Internet Engineering Task Force (IETF) A. Clark
Request for Comments: 7294 Telchemy
Category: Standards Track G. Zorn
ISSN: 2070-1721 Network Zen
C. Bi
STTRI
Q. Wu
Huawei
July 2014
Internet Engineering Task Force (IETF) A. Clark
Request for Comments: 7294 Telchemy
Category: Standards Track G. Zorn
ISSN: 2070-1721 Network Zen
C. Bi
STTRI
Q. Wu
Huawei
July 2014
RTP Control Protocol (RTCP) Extended Report (XR) Blocks for Concealment Metrics Reporting on Audio Applications
RTP控制协议（RTCP）扩展报告（XR）块，用于在音频应用程序上报告隐藏度量
Abstract
摘要
This document defines two RTP Control Protocol (RTCP) Extended Report (XR) blocks that allow the reporting of concealment metrics for audio applications of RTP.
本文档定义了两个RTP控制协议（RTCP）扩展报告（XR）块，用于报告RTP音频应用的隐藏度量。
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/rfc7294.
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/rfc7294.
Copyright Notice
版权公告
Copyright (c) 2014 IETF Trust and the persons identified as the document authors. All rights reserved.
版权所有（c）2014 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 . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Loss Concealment and Concealed Seconds Metrics
Blocks . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.2. RTCP and RTCP Extended Reports . . . . . . . . . . . . . 3
1.3. Performance Metrics Framework . . . . . . . . . . . . . . 4
1.4. Applicability . . . . . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1. Standards Language . . . . . . . . . . . . . . . . . . . 4
2.2. Notations . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Loss Concealment Metrics Block . . . . . . . . . . . . . . . 5
3.1. Report Block Structure . . . . . . . . . . . . . . . . . 5
3.2. Definition of Fields in Loss Concealment Metrics Block . 5
4. Concealed Seconds Metrics Block . . . . . . . . . . . . . . . 9
4.1. Report Block Structure . . . . . . . . . . . . . . . . . 10
4.2. Definition of Fields in Concealed Seconds Metrics Block . 10
5. SDP Signaling . . . . . . . . . . . . . . . . . . . . . . . . 14
5.1. SDP rtcp-xr-attrib Attribute Extension . . . . . . . . . 14
5.2. Offer/Answer Usage . . . . . . . . . . . . . . . . . . . 14
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14
6.1. New RTCP XR Block Type Values . . . . . . . . . . . . . . 14
6.2. New RTCP XR SDP Parameters . . . . . . . . . . . . . . . 15
6.3. Contact Information for Registrations . . . . . . . . . . 15
7. Security Considerations . . . . . . . . . . . . . . . . . . . 15
8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 15
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 15
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 16
10.1. Normative References . . . . . . . . . . . . . . . . . . 16
10.2. Informative References . . . . . . . . . . . . . . . . . 16
Appendix A. Metrics Represented Using the Template from RFC 6390 17
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Loss Concealment and Concealed Seconds Metrics
Blocks . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.2. RTCP and RTCP Extended Reports . . . . . . . . . . . . . 3
1.3. Performance Metrics Framework . . . . . . . . . . . . . . 4
1.4. Applicability . . . . . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1. Standards Language . . . . . . . . . . . . . . . . . . . 4
2.2. Notations . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Loss Concealment Metrics Block . . . . . . . . . . . . . . . 5
3.1. Report Block Structure . . . . . . . . . . . . . . . . . 5
3.2. Definition of Fields in Loss Concealment Metrics Block . 5
4. Concealed Seconds Metrics Block . . . . . . . . . . . . . . . 9
4.1. Report Block Structure . . . . . . . . . . . . . . . . . 10
4.2. Definition of Fields in Concealed Seconds Metrics Block . 10
5. SDP Signaling . . . . . . . . . . . . . . . . . . . . . . . . 14
5.1. SDP rtcp-xr-attrib Attribute Extension . . . . . . . . . 14
5.2. Offer/Answer Usage . . . . . . . . . . . . . . . . . . . 14
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14
6.1. New RTCP XR Block Type Values . . . . . . . . . . . . . . 14
6.2. New RTCP XR SDP Parameters . . . . . . . . . . . . . . . 15
6.3. Contact Information for Registrations . . . . . . . . . . 15
7. Security Considerations . . . . . . . . . . . . . . . . . . . 15
8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 15
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 15
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 16
10.1. Normative References . . . . . . . . . . . . . . . . . . 16
10.2. Informative References . . . . . . . . . . . . . . . . . 16
Appendix A. Metrics Represented Using the Template from RFC 6390 17
At any instant, the audio output at a receiver may be classified as either 'normal' or 'concealed'. 'Normal' refers to playout of audio payload received from the remote end and also includes locally generated signals such as announcements, tones, and comfort noise. 'Concealed' refers to playout of locally generated signals used to mask the impact of network impairments or to reduce the audibility of jitter buffer adaptations.
在任何时刻，接收器上的音频输出都可能被归类为“正常”或“隐藏”“正常”指从远端接收的音频有效负载的播放，还包括本地生成的信号，如公告、铃声和舒适噪音“隐藏”是指本地生成信号的播放，用于掩盖网络损伤的影响或降低抖动缓冲区自适应的可听性。
This document defines two new concealment-related block types to augment those defined in [RFC3611] for use in a range of RTP applications. These two block types extend the packet loss concealment mechanism defined in Section 4.7.6 of [RFC3611].
本文档定义了两种新的与隐藏相关的块类型，以扩充[RFC3611]中定义的块类型，以便在一系列RTP应用中使用。这两种块类型扩展了[RFC3611]第4.7.6节中定义的丢包隐藏机制。
The first block type, the Loss Concealment Metrics Block, provides metrics for actions taken by the receiver to mitigate the effect of packet loss and packet discard. Specifically, the first metric (On-Time Playout Duration) reports the duration of normal playout of data that the receiver obtained from the sender's stream. A second metric (Loss Concealment Duration) reports the total time during which the receiver played out media data that was manufactured locally, because the sender's data for these periods was not available due to packet loss or discard. A similar metric (Buffer Adjustment Concealment Duration) reports the duration of playout of locally manufactured data replacing data that is unavailable due to adaptation of an adaptive de-jitter buffer. Further metrics (Playout Interrupt Count and Mean Playout Interrupt Size) report the number of times normal playout was interrupted and the mean duration of these interruptions.
第一种块类型，丢失隐藏度量块，为接收器采取的减轻分组丢失和分组丢弃影响的措施提供度量。具体地，第一度量（时间播放持续时间）报告接收器从发送方流获得的数据的正常播放的持续时间。第二个度量（丢失隐藏持续时间）报告接收器播放本地制造的媒体数据的总时间，因为发送方在这些时间段的数据由于数据包丢失或丢弃而不可用。类似的度量（缓冲区调整隐藏持续时间）报告本地制造的数据的播放持续时间，替换由于自适应去抖动缓冲区的自适应而不可用的数据。其他指标（播放中断计数和平均播放中断大小）报告正常播放中断的次数和这些中断的平均持续时间。
Loss Concealment Duration and Buffer Adjustment Concealment Duration are reported separately because buffer adjustment is typically arranged to occur in silence periods, so it may have very little impact on user experience, whilst loss concealment may occur at any time.
丢失隐藏持续时间和缓冲区调整隐藏持续时间是分开报告的，因为缓冲区调整通常安排在静默期进行，因此对用户体验的影响很小，而丢失隐藏可能随时发生。
The second block type, the Concealed Seconds Metrics Block, provides metrics for Concealed Seconds, which are measured at the receiving end of the RTP stream. Specifically, the first metric (Unimpaired Seconds) reports the number of whole seconds occupied only with normal playout of data that the receiver obtained from the sender's stream. The second metric (Concealed Seconds) reports the number of whole seconds during which the receiver played out any locally generated media data. A third metric, Severely Concealed Seconds (SCSs), reports the number of whole seconds during which the receiver played out locally generated data to conceal a lost or discarded frame percentage in excess of the configured SCS Threshold.
第二种块类型，隐藏秒度量块，提供隐藏秒的度量，这些度量在RTP流的接收端测量。具体地说，第一个度量（未损坏的秒数）报告接收机从发送方流获得的数据的正常播放所占用的整秒数。第二个指标（隐藏秒）报告接收器播放任何本地生成的媒体数据的整秒数。第三个度量，严重隐藏秒（SCSs），报告接收机播放本地生成的数据以隐藏丢失或丢弃的帧百分比超过配置的SCS阈值的整秒数。
These metrics belongs to the class of transport-related terminal metrics defined in [RFC6792].
这些指标属于[RFC6792]中定义的运输相关终端指标类别。
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 that MUST be used as defined in [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。本文档定义了必须按照[RFC3550]和[RFC3611]中的定义使用的新扩展报告块。
The Performance Metrics Framework [RFC6390] provides guidance on the definition and specification of performance metrics. The RTP Monitoring Framework [RFC6792] provides guidelines for reporting block format using RTCP XR. The metrics blocks described in this document are in accordance with those guidelines.
性能指标框架[RFC6390]提供了有关性能指标定义和规范的指导。RTP监控框架[RFC6792]提供了使用RTCP XR报告块格式的指南。本文档中描述的度量块符合这些指南。
These metrics are applicable to audio applications of RTP and the audio component of audio/video applications in which the packet loss concealment machinery is contained at the receiving end to mitigate the impact of network impairments to user's perception of media quality.
这些量度适用于RTP的音频应用和音频/视频应用的音频组件，其中分组丢失隐藏机制包含在接收端以减轻网络损伤对用户对媒体质量的感知的影响。
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。
The report blocks in this document make use of binary fractions. The following terminology is used:
本文档中的报告块使用二进制分数。使用以下术语：
Numeric formats S X:Y
数字格式S X:Y
where S indicates a two's complement signed representation, X the number of bits prior to the decimal place, and Y the number of bits after the decimal place.
其中S表示2的补码符号表示，X表示小数点前的位数，Y表示小数点后的位数。
Hence, 8:8 represents an unsigned number in the range 0.0 to 255.996 with a granularity of 0.0039. S7:8 would represent the range -127.996 to +127.996. 0:16 represents a proper binary fraction with range
因此，8:8表示0.0到255.996范围内的无符号数，粒度为0.0039。S7:8表示-127.996至+127.996的范围。0:16表示具有范围的适当二进制分数
0.0 to 1 - 1/65536 = 0.9999847
0.0 to 1 - 1/65536 = 0.9999847
though note that use of flag values at the top of the numeric range slightly reduces this upper limit. For example, if the 16-bit values 0xFFFE and 0xFFFF are used as flags for "over-range" and "unavailable" conditions, a 0:16 quantity has range
但请注意，在数值范围顶部使用标志值会略微降低此上限。例如，如果16位值0xFFFE和0xFFFF用作“超出范围”和“不可用”条件的标志，则0:16的数量具有范围
0.0 to 1 - 3/65536 = 0.9999542
0.0 to 1 - 3/65536 = 0.9999542
The Loss Concealment Metrics Block is intended to be used as described in this section, in conjunction with information from the Measurement Information Block [RFC6776]. Instances of this metrics block refer by synchronization source (SSRC) to the separate auxiliary Measurement Information Block [RFC6776], which describes measurement periods in use (see [RFC6776], Section 4.2). This metrics block relies on the measurement period in the Measurement Information Block indicating the span of the report and SHOULD be sent in the same compound RTCP packet as the Measurement Information Block. If the measurement period is not received in the same compound RTCP packet as this metrics block, this metrics block MUST be discarded.
如本节所述，损失隐藏度量块将与测量信息块[RFC6776]中的信息一起使用。此度量块的实例按同步源（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周期，并且应在与度量信息块相同的复合RTCP数据包中发送。如果测量周期未在与此度量块相同的复合RTCP数据包中接收，则必须丢弃此度量块。
The structure of the Loss Concealment Metrics Block is as follows.
丢失隐藏度量块的结构如下所示。
0 1 2 3
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BT=30 | I |plc| resv | block length=6 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SSRC of Source |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| On-Time Playout Duration |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Loss Concealment Duration |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Buffer Adjustment Concealment Duration |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Playout Interrupt Count | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Mean Playout Interrupt Size |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
0 1 2 3
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BT=30 | I |plc| resv | block length=6 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SSRC of Source |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| On-Time Playout Duration |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Loss Concealment Duration |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Buffer Adjustment Concealment Duration |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Playout Interrupt Count | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Mean Playout Interrupt Size |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Loss Concealment Metrics Block
图1：损失隐藏度量块
Block type (BT): 8 bits
块类型（BT）：8位
A Loss Concealment Metrics Block is identified by the constant 30.
丢失隐藏度量块由常数30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 loss concealment metrics are Sampled, Interval, or Cumulative metrics:
此字段用于指示损失隐藏度量是采样、间隔还是累积度量：
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。
I=01: Sampled Value - the reported value is a sampled instantaneous value (not allowed in this block).
I=01：采样值-报告值为采样瞬时值（此块中不允许）。
I=00: Reserved value - this value is reserved for future use.
I=00：保留值-此值保留供将来使用。
In this document, Loss Concealment metrics can only be measured over definite intervals and cannot be sampled. Senders MUST NOT use the values I=00 or I=01. If a block is received with I=00 or I=01, the receiver MUST discard the block.
在本文件中，损失掩盖指标只能在确定的时间间隔内进行测量，不能进行抽样。发件人不得使用I=00或I=01的值。如果接收到I=00或I=01的块，接收器必须丢弃该块。
Packet Loss Concealment Method (plc): 2 bits
丢包隐藏方法（plc）：2位
This field is used to identify the packet loss concealment method in use at the receiver, according to the following code:
该字段用于根据以下代码识别在接收器处使用的分组丢失隐藏方法：
bits 014-015
比特014-015
0 = silence insertion
0 = silence insertion
1 = simple replay, no attenuation
1=简单回放，无衰减
2 = simple replay, with attenuation
2=简单回放，具有衰减
3 = enhancement
3 = enhancement
Other values are reserved.
其他值保留。
Note that the enhancement method (plc=3) for packet loss concealment offers an improved audio quality and better robustness against packet losses [G.711] and is equivalent to "enhanced" in Section 4.7.6 of [RFC3611].
注意，用于包丢失隐藏的增强方法（plc=3）提供了改进的音频质量和更好的抗包丢失鲁棒性[G.711]，相当于[RFC3611]第4.7.6节中的“增强”。
Reserved (resv): 4 bits
保留（resv）：4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. For the Loss Concealment Metrics Block, the block length is equal to 6.
此报表块的长度（32位字）减去1。对于丢失隐藏度量块，块长度等于6。
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。
On-Time Playout Duration: 32 bits
实时播放持续时间：32位
'On-time playout' is the uninterrupted, in-sequence playout of valid decoded audio information originating from the remote endpoint. This includes comfort noise during periods of remote talker silence, if Voice Activity Detection (VAD) [VAD] is used, and locally generated or regenerated tones and announcements.
“实时播放”是指不间断地按顺序播放来自远程端点的有效解码音频信息。这包括在使用语音活动检测（VAD）[VAD]的情况下，远程通话者静默期间的舒适噪音，以及本地生成或重新生成的音调和公告。
An equivalent definition is that on-time playout is playout of any signal other than those used for concealment.
等效的定义是，实时播放是指除用于隐藏的信号外的任何信号的播放。
On-time playout duration is expressed in units of RTP timestamp and MUST include both speech and silence intervals, whether VAD is used or not.
实时播放持续时间以RTP时间戳为单位表示，必须包括语音和静音间隔，无论是否使用VAD。
Two values are reserved: a value of 0xFFFFFFFE indicates out of range (that is, a measured value exceeding 0xFFFFFFFD), and a value of 0xFFFFFFFF indicates that the measurement is unavailable.
保留两个值：0xFFFFFE表示超出范围（即，测量值超过0xFFFFFD），0xFFFFFFFF表示测量不可用。
Loss Concealment Duration: 32 bits
丢失隐藏持续时间：32位
The duration, expressed in units of RTP timestamp, of audio playout corresponding to Loss-Type concealment.
与丢失类型隐藏相对应的音频播放的持续时间，以RTP时间戳为单位表示。
Loss-Type concealment is reactive insertion or deletion of samples in the audio playout stream due to effective frame loss at the audio decoder. Effective frame loss is the event in which a frame of coded audio is simply not present at the audio decoder when required. In this case, substitute audio samples are generally formed, at the decoder or elsewhere, to reduce audible impairment.
丢失类型隐藏是由于音频解码器处的有效帧丢失而在音频播放流中反应性地插入或删除样本。有效帧丢失是指在需要时音频解码器中根本不存在编码音频帧的事件。在这种情况下，通常在解码器处或其他地方形成替代音频样本，以减少听觉损伤。
Two values are reserved: a value of 0xFFFFFFFE indicates out of range (that is, a measured value exceeding 0xFFFFFFFD), and a value of 0xFFFFFFFF indicates that the measurement is unavailable.
保留两个值：0xFFFFFE表示超出范围（即，测量值超过0xFFFFFD），0xFFFFFFFF表示测量不可用。
Buffer Adjustment Concealment Duration: 32 bits
缓冲区调整隐藏持续时间：32位
The duration, expressed in units of RTP timestamp, of audio playout corresponding to Buffer Adjustment-Type concealment, if known.
与缓冲区调整类型隐藏（如果已知）相对应的音频播放的持续时间，以RTP时间戳为单位表示。
Buffer Adjustment-Type concealment is proactive or controlled insertion or deletion of samples in the audio playout stream due to jitter buffer adaptation, re-sizing decisions, or re-centering decisions within the endpoint.
缓冲区调整类型隐藏是由于抖动缓冲区自适应、重新调整大小决定或端点内的重新定心决定而在音频播放流中主动或受控地插入或删除样本。
Because this insertion is controlled, rather than occurring randomly in response to losses, it is typically less audible than Loss-Type concealment. For example, jitter buffer adaptation events may be constrained to occur during periods of talker silence, in which case only silence duration is affected, or sophisticated time-stretching methods for insertion/deletion during favorable periods in active speech may be employed.
由于这种插入是受控的，而不是响应丢失而随机发生，因此它通常比丢失类型的隐藏声音小。例如，抖动缓冲器适配事件可以被限制在说话者静默期间发生，在这种情况下，仅静默持续时间受到影响，或者可以使用复杂的时间拉伸方法来在活动语音的有利期间插入/删除。
Concealment events that cannot be classified as Buffer Adjustment-Type MUST be classified as Loss-Type.
不能归类为缓冲调整类型的隐藏事件必须归类为损失类型。
Two values are reserved: a value of 0xFFFFFFFE indicates out of range (that is, a measured value exceeding 0xFFFFFFFD), and a value of 0xFFFFFFFF indicates that the measurement is unavailable.
保留两个值：0xFFFFFE表示超出范围（即，测量值超过0xFFFFFD），0xFFFFFFFF表示测量不可用。
Playout Interrupt Count: 16 bits
播放中断计数：16位
The number of interruptions to normal playout that occurred during the reporting period.
报告期内正常播放中断的次数。
Two values are reserved: a value of 0xFFFE indicates out of range (that is, a measured value exceeding 0xFFFD), and a value of 0xFFFF indicates that the measurement is unavailable.
保留两个值：0xFFFE值表示超出范围（即，测量值超过0xFFFD），0xFFFF值表示测量不可用。
Reserved: 16 bits
保留：16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）。
Mean Playout Interrupt Size: 32 bits
平均播放中断大小：32位
The mean duration, expressed in units of RTP timestamp, of interruptions to normal playout that occurred during the reporting period.
报告期内正常播放中断的平均持续时间，以RTP时间戳为单位表示。
Two values are reserved: a value of 0xFFFFFFFE indicates out of range (that is, a measured value exceeding 0xFFFFFFFD), and a value of 0xFFFFFFFF indicates that the measurement is unavailable.
保留两个值：0xFFFFFE表示超出范围（即，测量值超过0xFFFFFD），0xFFFFFFFF表示测量不可用。
The Concealed Seconds Metrics Block is intended to be used as described in this section, in conjunction with information from the Measurement Information Block [RFC6776]. It provides a description of potentially audible impairments due to lost and discarded packets at the endpoint, expressed on a time basis analogous to a traditional Public Switched Telephone Network (PSTN) T1/E1 errored seconds metric. Instances of this metrics block refer by synchronization source (SSRC) to the separate auxiliary Measurement Information Block [RFC6776] that describes measurement periods in use (see [RFC6776], Section 4.2). This metrics block relies on the measurement period in the Measurement Information Block indicating the span of the report and SHOULD be sent in the same compound RTCP packet as the Measurement Information Block. If the measurement period is not received in the same compound RTCP packet as this metrics block, this metrics block MUST be discarded.
隐藏秒度量块拟与测量信息块[RFC6776]中的信息一起使用，如本节所述。它提供了由于端点丢失和丢弃数据包而导致的潜在听觉损伤的描述，以时间为基础表示，类似于传统的公共交换电话网络（PSTN）T1/E1错误秒度量。此度量块的实例按同步源（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周期，并且应在与度量信息块相同的复合RTCP数据包中发送。如果测量周期未在与此度量块相同的复合RTCP数据包中接收，则必须丢弃此度量块。
The following metrics are based on successive one-second intervals as declared by an RTP clock. This RTP clock does not need to be synchronized to any external time reference. The starting time of this clock is unspecified. Note that this implies that the same loss pattern could result in slightly different count values, depending on where the losses occur relative to the particular one-second demarcation points. For example, two loss events occurring 50 ms apart could result in either one Concealed Second or two, depending on the particular one-second boundaries used.
以下指标基于RTP时钟声明的连续1秒间隔。此RTP时钟不需要与任何外部时间基准同步。此时钟的开始时间未指定。注意，这意味着相同的损耗模式可能导致略有不同的计数值，这取决于相对于特定1秒分界点的损耗发生的位置。例如，相隔50 ms发生的两个丢失事件可能导致一秒或两秒，具体取决于使用的特定1秒边界。
The seconds in this sub-block are not necessarily calendar seconds. At the tail end of a session, periods of time of less than one second shall be incorporated into these counts if they exceed 500 ms and shall be disregarded if they are less than 500 ms.
此子块中的秒数不一定是日历秒。在会议结束时，如果少于一秒的时间超过500毫秒，则应将其纳入这些计数中，如果少于500毫秒，则应忽略不计。
The structure of the Concealed Seconds Metrics Block is as follows.
隐藏秒度量块的结构如下所示。
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=31 | I |plc| resv | block length=4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SSRC of Source |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Unimpaired Seconds |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Concealed Seconds |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Severely Concealed Seconds | Reserved | SCS Threshold |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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=31 | I |plc| resv | block length=4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SSRC of Source |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Unimpaired Seconds |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Concealed Seconds |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Severely Concealed Seconds | Reserved | SCS Threshold |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Concealed Seconds Metrics Block
图2：隐藏秒度量块
Block type (BT): 8 bits
块类型（BT）：8位
A Concealed Seconds Metrics Block is identified by the constant 31.
隐藏的秒度量块由常数31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 Concealed Seconds metrics are Sampled, Interval, or Cumulative metrics:
此字段用于指示隐藏的秒数度量是采样、间隔还是累积度量：
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。
I=01: Sampled Value - the reported value is a sampled instantaneous value (Not allowed in this block).
I=01：采样值-报告值为采样瞬时值（此块中不允许）。
I=00: Reserved value - this value is reserved for future use.
I=00：保留值-此值保留供将来使用。
In this document, Concealed Seconds metrics can only be measured over definite intervals and cannot be sampled. Senders MUST NOT use the values I=00 or I=01. If a block is received with I=00 or I=01, the receiver MUST discard the block.
在本文件中，隐藏秒指标只能在确定的时间间隔内测量，不能取样。发件人不得使用I=00或I=01的值。如果接收到I=00或I=01的块，接收器必须丢弃该块。
Packet Loss Concealment Method (plc): 2 bits
丢包隐藏方法（plc）：2位
This field is used to identify the packet loss concealment method in use at the receiver, according to the following code:
该字段用于根据以下代码识别在接收器处使用的分组丢失隐藏方法：
bits 014-015
比特014-015
0 = silence insertion
0 = silence insertion
1 = simple replay, no attenuation
1=简单回放，无衰减
2 = simple replay, with attenuation
2=简单回放，具有衰减
3 = enhancement
3 = enhancement
Other values are reserved.
其他值保留。
Note that the enhancement method (plc=3) for packet loss concealment offers an improved audio quality and a better robustness against packet losses [G.711] and is equivalent to "enhanced" in Section 4.7.6 of [RFC3611].
注意，用于包丢失隐藏的增强方法（plc=3）提供了改进的音频质量和更好的抗包丢失鲁棒性[G.711]，相当于[RFC3611]第4.7.6节中的“增强”。
Reserved (resv): 4 bits
保留（resv）：4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. For the Concealed Seconds Metrics Block, the block length is equal to 4.
此报表块的长度（32位字）减去1。对于隐藏秒度量块，块长度等于4。
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。
Unimpaired Seconds: 32 bits
未损坏秒数：32位
A count of the number of Unimpaired Seconds that have occurred.
已发生的未损坏秒数的计数。
An Unimpaired Second is defined as a continuous period of one second during which no frame loss or discard due to late arrival has occurred. Every second in a session must be classified as either OK or Concealed.
未损坏秒被定义为连续1秒的时间段，在此期间不会发生因延迟到达而导致的帧丢失或丢弃。会话中的每一秒都必须分类为OK或隐藏。
Normal playout of comfort noise or other silence-concealment signals during periods of talker silence, if VAD is used, shall be counted as Unimpaired Seconds.
如果使用VAD，在通话者沉默期间，舒适噪音或其他沉默隐藏信号的正常播放应计为未受干扰秒。
Two values are reserved: a value of 0xFFFFFFFE indicates out of range (that is, a measured value exceeding 0xFFFFFFFD), and a value of 0xFFFFFFFF indicates that the measurement is unavailable.
保留两个值：0xFFFFFE表示超出范围（即，测量值超过0xFFFFFD），0xFFFFFFFF表示测量不可用。
Concealed Seconds: 32 bits
隐藏秒：32位
A count of the number of Concealed Seconds that have occurred.
已发生的隐藏秒数的计数。
A Concealed Second is defined as a continuous period of one second during which any frame loss or discard due to late arrival has occurred.
隐藏秒被定义为一秒的连续时间，在此期间，由于延迟到达而发生任何帧丢失或丢弃。
Equivalently, a Concealed Second is one in which some Loss-Type concealment has occurred. Buffer Adjustment-Type concealment SHOULD NOT cause Concealed Seconds to be incremented, with the following exception. An implementation MAY cause Concealed Seconds to be incremented for 'emergency' buffer adjustments made during talkspurts.
同样，隐藏的第二个是发生了某种损失类型的隐藏。缓冲区调整类型隐藏不应导致隐藏秒数增加，但以下情况除外。一个实现可能会导致增加隐藏秒数，以便在通话喷射期间进行“紧急”缓冲区调整。
Loss-Type concealment is reactive insertion or deletion of samples in the audio playout stream due to effective frame loss at the audio decoder. "Effective frame loss" is the event in which a frame of coded audio is simply not present at the audio decoder when required. In this case, substitute audio samples are generally formed, at the decoder or elsewhere, to reduce audible impairment.
丢失类型隐藏是由于音频解码器处的有效帧丢失而在音频播放流中反应性地插入或删除样本。“有效帧丢失”是指在需要时，编码音频帧根本不存在于音频解码器中的事件。在这种情况下，通常在解码器处或其他地方形成替代音频样本，以减少听觉损伤。
Buffer Adjustment-Type concealment is proactive or controlled insertion or deletion of samples in the audio playout stream due to jitter buffer adaptation, re-sizing decisions, or re-centering decisions within the endpoint.
缓冲区调整类型隐藏是由于抖动缓冲区自适应、重新调整大小决定或端点内的重新定心决定而在音频播放流中主动或受控地插入或删除样本。
Because this insertion is controlled, rather than occurring randomly in response to losses, it is typically less audible than Loss-Type concealment. For example, jitter buffer adaptation events may be constrained to occur during periods of talker silence, in which case only silence duration is affected, or sophisticated time-stretching methods for insertion/deletion during favorable periods in active speech may be employed. For these reasons, Buffer Adjustment-Type concealment MAY be exempted from inclusion in calculations of Concealed Seconds and Severely Concealed Seconds.
由于这种插入是受控的，而不是响应丢失而随机发生，因此它通常比丢失类型的隐藏声音小。例如，抖动缓冲器适配事件可以被限制在说话者静默期间发生，在这种情况下，仅静默持续时间受到影响，或者可以使用复杂的时间拉伸方法来在活动语音的有利期间插入/删除。由于这些原因，缓冲器调整型隐蔽可免于包含在隐蔽秒数和严重隐蔽秒数的计算中。
However, an implementation SHOULD include Buffer Adjustment-Type concealment in counts of Concealed Seconds and Severely Concealed Seconds if the event occurs at an 'inopportune' moment, such as an emergency or large, immediate adaptation during active speech or an unsophisticated adaptation during speech without regard for the underlying signal. In these cases, the assumption of low audibility cannot hold. In other words, jitter buffer adaptation events that may be presumed to be audible SHOULD be included in Concealed Seconds and Severely Concealed Seconds counts.
然而，如果事件发生在“不合时宜”的时刻，例如在活跃语音期间紧急或大规模、立即的自适应或在语音期间不考虑潜在信号的简单自适应，则实现应包括以隐藏秒和严重隐藏秒为计数的缓冲调节型隐藏。在这些情况下，低可听性的假设无法成立。换句话说，可能被认为是可听的抖动缓冲器自适应事件应包括在隐藏秒和严重隐藏秒计数中。
Concealment events that cannot be classified as Buffer Adjustment-Type MUST be classified as Loss-Type.
不能归类为缓冲调整类型的隐藏事件必须归类为损失类型。
For clarification, the count of Concealed Seconds MUST include the count of Severely Concealed Seconds.
为了澄清，隐蔽秒数必须包括严重隐蔽秒数。
Two values are reserved: a value of 0xFFFFFFFE indicates out of range (that is, a measured value exceeding 0xFFFFFFFD), and a value of 0xFFFFFFFF indicates that the measurement is unavailable.
保留两个值：0xFFFFFE表示超出范围（即，测量值超过0xFFFFFD），0xFFFFFFFF表示测量不可用。
Severely Concealed Seconds: 16 bits
严重隐藏秒：16位
A count of the number of Severely Concealed Seconds.
严重隐藏秒数的计数。
A Severely Concealed Second is defined as a non-overlapping period of one second during which the cumulative amount of time that has been subject to frame loss or discard due to late arrival exceeds the SCS Threshold.
严重隐藏秒被定义为1秒的非重叠时段，在此期间，由于延迟到达而遭受帧丢失或丢弃的累积时间超过SCS阈值。
Two values are reserved: a value of 0xFFFE indicates out of range (that is, a measured value exceeding 0xFFFD), and a value of 0xFFFF indicates that the measurement is unavailable.
保留两个值：0xFFFE值表示超出范围（即，测量值超过0xFFFD），0xFFFF值表示测量不可用。
Reserved: 8 bits
保留：8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）。
SCS Threshold: 8 bits
SCS阈值：8位
The SCS Threshold is defined as the percentage of packets corresponding to lost or discarded frames that must occur within a one second period in order for the second to be classified as a Severely Concealed Second. This is expressed in numeric format 0:8 and hence can represent a range of 0 to 99.6 percent loss or discard.
SCS阈值定义为与丢失或丢弃帧相对应的数据包的百分比，这些数据包必须在1秒的时间段内出现，以便将第二个数据包归类为严重隐藏的数据包。这以数字格式0:8表示，因此可以表示0到99.6%的损失或丢弃。
A default threshold of 5 percent effective frame loss (50 ms effective frame loss ) per second is suggested. This corresponds to an SCS Threshold in hexadecimal of 0x0D.
建议默认阈值为每秒5%的有效帧丢失（50毫秒的有效帧丢失）。这对应于十六进制0x0D的SCS阈值。
[RFC3611] defines the use of SDP (Session Description Protocol) [RFC4566] for signaling the use of XR blocks. XR blocks MAY be used without prior signaling.
[RFC3611]定义了SDP（会话描述协议）[RFC4566]的使用，用于发送使用XR块的信号。XR块可以在没有事先信令的情况下使用。
This section augments the SDP attribute "rtcp-xr" [RFC3611] by providing two additional values of "xr-format" to signal the use of the two report blocks defined in this document.
本节增加了SDP属性“rtcp xr”[RFC3611]，提供了两个额外的“xr format”值，表示使用了本文档中定义的两个报告块。
xr-format =/ xr-conceal-block / xr-conc-sec-block
xr format=/xr隐藏块/xr conc sec块
xr-conceal-block = "loss-conceal" xr-conc-sec-block = "conc-sec" ["=" thresh]
xr隐藏block=“丢失隐藏”xr conc sec block=“conc sec”[“=”阈值]
thresh = 1*DIGIT ; threshold for SCS (ms)
DIGIT = <as defined in Section 3 of [RFC5234]>
thresh = 1*DIGIT ; threshold for SCS (ms)
DIGIT = <as defined in Section 3 of [RFC5234]>
When SDP is used in Offer/Answer context, the SDP Offer/Answer usage defined in [RFC3611] applies. Note that "thresh" is declared by the offer.
在报价/应答上下文中使用SDP时，[RFC3611]中定义的SDP报价/应答用法适用。请注意，“thresh”由要约声明。
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 two block type values in the IANA "RTP Control Protocol Extended Reports (RTCP XR) Block Type Registry" under the subregistry "RTCP XR Block Type":
本文档在IANA“RTP控制协议扩展报告（RTCP XR）块类型注册表”子目录“RTCP XR块类型”下分配两个块类型值：
Name: LCB Long Name: Loss Concealment Metrics Block Value 30 Reference: Section 3.1
名称：LCB长名称：损失隐藏度量块值30参考：第3.1节
Name: CSB Long Name: Concealed Seconds Metrics Block Value 31 Reference: Section 4.1
名称：CSB长名称：隐藏秒度量块值31参考：第4.1节
This document also registers two new parameters 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”中注册了两个新参数：
o "loss-conceal"
o “隐瞒损失”
o "conc-sec"
o “conc sec”
The contact information for the registrations is:
注册的联系信息为：
RAI Area Directors
区域主任
rai-ads@tools.ietf.org
雷-ads@tools.ietf.org
It is believed that the RTCP XR blocks defined in this document introduce no new security considerations beyond those described in [RFC3611]. These blocks do not provide per-packet statistics, so the risk to confidentiality documented in Section 7, Paragraph 3 of [RFC3611] does not apply.
除[RFC3611]中所述的安全注意事项外，本文档中定义的RTCP XR块不会引入任何新的安全注意事项。这些数据块不提供每个数据包的统计数据，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 version of this document.
杰夫·亨特（Geoff Hunt）编写了本文档的初始版本。
The authors gratefully acknowledge reviews and feedback provided by Bruce Adams, Philip Arden, Amit Arora, Bob Biskner, Kevin Connor, Alissa Cooper, Claus Dahm, Randy Ethier, Roni Even, Adrian Farrel, Jim Frauenthal, Albert Higashi, Tom Hock, Shane Holthaus, Paul Jones, Rajesh Kumar, Keith Lantz, Alfred C. Morton, Mohamed Mostafa, Amy Pendleton, Colin Perkins, Mike Ramalho, Ravi Raviraj, Pete Resnick, Albrecht Schwarz, Meral Shirazipour, Tom Taylor, and Hideaki Yamada.
The authors gratefully acknowledge reviews and feedback provided by Bruce Adams, Philip Arden, Amit Arora, Bob Biskner, Kevin Connor, Alissa Cooper, Claus Dahm, Randy Ethier, Roni Even, Adrian Farrel, Jim Frauenthal, Albert Higashi, Tom Hock, Shane Holthaus, Paul Jones, Rajesh Kumar, Keith Lantz, Alfred C. Morton, Mohamed Mostafa, Amy Pendleton, Colin Perkins, Mike Ramalho, Ravi Raviraj, Pete Resnick, Albrecht Schwarz, Meral Shirazipour, Tom Taylor, and Hideaki Yamada.translate error, please retry
[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。
[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。
[RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax Specifications: ABNF", STD 68, RFC 5234, January 2008.
[RFC5234]Crocker，D.和P.Overell，“语法规范的扩充BNF:ABNF”，STD 68，RFC 5234，2008年1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。
[G.711] ITU-T, "Pulse Code Modulation (PCM) of Voice Frequencies", ITU-T Recommendation G.711, 1988.
[G.711]ITU-T，“语音频率的脉冲编码调制（PCM）”，ITU-T建议G.7111988。
[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。
[VAD] Wikipedia, "Voice activity detection", January 2014, <http://en.wikipedia.org/w/ index.php?title=Voice_activity_detection&oldid=593287643>.
[VAD]维基百科，“语音活动检测”，2014年1月<http://en.wikipedia.org/w/ index.php？title=Voice\u activity\u detection&oldid=593287643>。
a. On-Time Playout Duration Metric
a. 实时播放持续时间度量
* Metric Name: On-Time Playout Duration
* 度量名称：准时播放持续时间
* Metric Description: 'On-time playout' is the uninterrupted, in-sequence playout of valid decoded audio information originating from the remote endpoint. On-time playout duration is playout duration of any signal other than those used for concealment.
* 指标说明：“按时播放”是指从远程端点发出的有效解码音频信息的连续播放。On time playout duration（定时播放持续时间）是除用于隐藏的信号外的任何信号的播放持续时间。
* Method of Measurement or Calculation: See Section 3.2, On-Time Playout Duration definition.
* 测量或计算方法：见第3.2节“时间播放持续时间定义”。
* Units of Measurement: See Section 3.2, On-Time Playout Duration definition.
* 计量单位：见第3.2节“时间播放持续时间定义”。
* Measurement Point(s) with Potential Measurement Domain: See Section 1.1, 3rd paragraph.
* 具有潜在测量域的测量点：见第1.1节第3段。
* Measurement Timing: See Section 3, 1st paragraph for measurement timing and Section 3.2 for Interval Metric flag.
* 测量时间：测量时间见第3节第1段，间隔公制标志见第3.2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. Loss Concealment Duration Metric
b. 损失掩盖持续时间度量
* Metric Name: Loss Concealment Duration
* 度量名称：损失掩盖持续时间
* Metric Description: The duration of audio playout corresponding to Loss-Type concealment.
* 度量说明：与丢失类型隐藏相对应的音频播放持续时间。
* Method of Measurement or Calculation: See Section 3.2, Loss Concealment Duration definition.
* 计量或计算方法：见第3.2节，损失掩盖期限定义。
* Units of Measurement: See Section 3.2, Loss Concealment Duration definition.
* 计量单位：见第3.2节，损失隐瞒期限定义。
* Measurement Point(s) with Potential Measurement Domain: See Section 1.1, 3rd paragraph.
* 具有潜在测量域的测量点：见第1.1节第3段。
* Measurement Timing: See Section 3, 1st paragraph for measurement timing and Section 3.2 for Interval Metric flag.
* 测量时间：测量时间见第3节第1段，间隔公制标志见第3.2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. Buffer Adjustment Concealment Duration Metric
c. 缓冲区调整隐藏持续时间度量
* Metric Name: Buffer Adjustment Concealment Duration
* 度量名称：缓冲区调整隐藏持续时间
* Metric Description: The duration of audio playout corresponding to Buffer Adjustment-Type concealment.
* 度量说明：与缓冲区调整类型隐藏相对应的音频播放持续时间。
* Method of Measurement or Calculation: See Section 3.2, Buffer Adjustment Concealment Duration definition.
* 测量或计算方法：见第3.2节，缓冲区调整隐藏持续时间定义。
* Units of Measurement: See Section 3.2, Buffer Adjustment Concealment Duration definition.
* 测量单位：见第3.2节“缓冲区调整隐藏持续时间定义”。
* Measurement Point(s) with Potential Measurement Domain: See Section 1.1, 3rd paragraph.
* 具有潜在测量域的测量点：见第1.1节第3段。
* Measurement Timing: See Section 3, 1st paragraph for measurement timing and Section 3.2 for Interval Metric flag.
* 测量时间：测量时间见第3节第1段，间隔公制标志见第3.2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. Playout Interrupt Count Metric
d. 播放中断计数度量
* Metric Name: Playout Interrupt Count
* 度量名称：播放中断计数
* Metric Description: The number of interruptions to normal playout that occurred during the reporting period.
* 指标说明：报告期内正常播放中断的次数。
* Method of Measurement or Calculation: See Section 3.2, Playout Interrupt Count definition.
* 测量或计算方法：见第3.2节，播放中断计数定义。
* Units of Measurement: See Section 3.2, Playout Interrupt Count definition.
* 测量单位：见第3.2节，播放中断计数定义。
* Measurement Point(s) with Potential Measurement Domain: See Section 1.1, 3rd paragraph.
* 具有潜在测量域的测量点：见第1.1节第3段。
* Measurement Timing: See Section 3, 1st paragraph for measurement timing and Section 3.2 for Interval Metric flag.
* 测量时间：测量时间见第3节第1段，间隔公制标志见第3.2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。
e. Mean Playout Interrupt Size Metric
e. 平均播放中断大小度量
* Metric Name: Mean Playout Interrupt Size
* 度量名称：平均播放中断大小
* Metric Description: The mean duration of interruptions to normal playout that occurred during the reporting period.
* 指标说明：报告期内正常播放中断的平均持续时间。
* Method of Measurement or Calculation: See Section 3.2, Playout Interrupt Count definition.
* 测量或计算方法：见第3.2节，播放中断计数定义。
* Units of Measurement: See Section 3.2, Playout Interrupt Count definition.
* 测量单位：见第3.2节，播放中断计数定义。
* Measurement Point(s) with Potential Measurement Domain: See Section 1.1, 3rd paragraph.
* 具有潜在测量域的测量点：见第1.1节第3段。
* Measurement Timing: See Section 3, 1st paragraph for measurement timing and Section 3.2 for Interval Metric flag.
* 测量时间：测量时间见第3节第1段，间隔公制标志见第3.2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。
f. Unimpaired Seconds Metric
f. 未损坏秒度量
* Metric Name: Unimpaired Seconds
* 度量名称：未损坏秒数
* Metric Description: A count of the number of Unimpaired Seconds that have occurred.
* 度量描述：发生的未损坏秒数的计数。
* Method of Measurement or Calculation: See Section 4.2, Unimpaired Seconds definition.
* 测量或计算方法：见第4.2节，未损坏秒定义。
* Units of Measurement: See Section 4.2, Unimpaired Seconds definition.
* 测量单位：见第4.2节，未损坏秒定义。
* Measurement Point(s) with Potential Measurement Domain: See Section 1.1, 5th paragraph.
* 具有潜在测量域的测量点：见第1.1节第5段。
* Measurement Timing: See Section 4, 1st paragraph for measurement timing and Section 4.2 paragraph for Interval Metric flag.
* 测量定时：测量定时见第4节第1段，间隔公制标志见第4.2段。
* 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。
g. Concealed Seconds Metric
g. 隐藏秒度量
* Metric Name: Concealed Seconds
* 公制名称：隐藏秒数
* Metric Description: A count of the number of Concealed Seconds that have occurred.
* 度量描述：已发生的隐藏秒数的计数。
* Method of Measurement or Calculation: See Section 4.2, Concealed Seconds definition.
* 测量或计算方法：见第4.2节，隐蔽秒定义。
* Units of Measurement: See Section 4.2, Concealed Seconds definition.
* 计量单位：见第4.2节，隐蔽秒定义。
* Measurement Point(s) with Potential Measurement Domain: See Section 1.1, 5th paragraph.
* 具有潜在测量域的测量点：见第1.1节第5段。
* Measurement Timing: See Section 4, 1st paragraph for measurement timing and Section 4.2 for Interval Metric flag.
* 测量定时：测量定时见第4节第1段，间隔公制标志见第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。
h. Severely Concealed Seconds Metric
h. 严重隐蔽秒度量
* Metric Name: Severely Concealed Seconds
* 度量名称：严重隐藏秒
* Metric Description: A count of the number of Severely Concealed Seconds that have occurred.
* 度量描述：已发生的严重隐藏秒数的计数。
* Method of Measurement or Calculation: See Section 4.2, Severely Concealed Seconds definition.
* 测量或计算方法：见第4.2节，定义。
* Units of Measurement: See Section 4.2, Severely Concealed Seconds definition.
* 计量单位：见第4.2节，严重隐蔽秒定义。
* Measurement Point(s) with Potential Measurement Domain: See Section 1.1, 5th paragraph.
* 具有潜在测量域的测量点：见第1.1节第5段。
* Measurement Timing: See Section 4, 1st paragraph for measurement timing and Section 4.2 for Interval Metric flag.
* 测量定时：测量定时见第4节第1段，间隔公制标志见第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。
i. SCS Threshold Metric
i. SCS阈值度量
* Metric Name: SCS Threshold
* 指标名称：SCS阈值
* Metric Description: The amount of time corresponding to lost or discarded frames that must occur within a one-second period in order for the second to be classified as a Severely Concealed Second.
* 度量描述：与丢失或丢弃的帧相对应的时间量，必须在一秒钟内发生，以便将第二帧归类为严重隐藏的第二帧。
* Method of Measurement or Calculation: See Section 4.2, SCS Threshold definition.
* 测量或计算方法：见第4.2节，SCS阈值定义。
* Units of Measurement: See Section 4.2, SCS Threshold definition.
* 测量单位：见第4.2节，SCS阈值定义。
* Measurement Point(s) with Potential Measurement Domain: See Section 1.1, 5th paragraph.
* 具有潜在测量域的测量点：见第1.1节第5段。
* Measurement Timing: See Section 4, 1st paragraph for measurement timing and Section 4.2 for Interval Metric flag.
* 测量定时：测量定时见第4节第1段，间隔公制标志见第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
Glen Zorn Network Zen 77/440 Soi Phoomjit, Rama IV Road Phra Khanong, Khlong Toie Bangkok 10110 Thailand
泰国曼谷Khlong Toie Phra Khanong Rama IV路Soli Phoomjit 77/440号Glen Zorn Network Zen邮编：10110
Phone: +66 (0) 87 502 4274
EMail: gwz@net-zen.net
Phone: +66 (0) 87 502 4274
EMail: gwz@net-zen.net
Claire Bi Shanghai Research Institute of China Telecom Corporation Limited No. 1835, South Pudong Road Shanghai 200122 China
中国电信股份有限公司上海研究院上海浦东南路1835号，邮编：200122
EMail: bijy@sttri.com.cn
EMail: bijy@sttri.com.cn
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