Internet Engineering Task Force (IETF) A. Clark
Request for Comments: 7005 Telchemy
Category: Standards Track V. Singh
ISSN: 2070-1721 Aalto University
Q. Wu
Huawei
September 2013
Internet Engineering Task Force (IETF) A. Clark
Request for Comments: 7005 Telchemy
Category: Standards Track V. Singh
ISSN: 2070-1721 Aalto University
Q. Wu
Huawei
September 2013
RTP Control Protocol (RTCP) Extended Report (XR) Block for De-Jitter Buffer Metric Reporting
用于去抖动缓冲区度量报告的RTP控制协议（RTCP）扩展报告（XR）块
Abstract
摘要
This document defines an RTP Control Protocol (RTCP) Extended Report (XR) block that allows the reporting of de-jitter buffer metrics for a range of RTP applications.
本文档定义了一个RTP控制协议（RTCP）扩展报告（XR）块，该块允许报告一系列RTP应用程序的去抖动缓冲区指标。
Status of This Memo
关于下段备忘
This is an Internet Standards Track document.
这是一份互联网标准跟踪文件。
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). Further information on Internet Standards is available in 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。有关互联网标准的更多信息，请参见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/rfc7005.
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/rfc7005.
Copyright Notice
版权公告
Copyright (c) 2013 IETF Trust and the persons identified as the document authors. All rights reserved.
版权所有（c）2013 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. De-Jitter Buffer Metrics Block . . . . . . . . . . . . . . 3
1.2. RTCP and RTCP Extended Reports . . . . . . . . . . . . . . 3
1.3. Performance Metrics Framework . . . . . . . . . . . . . . 3
1.4. Applicability . . . . . . . . . . . . . . . . . . . . . . 3
2. Standards Language . . . . . . . . . . . . . . . . . . . . . . 4
3. De-Jitter Buffer Operation . . . . . . . . . . . . . . . . . . 4
3.1. Idealized De-Jitter Buffer . . . . . . . . . . . . . . . . 4
3.2. Fixed De-Jitter Buffer . . . . . . . . . . . . . . . . . . 5
3.3. Adaptive De-Jitter Buffer . . . . . . . . . . . . . . . . 5
4. De-Jitter Buffer Metrics Block . . . . . . . . . . . . . . . . 6
4.1. Report Block Structure . . . . . . . . . . . . . . . . . . 6
4.2. Definition of Fields in De-Jitter Buffer Metrics Block . . 6
5. SDP Signaling . . . . . . . . . . . . . . . . . . . . . . . . 9
5.1. SDP rtcp-xr-attrib Attribute Extension . . . . . . . . . . 9
5.2. Offer/Answer Usage . . . . . . . . . . . . . . . . . . . . 9
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
6.1. New RTCP XR Block Type Value . . . . . . . . . . . . . . . 9
6.2. New RTCP XR SDP Parameter . . . . . . . . . . . . . . . . 10
6.3. Contact Information for Registrations . . . . . . . . . . 10
7. Security Considerations . . . . . . . . . . . . . . . . . . . 10
8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 10
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 10
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10
10.1. Normative References . . . . . . . . . . . . . . . . . . . 10
10.2. Informative References . . . . . . . . . . . . . . . . . . 11
Appendix A. Metrics Represented Using the Template from
RFC 6390 . . . . . . . . . . . . . . . . . . . . . . 12
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. De-Jitter Buffer Metrics Block . . . . . . . . . . . . . . 3
1.2. RTCP and RTCP Extended Reports . . . . . . . . . . . . . . 3
1.3. Performance Metrics Framework . . . . . . . . . . . . . . 3
1.4. Applicability . . . . . . . . . . . . . . . . . . . . . . 3
2. Standards Language . . . . . . . . . . . . . . . . . . . . . . 4
3. De-Jitter Buffer Operation . . . . . . . . . . . . . . . . . . 4
3.1. Idealized De-Jitter Buffer . . . . . . . . . . . . . . . . 4
3.2. Fixed De-Jitter Buffer . . . . . . . . . . . . . . . . . . 5
3.3. Adaptive De-Jitter Buffer . . . . . . . . . . . . . . . . 5
4. De-Jitter Buffer Metrics Block . . . . . . . . . . . . . . . . 6
4.1. Report Block Structure . . . . . . . . . . . . . . . . . . 6
4.2. Definition of Fields in De-Jitter Buffer Metrics Block . . 6
5. SDP Signaling . . . . . . . . . . . . . . . . . . . . . . . . 9
5.1. SDP rtcp-xr-attrib Attribute Extension . . . . . . . . . . 9
5.2. Offer/Answer Usage . . . . . . . . . . . . . . . . . . . . 9
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
6.1. New RTCP XR Block Type Value . . . . . . . . . . . . . . . 9
6.2. New RTCP XR SDP Parameter . . . . . . . . . . . . . . . . 10
6.3. Contact Information for Registrations . . . . . . . . . . 10
7. Security Considerations . . . . . . . . . . . . . . . . . . . 10
8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 10
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 10
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10
10.1. Normative References . . . . . . . . . . . . . . . . . . . 10
10.2. Informative References . . . . . . . . . . . . . . . . . . 11
Appendix A. Metrics Represented Using the Template from
RFC 6390 . . . . . . . . . . . . . . . . . . . . . . 12
This document defines a new block type to augment those defined in [RFC3611] for use in a range of RTP applications.
本文件定义了一种新的块类型，以扩充[RFC3611]中定义的块类型，以便在一系列RTP应用中使用。
The new block type provides information on de-jitter buffer configuration and performance.
新的块类型提供关于去抖动缓冲配置和性能的信息。
The metric belongs to the class of transport-related end-system metrics defined in [RFC6792].
该指标属于[RFC6792]中定义的与传输相关的终端系统指标类别。
Instances of this metrics block refer by synchronization source (SSRC) to the separate auxiliary Measurement Information Block [RFC6776], which contains information such as the SSRC of the measured stream, and RTP sequence numbers and time intervals indicating the span of the report.
此度量块的实例通过同步源（SSRC）指向单独的辅助度量信息块[RFC6776]，该信息块包含测量流的SSRC、RTP序列号和指示报告范围的时间间隔等信息。
The use of RTCP for reporting is defined in [RFC3550]. [RFC3611] defines an extensible structure for reporting using an RTCP Extended Report (XR). This document defines a new Extended Report block for use with [RFC3550] and [RFC3611].
[RFC3550]中定义了使用RTCP进行报告。[RFC3611]定义了使用RTCP扩展报告（XR）进行报告的可扩展结构。本文档定义了一个新的扩展报告块，用于[RFC3550]和[RFC3611]。
"Guidelines for Considering New Performance Metric Development" [RFC6390] provides guidance on the definition and specification of performance metrics. "Guidelines for Use of the RTP Monitoring Framework" [RFC6792] provides guidance on the reporting block format using RTCP XR. Metrics described in this document are in accordance with the guidelines in [RFC6390]and [RFC6792].
“考虑制定新绩效指标的指南”[RFC6390]提供了关于绩效指标定义和规范的指南。“RTP监控框架使用指南”[RFC6792]提供了使用RTCP XR的报告块格式指南。本文件中描述的指标符合[RFC6390]和[RFC6792]中的指南。
Real-time applications employ a de-jitter buffer [RFC5481] to absorb jitter introduced on the path from source to destination. These metrics are used to report how the de-jitter buffer at the receiving end of the RTP stream behaves as a result of jitter in the network; they are applicable to a range of RTP applications.
实时应用程序使用去抖动缓冲器[RFC5481]来吸收从源到目标的路径上引入的抖动。这些量度用于报告RTP流的接收端的去抖动缓冲器作为网络中的抖动的结果的行为；它们适用于一系列RTP应用。
These metrics correspond to terminal-related factors that affect real-time application quality and are useful for providing a better end-user quality of experience (QoE) when these terminal-related factors are used as inputs to calculate QoE metrics [QMB].
这些指标对应于影响实时应用程序质量的终端相关因素，当这些终端相关因素用作计算QoE指标[QMB]的输入时，这些指标有助于提供更好的最终用户体验质量（QoE）。
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。
A de-jitter buffer is required to absorb delay variation in the network delivery of media packets. A de-jitter buffer works by holding media data for a period of time after it is received and before it is played out. Packets that arrive early are held in the de-jitter buffer longer. If packets arrive too early, they may be discarded if there is no available de-jitter buffer space. If packets are delayed excessively by the network, they may be discarded if they miss their playout time.
需要一个去抖动缓冲器来吸收媒体分组的网络传输中的延迟变化。去抖动缓冲区的工作原理是在接收到媒体数据后和播放之前将其保存一段时间。提前到达的数据包在去抖动缓冲区中保留的时间更长。如果数据包到达得太早，如果没有可用的去抖动缓冲区空间，它们可能会被丢弃。如果数据包被网络过度延迟，如果它们错过了播放时间，可能会被丢弃。
The de-jitter buffer can be considered a time window with the early edge aligned with the delay corresponding to the earliest arriving packet and the late edge representing the maximum permissible delay before a late arriving packet would be discarded. The delay applied to packets that arrive on time or at their expected arrival time is known as the nominal delay, and this is equivalent to the time difference/buffer size difference between the insertion point of the on-time packets and the point at which the packets are read out.
解抖动缓冲器可以被视为一个时间窗口，其早边缘与对应于最早到达的分组的延迟对齐，晚边缘表示丢弃晚到达分组之前的最大允许延迟。应用于准时到达或在其预期到达时间到达的分组的延迟被称为标称延迟，并且这相当于准时分组的插入点和分组被读出的点之间的时差/缓冲器大小差。
The reference for the expected arrival time may be, for example, the first packet in the session or the running average delay. If all packets arrived at their expected arrival time, then every packet would be held in the de-jitter buffer exactly the nominal delay.
预期到达时间的参考例如可以是会话中的第一个分组或运行平均延迟。如果所有数据包都在其预期到达时间到达，那么每个数据包都将被保存在去抖动缓冲区中，精确到标称延迟。
The de-jitter buffer maximum delay is the delay that is applied to the earliest arriving packet that is not discarded and corresponds to the early edge of the de-jitter buffer time window.
解抖动缓冲区最大延迟是应用于未丢弃的最早到达的数据包的延迟，并且对应于解抖动缓冲区时间窗口的早期边缘。
In practice, de-jitter buffer implementations vary considerably; however, they should behave in a manner conceptually consistent with an idealized de-jitter buffer, which is described as follows:
在实践中，去抖动缓冲器的实现差别很大；但是，它们的行为方式应与理想化去抖动缓冲器在概念上一致，描述如下：
(i) Receive the first packet and delay playout by D ms. Keep the RTP timestamp (TS) and receive time as a reference.
(i) 通过D ms接收第一个数据包和延迟播放。保留RTP时间戳（TS）和接收时间作为参考。
RTP TS[1]
RTP TS[1]
receive time[1]
接收时间[1]
Assume that both are normalized in ticks (there are 10,000 ticks in a millisecond).
假设两者都以滴答为单位进行标准化（一毫秒内有10000个滴答）。
(ii) Receive the next packet.
（ii）接收下一个数据包。
(iii) Calculate r = RTP TS[n] - RTP TS[1] and t = receive time[n] - receive time[1]. If r == t, then the packet arrived on time. If r < t, then the packet arrived late, and if r > t, then the packet arrived early.
（iii）计算r=RTP TS[n]-RTP TS[1]和t=接收时间[n]-接收时间[1]。如果r==t，则数据包准时到达。如果r<t，则数据包延迟到达，如果r>t，则数据包提前到达。
(iv) Delay playout of packet by D + (r-t).
（iv）通过D+（r-t）延迟数据包播放。
(v) Go back to (ii).
(v) 回到（ii）。
Note that this idealized implementation assumes that the sender's RTP clock is synchronized to the clock in the receiver, which is used to timestamp packet arrivals. If there is no such inherent synchronization, the system may need to use an adaptive de-jitter buffer or other techniques to ensure reliable reception.
注意，这种理想化的实现假设发送方的RTP时钟与接收机中的时钟同步，用于对数据包到达进行时间戳。如果没有这种固有的同步，系统可能需要使用自适应去抖动缓冲器或其他技术来确保可靠的接收。
A fixed de-jitter buffer lacks provision to track the condition of the network and has a fixed size, and packets leaving the de-jitter buffer have a constant delay. For fixed de-jitter buffer implementation, the nominal delay is set to a constant value corresponding to the packets that arrive at their expected arrival time, while the maximum delay is set to a constant value corresponding to the fixed size of the de-jitter buffer.
固定去抖动缓冲区缺少跟踪网络状况的设备，并且具有固定的大小，离开去抖动缓冲区的数据包具有恒定的延迟。对于固定去抖动缓冲器实现，标称延迟被设置为与到达其预期到达时间的分组相对应的恒定值，而最大延迟被设置为与去抖动缓冲器的固定大小相对应的恒定值。
An adaptive de-jitter buffer can adapt to the change in the network's delay and has variable size or variable delay. It allows the nominal delay to be set to a low value initially to minimize user perceived delay; however, it can automatically extend the late edge (and possibly also retract the early edge) of a buffer window if a significant proportion of the packets are arriving late (and hence being discarded).
自适应去抖动缓冲器能够适应网络延迟的变化，具有可变大小或可变延迟。它允许初始将标称延迟设置为低值，以最小化用户感知的延迟；然而，如果有很大一部分数据包延迟到达（因此被丢弃），它可以自动扩展缓冲窗口的延迟边缘（也可能收回早期边缘）。
This block describes the configuration and operating parameters of the de-jitter buffer in the receiver of the RTP end system or RTP mixer that sends the report. Instances of this metrics block use the SSRC to refer to the separate auxiliary Measurement Information Block [RFC6776], which describes the measurement periods in use (see [RFC6776], Section 4.2). This metrics block relies on the measurement interval in the Measurement Information Block indicating the span of the report and MUST be sent in the same compound RTCP packet as the Measurement Information Block. If the measurement interval is not received in the same compound RTCP packet as this metrics block, this metrics block MUST be discarded.
此块描述发送报告的RTP终端系统或RTP混频器接收器中的去抖动缓冲器的配置和操作参数。该度量块的实例使用SSRC引用单独的辅助度量信息块[RFC6776]，该信息块描述了使用中的度量周期（参见[RFC6776]，第4.2节）。此度量块依赖于度量信息块中指示报告范围的度量间隔，并且必须在与度量信息块相同的复合RTCP数据包中发送。如果在与此度量块相同的复合RTCP数据包中未接收到测量间隔，则必须丢弃此度量块。
De-Jitter Buffer (DJB) Metrics Block
去抖动缓冲区（DJB）度量块
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BT=23 | I |C| resv | Block Length=3 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SSRC of Source |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DJB nominal | DJB maximum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DJB high-water mark | DJB low-water mark |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BT=23 | I |C| resv | Block Length=3 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SSRC of Source |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DJB nominal | DJB maximum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DJB high-water mark | DJB low-water mark |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Report Block Structure
图1：报告块结构
Block Type (BT): 8 bits
块类型（BT）：8位
A De-Jitter Buffer Metrics Report Block is identified by the constant 23.
去抖动缓冲器度量报告块由常数23标识。
Interval Metric flag (I): 2 bits
间隔度量标志（I）：2位
This field is used to indicate whether the de-jitter buffer metrics are Sampled, Interval, or Cumulative metrics:
此字段用于指示去抖动缓冲区度量是采样、间隔还是累积度量：
I=01: Sampled Value - the reported value is a sampled instantaneous value.
I=01：采样值-报告值为采样瞬时值。
I=10: Interval Duration - the reported value applies to the most recent measurement interval duration between successive metrics reports.
I=10：间隔持续时间-报告值适用于连续度量报告之间的最新度量间隔持续时间。
I=11: Cumulative Duration - the reported value applies to the accumulation period characteristic of cumulative measurements.
I=11：累积持续时间-报告值适用于累积测量的累积周期特征。
In this document, de-jitter buffer metrics can only be sampled and cannot be measured over definite intervals. Also, the value I=00 is reserved for future use. Senders MUST NOT use the values I=00, I=10, or I=11. If a block is received with I=00, I=10, or I=11, the receiver MUST discard the block.
在本文档中，去抖动缓冲区度量只能进行采样，不能在确定的时间间隔内进行测量。此外，值I=00保留供将来使用。发件人不得使用值I=00、I=10或I=11。如果接收到I=00、I=10或I=11的块，则接收器必须丢弃该块。
Jitter Buffer Configuration (C): 1 bit
抖动缓冲配置（C）：1位
This field is used to identify the de-jitter buffer method in use at the receiver, according to the following code:
根据以下代码，该字段用于识别接收机中使用的去抖动缓冲方法：
0 = Fixed de-jitter buffer
0 = Fixed de-jitter buffer
1 = Adaptive de-jitter buffer
1 = Adaptive de-jitter buffer
Reserved (resv): 5 bits
保留（resv）：5位
These bits are reserved. They MUST be set to zero by senders and ignored by receivers (see [RFC6709], Section 4.2).
这些位是保留的。发送方必须将其设置为零，接收方必须忽略（见[RFC6709]，第4.2节）。
Block Length: 16 bits
块长度：16位
The length of this report block in 32-bit words, minus one, in accordance with the definition in [RFC3611]. This field MUST be set to 3 to match the fixed length of the report block.
根据[RFC3611]中的定义，此报告块的长度（以32位字减去1表示）。此字段必须设置为3，以匹配报告块的固定长度。
SSRC of Source: 32 bits
源的SSRC：32位
As defined in Section 4.1 of [RFC3611].
如[RFC3611]第4.1节所定义。
De-jitter buffer nominal delay (DJB nominal): 16 bits
去抖动缓冲器标称延迟（DJB标称）：16位
This is the current nominal de-jitter buffer delay (in milliseconds) that corresponds to the nominal de-jitter buffer delay for packets that arrive exactly on time. It is calculated based on the time spent in the de-jitter buffer for the packet that arrives exactly on time. This parameter MUST be provided for both fixed and adaptive de-jitter buffer implementations.
这是当前标称去抖动缓冲延迟（毫秒），对应于准时到达的数据包的标称去抖动缓冲延迟。它是根据准确按时到达的数据包在去抖动缓冲区中所花费的时间来计算的。必须为固定和自适应去抖动缓冲区实现提供此参数。
The measured value is an unsigned value. If the measured value exceeds 0xFFFD, the value 0xFFFE MUST be reported to indicate an over-range measurement. If the measurement is unavailable, the value 0xFFFF MUST be reported.
测量值为无符号值。如果测量值超过0xFFFD，则必须报告值0xFFFE以指示超量程测量。如果测量不可用，则必须报告值0xFFFF。
De-jitter buffer maximum delay (DJB maximum): 16 bits
去抖动缓冲区最大延迟（DJB最大）：16位
This is the current maximum de-jitter buffer delay (in milliseconds) that corresponds to the earliest arriving packet that would not be discarded. It is calculated based on the time spent in the de-jitter buffer for the earliest arriving packet. In simple queue implementations, this may correspond to the size of the de-jitter buffer. In adaptive de-jitter buffer implementations, this value may vary dynamically. This parameter MUST be provided for both fixed and adaptive de-jitter buffer implementations.
这是与不会丢弃的最早到达的数据包相对应的当前最大去抖动缓冲延迟（毫秒）。它是根据最早到达的数据包在去抖动缓冲区中花费的时间来计算的。在简单队列实现中，这可能对应于去抖动缓冲区的大小。在自适应去抖动缓冲区实现中，该值可能会动态变化。必须为固定和自适应去抖动缓冲区实现提供此参数。
The measured value is an unsigned value. If the measured value exceeds 0xFFFD, the value 0xFFFE MUST be reported to indicate an over-range measurement. If the measurement is unavailable, the value 0xFFFF MUST be reported.
测量值为无符号值。如果测量值超过0xFFFD，则必须报告值0xFFFE以指示超量程测量。如果测量不可用，则必须报告值0xFFFF。
De-jitter buffer high-water mark (DJB high-water mark): 16 bits
去抖动缓冲器高水位线（DJB高水位线）：16位
This is the highest value of the de-jitter buffer nominal delay (in milliseconds) that occurred at any time during the reporting interval. This parameter MUST be provided for adaptive de-jitter buffer implementations, and its value MUST be set to DJB maximum for fixed de-jitter buffer implementations.
这是报告间隔内任何时间发生的去抖动缓冲区标称延迟（以毫秒为单位）的最高值。必须为自适应去抖动缓冲区实现提供此参数，对于固定去抖动缓冲区实现，其值必须设置为DJB最大值。
The measured value is an unsigned value. If the measured value exceeds 0xFFFD, the value 0xFFFE MUST be reported to indicate an over-range measurement. If the measurement is unavailable, the value 0xFFFF MUST be reported.
测量值为无符号值。如果测量值超过0xFFFD，则必须报告值0xFFFE以指示超量程测量。如果测量不可用，则必须报告值0xFFFF。
De-jitter buffer low-water mark (DJB low-water mark): 16 bits
去抖动缓冲器低水位线（DJB低水位线）：16位
This is the lowest value of the de-jitter buffer nominal delay (in milliseconds) that occurred at any time during the reporting interval. This parameter MUST be provided for adaptive de-jitter buffer implementations, and its value MUST be set to DJB maximum for fixed de-jitter buffer implementations.
这是报告间隔内任何时间发生的去抖动缓冲区标称延迟（以毫秒为单位）的最低值。必须为自适应去抖动缓冲区实现提供此参数，对于固定去抖动缓冲区实现，其值必须设置为DJB最大值。
The measured value is an unsigned value. If the measured value exceeds 0xFFFD, the value 0xFFFE MUST be reported to indicate an over-range measurement. If the measurement is unavailable, the value 0xFFFF MUST be reported.
测量值为无符号值。如果测量值超过0xFFFD，则必须报告值0xFFFE以指示超量程测量。如果测量不可用，则必须报告值0xFFFF。
[RFC3611] defines the use of the Session Description Protocol (SDP) [RFC4566] for signaling the use of XR blocks. However, XR blocks MAY be used without prior signaling (see Section 5 of RFC 3611).
[RFC3611]定义了会话描述协议（SDP）[RFC4566]的使用，用于发送使用XR块的信号。然而，可以在没有事先信令的情况下使用XR块（参见RFC 3611的第5节）。
This section augments the SDP [RFC4566] attribute "rtcp-xr" defined in [RFC3611] by providing an additional value of "xr-format" to signal the use of the report block defined in this document.
本节增加了[RFC3611]中定义的SDP[RFC4566]属性“rtcp xr”，提供了“xr format”的附加值，以表示使用了本文档中定义的报告块。
xr-format =/ xr-djb-block
xr format=/xr djb块
xr-djb-block = "de-jitter-buffer"
xr-djb-block = "de-jitter-buffer"
When SDP is used in Offer/Answer context [RFC3264], the SDP Offer/ Answer usage defined in [RFC3611] for unilateral "rtcp-xr" attribute parameters applies. For detailed usage of Offer/Answer for unilateral parameters, refer to Section 5.2 of [RFC3611].
当在提供/应答上下文[RFC3264]中使用SDP时，[RFC3611]中为单边“rtcp xr”属性参数定义的SDP提供/应答用法适用。有关单边参数的报价/应答的详细用法，请参阅[RFC3611]第5.2节。
New block types for RTCP XR are subject to IANA registration. For general guidelines on IANA considerations for RTCP XR, refer to [RFC3611].
RTCP XR的新块类型需要IANA注册。有关RTCP XR的IANA注意事项的一般指南，请参阅[RFC3611]。
This document assigns the block type value 23 in the IANA "RTP Control Protocol Extended Reports (RTCP XR) Block Type Registry" to the "De-Jitter Buffer Metrics Block".
本文档将IANA“RTP控制协议扩展报告（RTCP XR）块类型注册表”中的块类型值23分配给“去抖动缓冲区度量块”。
This document also registers a new parameter "de-jitter-buffer" in the "RTP Control Protocol Extended Reports (RTCP XR) Session Description Protocol (SDP) Parameters Registry".
本文档还在“RTP控制协议扩展报告（RTCP XR）会话描述协议（SDP）参数注册表”中注册一个新参数“去抖动缓冲区”。
The contact information for registrations is:
注册的联系信息为：
Qin Wu (sunseawq@huawei.com) 101 Software Avenue, Yuhua District Nanjing, Jiangsu 210012 China
秦武(sunseawq@huawei.com)中国江苏省南京市雨花区软件大道101号210012
It is believed that this RTCP XR block introduces no new security considerations beyond those described in [RFC3611]. This block does not provide per-packet statistics, so the risk to confidentiality documented in Section 7, paragraph 3 of [RFC3611] does not apply.
据信，除了[RFC3611]中所述的安全注意事项外，该RTCP XR块未引入任何新的安全注意事项。该块不提供每包统计数据，因此[RFC3611]第7节第3段中记录的保密风险不适用。
Geoff Hunt wrote the initial draft of this document.
杰夫·亨特撰写了这份文件的初稿。
The authors gratefully acknowledge reviews and feedback provided by Bruce Adams, Philip Arden, Amit Arora, Claire Bi, Bob Biskner, Benoit Claise, Kevin Connor, Claus Dahm, Spencer Dawkins, Randy Ethier, Roni Even, Jim Frauenthal, Kevin Gross, Albert Higashi, Tom Hock, Shane Holthaus, Paul Jones, Rajesh Kumar, Keith Lantz, Mohamed Mostafa, Amy Pendleton, Colin Perkins, Mike Ramalho, Ravi Raviraj, Dan Romascanu, Albrecht Schwarz, Tom Taylor, Hideaki Yamada, and Glen Zorn.
作者感谢Bruce Adams、Philip Arden、Amit Arora、Claire Bi、Bob Biskner、Benoit Claise、Kevin Connor、Claus Dahm、Spencer Dawkins、Randy Ethier、Roni Even、Jim Frauenthal、Kevin Gross、Albert Higashi、Tom Hock、Shane Holthaus、Paul Jones、Rajesh Kumar、Keith Lantz、Mohamed Mostafa、，艾米·彭德尔顿、科林·帕金斯、迈克·拉马霍、拉维·拉维拉吉、丹·罗马斯坎努、阿尔布雷希特·施瓦兹、汤姆·泰勒、山田英代基和格伦·佐恩。
[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。
[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。
[RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V. Jacobson, "RTP: A Transport Protocol for Real-Time Applications", STD 64, RFC 3550, July 2003.
[RFC3550]Schulzrinne，H.，Casner，S.，Frederick，R.，和V.Jacobson，“RTP：实时应用的传输协议”，STD 64，RFC 35502003年7月。
[RFC3611] Friedman, T., Caceres, R., and A. Clark, "RTP Control Protocol Extended Reports (RTCP XR)", RFC 3611, November 2003.
[RFC3611]Friedman，T.，Caceres，R.，和A.Clark，“RTP控制协议扩展报告（RTCP XR）”，RFC 36112003年11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。
[RFC6776] Clark, A. and Q. Wu, "Measurement Identity and Information Reporting Using a Source Description (SDES) Item and an RTCP Extended Report (XR) Block", RFC 6776, October 2012.
[RFC6776]Clark，A.和Q.Wu，“使用源描述（SDES）项和RTCP扩展报告（XR）块的测量标识和信息报告”，RFC 6776，2012年10月。
[QMB] Clark, A., "RTP Control Protocol (RTCP) Extended Report (XR) Blocks for QoE Metric Reporting", Work in Progress, May 2013.
[QMB]Clark，A.，“用于QoE度量报告的RTP控制协议（RTCP）扩展报告（XR）块”，正在进行的工作，2013年5月。
[RFC5481] Morton, A. and B. Claise, "Packet Delay Variation Applicability Statement", RFC 5481, March 2009.
[RFC5481]Morton，A.和B.Claise，“数据包延迟变化适用性声明”，RFC 54812009年3月。
[RFC6390] Clark, A. and B. Claise, "Guidelines for Considering New Performance Metric Development", BCP 170, RFC 6390, October 2011.
[RFC6390]Clark，A.和B.Claise，“考虑新性能指标开发的指南”，BCP 170，RFC 63902011年10月。
[RFC6709] Carpenter, B., Aboba, B., and S. Cheshire, "Design Considerations for Protocol Extensions", RFC 6709, September 2012.
[RFC6709]Carpenter，B.，Aboba，B.，和S.Cheshire，“协议扩展的设计考虑”，RFC 6709，2012年9月。
[RFC6792] Wu, Q., Hunt, G., and P. Arden, "Guidelines for Use of the RTP Monitoring Framework", RFC 6792, November 2012.
[RFC6792]Wu，Q.，Hunt，G.，和P.Arden，“RTP监控框架的使用指南”，RFC 6792，2012年11月。
a. De-Jitter Buffer Nominal Delay Metric
a. 去抖动缓冲器标称延迟度量
* Metric Name: De-jitter buffer nominal delay in RTP
* 度量名称：RTP中的去抖动缓冲区标称延迟
* Metric Description: The "expected arrival time" is the time that an RTP packet would arrive if there was no delay variation. The delay applied to packets that arrive at their expected time is known as the Nominal Delay.
* 度量说明：“预期到达时间”是指如果没有延迟变化，RTP数据包将到达的时间。应用于到达其预期时间的数据包的延迟称为标称延迟。
* Method of Measurement or Calculation: See Section 4.2, de-jitter buffer nominal delay definition.
* 测量或计算方法：见第4.2节，去抖动缓冲器标称延迟定义。
* Units of Measurement: See Section 4.2, de-jitter buffer nominal delay definition.
* 测量单位：见第4.2节，去抖动缓冲器标称延迟定义。
* Measurement Point(s) with Potential Measurement Domain: See Section 4.
* 具有潜在测量域的测量点：见第4节。
* Measurement Timing: See Section 4 for measurement timing and Section 4.2 for Interval Metric flag.
* 测量定时：测量定时见第4节，间隔度量标志见第4.2节。
* Use and Applications: See Section 1.4.
* 用途和应用：见第1.4节。
* Reporting Model: See RFC 3611.
* 报告模式：见RFC 3611。
b. De-Jitter Buffer Maximum Delay Metric
b. 去抖动缓冲区最大延迟度量
* Metric Name: De-jitter buffer maximum delay in RTP.
* 度量名称：RTP中的去抖动缓冲区最大延迟。
* Metric Description: It is the current maximum de-jitter buffer delay for RTP traffic that corresponds to the earliest arriving packet that would not be discarded.
* 度量说明：它是RTP流量的当前最大去抖动缓冲延迟，对应于不会被丢弃的最早到达的数据包。
* Method of Measurement or Calculation: See Section 4.2, de-jitter buffer maximum delay definition and Section 3, the last paragraph.
* 测量或计算方法：见第4.2节，去抖动缓冲器最大延迟定义和第3节，最后一段。
* Units of Measurement: See Section 4.2, de-jitter buffer maximum delay definition.
* 测量单位：见第4.2节，去抖动缓冲器最大延迟定义。
* Measurement Point(s) with Potential Measurement Domain: See Section 4.
* 具有潜在测量域的测量点：见第4节。
* Measurement Timing: See Section 4 for measurement timing and Section 4.2 for Interval Metric flag.
* 测量定时：测量定时见第4节，间隔度量标志见第4.2节。
* Use and Applications: See Section 1.4.
* 用途和应用：见第1.4节。
* Reporting Model: See RFC 3611.
* 报告模式：见RFC 3611。
c. De-Jitter Buffer High-Water Mark Metric
c. 去抖动缓冲区高水位指标
* Metric Name: De-jitter buffer high-water mark in RTP.
* 度量名称：RTP中的去抖动缓冲高水位标记。
* Metric Description: It is the highest value of the de-jitter buffer nominal delay for RTP traffic which occurred at any time during the reporting interval.
* 度量说明：它是报告间隔内任何时间发生的RTP流量的去抖动缓冲区标称延迟的最高值。
* Method of Measurement or Calculation: See Section 4.2, de-jitter buffer high-water mark definition.
* 测量或计算方法：见第4.2节，去抖动缓冲器高水位线定义。
* Units of Measurement: See Section 4.2, de-jitter buffer nominal delay definition.
* 测量单位：见第4.2节，去抖动缓冲器标称延迟定义。
* Measurement Point(s) with Potential Measurement Domain: See Section 4.
* 具有潜在测量域的测量点：见第4节。
* Measurement Timing: See Section 4 for measurement timing and Section 4.2 for Interval Metric flag.
* 测量定时：测量定时见第4节，间隔度量标志见第4.2节。
* Use and Applications: See Section 1.4.
* 用途和应用：见第1.4节。
* Reporting Model: See RFC 3611.
* 报告模式：见RFC 3611。
d. De-Jitter Buffer Low-Water Mark Metric
d. 去抖动缓冲低水位指标
* Metric Name: De-jitter buffer low-water mark in RTP.
* 度量名称：RTP中的去抖动缓冲低水位线。
* Metric Description: It is the lowest value of the de-jitter buffer nominal delay (for RTP traffic) that occurred at any time during the reporting interval.
* 度量说明：它是报告间隔内任何时间发生的去抖动缓冲区标称延迟（对于RTP流量）的最低值。
* Method of Measurement or Calculation: See Section 4.2, de-jitter buffer low-water mark definition.
* 测量或计算方法：见第4.2节，去抖动缓冲器低水位线定义。
* Units of Measurement: See Section 4.2, de-jitter buffer low water mark definition.
* 测量单位：见第4.2节，去抖动缓冲器低水位线定义。
* Measurement Point(s) with Potential Measurement Domain: See Section 4, 1st paragraph.
* 具有潜在测量域的测量点：见第4节第1段。
* Measurement Timing: See Section 4 for measurement timing and Section 4.2 for Interval Metric flag.
* 测量定时：测量定时见第4节，间隔度量标志见第4.2节。
* Use and Applications: See Section 1.4.
* 用途和应用：见第1.4节。
* Reporting Model: See RFC 3611.
* 报告模式：见RFC 3611。
Authors' Addresses
作者地址
Alan Clark Telchemy Incorporated 2905 Premiere Parkway, Suite 280 Duluth, GA 30097 USA
Alan Clark Telchemy Incorporated 2905 Premiere Parkway，美国佐治亚州德卢斯280号套房，邮编30097
EMail: alan.d.clark@telchemy.com
EMail: alan.d.clark@telchemy.com
Varun Singh Aalto University School of Electrical Engineering Otakaari 5 A Espoo, FIN 02150 Finland
瓦伦·辛格·阿尔托大学电气工程学院奥塔卡里5 A埃斯波，芬兰02150
EMail: varun@comnet.tkk.fi
EMail: varun@comnet.tkk.fi
Qin Wu Huawei 101 Software Avenue, Yuhua District Nanjing, Jiangsu 210012 China
中国江苏省南京市雨花区华为软件大道101号秦武210012
EMail: sunseawq@huawei.com
EMail: sunseawq@huawei.com