Internet Engineering Task Force (IETF) T. Kristensen
Request for Comments: 6185 P. Luthi
Category: Standards Track TANDBERG
ISSN: 2070-1721 May 2011
Internet Engineering Task Force (IETF) T. Kristensen
Request for Comments: 6185 P. Luthi
Category: Standards Track TANDBERG
ISSN: 2070-1721 May 2011
RTP Payload Format for H.264 Reduced-Complexity Decoding Operation (RCDO) Video
用于H.264降低复杂度解码操作（RCDO）视频的RTP有效负载格式
Abstract
摘要
This document describes an RTP payload format for the Reduced-Complexity Decoding Operation (RCDO) for H.264 Baseline profile bitstreams, as specified in ITU-T Recommendation H.241. RCDO reduces the decoding cost and resource consumption of the video processing. The RCDO RTP payload format is based on the H.264 RTP payload format.
本文档描述了ITU-T建议H.241中规定的H.264基线配置文件比特流的降低复杂度解码操作（RCDO）的RTP有效负载格式。RCDO降低了视频处理的解码成本和资源消耗。RCDO RTP有效负载格式基于H.264 RTP有效负载格式。
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/rfc6185.
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/rfc6185.
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。
This document may contain material from IETF Documents or IETF Contributions published or made publicly available before November 10, 2008. The person(s) controlling the copyright in some of this material may not have granted the IETF Trust the right to allow modifications of such material outside the IETF Standards Process. Without obtaining an adequate license from the person(s) controlling the copyright in such materials, this document may not be modified outside the IETF Standards Process, and derivative works of it may not be created outside the IETF Standards Process, except to format it for publication as an RFC or to translate it into languages other than English.
本文件可能包含2008年11月10日之前发布或公开的IETF文件或IETF贡献中的材料。控制某些材料版权的人员可能未授予IETF信托允许在IETF标准流程之外修改此类材料的权利。在未从控制此类材料版权的人员处获得充分许可的情况下，不得在IETF标准流程之外修改本文件，也不得在IETF标准流程之外创建其衍生作品，除了将其格式化以RFC形式发布或将其翻译成英语以外的其他语言。
Table of Contents
目录
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions Used in This Document . . . . . . . . . . . . . . 3
3. Media Format Background . . . . . . . . . . . . . . . . . . . 3
4. Payload Format . . . . . . . . . . . . . . . . . . . . . . . . 3
5. Congestion Control Considerations . . . . . . . . . . . . . . 3
6. Payload Format Parameters . . . . . . . . . . . . . . . . . . 3
6.1. Media Type Definition . . . . . . . . . . . . . . . . . . 4
7. Mapping to SDP . . . . . . . . . . . . . . . . . . . . . . . . 19
7.1. Offer/Answer Considerations . . . . . . . . . . . . . . . 20
7.2. Declarative SDP Considerations . . . . . . . . . . . . . . 20
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 20
9. Security Considerations . . . . . . . . . . . . . . . . . . . 20
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 21
11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 21
11.1. Normative References . . . . . . . . . . . . . . . . . . . 21
11.2. Informative References . . . . . . . . . . . . . . . . . . 21
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions Used in This Document . . . . . . . . . . . . . . 3
3. Media Format Background . . . . . . . . . . . . . . . . . . . 3
4. Payload Format . . . . . . . . . . . . . . . . . . . . . . . . 3
5. Congestion Control Considerations . . . . . . . . . . . . . . 3
6. Payload Format Parameters . . . . . . . . . . . . . . . . . . 3
6.1. Media Type Definition . . . . . . . . . . . . . . . . . . 4
7. Mapping to SDP . . . . . . . . . . . . . . . . . . . . . . . . 19
7.1. Offer/Answer Considerations . . . . . . . . . . . . . . . 20
7.2. Declarative SDP Considerations . . . . . . . . . . . . . . 20
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 20
9. Security Considerations . . . . . . . . . . . . . . . . . . . 20
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 21
11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 21
11.1. Normative References . . . . . . . . . . . . . . . . . . . 21
11.2. Informative References . . . . . . . . . . . . . . . . . . 21
ITU-T Recommendation H.241 [3] specifies a Reduced-Complexity Decoding Operation (RCDO) for use with H.264 [2] Baseline profile bitstreams. It also specifies a bitstream constraint associated with RCDO and a mechanism for signaling RCDO within the bitstream. The RCDO signaling indicates that the bitstream conforms to the bitstream constraint and that the decoder shall apply the RCDO decoding process to the bitstream.
ITU-T建议H.241[3]规定了用于H.264[2]基线配置文件比特流的降低复杂度解码操作（RCDO）。它还指定了与RCDO相关联的位流约束，以及在位流中发送RCDO信号的机制。RCDO信令指示比特流符合比特流约束，并且解码器应将RCDO解码过程应用于比特流。
RCDO for H.264 offers a solution to support higher resolutions at the same high frame rates used in current implementations. This is achieved by reducing the processing requirements and thus reducing the decoding cost/resource consumption of the video processing.
RCDO for H.264提供了一种解决方案，可以在当前实现中使用的相同高帧速率下支持更高的分辨率。这是通过降低处理要求从而降低视频处理的解码成本/资源消耗来实现的。
This document defines media type parameters and allows use in systems based on the Session Description Protocol (SDP) [8] for signaling.
本文件定义了媒体类型参数，并允许在基于会话描述协议（SDP）[8]的系统中用于信令。
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 [4].
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[4]中所述进行解释。
The Reduced-Complexity Decoding Operation (RCDO) for H.264 Baseline profile bitstreams is specified in Annex B of H.241 [3]. RCDO is specified as a separate H.264 mode and is distinct from any profile defined in H.264. An RCDO bitstream obeys all the constraints of the Baseline profile.
H.264基线配置文件比特流的降低复杂度解码操作（RCDO）在H.241[3]的附录B中规定。RCDO被指定为单独的H.264模式，与H.264中定义的任何配置文件都不同。RCDO比特流遵守基线配置文件的所有约束。
The media format is based on the H.264 RTP payload format as specified in RFC 6184 [1]. Therefore, RFC 6184 constitutes the basis for this document and is referred to several times.
媒体格式基于RFC 6184[1]中规定的H.264 RTP有效负载格式。因此，RFC 6184构成本文件的基础，并多次引用。
In order to signal H.264 additional modes, Table 8-13 of H.241 [3] specifies an AdditionalModesSupported parameter. Currently, the only additional mode defined is RCDO.
为了向H.264附加模式发送信号，H.241[3]的表8-13指定了附加模式支持参数。目前，唯一定义的附加模式是RCDO。
Informative note: Other additional modes may be defined in the future. H.264 additional modes may or may not be distinct from the profiles in H.264.
资料性说明：将来可能会定义其他附加模式。H.264附加模式可能不同于H.264中的配置文件，也可能不同于H.264中的配置文件。
A separate media subtype, named H264-RCDO, is defined to ensure backward compatibility with deployed implementations of H.264.
定义了一个单独的媒体子类型H264-RCDO，以确保与部署的H.264实现的向后兼容性。
The payload format defined in Section 5 of RFC 6184 [1] SHALL be used. This includes the RTP header usage and the payload format in RFC 6184. Examples of typical RTP packets can be found in RFC 6184.
应使用RFC 6184[1]第5节中定义的有效载荷格式。这包括RFC6184中的RTP报头使用和有效负载格式。典型RTP包的示例可在RFC6184中找到。
Congestion control for RTP SHALL be used in accordance with RFC 3550 [6] and with any applicable RTP profile, e.g., RFC 3551 [7]. If best-effort service is being used, users of this payload format SHALL monitor packet loss to ensure that the packet loss rate is within acceptable parameters.
RTP的拥塞控制应根据RFC 3550[6]和任何适用的RTP配置文件（如RFC 3551[7]）使用。如果正在使用尽力而为服务，此有效负载格式的用户应监控数据包丢失，以确保数据包丢失率在可接受的参数范围内。
This RTP payload format is identified using the H264-RCDO media subtype, which is registered in accordance with RFC 4855 [10], and using the template of RFC 4288 [13].
该RTP有效负载格式使用H264-RCDO介质子类型标识，该子类型根据RFC 4855[10]注册，并使用RFC 4288[13]模板标识。
Informative note: The media subtype definition for H264-RCDO is based on the definition of the H264 media subtype as specified in Section 8.1 of RFC 6184 [1]. Except for the profile-level-id parameter, for which new semantics are specified below, the optional parameters are copied from RFC 6184 [1] in order to provide a complete, self-contained media subtype registration to IANA. The references are updated to match the numbering used in this document.
资料性说明：H264-RCDO的介质子类型定义基于RFC 6184[1]第8.1节规定的H264介质子类型定义。除了下面指定了新语义的概要文件级别id参数外，可选参数从RFC 6184[1]复制，以便向IANA提供完整、自包含的媒体子类型注册。更新参考文件以匹配本文件中使用的编号。
The media subtype for RCDO for H.264 has been allocated from the IETF tree.
用于H.264的RCDO的媒体子类型已从IETF树中分配。
Type name: video
类型名称：视频
Subtype name: H264-RCDO
子类型名称：H264-RCDO
Required parameters:
所需参数：
rate: Indicates the RTP timestamp clock rate. The rate value MUST be 90000.
速率：指示RTP时间戳时钟速率。比率值必须为90000。
Optional parameters:
可选参数：
profile-level-id: A base16 RFC 4648 [9] (hexadecimal) representation of the following three bytes in the sequence parameter set NAL unit is specified in H.264 [2]: 1) profile_idc, 2) a byte herein referred to as profile-iop, composed of the values of constraint_set0_flag, constraint_set1_flag, constraint_set2_flag, constraint_set3_flag, constraint_set4_flag, constraint_set5_flag, and reserved_zero_2bits in bit-significance order, starting from the most-significant bit, and 3) level_idc. Note that reserved_zero_2bits is required to be equal to 0 in H.264 [2], but other values for it may be specified in the future by ITU-T or ISO/IEC.
配置文件级别id:H.264[2]中指定了序列参数集NAL单元中以下三个字节的base16 RFC 4648[9]（十六进制）表示形式：1）配置文件\u idc，2）此处称为配置文件iop的字节，由约束设置0\u标志、约束设置1\u标志、约束设置2\u标志、约束设置3\u标志的值组成，约束设置4、约束设置5和保留零位按位重要性顺序排列，从最高有效位开始，3）级别idc。请注意，H.264[2]中要求保留的0位等于0，但ITU-T或ISO/IEC将来可能会指定其其他值。
The profile-level-id parameter indicates the default sub-profile (i.e., the subset of coding tools that may have been used to generate the stream or that the receiver supports) and the default level of the stream or the receiver supports.
profile level id参数指示默认子概要文件（即，可能已用于生成流或接收器支持的编码工具子集）和流或接收器支持的默认级别。
RCDO is distinct from any profile; this implies that the profile value 0 (no profile) and the profile_idc byte of the profile-level-id parameter are equal to 0. An RCDO bitstream MUST obey all the constraints of the Baseline profile. Therefore, only constraint_set0_flag is equal to 1 in the profile-iop part of the profile-level-id parameter; the remaining bits are set to 0.
RCDO不同于任何配置文件；这意味着配置文件值0（无配置文件）和配置文件级别id参数的配置文件字节等于0。RCDO比特流必须遵守基线配置文件的所有约束。因此，在profile level id参数的profile iop部分中，只有constraint_set0_flag等于1；其余位设置为0。
If the profile-level-id parameter is used to indicate properties of a NAL unit stream, it indicates that, to decode the stream, the minimum subset of coding tools a decoder has to support is the default sub-profile, and the lowest level the decoder has to support is the default level.
如果profile-level id参数用于指示NAL单元流的属性，则它指示为了解码该流，解码器必须支持的编码工具的最小子集是默认子profile，并且解码器必须支持的最低级别是默认级别。
If the profile-level-id parameter is used for capability exchange or session setup, it indicates the subset of coding tools, which is equal to the default sub-profile, that the codec supports for both receiving and sending. If max-recv-level is not present, the default level from profile-level-id indicates the highest level the codec wishes to support. If max-recv-level is present, it indicates the highest level the codec supports for receiving. For either receiving or sending, all levels that are lower than the highest level supported MUST also be supported.
如果profile level id参数用于功能交换或会话设置，则它表示编解码器在接收和发送时支持的编码工具子集，该子集等于默认子配置文件。如果不存在max recv level，则配置文件级别id中的默认级别表示编解码器希望支持的最高级别。如果存在max recv level，则表示编解码器支持接收的最高级别。对于接收或发送，还必须支持低于支持的最高级别的所有级别。
For example, if a codec supports level 1.3, the profile-level-id becomes 00800d, in which 00 indicates the "no profile" value, 80 indicates the constraints of the Baseline profile, and 0d indicates level 1.3. When level 2.1 is supported, the profile-level-id becomes 008015.
例如，如果编解码器支持级别1.3，则配置文件级别id变为00800d，其中00表示“无配置文件”值，80表示基线配置文件的约束，0d表示级别1.3。当支持级别2.1时，配置文件级别id变为008015。
If no profile-level-id is present, level 1 (i.e., equivalent to profile-level-id 00800a) MUST be implied.
如果没有配置文件级别id，则必须暗示级别1（即，相当于配置文件级别id 00800a）。
Informative note: The definitions of the remaining optional parameters below are copied verbatim from Section 8.1 of RFC 6184 [1]. Only the references are updated to match the numbering used in this document.
资料性说明：以下剩余可选参数的定义逐字复制自RFC 6184[1]第8.1节。仅更新参考文件以匹配本文件中使用的编号。
max-recv-level: This parameter MAY be used to indicate the highest level a receiver supports when the highest level is higher than the default level (the level indicated by profile-level-id). The value of max-recv-level is a base16 (hexadecimal) representation of the two bytes after the syntax element profile_idc in the sequence parameter set NAL unit specified in H.264 [2]: profile-iop (as defined above) and level_idc. If the level_idc byte of max-recv-level is equal to 11 and bit 4 of the profile-iop byte of max-recv-level is equal to 1 or if the level_idc byte of max-recv-level is equal to 9 and bit 4 of the profile-iop byte of max-recv-level is equal to 0, the highest level the receiver supports is Level 1b. Otherwise, the highest level the receiver supports is equal to the level_idc byte of max-recv-level divided by 10.
最大recv级别：当最高级别高于默认级别（由配置文件级别id指示的级别）时，此参数可用于指示接收器支持的最高级别。max recv level的值是H.264[2]：profile iop（如上定义）和level_idc中指定的序列参数集NAL unit中语法元素profile_idc之后两个字节的base16（十六进制）表示。如果max recv level的level_idc字节等于11，max recv level的配置文件iop字节的位4等于1，或者max recv level的level_idc字节等于9，max recv level的配置文件iop字节的位4等于0，则接收机支持的最高级别为1b。否则，接收器支持的最高电平等于max recv level的level_idc字节除以10。
max-recv-level MUST NOT be present if the highest level the receiver supports is not higher than the default level.
如果接收器支持的最高电平不高于默认电平，则不得出现最大recv电平。
max-mbps, max-smbps, max-fs, max-cpb, max-dpb, and max-br: These parameters MAY be used to signal the capabilities of a receiver implementation. These parameters MUST NOT be used for any other purpose. The highest level conveyed in the value of the profile-level-id parameter or the max-recv-level parameter MUST be such that the receiver is fully capable of supporting. max-mbps, max-smbps, max-fs, max-cpb, max-dpb, and max-br MAY be used to indicate capabilities of the receiver that extend the required capabilities of the signaled highest level, as specified below.
max-mbps、max-smbps、max-fs、max-cpb、max-dpb和max-br：这些参数可用于表示接收机实现的能力。这些参数不得用于任何其他目的。在profile level id参数或max recv level参数的值中传递的最高电平必须确保接收器完全能够支持。max-mbps、max-smbps、max-fs、max-cpb、max-dpb和max-br可用于指示扩展信号化最高级别所需能力的接收机能力，如下所述。
When more than one parameter from the set (max-mbps, max-smbps, max-fs, max-cpb, max-dpb, max-br) is present, the receiver MUST support all signaled capabilities simultaneously. For example, if both max-mbps and max-br are present, the signaled highest level with the extension of both the frame rate and bitrate is supported. That is, the receiver is able to decode NAL unit streams in which the macroblock processing rate is up to max-mbps (inclusive), the bitrate is up to max-br (inclusive), the coded picture buffer size is derived as specified in the semantics of the max-br parameter below, and the other properties comply with the highest level specified in the value of the profile-level-id parameter or the max-recv-level parameter.
当集合中存在多个参数（最大mbps、最大smbps、最大fs、最大cpb、最大dpb、最大br）时，接收器必须同时支持所有信号功能。例如，如果存在max mbps和max br，则支持扩展帧速率和比特率的信号化最高级别。也就是说，接收机能够解码其中宏块处理速率高达max mbps（包括），比特率高达max br（包括），编码图片缓冲区大小如下面max br参数的语义中所指定的那样导出的NAL单元流，其他属性符合配置文件级别id参数值或max recv级别参数值中指定的最高级别。
If a receiver can support all the properties of Level A, the highest level specified in the value of the profile-level-id parameter or the max-recv-level parameter MUST be Level A (i.e., MUST NOT be lower than Level A). In other words, a receiver MUST NOT signal values of max-mbps, max-fs, max-cpb, max-dpb, and max-br that taken together meet the requirements of a higher level compared to the highest level specified in the value of the profile-level-id parameter or the max-recv-level parameter.
如果接收器可以支持级别a的所有属性，则配置文件级别id参数或最大recv级别参数的值中指定的最高级别必须为级别a（即，不得低于级别a）。换句话说，接收器不得发送最大mbps、最大fs、最大cpb、最大dpb和最大br值的信号，与配置文件级别id参数或最大recv级别参数的值中指定的最高级别相比，这些值一起满足更高级别的要求。
Informative note: When the OPTIONAL media type parameters are used to signal the properties of a NAL unit stream, max-mbps, max-smbps, max-fs, max-cpb, max-dpb, and max-br are not present, and the value of profile-level-id must always be such that the NAL unit stream complies fully with the specified profile and level.
资料性说明：当使用可选媒体类型参数来表示NAL单元流的属性时，max mbps、max smbps、max fs、max cpb、max dpb和max br不存在，并且配置文件级别id的值必须始终确保NAL单元流完全符合指定的配置文件和级别。
max-mbps: The value of max-mbps is an integer indicating the maximum macroblock processing rate in units of macroblocks per second. The max-mbps parameter signals that the receiver is capable of decoding video at a higher rate than is required by the signaled highest level conveyed in the value of the profile-level-id parameter or the max-recv-level parameter. When max-mbps is signaled, the receiver MUST be able to decode NAL unit streams that conform to the signaled highest level, with the exception that the MaxMBPS value in Table A-1 of H.264 [2] for the signaled
max-mbps：max-mbps的值是一个整数，表示以每秒宏块为单位的最大宏块处理速率。max mbps参数表示接收器能够以高于在简档电平id参数或max recv电平参数的值中传送的信号化最高电平所要求的速率解码视频。当发送最大mbps信号时，接收机必须能够解码符合发送信号的最高电平的NAL单元流，但H.264[2]表A-1中发送信号的NAL单元流的最大mbps值除外
highest level is replaced with the value of max-mbps. The value of max-mbps MUST be greater than or equal to the value of MaxMBPS given in Table A-1 of H.264 [2] for the highest level. Senders MAY use this knowledge to send pictures of a given size at a higher picture rate than is indicated in the signaled highest level.
最高级别将替换为最大mbps的值。对于最高级别，最大mbps的值必须大于或等于H.264[2]表A-1中给出的最大mbps值。发送者可以使用此知识以高于信号最高级别中指示的图片速率发送给定大小的图片。
max-smbps: The value of max-smbps is an integer indicating the maximum static macroblock processing rate in units of static macroblocks per second, under the hypothetical assumption that all macroblocks are static macroblocks. When max-smbps is signaled, the MaxMBPS value in Table A-1 of H.264 [2] should be replaced with the result of the following computation:
max smbps：max smbps的值是一个整数，表示在假设所有宏块都是静态宏块的情况下，以每秒静态宏块为单位的最大静态宏块处理速率。当发出max smbps信号时，H.264[2]表A-1中的MaxMBPS值应替换为以下计算结果：
o If the parameter max-mbps is signaled, set a variable MaxMacroblocksPerSecond to the value of max-mbps. Otherwise, set MaxMacroblocksPerSecond equal to the value of MaxMBPS in Table A-1 of H.264 [2] for the signaled highest level conveyed in the value of the profile-level-id parameter or the max-recv-level parameter.
o 如果参数max mbps发出信号，则将变量MaxMacroblocksPerSecond设置为max mbps的值。否则，将MaxMacroblocksPerSecond设置为等于H.264[2]表A-1中MaxMBPS的值，用于配置文件级别id参数或最大recv级别参数值中传输的信号最高级别。
o Set a variable P_non-static to the proportion of non-static macroblocks in picture n.
o 将变量P_non-static设置为图片n中非静态宏块的比例。
o Set a variable P_static to the proportion of static macroblocks in picture n.
o 将变量P_static设置为图片n中静态宏块的比例。
o The value of MaxMBPS in Table A-1 of H.264 [2] should be considered by the encoder to be equal to:
o 编码器应认为H.264[2]表A-1中的MaxMBPS值等于：
MaxMacroblocksPerSecond * max-smbps / (P_non-static * max-smbps
+ P_static * MaxMacroblocksPerSecond)
MaxMacroblocksPerSecond * max-smbps / (P_non-static * max-smbps
+ P_static * MaxMacroblocksPerSecond)
The encoder should recompute this value for each picture. The value of max-smbps MUST be greater than or equal to the value of MaxMBPS given explicitly as the value of the max-mbps parameter or implicitly in Table A-1 of H.264 [2] for the signaled highest level. Senders MAY use this knowledge to send pictures of a given size at a higher picture rate than is indicated in the signaled highest level.
编码器应该为每个图片重新计算该值。max smbps的值必须大于或等于MaxMBPS的值，MaxMBPS的值在H.264[2]的表A-1中显式地作为max mbps参数的值给出，或隐式地作为信号最高电平给出。发送者可以使用此知识以高于信号最高级别中指示的图片速率发送给定大小的图片。
max-fs: The value of max-fs is an integer indicating the maximum frame size in units of macroblocks. The max-fs parameter signals that the receiver is capable of decoding larger picture sizes than are required by the signaled highest level conveyed in the value of the profile-level-id parameter or the max-recv-level parameter. When max-fs is signaled, the receiver MUST be able to decode NAL unit streams that conform to the signaled highest level, with the
max fs:max fs的值是一个整数，表示以宏块为单位的最大帧大小。max fs参数表示接收器能够解码大于在profile level id参数或max recv level参数的值中传送的信号化最高电平所需的图像大小。当发送max fs信号时，接收器必须能够解码符合所发送的最高电平的NAL单元流，并且
exception that the MaxFS value in Table A-1 of H.264 [2] for the signaled highest level is replaced with the value of max-fs. The value of max-fs MUST be greater than or equal to the value of MaxFS given in Table A-1 of H.264 [2] for the highest level. Senders MAY use this knowledge to send larger pictures at a proportionally lower frame rate than is indicated in the signaled highest level.
例外情况是，H.264[2]表A-1中用于信号最高级别的MaxFS值被替换为max fs值。对于最高级别，max fs的值必须大于或等于H.264[2]表A-1中给出的MaxFS值。发送者可以利用这一知识以比信号最高级别指示的帧速率低的比例发送较大的图片。
max-cpb: The value of max-cpb is an integer indicating the maximum coded picture buffer size in units of 1000 bits for the VCL HRD parameters and in units of 1200 bits for the NAL HRD parameters. Note that this parameter does not use units of cpbBrVclFactor and cpbBrNALFactor (see Table A-1 of H.264 [2]). The max-cpb parameter signals that the receiver has more memory than the minimum amount of coded picture buffer memory required by the signaled highest level conveyed in the value of the profile-level-id parameter or the max-recv-level parameter. When max-cpb is signaled, the receiver MUST be able to decode NAL unit streams that conform to the signaled highest level, with the exception that the MaxCPB value in Table A-1 of H.264 [2] for the signaled highest level is replaced with the value of max-cpb (after taking cpbBrVclFactor and cpbBrNALFactor into consideration when needed). The value of max-cpb (after taking cpbBrVclFactor and cpbBrNALFactor into consideration when needed) MUST be greater than or equal to the value of MaxCPB given in Table A-1 of H.264 [2] for the highest level. Senders MAY use this knowledge to construct coded video streams with greater variation of bitrate than can be achieved with the MaxCPB value in Table A-1 of H.264 [2].
max cpb：max cpb的值是一个整数，表示VCL HRD参数的最大编码图片缓冲区大小，以1000位为单位，NAL HRD参数以1200位为单位。请注意，此参数不使用cpbBrVclFactor和cpbBrNALFactor的单位（参见H.264[2]中的表A-1）。max cpb参数表示接收器的内存大于在profile level id参数或max recv level参数的值中传送的信号化最高电平所需的最小编码图片缓冲内存量。当发送最大cpb信号时，接收机必须能够解码符合发送信号的最高电平的NAL单位流，但H.264[2]表A-1中发送信号的最高电平的最大cpb值被替换为最大cpb值（在需要时考虑cpbBrVclFactor和cpbBrNALFactor后）。最大cpb的值（在需要时考虑cpbBrVclFactor和CpBbBrnalFactor后）必须大于或等于H.264[2]表A-1中给出的最高级别的最大cpb值。发送者可以使用该知识来构造比特率变化比H.264[2]表A-1中的MaxCPB值更大的编码视频流。
Informative note: The coded picture buffer is used in the hypothetical reference decoder (Annex C of H.264). The use of the hypothetical reference decoder is recommended in H.264 encoders to verify that the produced bitstream conforms to the standard and to control the output bitrate. Thus, the coded picture buffer is conceptually independent of any other potential buffers in the receiver, including de-interleaving and de-jitter buffers. The coded picture buffer need not be implemented in decoders as specified in Annex C of H.264, but rather standard-compliant decoders can have any buffering arrangements provided that they can decode standard-compliant bitstreams. Thus, in practice, the input buffer for a video decoder can be integrated with de-interleaving and de-jitter buffers of the receiver.
资料性说明：编码图片缓冲器用于假设参考解码器（H.264附录C）。建议在H.264编码器中使用假设参考解码器，以验证生成的比特流是否符合标准并控制输出比特率。因此，编码图片缓冲器在概念上独立于接收机中的任何其他潜在缓冲器，包括解交错和解抖动缓冲器。编码图片缓冲器不需要在H.264的附录C中规定的解码器中实现，而是符合标准的解码器可以具有任何缓冲布置，只要它们能够解码符合标准的比特流。因此，在实践中，视频解码器的输入缓冲器可以与接收机的解交错和解抖动缓冲器集成。
max-dpb: The value of max-dpb is an integer indicating the maximum decoded picture buffer size in units of 8/3 macroblocks. The max-dpb parameter signals that the receiver has more memory than the minimum amount of decoded picture buffer memory required by the signaled highest level conveyed in the value of the profile-level-id parameter or the max-recv-level parameter. When max-dpb is signaled, the receiver MUST be able to decode NAL unit streams that conform to the signaled highest level, with the exception that the MaxDpbMbs value in Table A-1 of H.264 [2] for the signaled highest level is replaced with the value of max-dpb * 3 / 8. Consequently, a receiver that signals max-dpb MUST be capable of storing the following number of decoded frames, complementary field pairs, and non-paired fields in its decoded picture buffer:
max dpb：max dpb的值是一个整数，表示以8/3宏块为单位的最大解码图片缓冲区大小。max dpb参数表示接收器的内存大于在配置文件级别id参数或max recv级别参数的值中传送的信号化最高级别所需的解码图片缓冲内存的最小量。当发送最大dpb信号时，接收机必须能够解码符合发送信号的最高电平的NAL单元流，但H.264[2]表A-1中发送信号的最高电平的最大DPBMBS值被替换为最大dpb*3/8的值除外。因此，发送max dpb信号的接收器必须能够在其解码图片缓冲器中存储以下数量的解码帧、互补场对和非成对场：
Min(max-dpb * 3 / 8 / ( PicWidthInMbs * FrameHeightInMbs), 16)
Min(max-dpb * 3 / 8 / ( PicWidthInMbs * FrameHeightInMbs), 16)
Wherein PicWidthInMbs and FrameHeightInMbs are defined in H.264 [2].
其中，PicWidthInMbs和FrameHeightInMbs在H.264[2]中定义。
The value of max-dpb MUST be greater than or equal to the value of MaxDpbMbs * 3 / 8, wherein the value of MaxDpbMbs is given in Table A-1 of H.264 [2] for the highest level. Senders MAY use this knowledge to construct coded video streams with improved compression.
max dpb的值必须大于或等于MaxDpbMbs*3/8的值，其中MaxDpbMbs的值在H.264[2]的表A-1中给出了最高级别。发送者可以使用此知识构造具有改进的压缩的编码视频流。
Informative note: This parameter was added primarily to complement a similar codepoint in the ITU-T Recommendation H.245, so as to facilitate signaling gateway designs. The decoded picture buffer stores reconstructed samples. There is no relationship between the size of the decoded picture buffer and the buffers used in RTP, especially de-interleaving and de-jitter buffers.
资料性说明：添加此参数主要是为了补充ITU-T建议H.245中的类似代码点，以便于信令网关设计。解码的图片缓冲器存储重构的样本。解码图片缓冲区的大小与RTP中使用的缓冲区之间没有关系，尤其是去交错和去抖动缓冲区。
Informative note: In RFC 3984, which is obsoleted by RFC 6184, the unit of this parameter was 1024 bytes. The unit has been changed to 8/3 macroblocks in this document. The reason for this change was due to the changes from the 2003 version of the H.264 specification referenced by RFC 3984 to the 2010 version of the H.264 specification referenced by this document, particularly the changes to Table A-1 in the H.264 specification due to addition of color formats and bit depths not supported earlier. The changed semantics of this parameter keeps backward compatibility to RFC 3984 and supports all profiles defined in the 2010 version of the H.264 specification.
资料性说明：在RFC 3984中，该参数的单位为1024字节，已被RFC 6184淘汰。在本文档中，该单元已更改为8/3宏块。此更改的原因是由于从RFC 3984引用的2003版H.264规范更改为本文档引用的2010版H.264规范，特别是由于添加了先前不支持的颜色格式和位深度，H.264规范中的表A-1发生了更改。此参数的更改语义保持了与RFC 3984的向后兼容性，并支持2010版H.264规范中定义的所有配置文件。
max-br: The value of max-br is an integer indicating the maximum video bitrate in units of 1000 bits per second for the VCL HRD parameters and in units of 1200 bits per second for the NAL HRD parameters. Note that this parameter does not use units of cpbBrVclFactor and cpbBrNALFactor (see Table A-1 of H.264 [2]).
max br：max br的值是一个整数，表示VCL HRD参数的最大视频比特率，单位为1000比特/秒，NAL HRD参数的最大视频比特率单位为1200比特/秒。请注意，此参数不使用cpbBrVclFactor和cpbBrNALFactor的单位（参见H.264[2]中的表A-1）。
The max-br parameter signals that the video decoder of the receiver is capable of decoding video at a higher bitrate than is required by the signaled highest level conveyed in the value of the profile-level-id parameter or the max-recv-level parameter.
max-br参数表示接收器的视频解码器能够以高于在简档电平id参数或max-recv电平参数的值中传送的信号化最高电平所要求的比特率解码视频。
When max-br is signaled, the video codec of the receiver MUST be able to decode NAL unit streams that conform to the signaled highest level, with the following exceptions in the limits specified by the highest level:
当发送max br信号时，接收器的视频编解码器必须能够解码符合所发送信号的最高级别的NAL单元流，但在最高级别指定的限制范围内存在以下例外情况：
o The value of max-br (after taking cpbBrVclFactor and cpbBrNALFactor into consideration when needed) replaces the MaxBR value in Table A-1 of H.264 [2] for the highest level.
o max br的值（在需要时考虑cpbBrVclFactor和cpbBrNALFactor后）替换H.264[2]表A-1中最高级别的MaxBR值。
o When the max-cpb parameter is not present, the result of the following formula replaces the value of MaxCPB in Table A-1 of H.264 [2]: (MaxCPB of the signaled level) * max-br / (MaxBR of the signaled highest level).
o 当max cpb参数不存在时，以下公式的结果将替换H.264[2]表A-1中的MaxCPB值：（信号电平的MaxCPB）*max br/（信号最高电平的MaxBR）。
For example, if a receiver signals capability for Main profile Level 1.2 with max-br equal to 1550, this indicates a maximum video bitrate of 1550 kbits/sec for VCL HRD parameters, a maximum video bitrate of 1860 kbits/sec for NAL HRD parameters, and a CPB size of 4036458 bits (1550000 / 384000 * 1000 * 1000).
例如，如果接收机向主配置文件级别1.2发送信号，最大br等于1550，则表示VCL HRD参数的最大视频比特率为1550 kbits/sec，NAL HRD参数的最大视频比特率为1860 kbits/sec，CPB大小为4036458比特（1550000/384000*1000*1000）。
The value of max-br (after taking cpbBrVclFactor and cpbBrNALFactor into consideration when needed) MUST be greater than or equal to the value MaxBR given in Table A-1 of H.264 [2] for the signaled highest level.
max br的值（在需要时考虑cpbBrVclFactor和cpbBrNALFactor后）必须大于或等于H.264[2]表A-1中给出的信号最高电平的MaxBR值。
Senders MAY use this knowledge to send higher bitrate video as allowed in the level definition of Annex A of H.264 to achieve improved video quality.
发送者可以使用此知识发送H.264附件A的级别定义中允许的更高比特率视频，以实现改进的视频质量。
Informative note: This parameter was added primarily to complement a similar codepoint in the ITU-T Recommendation H.245, so as to facilitate signaling gateway designs. The assumption that the network is capable of handling such bitrates at any given time cannot be made from the value of this parameter. In particular, no conclusion can be drawn that the signaled bitrate is possible under congestion control constraints.
资料性说明：添加此参数主要是为了补充ITU-T建议H.245中的类似代码点，以便于信令网关设计。根据该参数的值，不能假设网络能够在任何给定时间处理此类比特率。特别地，不能得出在拥塞控制约束下信号比特率是可能的结论。
redundant-pic-cap: This parameter signals the capabilities of a receiver implementation. When equal to 0, the parameter indicates that the receiver makes no attempt to use redundant coded pictures to correct incorrectly decoded primary coded pictures. When equal to 0, the receiver is not capable of using redundant slices; therefore, a sender SHOULD avoid sending redundant slices to save bandwidth. When equal to 1, the receiver is capable of decoding any such redundant slice that covers a corrupted area in a primary decoded picture (at least partly), and therefore a sender MAY send redundant slices. When the parameter is not present, a value of 0 MUST be used for redundant-pic-cap. When present, the value of redundant-pic-cap MUST be either 0 or 1.
冗余pic cap：此参数表示接收器实现的能力。当等于0时，该参数表示接收器不尝试使用冗余编码图片来纠正未正确解码的主编码图片。当等于0时，接收器不能使用冗余片；因此，发送方应避免发送冗余片以节省带宽。当等于1时，接收器能够解码覆盖主解码图片中损坏区域的任何此类冗余片（至少部分），因此发送器可以发送冗余片。当参数不存在时，冗余pic cap必须使用0值。存在时，冗余pic cap的值必须为0或1。
When the profile-level-id parameter is present in the same signaling as the redundant-pic-cap parameter and the profile indicated in profile-level-id is such that it disallows the use of redundant coded pictures (e.g., Main profile), the value of redundant-pic-cap MUST be equal to 0. When a receiver indicates redundant-pic-cap equal to 0, the received stream SHOULD NOT contain redundant coded pictures.
当配置文件级别id参数与冗余pic cap参数存在于同一信令中，并且配置文件级别id中指示的配置文件不允许使用冗余编码图片（例如，主配置文件）时，冗余pic cap的值必须等于0。当接收器指示冗余pic cap等于0时，接收的流不应包含冗余编码图片。
Informative note: Even if redundant-pic-cap is equal to 0, the decoder is able to ignore redundant codec pictures provided that the decoder supports a profile (Baseline, Extended) in which redundant coded pictures are allowed.
资料性说明：即使冗余pic cap等于0，只要解码器支持允许冗余编码图片的配置文件（基线、扩展），解码器也可以忽略冗余编解码器图片。
Informative note: Even if redundant-pic-cap is equal to 1, the receiver may also choose other error concealment strategies to replace or complement decoding of redundant slices.
资料性说明：即使冗余pic cap等于1，接收机也可以选择其他错误隐藏策略来替换或补充冗余切片的解码。
sprop-parameter-sets: This parameter MAY be used to convey any sequence and picture parameter set NAL units (herein referred to as the initial parameter set NAL units) that can be placed in the NAL unit stream to precede any other NAL units in decoding order. The parameter MUST NOT be used to indicate codec capability in any capability exchange procedure. The value of the parameter is a comma-separated (',') list of base64 RFC 4648 [9] representations of parameter set NAL units as specified in Sections 7.3.2.1 and 7.3.2.2 of H.264 [2]. Note that the number of bytes in a parameter set NAL unit is typically less than 10, but a picture parameter set NAL unit can contain several hundred bytes.
sprop参数集：该参数可用于传送任何序列和图片参数集NAL单元（本文称为初始参数集NAL单元），其可置于NAL单元流中，以解码顺序先于任何其他NAL单元。在任何功能交换过程中，该参数不得用于指示编解码器功能。参数值为H.264[2]第7.3.2.1节和第7.3.2.2节中规定的参数集NAL单位的base64 RFC 4648[9]表示的逗号分隔（“，”）列表。注意，参数集NAL单元中的字节数通常小于10，但图片参数集NAL单元可以包含几百个字节。
Informative note: When several payload types are offered in the SDP Offer/Answer model, each with its own sprop-parameter-sets parameter, the receiver cannot assume that those parameter sets do not use conflicting storage locations (i.e., identical values of parameter set identifiers). Therefore, a receiver
资料性说明：当SDP提供/应答模型中提供了几种有效负载类型，每种类型都有自己的sprop参数集参数时，接收方不能假设这些参数集没有使用冲突的存储位置（即参数集标识符的相同值）。因此，接收器
should buffer all sprop-parameter-sets and make them available to the decoder instance that decodes a certain payload type.
应该缓冲所有sprop参数集，并使它们可用于解码特定负载类型的解码器实例。
The sprop-parameter-sets parameter MUST only contain parameter sets that are conforming to the profile-level-id, i.e., the subset of coding tools indicated by any of the parameter sets MUST be equal to the default sub-profile, and the level indicated by any of the parameter sets MUST be equal to the default level.
sprop参数集参数必须仅包含符合配置文件级别id的参数集，即任何参数集指示的编码工具子集必须等于默认子配置文件，并且任何参数集指示的级别必须等于默认级别。
sprop-level-parameter-sets: This parameter MAY be used to convey any sequence and picture parameter set NAL units (herein referred to as the initial parameter set NAL units) that can be placed in the NAL unit stream to precede any other NAL units in decoding order and that are associated with one or more levels different than the default level. The parameter MUST NOT be used to indicate codec capability in any capability exchange procedure.
sprop-level参数集：该参数可用于传送任何序列和图片参数集NAL单元（本文称为初始参数集NAL单元），其可置于NAL单元流中以解码顺序先于任何其他NAL单元，并且与不同于默认级别的一个或多个级别相关联。在任何功能交换过程中，该参数不得用于指示编解码器功能。
The sprop-level-parameter-sets parameter contains parameter sets for one or more levels that are different than the default level. All parameter sets associated with one level are clustered and prefixed with a three-byte field that has the same syntax as profile-level-id. This enables the receiver to install the parameter sets for one level and discard the rest. The three-byte field is named PLId, and all parameter sets associated with one level are named PSL, which has the same syntax as sprop-parameter-sets. Parameter sets for each level are represented in the form of PLId:PSL, i.e., PLId followed by a colon (':') and the base64 RFC 4648 [9] representation of the initial parameter set NAL units for the level. Each pair of PLId:PSLs is also separated by a colon. Note that a PSL can contain multiple parameter sets for that level, separated with commas (',').
“存储级别参数集”参数包含一个或多个与默认级别不同的级别的参数集。与一个级别关联的所有参数集都是集群的，并以一个三字节字段作为前缀，该字段的语法与profile-level-id相同。这使接收器能够为一个级别安装参数集，并丢弃其余的参数集。三字节字段命名为PLId，与一个级别关联的所有参数集命名为PSL，其语法与sprop参数集相同。每个级别的参数集以PLId:PSL的形式表示，即PLId后跟冒号（“：”）和级别初始参数集NAL单位的base64 RFC 4648[9]表示。每对PLId:PSLs也用冒号分隔。请注意，PSL可以包含该级别的多个参数集，用逗号（“，”）分隔。
The subset of coding tools indicated by each PLId field MUST be equal to the default sub-profile, and the level indicated by each PLId field MUST be different than the default level. All sequence parameter sets contained in each PSL MUST have the three bytes from profile_idc to level_idc, inclusive, equal to the preceding PLId.
每个PLId字段指示的编码工具子集必须等于默认子配置文件，并且每个PLId字段指示的级别必须不同于默认级别。每个PSL中包含的所有序列参数集必须具有从profile_idc到level_idc（含）的三个字节，等于前面的PLId。
Informative note: This parameter allows for efficient level downgrade or upgrade in SDP Offer/Answer and out-of-band transport of parameter sets simultaneously.
资料性说明：此参数允许在SDP提供/应答和参数集带外传输中同时进行有效的级别降级或升级。
use-level-src-parameter-sets: This parameter MAY be used to indicate a receiver capability. The value MAY be equal to either 0 or 1. When the parameter is not present, the value MUST be inferred to be equal to 0. The value 0 indicates that the receiver does not understand the sprop-level-parameter-sets parameter, does not
使用级别src参数集：此参数可用于指示接收器能力。该值可以等于0或1。当参数不存在时，必须将该值推断为等于0。值0表示接收器不理解sprop level参数sets参数，不理解
understand the "fmtp" source attribute as specified in Section 6.3 of RFC 5576 [14], will ignore sprop-level-parameter-sets when present, and will ignore sprop-parameter-sets when conveyed using the "fmtp" source attribute. The value 1 indicates that the receiver understands the sprop-level-parameter-sets parameter, understands the "fmtp" source attribute as specified in Section 6.3 of RFC 5576 [14], and is capable of using parameter sets contained in the sprop-level-parameter-sets or contained in the sprop-parameter-sets that is conveyed using the "fmtp" source attribute.
理解RFC 5576[14]第6.3节中规定的“fmtp”源属性，当存在时将忽略sprop级别参数集，当使用“fmtp”源属性传达时将忽略sprop参数集。值1表示接收器理解sprop级别参数集参数，理解RFC 5576[14]第6.3节中规定的“fmtp”源属性，并且能够使用sprop级别参数集中包含的参数集或使用“fmtp”传输的sprop参数集中包含的参数集源属性。
Informative note: An RFC 3984 receiver does not understand sprop-level-parameter-sets, use-level-src-parameter-sets, or the "fmtp" source attribute as specified in Section 6.3 of RFC 5576 [14]. Therefore, during SDP Offer/Answer, an RFC 3984 receiver as the answerer will simply ignore sprop-level-parameter-sets when present in an offer and sprop-parameter-sets conveyed using the "fmtp" source attribute, as specified in Section 6.3 of RFC 5576 [14]. Assume that the offered payload type was accepted at a level lower than the default level. If the offered payload type included sprop-level-parameter-sets or included sprop-parameter-sets conveyed using the "fmtp" source attribute and if the offerer sees that the answerer has not included use-level-src-parameter-sets equal to 1 in the answer, the offerer knows that in-band transport of parameter sets is needed.
资料性说明：RFC 3984接收器不理解sprop级别参数集、使用级别src参数集或RFC 5576[14]第6.3节中规定的“fmtp”源属性。因此，在SDP报价/应答期间，RFC 3984接收者作为应答者将忽略使用“fmtp”源属性传送的报价和sprop参数集中的sprop级别参数集，如RFC 5576[14]第6.3节所述。假设提供的有效负载类型在低于默认级别的级别上被接受。如果提供的有效载荷类型包括sprop级别参数集或使用“fmtp”源属性传送的包括的sprop参数集，并且如果报价人发现应答人在回答中没有包括等于1的使用级别src参数集，报价人知道需要带内传输参数集。
in-band-parameter-sets: This parameter MAY be used to indicate a receiver capability. The value MAY be equal to either 0 or 1. The value 1 indicates that the receiver discards out-of-band parameter sets in sprop-parameter-sets and sprop-level-parameter-sets; therefore, the sender MUST transmit all parameter sets in-band. The value 0 indicates that the receiver utilizes out-of-band parameter sets included in sprop-parameter-sets and/or sprop-level-parameter-sets. However, in this case, the sender MAY still choose to send parameter sets in-band. When in-band-parameter-sets is equal to 1, use-level-src-parameter-sets MUST NOT be present or MUST be equal to 0. When the parameter is not present, this receiver capability is not specified, and therefore the sender MAY send out-of-band parameter sets only, it MAY send in-band-parameter-sets only, or it MAY send both.
带内参数集：此参数可用于指示接收器能力。该值可以等于0或1。值1表示接收器丢弃sprop参数集和sprop级别参数集中的带外参数集；因此，发送方必须在频带内传输所有参数集。值0表示接收器使用sprop参数集和/或sprop级别参数集中包含的带外参数集。然而，在这种情况下，发送方仍然可以选择在频带内发送参数集。当带内参数集等于1时，use level src参数集不得存在或必须等于0。如果参数不存在，则不指定此接收器功能，因此发送方可以仅发送带外参数集，也可以仅发送带内参数集，或者两者都发送。
level-asymmetry-allowed: This parameter MAY be used in SDP Offer/ Answer to indicate whether level asymmetry, i.e., sending media encoded at a different level in the offerer-to-answerer direction than the level in the answerer-to-offerer direction, is allowed. The value MAY be equal to either 0 or 1. When the parameter is not present, the value MUST be inferred to be equal to 0. The
允许的级别不对称：此参数可用于SDP报价/应答中，以指示是否允许级别不对称，即在报价人至报价人方向上发送编码为不同级别的媒体，而不是在报价人至报价人方向上发送编码为不同级别的媒体。该值可以等于0或1。当参数不存在时，必须将该值推断为等于0。这个
value 1 in both the offer and the answer indicates that level asymmetry is allowed. The value of 0 in either the offer or the answer indicates that level asymmetry is not allowed.
报价和答案中的值1表示允许水平不对称。报价或答案中的值0表示不允许水平不对称。
If level-asymmetry-allowed is equal to 0 (or not present) in either the offer or the answer, level asymmetry is not allowed. In this case, the level to use in the direction from the offerer to the answerer MUST be the same as the level to use in the opposite direction.
如果报价或答案中允许的水平不对称等于0（或不存在），则不允许水平不对称。在这种情况下，从报价人到应答人的方向上使用的电平必须与在相反方向上使用的电平相同。
packetization-mode: This parameter signals the properties of an RTP payload type or the capabilities of a receiver implementation. Only a single configuration point can be indicated; thus, when capabilities to support more than one packetization-mode are declared, multiple configuration points (RTP payload types) must be used.
打包模式：此参数表示RTP有效负载类型的属性或接收器实现的能力。只能指示一个配置点；因此，当声明支持多个打包模式的能力时，必须使用多个配置点（RTP有效负载类型）。
When the value of packetization-mode is equal to 0 or packetization-mode is not present, the single NAL mode MUST be used. This mode is in use in standards using ITU-T Recommendation H.241 [3] (see Section 12.1). When the value of packetization-mode is equal to 1, the non-interleaved mode MUST be used. When the value of packetization-mode is equal to 2, the interleaved mode MUST be used. The value of packetization-mode MUST be an integer in the range of 0 to 2, inclusive.
当打包模式的值等于0或不存在打包模式时，必须使用单一NAL模式。该模式在使用ITU-T建议H.241[3]的标准中使用（见第12.1节）。当packetization mode的值等于1时，必须使用非交织模式。当打包模式的值等于2时，必须使用交织模式。packetization mode的值必须是0到2（包括0到2）范围内的整数。
sprop-interleaving-depth: This parameter MUST NOT be present when packetization-mode is not present or the value of packetization-mode is equal to 0 or 1. This parameter MUST be present when the value of packetization-mode is equal to 2.
sprop交错深度：当分组模式不存在或分组模式的值等于0或1时，此参数不得存在。当打包模式的值等于2时，此参数必须存在。
This parameter signals the properties of an RTP packet stream. It specifies the maximum number of VCL NAL units that precede any VCL NAL unit in the RTP packet stream in transmission order and that follow the VCL NAL unit in decoding order. Consequently, it is guaranteed that receivers can reconstruct NAL unit decoding order when the buffer size for NAL unit decoding order recovery is at least the value of sprop-interleaving-depth + 1 in terms of VCL NAL units.
此参数表示RTP数据包流的属性。它指定了RTP数据包流中任何VCL NAL单元之前（按传输顺序）和之后（按解码顺序）的VCL NAL单元的最大数量。因此，当用于NAL单元解码顺序恢复的缓冲器大小至少是相对于VCL NAL单元的sprop交织深度+1的值时，保证接收机能够重构NAL单元解码顺序。
The value of sprop-interleaving-depth MUST be an integer in the range of 0 to 32767, inclusive.
sprop交错深度的值必须是0到32767（包括0到32767）范围内的整数。
sprop-deint-buf-req: This parameter MUST NOT be present when packetization-mode is not present or the value of packetization-mode is equal to 0 or 1. It MUST be present when the value of packetization-mode is equal to 2.
sprop deint buf req：当打包模式不存在或打包模式的值等于0或1时，此参数不得存在。当packetization mode的值等于2时，它必须存在。
sprop-deint-buf-req signals the required size of the de-interleaving buffer for the RTP packet stream. The value of the parameter MUST be greater than or equal to the maximum buffer occupancy (in units of bytes) required in such a de-interleaving buffer that is specified in Section 7.2 of RFC 6184 [1]. It is guaranteed that receivers can perform the de-interleaving of interleaved NAL units into NAL unit decoding order, when the de-interleaving buffer size is at least the value of sprop-deint-buf-req in terms of bytes.
sprop deint buf req向RTP数据包流发送所需大小的解交织缓冲区信号。该参数的值必须大于或等于RFC 6184[1]第7.2节中规定的这种解交错缓冲区所需的最大缓冲区占用率（以字节为单位）。当解交织缓冲器大小至少是以字节为单位的sprop deint buf req的值时，保证接收机能够将交织的NAL单元解交织成NAL单元解码顺序。
The value of sprop-deint-buf-req MUST be an integer in the range of 0 to 4294967295, inclusive.
sprop deint buf req的值必须是0到4294967295（包括0到4294967295）范围内的整数。
Informative note: sprop-deint-buf-req indicates the required size of the de-interleaving buffer only. When network jitter can occur, an appropriately sized jitter buffer has to be provisioned for as well.
资料性说明：sprop deint buf req仅表示所需的解交织缓冲区大小。当网络抖动可能发生时，还必须为其配置适当大小的抖动缓冲区。
deint-buf-cap: This parameter signals the capabilities of a receiver implementation and indicates the amount of de-interleaving buffer space in units of bytes that the receiver has available for reconstructing the NAL unit decoding order. A receiver is able to handle any stream for which the value of the sprop-deint-buf-req parameter is smaller than or equal to this parameter.
deint buf cap：此参数表示接收器实现的能力，并指示接收器可用于重建NAL单元解码顺序的以字节为单位的解交织缓冲区空间量。接收器能够处理sprop deint buf req参数值小于或等于此参数的任何流。
If the parameter is not present, then a value of 0 MUST be used for deint-buf-cap. The value of deint-buf-cap MUST be an integer in the range of 0 to 4294967295, inclusive.
如果参数不存在，则deint buf cap必须使用0值。deint buf cap的值必须是0到4294967295（包括0到4294967295）范围内的整数。
Informative note: deint-buf-cap indicates the maximum possible size of the de-interleaving buffer of the receiver only. When network jitter can occur, an appropriately sized jitter buffer has to be provisioned for as well.
资料性说明：deint buf cap仅表示接收机解交错缓冲器的最大可能大小。当网络抖动可能发生时，还必须为其配置适当大小的抖动缓冲区。
sprop-init-buf-time: This parameter MAY be used to signal the properties of an RTP packet stream. The parameter MUST NOT be present if the value of packetization-mode is equal to 0 or 1.
sprop init buf time：此参数可用于表示RTP数据包流的属性。如果打包模式的值等于0或1，则该参数不得存在。
The parameter signals the initial buffering time that a receiver MUST wait before starting decoding to recover the NAL unit decoding order from the transmission order. The parameter is the maximum value of (decoding time of the NAL unit - transmission time of a NAL unit), assuming reliable and instantaneous transmission, the same timeline for transmission and decoding, and commencement of decoding when the first packet arrives.
该参数表示接收器在开始解码之前必须等待的初始缓冲时间，以从传输顺序恢复NAL单元解码顺序。该参数是（NAL单元的解码时间-NAL单元的传输时间）的最大值，假设可靠和瞬时传输，传输和解码的时间线相同，并且在第一个数据包到达时开始解码。
An example of specifying the value of sprop-init-buf-time follows. A NAL unit stream is sent in the following interleaved order, in
下面是一个指定sprop init buf time值的示例。NAL单元流按以下交织顺序发送，如下所示：
which the value corresponds to the decoding time and the transmission order is from left to right:
该值对应于解码时间，且传输顺序为从左到右：
0 2 1 3 5 4 6 8 7 ...
0 2 1 3 5 4 6 8 7 ...
Assuming a steady transmission rate of NAL units, the transmission times are:
假设NAL单元的稳定传输速率，传输时间为：
0 1 2 3 4 5 6 7 8 ...
0 1 2 3 4 5 6 7 8 ...
Subtracting the decoding time from the transmission time column-wise results in the following series:
从传输时间列中减去解码时间，得到以下序列：
0 -1 1 0 -1 1 0 -1 1 ...
0 -1 1 0 -1 1 0 -1 1 ...
Thus, in terms of intervals of NAL unit transmission times, the value of sprop-init-buf-time in this example is 1. The parameter is coded as a non-negative base10 integer representation in clock ticks of a 90-kHz clock. If the parameter is not present, then no initial buffering time value is defined. Otherwise, the value of sprop-init-buf-time MUST be an integer in the range of 0 to 4294967295, inclusive.
因此，就NAL单位发送时间的间隔而言，本示例中的sprop init buf time的值为1。该参数以90 kHz时钟的时钟信号为单位编码为非负的base10整数表示。如果参数不存在，则不定义初始缓冲时间值。否则，sprop init buf time的值必须是介于0到4294967295（包括0到4294967295）之间的整数。
In addition to the signaled sprop-init-buf-time, receivers SHOULD take into account the transmission delay jitter buffering, including buffering for the delay jitter caused by mixers, translators, gateways, proxies, traffic-shapers, and other network elements.
除了信号sprop init buf time外，接收机还应考虑传输延迟抖动缓冲，包括混频器、转换器、网关、代理、流量整形器和其他网络元件引起的延迟抖动缓冲。
sprop-max-don-diff: This parameter MAY be used to signal the properties of an RTP packet stream. It MUST NOT be used to signal transmitter, receiver, or codec capabilities. The parameter MUST NOT be present if the value of packetization-mode is equal to 0 or 1. sprop-max-don-diff is an integer in the range of 0 to 32767, inclusive. If sprop-max-don-diff is not present, the value of the parameter is unspecified. sprop-max-don-diff is calculated as follows:
sprop max don diff：此参数可用于表示RTP数据包流的属性。不得将其用于信号发射器、接收器或编解码器功能。如果打包模式的值等于0或1，则该参数不得存在。sprop max don diff是一个介于0到32767（包括0到32767）之间的整数。如果sprop max don diff不存在，则该参数的值未指定。sprop max don diff的计算如下：
sprop-max-don-diff = max{AbsDON(i) - AbsDON(j)}, for any i and any j>i,
sprop max don diff=max{AbsDON（i）-AbsDON（j）}，对于任意i和任意j>i，
where i and j indicate the index of the NAL unit in the transmission order and AbsDON denotes a decoding order number of the NAL unit that does not wrap around to 0 after 65535. In other words, AbsDON is calculated as follows: let m and n be consecutive NAL units in transmission order. For the very first NAL unit in transmission order (whose index is 0), AbsDON(0) = DON(0). For other NAL units, AbsDON is calculated as follows:
其中i和j表示传输顺序中的NAL单元的索引，AbsDON表示在65535之后不环绕到0的NAL单元的解码顺序号。换句话说，AbsDON的计算如下：设m和n是传输顺序上的连续NAL单元。对于传输顺序中的第一个NAL单元（其索引为0），AbsDON（0）=DON（0）。对于其他NAL装置，AbsDON的计算如下：
If DON(m) == DON(n), AbsDON(n) = AbsDON(m)
If DON(m) == DON(n), AbsDON(n) = AbsDON(m)
If (DON(m) < DON(n) and DON(n) - DON(m) < 32768),
如果（DON（m）<DON（n）和DON（n）-DON（m）<32768），
AbsDON(n) = AbsDON(m) + DON(n) - DON(m)
AbsDON(n) = AbsDON(m) + DON(n) - DON(m)
If (DON(m) > DON(n) and DON(m) - DON(n) >= 32768),
如果（DON（m）>DON（n）和DON（m）-DON（n）>=32768），
AbsDON(n) = AbsDON(m) + 65536 - DON(m) + DON(n)
AbsDON(n) = AbsDON(m) + 65536 - DON(m) + DON(n)
If (DON(m) < DON(n) and DON(n) - DON(m) >= 32768),
如果（DON（m）<DON（n）和DON（n）-DON（m）>=32768），
AbsDON(n) = AbsDON(m) - (DON(m) + 65536 - DON(n))
AbsDON(n) = AbsDON(m) - (DON(m) + 65536 - DON(n))
If (DON(m) > DON(n) and DON(m) - DON(n) < 32768),
如果（DON（m）>DON（n）和DON（m）-DON（n）<32768），
AbsDON(n) = AbsDON(m) - (DON(m) - DON(n))
AbsDON(n) = AbsDON(m) - (DON(m) - DON(n))
where DON(i) is the decoding order number of the NAL unit having index i in the transmission order. The decoding order number is specified in Section 5.5 of RFC 6184 [1].
其中DON（i）是在传输顺序中具有索引i的NAL单元的解码顺序号。RFC 6184[1]第5.5节规定了解码顺序号。
Informative note: Receivers may use sprop-max-don-diff to trigger which NAL units in the receiver buffer can be passed to the decoder.
资料性说明：接收机可使用sprop max don diff触发接收机缓冲区中哪些NAL单元可传递给解码器。
max-rcmd-nalu-size: This parameter MAY be used to signal the capabilities of a receiver. The parameter MUST NOT be used for any other purposes. The value of the parameter indicates the largest NALU size in bytes that the receiver can handle efficiently. The parameter value is a recommendation, not a strict upper boundary. The sender MAY create larger NALUs but must be aware that the handling of these may come at a higher cost than NALUs conforming to the limitation.
最大rcmd nalu大小：此参数可用于向接收器的功能发送信号。该参数不得用于任何其他目的。该参数的值表示接收器可以有效处理的最大NALU大小（以字节为单位）。参数值是建议值，而不是严格的上限。发送方可以创建更大的NALU，但必须注意，处理这些NALU的成本可能高于符合限制的NALU。
The value of max-rcmd-nalu-size MUST be an integer in the range of 0 to 4294967295, inclusive. If this parameter is not specified, no known limitation to the NALU size exists. Senders still have to consider the MTU size available between the sender and the receiver and SHOULD run MTU discovery for this purpose.
max rcmd nalu size的值必须是介于0到4294967295（包括0和4294967295）之间的整数。如果未指定此参数，则NALU大小不存在已知限制。发送者仍然需要考虑发送者和接收者之间可用的MTU大小，为此应该运行MTU发现。
This parameter is motivated by, for example, an IP to H.223 video telephony gateway, where NALUs smaller than the H.223 transport data unit will be more efficient. A gateway may terminate IP; thus, MTU discovery will normally not work beyond the gateway.
例如，该参数由IP到H.223视频电话网关驱动，其中小于H.223传输数据单元的NALU将更高效。网关可以终止IP；因此，MTU发现通常不会在网关之外工作。
Informative note: Setting this parameter to a lower than necessary value may have a negative impact.
资料性说明：将此参数设置为低于必要值可能会产生负面影响。
sar-understood: This parameter MAY be used to indicate a receiver capability and nothing else. The parameter indicates the maximum value of aspect_ratio_idc (specified in H.264 [2]) smaller than 255 that the receiver understands. Table E-1 of H.264 [2] specifies aspect_ratio_idc equal to 0 as "unspecified"; 1 to 16, inclusive, as specific Sample Aspect Ratios (SARs); 17 to 254, inclusive, as "reserved"; and 255 as the Extended SAR, for which SAR width and SAR height are explicitly signaled. Therefore, a receiver with a decoder according to H.264 [2] understands aspect_ratio_idc in the range of 1 to 16, inclusive, and aspect_ratio_idc equal to 255, in the sense that the receiver knows exactly what the SAR is. For such a receiver, the value of sar-understood is 16. In the future, if Table E-1 of H.264 [2] is extended, e.g., such that the SAR for aspect_ratio_idc equal to 17 is specified, then for a receiver with a decoder that understands the extension, the value of sar-understood is 17. For a receiver with a decoder according to the 2003 version of H.264 [2], the value of sar-understood is 13, as the minimum reserved aspect_ratio_idc therein is 14.
理解sar：此参数可用于指示接收机能力，而不是其他。该参数表示接收器理解的小于255的纵横比（在H.264[2]中指定）的最大值。H.264[2]的表E-1规定纵横比等于0为“未指定”；1至16（含），作为特定样本纵横比（SARs）；17至254，包括在内，为“保留”；255作为扩展SAR，其SAR宽度和SAR高度均明确表示。因此，具有根据H.264[2]的解码器的接收机理解范围为1到16（包括1到16）的纵横比idc，并且纵横比idc等于255，这意味着接收机确切地知道SAR是什么。对于这样的接收机，所理解的sar值为16。将来，如果扩展H.264[2]的表E-1，例如，指定纵横比为17的SAR，则对于具有理解扩展的解码器的接收机，理解的SAR值为17。对于具有根据H.264[2]的2003版本的解码器的接收机，所理解的sar的值是13，因为其中的最小保留纵横比是14。
When sar-understood is not present, the value MUST be inferred to be equal to 13.
当sar不存在时，必须推断该值等于13。
sar-supported: This parameter MAY be used to indicate a receiver capability and nothing else. The value of this parameter is an integer in the range of 1 to sar-understood, inclusive, equal to 255. The value of sar-supported equal to N smaller than 255 indicates that the receiver supports all the SARs corresponding to H.264 aspect_ratio_idc values (see Table E-1 of H.264 [2]) in the range from 1 to N, inclusive, without geometric distortion. The value of sar-supported equal to 255 indicates that the receiver supports all sample aspect ratios that are expressible using two 16-bit integer values as the numerator and denominator, i.e., those that are expressible using the H.264 aspect_ratio_idc value of 255 (Extended_SAR, see Table E-1 of H.264 [2]), without geometric distortion.
支持sar：此参数可用于指示接收器能力，而不是其他。此参数的值是一个范围为1到255（含）的整数。支持的sar值等于N小于255表示接收机支持与H.264纵横比idc值（见H.264[2]表E-1）对应的1到N范围内的所有sar，且不存在几何失真。支持的sar值等于255表示接收器支持使用两个16位整数值作为分子和分母表示的所有样本纵横比，即使用H.264纵横比idc值255表示的所有样本纵横比（扩展的sar，见H.264[2]的表e-1），无几何失真。
H.264-compliant encoders SHOULD NOT send an aspect_ratio_idc equal to 0 or an aspect_ratio_idc larger than sar-understood and smaller than 255. H.264-compliant encoders SHOULD send an aspect_ratio_idc that the receiver is able to display without geometrical distortion. However, H.264-compliant encoders MAY choose to send pictures using any SAR.
H.264兼容编码器不应发送等于0的纵横比idc或大于sar理解值且小于255的纵横比idc。符合H.264标准的编码器应发送一个纵横比idc，接收器能够在没有几何失真的情况下显示。然而，兼容H.264的编码器可以选择使用任何SAR发送图片。
Note that the actual sample aspect ratio or extended sample aspect ratio, when present, of the stream is conveyed in the Video Usability Information (VUI) part of the sequence parameter set.
注意，流的实际样本纵横比或扩展样本纵横比（当存在时）在序列参数集的视频可用性信息（VUI）部分中传送。
Encoding considerations: This type is only defined for transfer via RTP (RFC 3550) and is framed and binary (see Section 4.8 in RFC 4288).
编码注意事项：此类型仅定义为通过RTP（RFC 3550）传输，并且是帧和二进制的（参见RFC 4288中的第4.8节）。
Security considerations: See Section 9 of RFC 6185.
安全注意事项：见RFC 6185第9节。
Interoperability considerations: None
互操作性注意事项：无
Published specification: RFC 6185 and its reference section
出版规范：RFC 6185及其参考章节
Applications that use this media type: Video streaming and conferencing applications
使用此媒体类型的应用程序：视频流和会议应用程序
Additional information: None
其他信息：无
Magic number(s):
幻数：
File extension(s):
文件扩展名：
Macintosh file type code(s):
Macintosh文件类型代码：
Person & email address to contact for further information:
联系人和电子邮件地址，以获取更多信息：
Tom Kristensen <tom.kristensen@tandberg.com>, <tomkri@ifi.uio.no>
Tom Kristensen <tom.kristensen@tandberg.com>, <tomkri@ifi.uio.no>
Intended usage: COMMON
预期用途：普通
Restrictions on usage: This type depends on RTP framing; hence, it is only defined for transfer via RTP (see RFC 3550). Transport within other framing protocols is not defined at this time.
使用限制：此类型取决于RTP帧；因此，它仅定义为通过RTP传输（见RFC 3550）。此时未定义其他帧协议内的传输。
Author: Tom Kristensen
作者：汤姆·克里斯滕森
Change controller: IETF Audio/Video Transport Working Group delegated from the IESG
变更控制员：IESG授权的IETF音频/视频传输工作组
The mapping of the above defined payload format media subtype and its parameters SHALL be done according to Section 3 of RFC 4855 [10].
应根据RFC 4855[10]第3节的规定，映射上述定义的有效负载格式媒体子类型及其参数。
An example of the "fmtp" attribute in the media representation of a level 2.2 bitstream is as follows:
2.2级比特流的媒体表示中的“fmtp”属性的示例如下：
a=fmtp:97 profile-level-id=008016
a=fmtp:97 profile-level-id=008016
When H264-RCDO is offered over RTP using SDP in an Offer/Answer model [5] for unicast and multicast usage, the limitations and rules described in Section 8.2.2 of RFC 6184 [1] apply. Note that the profile_idc byte of the H264-RCDO profile-level-id parameter can only take the value of 0 (no profile).
当H264-RCDO在RTP上使用SDP在提供/应答模型[5]中提供单播和多播使用时，RFC 6184[1]第8.2.2节中描述的限制和规则适用。请注意，H264-RCDO profile level id参数的profile_idc字节只能取值为0（无profile）。
For interoperability with systems not supporting H264-RCDO, it is RECOMMENDED to offer the H264 media subtype as well. As specified in RFC 3264 [5], listing the payload number for H264-RCDO before H264 in the format list on the "m=" line signals that H264-RCDO is preferred over H264. Following is an example where this scheme is applied:
对于不支持H264-RCDO的系统的互操作性，建议也提供H264媒体子类型。按照RFC 3264[5]中的规定，在“m=”行上的格式列表中列出H264之前H264-RCDO的有效载荷编号表示H264-RCDO优先于H264。以下是应用此方案的示例：
m=video 5555 RTP/AVP 97 98
m=视频5555 RTP/AVP 97 98
a=rtpmap:97 H264-RCDO/90000
a=rtpmap:97 H264-RCDO/90000
a=fmtp:97 profile-level-id=008016;max-mbps=42000;max-smbps=323500
a=fmtp:97 profile-level-id=008016;max-mbps=42000;max-smbps=323500
a=rtpmap:98 H264/90000
a=rtpmap:98 H264/90000
a=fmtp:98 profile-level-id=428016;max-mbps=35000;max-smbps=323500
a=fmtp:98 profile-level-id=428016;max-mbps=35000;max-smbps=323500
When H264-RCDO over RTP is offered with SDP in a declarative style, as in the Real Time Streaming Protocol (RTSP) [11] or the Session Announcement Protocol (SAP) [12], the considerations in Section 8.2.3 of RFC 6184 [1] apply. Note that the profile_idc byte of the H264- RCDO profile-level-id parameter can only take the value of 0 (no profile).
当H264-RCDO over RTP以声明式方式与SDP一起提供时，如在实时流协议（RTSP）[11]或会话公告协议（SAP）[12]中，RFC 6184[1]第8.2.3节中的注意事项适用。请注意，H264-RCDO profile level id参数的profile_idc字节只能取值为0（无profile）。
IANA has registered H264-RCDO as specified in Section 6.1. The media subtype has also been added to the IANA registry for "RTP Payload Format MIME types" (http://www.iana.org).
IANA已按照第6.1节的规定注册了H264-RCDO。媒体子类型也已添加到IANA注册表中，用于“RTP有效负载格式MIME类型”(http://www.iana.org).
RTP packets using the payload format defined in this specification are subject to the security considerations discussed in the RTP specification [6] and in any applicable RTP profile. Refer also to the security considerations of the RTP Payload Format for H.264 Video specification in RFC 6184 [1]. No additional security considerations are introduced by this specification.
使用本规范中定义的有效负载格式的RTP数据包应遵守RTP规范[6]和任何适用RTP配置文件中讨论的安全注意事项。另请参阅RFC 6184[1]中H.264视频规范的RTP有效负载格式的安全注意事项。本规范未引入其他安全注意事项。
The authors would like to acknowledge Gisle Bjoentegaard and Arild Fuldseth for their technical contribution to the specification. In the final phases, Roni Even did a helpful review.
作者要感谢Gisle Bjoentegaard和Arild Fuldseth对规范的技术贡献。在最后阶段，Roni甚至做了一次有益的回顾。
[1] Wang, Y., Even, R., Kristensen, T., and R. Jesup, "RTP Payload Format for H.264 Video", RFC 6184, May 2011.
[1] Wang，Y.，Even，R.，Kristensen，T.，和R.Jesup，“H.264视频的RTP有效载荷格式”，RFC 6184，2011年5月。
[2] International Telecommunications Union, "Advanced video coding for generic audiovisual services", ITU-T Recommendation H.264, March 2010.
[2] 国际电信联盟，“通用视听服务的高级视频编码”，ITU-T建议H.264，2010年3月。
[3] International Telecommunications Union, "Extended video procedures and control signals for H.300-series terminals", ITU-T Recommendation H.241, May 2006.
[3] 国际电信联盟，“H.300系列终端的扩展视频程序和控制信号”，ITU-T建议H.241，2006年5月。
[4] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997.
[4] Bradner，S.，“RFC中用于表示需求水平的关键词”，BCP 14，RFC 2119，1997年3月。
[5] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model with Session Description Protocol (SDP)", RFC 3264, June 2002.
[5] 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。
[6] Schulzrinne, H., Casner, S., Frederick, R., and V. Jacobson, "RTP: A Transport Protocol for Real-Time Applications", STD 64, RFC 3550, July 2003.
[6] 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。
[7] Schulzrinne, H. and S. Casner, "RTP Profile for Audio and Video Conferences with Minimal Control", STD 65, RFC 3551, July 2003.
[7] 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。
[8] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session Description Protocol", RFC 4566, July 2006.
[8] Handley，M.，Jacobson，V.，和C.Perkins，“SDP：会话描述协议”，RFC4566，2006年7月。
[9] Josefsson, S., "The Base16, Base32, and Base64 Data Encodings", RFC 4648, October 2006.
[9] Josefsson，S.，“Base16、Base32和Base64数据编码”，RFC4648，2006年10月。
[10] Casner, S., "Media Type Registration of RTP Payload Formats", RFC 4855, February 2007.
[10] Casner，S.，“RTP有效载荷格式的媒体类型注册”，RFC 4855，2007年2月。
[11] Schulzrinne, H., Rao, A., and R. Lanphier, "Real Time Streaming Protocol (RTSP)", RFC 2326, April 1998.
[11] Schulzrinne，H.，Rao，A.，和R.Lanphier，“实时流协议（RTSP）”，RFC2326，1998年4月。
[12] Handley, M., Perkins, C., and E. Whelan, "Session Announcement Protocol", RFC 2974, October 2000.
[12] Handley，M.，Perkins，C.，和E.Whelan，“会话公告协议”，RFC 29742000年10月。
[13] Freed, N. and J. Klensin, "Media Type Specifications and Registration Procedures", BCP 13, RFC 4288, December 2005.
[13] Freed，N.和J.Klensin，“介质类型规范和注册程序”，BCP 13，RFC 4288，2005年12月。
[14] Lennox, J., Ott, J., and T. Schierl, "Source-Specific Media Attributes in the Session Description Protocol (SDP)", RFC 5576, June 2009.
[14] Lennox，J.，Ott，J.，和T.Schierl，“会话描述协议（SDP）中的源特定媒体属性”，RFC 55762009年6月。
Authors' Addresses
作者地址
Tom Kristensen TANDBERG Philip Pedersens vei 22 N-1366 Lysaker Norway
Tom Kristensen TANDBERG Philip Pedersens vei 22 N-1366挪威莱赛克
Phone: +47 67125125
EMail: tom.kristensen@tandberg.com, tomkri@ifi.uio.no
URI: http://www.tandberg.com
Phone: +47 67125125
EMail: tom.kristensen@tandberg.com, tomkri@ifi.uio.no
URI: http://www.tandberg.com
Patrick Luthi TANDBERG Philip Pedersens vei 22 N-1366 Lysaker Norway
Patrick Luthi TANDBERG Philip Pedersens vei 22 N-1366挪威莱赛克
EMail: patrick.luthi@tandberg.com
URI: http://www.tandberg.com
EMail: patrick.luthi@tandberg.com
URI: http://www.tandberg.com