of [PSS-234].
这些属性都用于配置[PSS-234]附录K（第K.2.2.1、K.2.2.2和K.2.2.3节）中定义的完整性保护机制。
o The session-level attribute "a=3GPP-Integrity-Key" carries the integrity key used to derive SRTP master keys for integrity protection. The key is protected in different ways depending on a method identifier. When using Open Mobile Alliance (OMA) DRM key management, the key is encrypted using AES [AES] before it is base64 encoded [RFC4648].
o 会话级属性“a＝3GPP完整性密钥”携带用于派生用于完整性保护的SRTP主密钥的完整性密钥。根据方法标识符的不同，密钥受到不同的保护。当使用开放移动联盟（OMA）DRM密钥管理时，密钥在base64编码[RFC4648]之前使用AES[AES]进行加密。
o The media-level attribute "a=3GPP-SRTP-Config" is used to configure SRTP for integrity protection and contains an integrity nonce, a key salt used in deriving the SRTP master key from the integrity key, and any SRTP configuration parameters, such as the integrity tag length.
o 媒体级属性“a＝3GPP SRTP Config”用于配置SRTP以进行完整性保护，并包含完整性nonce、用于从完整性密钥导出SRTP主密钥的密钥salt以及任何SRTP配置参数，例如完整性标签长度。
o The session-level attribute "a=3GPP-SDP-Auth" is used to carry an authentication tag calculated over certain parts of the SDP to prevent manipulation of the security attributes.
o 会话级属性“a＝3GPP SDP Auth”用于携带在SDP的某些部分上计算的认证标签，以防止操纵安全属性。
Two media-level and one session-level attributes are used in a mechanism for providing alternative SDP lines. One or more SDP lines at media level can be replaced, if desired, by alternatives. The mechanism is backwards compatible in the way that a receiver that does not support the attributes will get the default configuration. The different alternatives can be grouped using different attributes that can be specified hierarchically with a top and a lower level. 3GPP Release 6 supports grouping based on bit-rate, according to the SDP bandwidth modifiers AS [RFC4566] and TIAS [RFC3890], and language.
两个媒体级和一个会话级属性用于提供备用SDP线路的机制中。如果需要，可以用替代品替换媒体级的一条或多条SDP线。该机制向后兼容，不支持属性的接收器将获得默认配置。可以使用不同的属性对不同的备选方案进行分组，这些属性可以通过顶层和底层分层指定。3GPP Release 6支持根据SDP带宽修饰符[RFC4566]和TIAS[RFC3890]以及语言基于比特率进行分组。
The SDP attributes (see Sections 5.3.3.3 and 5.3.3.4 of [PSS-234]) are:
SDP属性（见[PSS-234]第5.3.3.3节和第5.3.3.4节）为：
o The media-level attribute "a=alt:<id>:<SDP-Line>" carries any SDP line and an alternative identifier.
o 媒体级属性“a=alt:<id>：<SDP Line>”包含任何SDP行和备用标识符。
o The media-level attribute "a=alt-default-id:<id>" identifies the default configuration to be used in groupings.
o 媒体级属性“a=alt default id:<id>”标识分组中要使用的默认配置。
o The session-level attribute "a=alt-group" is used to group different recommended media alternatives. This allows providing aggregated properties for the whole group according to the grouping type. Language and bit-rate are two defined grouping types.
o 会话级别属性“a=alt group”用于对不同的推荐媒体备选方案进行分组。这允许根据分组类型为整个组提供聚合属性。语言和比特率是两种定义的分组类型。
The media-level SDP attribute "a=3GPP-Adaptation-Support" (see Section 5.3.3.5 in [PSS-234]) is defined as part of the negotiation procedure of the PSS adaptation mechanism. The attribute carries a single value indicating how often the RTCP "Next Application Data Unit" (NADU) APP packet shall be included in sent RTCP compound packets. The adaptation mechanism allows the client to provide the server with information on the available transmission bit-rate and receiver buffer status.
媒体级SDP属性“a=3GPP适配支持”（参见[PSS-234]中的第5.3.3.5节）被定义为PSS适配机制协商过程的一部分。该属性携带一个值，指示RTCP“下一个应用程序数据单元”（NADU）应用程序数据包应包含在发送的RTCP复合数据包中的频率。自适应机制允许客户端向服务器提供有关可用传输比特率和接收机缓冲区状态的信息。
The session- and media-level attribute "a=3GPP-QoE-Metrics" (see Section 5.3.3.6 of [PSS-234]) is used to negotiate the usage of the QoE metrics. The included parameters indicate which metrics should be used, over which duration there should be measurements, and how often reports should be sent.
会话和媒体级属性“a=3GPP QoE度量”（见[PSS-234]第5.3.3.6节）用于协商QoE度量的使用。包含的参数指示应使用哪些度量、应在多长时间内进行度量以及应发送报告的频率。
The session- and media-level attribute "a=3GPP-Asset-Information" (see Section 5.3.3.7 of [PSS-234]) can exist in multiple instances in a description and describes different types of asset information. The different asset classes defined in Release 6 are Title, Description, Copyright, Performer, Author, Genre, Rating, Classification, Keywords, Location, Album, and Recording Year. The different assets are described with a base64-encoded asset box from the 3GP file format [PSS-3GP].
会话级和媒体级属性“a=3GPP资产信息”（见[PSS-234]第5.3.3.7节）可以存在于描述中的多个实例中，并描述不同类型的资产信息。第6版中定义的不同资产类别包括标题、描述、版权、表演者、作者、流派、评级、分类、关键字、位置、专辑和录制年份。使用3GP文件格式[PSS-3GP]中的base64编码资产框描述不同的资产。
The MBMS specification [MBMS] defines a number of different SDP attributes for different purposes. They are informatively listed below.
MBMS规范[MBMS]为不同目的定义了许多不同的SDP属性。下文详细列出了它们。
The session- and media-level attribute "a=mbms-mode" (see Section 7.3.2.7 of [MBMS]) is used to describe MBMS broadcast mode media. The attribute may be used at the session level to set the default for all media and at the media level to specify differences between media. However, the attribute is never used at the session level when the session includes MBMS multicast mode media, nor at the media level to describe MBMS multicast mode media.
会话和媒体级属性“a=mbms模式”（见[mbms]第7.3.2.7节）用于描述mbms广播模式媒体。该属性可在会话级别用于设置所有介质的默认值，在介质级别用于指定介质之间的差异。但是，当会话包括MBMS多播模式媒体时，该属性从不在会话级别使用，也不在媒体级别用于描述MBMS多播模式媒体。
The media-level attribute "a=mbms-flowid" (see Section 8.3.1.9 of [MBMS]) maps one or more FEC source block flow IDs to their corresponding destination IP addresses and UDP port numbers. It is present in each SDP media block for repair packet streams.
媒体级属性“a=mbms flowid”（见[mbms]第8.3.1.9节）将一个或多个FEC源块流ID映射到其相应的目标IP地址和UDP端口号。它存在于每个SDP媒体块中，用于修复数据包流。
The session- and media-level attribute "a=mbms-repair" (see Section 8.3.1.8 of [MBMS]) is used to provide FEC repair packets with non-FEC specific parameters. For Release 6, one such parameter is defined to specify the required minimum receiver buffer time.
会话和媒体级属性“a=mbms修复”（见[mbms]第8.3.1.8节）用于提供具有非FEC特定参数的FEC修复数据包。对于版本6，定义了一个这样的参数来指定所需的最小接收器缓冲时间。
MBMS defines a mechanism to provide block-based FEC for UDP-based traffic. This solution uses the SDP protocol "proto" identifier to identify the media streams that use the FEC shim layer. The media
MBMS定义了一种机制，用于为基于UDP的流量提供基于块的FEC。此解决方案使用SDP协议“proto”标识符来标识使用FEC垫片层的媒体流。媒体
streams may be either source streams or repair streams. As required by SDP [RFC4566], these protocol identifiers are normatively defined in this document in accordance with their usage specified by 3GPP.
流可以是源流或修复流。根据SDP[RFC4566]的要求，这些协议标识符在本文件中根据3GPP规定的用途进行规范性定义。
For FEC-protected RTP streams, the following two "proto" identifiers are defined:
对于FEC保护的RTP流，定义了以下两个“proto”标识符：
o UDP/MBMS-FEC/RTP/AVP
o UDP/MBMS-FEC/RTP/AVP
o UDP/MBMS-FEC/RTP/SAVP
o UDP/MBMS-FEC/RTP/SAVP
They indicate the usage of UDP [RFC0768] with MBMS FEC source packet formats, as defined in Section 8.2.2.4 of [MBMS], that transport RTP packets in accordance with the AVP [RFC3551] or SAVP (Secure RTP) [RFC3711] profiles, respectively. These protocol identifiers SHALL use the media formats ("fmt") namespace rules that are used for RTP/ AVP and RTP/SAVP, respectively.
它们表示UDP[RFC0768]与MBMS FEC源数据包格式的使用，如[MBMS]第8.2.2.4节所定义，分别根据AVP[RFC3551]或SAVP（安全RTP）[RFC3711]配置文件传输RTP数据包。这些协议标识符应分别使用RTP/AVP和RTP/SAVP使用的媒体格式（“fmt”）命名空间规则。
A media stream carrying MBMS FEC repair information over UDP requires its own "proto" identifier. Protocol identifier "UDP/MBMS-REPAIR" identifies the FEC repair packet containing the protocol combination of UDP [RFC0768], FEC repair payload ID, and repair symbols as specified in Section 8.2.2.5 of [MBMS]. The "fmt" namespace is not used and SHALL be set to "*".
通过UDP传输MBMS FEC修复信息的媒体流需要自己的“proto”标识符。协议标识符“UDP/MBMS-REPAIR”标识包含UDP[RFC0768]、FEC修复有效负载ID和[MBMS]第8.2.2.5节中规定的修复符号的协议组合的FEC修复数据包。不使用“fmt”名称空间，应将其设置为“*”。
The PSS media-level buffer attribute "a=X-initpredecbufperiod" (see Section 4.1) that specifies an initial buffering time is also used for MBMS in Release 7. It is mainly intended for video streams, but may be used for other media types as well (see Section 8.3.1.1 of [MBMS]).
PSS媒体级缓冲区属性“a=X-initpredecbufperiod”（见第4.1节），用于指定初始缓冲时间，也用于版本7中的MBMS。它主要用于视频流，但也可用于其他媒体类型（见[MBMS]第8.3.1.1节）。
The usage of the SDP attributes in an offer/answer [RFC3264] context is not defined. These SDP attributes are defined for use in a declarative context, and for PSS specifically in the RTSP [RFC2326] context.
未定义提供/应答[RFC3264]上下文中SDP属性的用法。这些SDP属性定义为在声明性上下文中使用，特别是在RTSP[RFC2326]上下文中用于PSS。
The RTSP extensions for PSS consist of a number of new RTSP headers and option tags and a narrowing of URI usage in regards to 3GP files. The headers and option tags are informatively described here; see [PSS-234] for the normative declaration.
PSS的RTSP扩展包括许多新的RTSP头和选项标记，并缩小了3GP文件的URI使用范围。此处对标题和选项标记进行了详细描述；规范性声明见[PSS-234]。
The "3GPP-Link-Char" header (see Section 5.3.2.1 of [PSS-234]) is used by clients to provide the server with QoS information about the wireless link it is currently using. The header can be used to provide the server with three different QoS parameters:
客户端使用“3GPP链路字符”报头（参见[PSS-234]第5.3.2.1节）向服务器提供有关其当前使用的无线链路的QoS信息。标头可用于向服务器提供三个不同的QoS参数：
o Guaranteed Bandwidth
o 保证带宽
o Maximum Bandwidth
o 最大带宽
o Maximum Transfer Delay
o 最大传输延迟
The header may be included in RTSP requests using either of the methods SETUP, PLAY, OPTIONS, or SET_PARAMETER.
报头可以使用SETUP、PLAY、OPTIONS或SET_参数中的任何一种方法包含在RTSP请求中。
The "3GPP-Adaptation" header (see Section 5.3.2.2 of [PSS-234]) is used by the client to provide the server with adaptation-related parameters and to indicate support of the adaptation function. The header carries the resource identification as a URI, the client's buffer size, and the desired target time.
客户端使用“3GPP适配”报头（参见[PSS-234]第5.3.2.2节）向服务器提供适配相关参数，并指示对适配功能的支持。标头以URI的形式携带资源标识、客户端的缓冲区大小和所需的目标时间。
The header may be included in requests using the methods SETUP, PLAY, OPTIONS, and SET_PARAMETER. The response to a request using this method shall include this header.
可以使用方法SETUP、PLAY、OPTIONS和SET_参数在请求中包括标头。使用此方法对请求的响应应包括此标头。
The "3GPP-QoE-Metrics" header (see Section 5.3.2.3.1 of [PSS-234]) is used to negotiate the usage of the QoE metrics (see Section 11 of [PSS-234]).
“3GPP QoE指标”标题（见[PSS-234]第5.3.2.3.1节）用于协商QoE指标的使用（见[PSS-234]第11节）。
The header may be included in requests and responses using the SETUP, SET_PARAMETER, OPTIONS, or PLAY method.
可以使用SETUP、SET_参数、OPTIONS或PLAY方法将标头包括在请求和响应中。
The "3GPP-QoE-Feedback" header (see Section 5.3.2.3.2 of [PSS-234]) is used to carry QoE metrics from the client to the server when it reports, which happens either during or at the end of the media delivery.
“3GPP QoE反馈”标头（见[PSS-234]第5.3.2.3.2节）用于在报告时将QoE指标从客户端传送到服务器，报告发生在媒体交付期间或结束时。
The header may be included in requests using the SET_PARAMETER, PAUSE, or TEARDOWN method.
可以使用SET_参数、PAUSE或TEARDOWN方法在请求中包括报头。
PSS uses several headers to provide the client with the different buffer parameters. They provide the buffer status at the point of a stream from which a PLAY request plays. These headers may only be used in PLAY responses. See Section 5.3.2.4 and Annex G of [PSS-234] for normative definitions.
PSS使用多个头向客户机提供不同的缓冲区参数。它们在播放请求的流点提供缓冲区状态。这些标题只能在播放响应中使用。规范性定义见[PSS-234]第5.3.2.4节和附录G。
The three "x-" headers were defined in 3GPP Release 5. When it was realized that they should not have been given "x-" names, it was too late to rename them due to deployment.
三个“x-”头在3GPP版本5中定义。当意识到它们不应该被命名为“x-”名称时，由于部署的原因，对它们进行重命名为时已晚。
The RTSP headers are:
RTSP标头包括：
o x-predecbufsize
o x-predecbufsize
o x-initpredecbufperiod
o x-initpredecbufperiod
o x-initpostdecbufperiod
o x-初始后十二周期
o 3gpp-videopostdecbufsize
o 3gpp videopostdecbufsize
The integrity-protection mechanism defined in PSS Annex K uses the "3GPP-Freshness-Token" RTSP header (see Section K.2.2.4 of [PSS-234]) to carry a freshness token in DESCRIBE requests.
PSS附录K中定义的完整性保护机制使用“3GPP新鲜度令牌”RTSP报头（见[PSS-234]第K.2.2.4节）在请求中携带新鲜度令牌。
The PSS specification also defines syntax for referencing tracks within the 3GP file format [PSS-3GP]. The 3GP format is based on the ISO base media file format and is defined in several different profiles, including a streaming-server profile, in Release 6.
PSS规范还定义了3GP文件格式[PSS-3GP]中引用磁道的语法。3GP格式基于ISO基本媒体文件格式，并在几个不同的配置文件中定义，包括版本6中的流媒体服务器配置文件。
This syntax is fully contained within the generic URI syntax defined for RTSP URIs. It is only a syntax restriction that server manufacturers follow to allow clients or proxies to understand what encodes the track number in the URI. This is provided for information only.
此语法完全包含在为RTSP URI定义的通用URI语法中。这只是服务器制造商遵循的语法限制，以允许客户端或代理理解URI中的曲目编号编码。这仅供参考。
To identify a track within a 3GP file, the last URI segment has to contain a structure that is <alpha string>=<track nr>. (See Section 5.3.3.1 of [PSS-234].)
要识别3GP文件中的曲目，最后一个URI段必须包含<alpha string>=<track nr>结构。（见[PSS-234]第5.3.3.1节）
Release 7 of PSS defines a number of extensions in terms of headers and option tags (see Section 5.5 of [PSS-234]) for support of fast start-up and switching of content for on-demand and live applications built on top of PSS. Clients are enabled to reuse the existing RTSP control session and RTP resources while switching to new content.
PSS第7版在标题和选项标签方面定义了许多扩展（见[PSS-234]第5.5节），以支持在PSS之上构建的按需和实时应用程序的快速启动和内容切换。客户端可以在切换到新内容时重用现有RTSP控制会话和RTP资源。
The RTSP headers are:
RTSP标头包括：
o Switch-Stream
o 交换流
o SDP-Requested
o SDP请求
o Pipelined-Requests
o 流水线请求
The RTSP option tags are:
RTSP选项标签包括：
o 3gpp-pipelined
o 3gpp流水线
o 3gpp-switch
o 3gpp交换机
o 3gpp-switch-req-sdp
o 3gpp交换机请求sdp
o 3gpp-switch-stream
o 3gpp交换流
IANA has registered the SDP attributes listed below in the "Session Description Protocol (SDP) Parameters" registry available from http://www.iana.org/.
IANA已在“会话描述协议（SDP）参数”注册表中注册了下列SDP属性，该注册表可从http://www.iana.org/.
The contact person for this registration is Magnus Westerlund (email: magnus.westerlund@ericsson.com; phone: +46 8 719 0000).
此注册的联系人是Magnus Westerlund（电子邮件：Magnus。westerlund@ericsson.com电话：+468719 0000）。
SDP Protocol Identifiers ("proto"):
SDP协议标识符（“协议”）：
Name: UDP/MBMS-FEC/RTP/AVP Long form: 3GPP MBMS FEC-protected RTP/AVP over UDP Type of name: proto Purpose: 3GPP MBMS defines a mechanism to provide block-based FEC for UDP-based traffic. This solution uses the SDP protocol "proto" identifier to identify the media streams that use the FEC shim layer. This protocol identifier indicates that the FEC-protected data is RTP using the AVP profile. Reference: RFC 6064, 3GPP TS 26.346
名称：UDP/MBMS-FEC/RTP/AVP长格式：3GPP MBMS FEC通过UDP保护RTP/AVP名称类型：协议用途：3GPP MBMS定义了一种机制，用于为基于UDP的流量提供基于块的FEC。此解决方案使用SDP协议“proto”标识符来标识使用FEC垫片层的媒体流。此协议标识符表示FEC保护的数据是使用AVP配置文件的RTP。参考：RFC6064，3GPP TS 26.346
Name: UDP/MBMS-FEC/RTP/SAVP Long form: 3GPP MBMS FEC-protected RTP/SAVP over UDP Type of name: proto Purpose: 3GPP MBMS defines a mechanism to provide block-based FEC for UDP-based traffic. This solution uses the SDP protocol "proto" identifier to identify the media streams that use the FEC shim layer. This protocol identifier indicates that the FEC-protected data is RTP using the Secure AVP profile (SAVP). Reference: RFC 6064, 3GPP TS 26.346
名称：UDP/MBMS-FEC/RTP/SAVP长格式：3GPP MBMS FEC通过UDP保护RTP/SAVP名称类型：协议用途：3GPP MBMS定义了一种机制，用于为基于UDP的流量提供基于块的FEC。此解决方案使用SDP协议“proto”标识符来标识使用FEC垫片层的媒体流。此协议标识符表示FEC保护的数据是使用安全AVP配置文件（SAVP）的RTP。参考：RFC6064，3GPP TS 26.346
Name: UDP/MBMS-REPAIR Long form: 3GPP MBMS FEC repair symbols over UDP Type of name: proto Purpose: 3GPP MBMS defines a mechanism to provide block-based FEC for UDP-based traffic. This solution uses the SDP protocol "proto" identifier to identify the media streams that use the FEC shim layer. This protocol identifier indicates that the FEC repair data is sent over UDP. Reference: RFC 6064, 3GPP TS 26.346
名称：UDP/MBMS-REPAIR长格式：3GPP MBMS FEC UDP上的修复符号名称类型：协议用途：3GPP MBMS定义了一种机制，用于为基于UDP的流量提供基于块的FEC。此解决方案使用SDP协议“proto”标识符来标识使用FEC垫片层的媒体流。此协议标识符指示通过UDP发送FEC修复数据。参考：RFC6064，3GPP TS 26.346
SDP Attribute ("att-field"):
SDP属性（“att字段”）：
Attribute name: X-predecbufsize Long form: Pre-decoder buffer size Type of name: att-field Type of attribute: Media level only Subject to charset: No Purpose: See Section 4.1 Reference: 3GPP TS 26.234, Section 5.3.3.2 Values: See Reference
属性名称：X-predecbufsize长格式：预解码器缓冲区大小名称类型：att字段类型属性类型：媒体级别仅受字符集限制：无用途：参见第4.1节参考：3GPP TS 26.234，第5.3.3.2节值：参见参考
Attribute name: X-initpredecbufperiod Long form: Pre-decoder initial buffering period Type of name: att-field Type of attribute: Media level only Subject to charset: No Purpose: See Section 4.1 Reference: 3GPP TS 26.234, Section 5.3.3.2 Values: See Reference
属性名称：X-initpredecbufperiod长格式：预解码器初始缓冲期名称类型：att字段属性类型：仅受字符集约束的媒体级别：无用途：参见第4.1节参考：3GPP TS 26.234，第5.3.3.2节值：参见参考
Attribute name: X-initpostdecbufperiod Long form: Post-decoder initial buffering period Type of name: att-field Type of attribute: Media level only Subject to charset: No Purpose: See Section 4.1 Reference: 3GPP TS 26.234, Section 5.3.3.2 Values: See Reference
属性名称：X-initpostdecbufperiod长格式：后解码器初始缓冲期名称类型：att字段属性类型：仅受字符集约束的媒体级别：无用途：参见第4.1节参考：3GPP TS 26.234，第5.3.3.2节值：参见参考
Attribute name: X-decbyterate Long form: Peak decoding rate in bytes per second Type of name: att-field Type of attribute: Media level only Subject to charset: No Purpose: See Section 4.1 Reference: 3GPP TS 26.234, Section 5.3.3.2 Values: See Reference
属性名称：X-Decbytate长格式：峰值解码速率（字节/秒）名称类型：att字段属性类型：仅受字符集限制的媒体级别：无用途：参见第4.1节参考：3GPP TS 26.234，第5.3.3.2节值：参见参考
Attribute name: 3gpp-videopostdecbufsize Long form: Post decoder buffer size Type of name: att-field Type of attribute: Media level only Subject to charset: No Purpose: See Section 4.1 Reference: 3GPP TS 26.234, Section 5.3.3.2 Values: See Reference
属性名称：3gpp videopostdecbufsize长格式：后解码器缓冲区大小名称类型：att字段类型属性类型：媒体级别仅受字符集限制：无用途：参见第4.1节参考：3gpp TS 26.234，第5.3.3.2节值：参见参考
Attribute name: framesize Long form: Maximum Video Frame Size Type of name: att-field Type of attribute: Media level only Subject to charset: No Purpose: See Section 4.2 Reference: 3GPP TS 26.234, Section 5.3.3.2 Values: See Reference
属性名称：帧大小长格式：最大视频帧大小名称类型：att字段类型属性：媒体级别仅受字符集限制：无用途：参见第4.2节参考：3GPP TS 26.234，第5.3.3.2节值：参见参考
Attribute name: 3GPP-Integrity-Key Long form: 3GPP DRM Integrity Key Type of name: att-field Type of attribute: Session level only Subject to charset: No Purpose: See Section 4.3 Reference: 3GPP TS 26.234, Sections 5.3.3.2 and K.2.2.1 Values: See Reference
属性名称：3GPP完整性密钥长格式：3GPP DRM完整性密钥名称类型：att字段属性类型：会话级别仅受字符集限制：无用途：参见第4.3节参考：3GPP TS 26.234、第5.3.3.2节和K.2.2.1值：参见参考
Attribute name: 3GPP-SRTP-Config Long form: 3GPP DRM SRTP Configuration Type of name: att-field Type of attribute: Media level only Subject to charset: No Purpose: See Section 4.3 Reference: 3GPP TS 26.234, Sections 5.3.3.2 and K.2.2.2 Values: See Reference
属性名称：3GPP SRTP配置长格式：3GPP DRM SRTP配置名称类型：att字段属性类型：仅受字符集约束的媒体级别：无用途：参见第4.3节参考：3GPP TS 26.234、第5.3.3.2节和K.2.2.2值：参见参考
Attribute name: 3GPP-SDP-Auth Long form: 3GPP DRM Integrity SDP Authentication Type of name: att-field Type of attribute: Session level only Subject to charset: No Purpose: See Section 4.3 Reference: 3GPP TS 26.234, Sections 5.3.3.2 and K.2.2.3 Values: See Reference
属性名称：3GPP SDP Auth Long form:3GPP DRM Integrity SDP身份验证名称类型：att字段属性类型：仅受字符集约束的会话级别：无用途：参见第4.3节参考：3GPP TS 26.234、第5.3.3.2节和第K.2.2.3.3节值：参见参考
Attribute name: alt Long form: Alternative SDP line Type of name: att-field Type of attribute: Media level only Subject to charset: No Purpose: See Section 4.4 Reference: 3GPP TS 26.234, Section 5.3.3.3 Values: See Reference
属性名称：alt长格式：可选SDP行名称类型：att字段属性类型：仅受字符集约束的媒体级别：无用途：参见第4.4节参考：3GPP TS 26.234，第5.3.3.3节值：参见参考
Attribute name: alt-default-id Long form: Default alternative ID Type of name: att-field Type of attribute: Media level only Subject to charset: No Purpose: See Section 4.4 Reference: 3GPP TS 26.234, Section 5.3.3.3 Values: See Reference
属性名称：alt default id长格式：默认备选id名称类型：att字段属性类型：仅受字符集约束的媒体级别：无用途：参见第4.4节参考：3GPP TS 26.234，第5.3.3.3节值：参见参考
Attribute name: alt-group Long form: Grouping of SDP Line alternatives Type of name: att-field Type of attribute: Session level only Subject to charset: No Purpose: See Section 4.4 Reference: 3GPP TS 26.234, Section 5.3.3.4 Values: See Reference
属性名称：alt group长格式：SDP行备选方案分组名称类型：att字段属性类型：仅受字符集约束的会话级别：无用途：参见第4.4节参考：3GPP TS 26.234，第5.3.3.4节值：参见参考
Attribute name: 3GPP-Adaptation-Support Long form: 3GPP Adaptation Support Type of name: att-field Type of attribute: Media level only Subject to charset: No Purpose: See Section 4.5 Reference: 3GPP TS 26.234, Section 5.3.3.5 Values: See Reference
属性名称：3GPP适配支持长格式：3GPP适配支持类型名称：att字段类型属性：媒体级别仅受字符集限制：无用途：参见第4.5节参考：3GPP TS 26.234，第5.3.3.5节值：参见参考
Attribute name: 3GPP-QoE-Metrics Long form: 3GPP Quality of Experience Metrics Type of name: att-field Type of attribute: Session and Media level Subject to charset: No Purpose: See Section 4.6 Reference: 3GPP TS 26.234, Section 5.3.3.6 Values: See Reference
属性名称：3GPP QoE度量长格式：3GPP体验质量度量名称类型：att字段属性类型：会话和媒体级别取决于字符集：无目的：参见第4.6节参考：3GPP TS 26.234，第5.3.3.6节值：参见参考
Attribute name: 3GPP-Asset-Information Long form: 3GPP Asset Information Type of name: att-field Type of attribute: Session and Media level Subject to charset: No Purpose: See Section 4.7 Reference: 3GPP TS 26.234, Section 5.3.3.7 Values: See Reference
属性名称：3GPP资产信息长格式：3GPP资产信息名称类型：att字段属性类型：会话和媒体级别取决于字符集：无用途：参见第4.7节参考：3GPP TS 26.234，第5.3.3.7节值：参见参考
Attribute name: mbms-mode Long form: MBMS Bearer Mode Declaration Type of name: att-field Type of attribute: Session and Media level Subject to charset: No Purpose: See Section 5.1 Reference: 3GPP TS 26.346, Section 7.3.2.7 Values: See Reference
属性名称：mbms模式长格式：mbms承载模式声明名称类型：att字段属性类型：会话和媒体级别取决于字符集：无用途：参见第5.1节参考：3GPP TS 26.346，第7.3.2.7节值：参见参考
Attribute name: mbms-flowid Long form: FEC Flow ID Type of name: att-field Type of attribute: Media level Subject to charset: No Purpose: See Section 5.2 Reference: 3GPP TS 26.346, Section 8.3.1.9 Values: See Reference
属性名称：mbms flowid长格式：FEC Flow ID名称类型：att字段属性类型：媒体级别取决于字符集：无用途：参见第5.2节参考：3GPP TS 26.346，第8.3.1.9节值：参见参考
Attribute name: mbms-repair Long form: MBMS Repair Type of name: att-field Type of attribute: Session and Media level Subject to charset: No Purpose: See Section 5.3 Reference: 3GPP TS 26.346, Section 8.3.1.8 Values: See Reference
属性名称：mbms修复长格式：mbms修复类型名称：att字段类型属性：会话和媒体级别取决于字符集：无用途：参见第5.3节参考：3GPP TS 26.346，第8.3.1.8节值：参见参考
IANA has registered the RTSP headers listed below in the RTSP/1.0 Headers table of the "Real Time Streaming Protocol (RTSP)/1.0 Parameters" registry available from http://www.iana.org/.
IANA已在“实时流协议（RTSP）/1.0参数”注册表的RTSP/1.0标头表中注册了以下列出的RTSP标头，该注册表可从http://www.iana.org/.
Note: This registry requires a Standards document, preferably an IETF RFC. The document that defines the registered headers below is a technical standards document from 3GPP, although the request for registration is submitted using this document to achieve further information spreading within IETF.
注：此注册表需要标准文档，最好是IETF RFC。下面定义注册标题的文档是来自3GPP的技术标准文档，尽管注册请求是使用该文档提交的，以实现IETF内的进一步信息传播。
The contact person for this registration is Magnus Westerlund (email: magnus.westerlund@ericsson.com; phone: +46 8 719 0000).
此注册的联系人是Magnus Westerlund（电子邮件：Magnus。westerlund@ericsson.com电话：+468719 0000）。
Header Name: 3GPP-Freshness-Token Purpose: See Section K.2 of 3GPP TS 26.234 Methods: DESCRIBE Requests Reference: Section K.2.2.4 of 3GPP TS 26.234 Values: See Reference
标题名称：3GPP新鲜度令牌用途：参见3GPP TS 26.234第K.2节方法：描述请求参考：3GPP TS 26.234第K.2.2.4节值：参见参考
Header Name: 3GPP-Link-Char Purpose: See Section 5.3.2.1 of 3GPP TS 26.234 Methods: SETUP, PLAY, OPTIONS, or SET_PARAMETER Requests Reference: Section 5.3.2.1 of 3GPP TS 26.234 Values: See Reference
标题名称：3GPP链接字符用途：参见3GPP TS 26.234第5.3.2.1节方法：设置、播放、选项或设置参数请求参考：3GPP TS 26.234第5.3.2.1节值：参见参考
Header Name: 3GPP-Adaptation Purpose: See Section 5.3.2.2 of 3GPP TS 26.234 Methods: SETUP, PLAY, OPTIONS, or SET_PARAMETER Requests and Responses Reference: Section 5.3.2.2 of 3GPP TS 26.234 Values: See Reference
标题名称：3GPP适配用途：参见3GPP TS 26.234第5.3.2.2节方法：设置、播放、选项或设置_参数请求和响应参考：3GPP TS 26.234第5.3.2.2节值：参见参考
Header Name: 3GPP-QoE-Metrics Purpose: See Section 5.3.2.3.1 of 3GPP TS 26.234 Methods: SETUP, PLAY, OPTIONS, or SET_PARAMETER Requests and Responses Reference: Section 5.3.2.3.1 of 3GPP TS 26.234 Values: See Reference
标题名称：3GPP QoE指标用途：参见3GPP TS 26.234第5.3.2.3.1节方法：设置、播放、选项或设置参数请求和响应参考：3GPP TS 26.234第5.3.2.3.1节值：参见参考
Header Name: 3GPP-QoE-Feedback Purpose: See Section 5.3.2.3.2 of 3GPP TS 26.234 Methods: SET_PARAMETER, PAUSE, or TEARDOWN Requests Reference: Section 5.3.2.3.2 of 3GPP TS 26.234 Values: See Reference
标题名称：3GPP QoE反馈目的：参见3GPP TS 26.234第5.3.2.3.2节方法：设置参数、暂停或拆卸请求参考：3GPP TS 26.234第5.3.2.3.2节值：参见参考
Header Name: Switch-Stream Purpose: See Section 5.5.4.2 of 3GPP TS 26.234 Methods: PLAY Requests and Responses Reference: Section 5.5.4.2 of 3GPP TS 26.234 Values: See Reference
标题名称：交换机流用途：参见3GPP TS 26.234第5.5.4.2节方法：播放请求和响应参考：3GPP TS 26.234第5.5.4.2节值：参见参考
Header Name: SDP-Requested Purpose: See Section 5.5.4.4 of 3GPP TS 26.234 Methods: PLAY Requests Reference: Section 5.5.4.4 of 3GPP TS 26.234 Values: See Reference
报头名称：SDP请求用途：参见3GPP TS 26.234第5.5.4.4节方法：播放请求参考：3GPP TS 26.234第5.5.4.4节值：参见参考
Header Name: Pipelined-Requests Purpose: See Section 5.5.3 of 3GPP TS 26.234 Methods: SETUP and PLAY Requests Reference: Section 5.5.3 of 3GPP TS 26.234 Values: See Reference
标题名称：流水线请求用途：参见3GPP TS 26.234第5.5.3节方法：设置和播放请求参考：3GPP TS 26.234第5.5.3节值：参见参考
Header Name: x-predecbufsize Purpose: See Section 5.3.2.4 of 3GPP TS 26.234 Methods: PLAY Response Reference: Section 5.3.2.4 of 3GPP TS 26.234 Values: See Reference
标题名称：x-predecbufsize用途：参见3GPP TS 26.234第5.3.2.4节方法：播放响应参考：3GPP TS 26.234第5.3.2.4节值：参见参考
Header Name: x-initpredecbufperiod Purpose: See Section 5.3.2.4 of 3GPP TS 26.234 Methods: PLAY Response Reference: Section 5.3.2.4 of 3GPP TS 26.234 Values: See Reference
报头名称：x-initpredecbufperiod用途：参见3GPP TS 26.234第5.3.2.4节方法：播放响应参考：3GPP TS 26.234第5.3.2.4节值：参见参考
Header Name: x-initpostdecbufperiod Purpose: See Section 5.3.2.4 of 3GPP TS 26.234 Methods: PLAY Response Reference: Section 5.3.2.4 of 3GPP TS 26.234 Values: See Reference
报头名称：x-initpostdecbufperiod用途：参见3GPP TS 26.234第5.3.2.4节方法：播放响应参考：3GPP TS 26.234第5.3.2.4节值：参见参考
Header Name: 3gpp-videopostdecbufsize Purpose: See Section 5.3.2.4 of 3GPP TS 26.234 Methods: PLAY Response Reference: Section 5.3.2.4 of 3GPP TS 26.234 Values: See Reference
标题名称：3gpp videopostdecbufsize用途：参见3gpp TS 26.234第5.3.2.4节方法：播放响应参考：3gpp TS 26.234第5.3.2.4节值：参见参考
Header Name: Supported Purpose: See Section 5.5.2.2.2 of 3GPP TS 26.234 Methods: Any Request and Response Reference: Section 5.5.2.2.2 of 3GPP TS 26.234 Values: See Reference
标题名称：支持用途：参见3GPP TS 26.234第5.5.2.2节方法：任何请求和响应参考：3GPP TS 26.234第5.5.2.2.2节值：参见参考
IANA has registered the RTSP Option tags (option tags) listed below in the RTSP/1.0 Option Tags table of the "Real Time Streaming Protocol (RTSP)/1.0 Parameters" registry available from http://www.iana.org/.
IANA已在“实时流协议（RTSP）/1.0参数”注册表的RTSP/1.0选项标签表中注册了下面列出的RTSP选项标签（选项标签），可从http://www.iana.org/.
Option tag: 3gpp-pipelined Purpose: See Section 5.5.3 of 3GPP TS 26.234 Applies to: Client and Server Reference: Section 5.5.3 of 3GPP TS 26.234 Values: See Reference
选项标签：3gpp流水线用途：参见3gpp TS 26.234第5.5.3节适用于：客户端和服务器参考：3gpp TS 26.234第5.5.3节值：参见参考
Option tag: 3gpp-switch Purpose: See Section 5.5.4.2 of 3GPP TS 26.234 Applies to: Client and Server Reference: Section 5.5.4.2 of 3GPP TS 26.234 Values: See Reference
选项标签：3gpp交换机用途：参见3gpp TS 26.234第5.5.4.2节适用于：客户端和服务器参考：3gpp TS 26.234第5.5.4.2节值：参见参考
Option tag: 3gpp-switch-req-sdp Purpose: See Section 5.5.4.4 of 3GPP TS 26.234 Applies to: Client and Server Reference: Section 5.5.4.4 of 3GPP TS 26.234 Values: See Reference
选项标签：3gpp交换机请求sdp用途：参见3gpp TS 26.234第5.5.4.4节适用于：客户端和服务器参考：3gpp TS 26.234第5.5.4.4节值：参见参考
Option tag: 3gpp-switch-stream Purpose: See Section 5.5.4.5 of 3GPP TS 26.234 Applies to: Client and Server Reference: Section 5.5.4.5 of 3GPP TS 26.234 Values: See Reference
选项标签：3gpp交换机流用途：参见3gpp TS 26.234第5.5.4.5节适用于：客户端和服务器参考：3gpp TS 26.234第5.5.4.5节值：参见参考
SDP attributes are subject to modification by an attacker unless they are integrity protected and authenticated. The security considerations of the SDP specification [RFC4566] should be reviewed in this regard. The registered SDP attributes are vulnerable to modification attacks or removal, which may result in problems of a serious nature, including failure to use service and reduced quality.
SDP属性可能会被攻击者修改，除非它们受到完整性保护并经过身份验证。在这方面，应审查SDP规范[RFC4566]的安全注意事项。注册的SDP属性容易受到修改攻击或删除，这可能导致严重的问题，包括无法使用服务和质量降低。
The registered RTSP headers are also vulnerable to insertion, deletion, or modification attacks similar to SDP attributes. Also in this case, attacks can result in failure of the service or reduced quality of streaming content.
注册的RTSP头也容易受到类似于SDP属性的插入、删除或修改攻击。同样在这种情况下，攻击可能导致服务失败或流媒体内容质量降低。
The three SDP protocol identifiers do not by themselves introduce any additional security threats that don't exist for other protocol identifiers in SDP. The media stream and the used protocols identified and configured by the SDP protocol identifier may, however, contain security issues by themselves.
三个SDP协议标识符本身不会带来SDP中其他协议标识符不存在的任何额外安全威胁。然而，由SDP协议标识符识别和配置的媒体流和所使用的协议本身可能包含安全问题。
[MBMS] 3GPP TS 26.346 version 7.10.0 (2009-03), "Multimedia Broadcast/Multicast Service (MBMS); Protocols and codecs".
[MBMS]3GPP TS 26.346版本7.10.0（2009-03），“多媒体广播/多播服务（MBMS）；协议和编解码器”。
[PSS-234] 3GPP TS 26.234 version 7.7.0 (2009-03), "Transparent end-to-end Packet-switched Streaming Service (PSS); Protocols and codecs".
[PSS-234]3GPP TS 26.234版本7.7.0（2009-03），“透明端到端分组交换流媒体服务（PSS）；协议和编解码器”。
[PSS-3GP] 3GPP TS 26.244 version 7.3.0 (2007-12), "Transparent end-to-end packet switched streaming service (PSS); 3GPP file format (3GP)".
[PSS-3GP]3GPP TS 26.244版本7.3.0（2007-12），“透明端到端分组交换流媒体服务（PSS）；3GPP文件格式（3GP）”。
[RFC0768] Postel, J., "User Datagram Protocol", STD 6, RFC 768, August 1980.
[RFC0768]Postel，J.，“用户数据报协议”，STD 6，RFC 768，1980年8月。
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2119]Bradner，S.，“RFC中用于表示需求水平的关键词”，BCP 14，RFC 2119，1997年3月。
[RFC3551] Schulzrinne, H. and S. Casner, "RTP Profile for Audio and Video Conferences with Minimal Control", STD 65, RFC 3551, July 2003.
[RFC3551]Schulzrinne，H.和S.Casner，“具有最小控制的音频和视频会议的RTP配置文件”，STD 65，RFC 3551，2003年7月。
[RFC3711] Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K. Norrman, "The Secure Real-time Transport Protocol (SRTP)", RFC 3711, March 2004.
[RFC3711]Baugher，M.，McGrew，D.，Naslund，M.，Carrara，E.，和K.Norrman，“安全实时传输协议（SRTP）”，RFC 37112004年3月。
[AES] NIST, "Advanced Encryption Standard (AES)", FIPS PUB 197, <http://www.nist.gov/itl/fipscurrent.cfm>.
[AES]NIST，“高级加密标准（AES）”，FIPS PUB 197<http://www.nist.gov/itl/fipscurrent.cfm>.
[PSS-233] 3GPP TS 26.233 version 7.0.0 (2007-06), "Transparent end-to-end packet switched streaming service (PSS) General Description".
[PSS-233]3GPP TS 26.233版本7.0.0（2007-06），“透明端到端分组交换流媒体服务（PSS）一般说明”。
[RFC2326] Schulzrinne, H., Rao, A., and R. Lanphier, "Real Time Streaming Protocol (RTSP)", RFC 2326, April 1998.
[RFC2326]Schulzrinne，H.，Rao，A.，和R.Lanphier，“实时流协议（RTSP）”，RFC2326，1998年4月。
[RFC3264] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model with Session Description Protocol (SDP)", RFC 3264, June 2002.
[RFC3264]Rosenberg，J.和H.Schulzrinne，“具有会话描述协议（SDP）的提供/应答模型”，RFC 3264，2002年6月。
[RFC3890] Westerlund, M., "A Transport Independent Bandwidth Modifier for the Session Description Protocol (SDP)", RFC 3890, September 2004.
[RFC3890]Westerlund，M.“会话描述协议（SDP）的传输无关带宽修改器”，RFC 38902004年9月。
[RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session Description Protocol", RFC 4566, July 2006.
[RFC4566]Handley，M.，Jacobson，V.，和C.Perkins，“SDP：会话描述协议”，RFC4566，2006年7月。
[RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data Encodings", RFC 4648, October 2006.
[RFC4648]Josefsson，S.，“Base16、Base32和Base64数据编码”，RFC4648，2006年10月。
Authors' Addresses
作者地址
Magnus Westerlund Ericsson Farogatan 6 Stockholm SE-164 80 SWEDEN
Magnus Westerlund Ericsson Farogatan 6斯德哥尔摩SE-164 80瑞典
Phone: +46 10 7190000
Fax: +46 10 757 55 50
EMail: magnus.westerlund@ericsson.com
Phone: +46 10 7190000
Fax: +46 10 757 55 50
EMail: magnus.westerlund@ericsson.com
Per Frojdh Ericsson Farogatan 6 Stockholm SE-164 80 SWEDEN
Per Frojdh Ericsson Farogatan 6斯德哥尔摩SE-164 80瑞典
Phone: +46 10 7190000
Fax: +46 10 757 55 50
EMail: per.frojdh@ericsson.com
Phone: +46 10 7190000
Fax: +46 10 757 55 50
EMail: per.frojdh@ericsson.com