Network Working Group C. Perkins
Request for Comments: 4421 University of Glasgow
Updates: 4175 February 2006
Category: Standards Track
Network Working Group C. Perkins
Request for Comments: 4421 University of Glasgow
Updates: 4175 February 2006
Category: Standards Track
RTP Payload Format for Uncompressed Video: Additional Colour Sampling Modes
未压缩视频的RTP有效负载格式：附加颜色采样模式
Status of This Memo
关于下段备忘
This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited.
本文件规定了互联网社区的互联网标准跟踪协议，并要求进行讨论和提出改进建议。有关本协议的标准化状态和状态，请参考当前版本的“互联网官方协议标准”（STD 1）。本备忘录的分发不受限制。
Copyright Notice
版权公告
Copyright (C) The Internet Society (2006).
版权所有（C）互联网协会（2006年）。
Abstract
摘要
The RFC Payload Format for Uncompressed Video, RFC 4175, defines a scheme to packetise uncompressed, studio-quality, video streams for transport using RTP. This memo extends the format to support additional colour sampling modes.
未压缩视频的RFC有效负载格式RFC 4175定义了一种方案，用于打包未压缩的、工作室质量的视频流，以便使用RTP进行传输。此备忘录扩展了格式以支持其他颜色采样模式。
The RTP Payload Format for Uncompressed Video [1] defines a scheme to packetise uncompressed, studio-quality, video streams for transport using RTP [2]. A range of standard and high-definition video formats is supported, and parameters are defined so sender and receiver can negotiate the image size, colour space, pixel depth, and colour sampling mode.
未压缩视频的RTP有效负载格式[1]定义了一种方案，用于打包未压缩、工作室质量的视频流，以便使用RTP[2]进行传输。支持一系列标准和高清视频格式，并定义参数，以便发送方和接收方可以协商图像大小、颜色空间、像素深度和颜色采样模式。
A limitation of the signalling is that the number of bits per sample is assumed to be the same for each colour component. For example, it is possible to signal video using RGB colour sampling with 8 bits for each of the Red, Green, and Blue components (24 bits per pixel), but not video using RGB colour sampling with 5 bits each for the Red and Blue components, but 6 bits for the Green component (16 bits per pixel). Such video formats can easily be transported by the payload format, but cannot be signalled using the parameters defined. This memo extends [1] with additional colour sampling modes, to signal such video formats.
信令的一个限制是，假定每个颜色分量的每个样本的位数相同。例如，对于红色、绿色和蓝色分量，可以使用8位的RGB颜色采样（每像素24位）为视频发送信号，但是对于红色和蓝色分量，可以使用5位的RGB颜色采样，但是对于绿色分量，可以使用6位（每像素16位）为视频发送信号。这种视频格式可以通过有效负载格式轻松传输，但不能使用定义的参数发出信号。此备忘录扩展了[1]的附加颜色采样模式，以向此类视频格式发送信号。
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [3].
本文件中的关键词“必须”、“不得”、“要求”、“应”、“不应”、“应”、“不应”、“建议”、“可”和“可选”应按照RFC 2119[3]中所述进行解释。
This memo defines six new colour sampling modes that MAY be signalled for use with [1]. The new modes are "RGB+", "RG+B", "R+GB", "BGR+", "BG+R", and "B+GR". These sampling modes use the same packing order of samples as do the RGB and BGR colour sampling modes, respectively (Section 4.3 of [1]), except that an additional bit per sample of colour depth MUST be used for the component marked by the + symbol. The mandatory parameter "depth=N" indicates that N bits per sample are used by the unmarked components, but N+1 bits are used by the marked component. All other features of the payload format are as defined in [1].
本备忘录定义了六种新的颜色采样模式，可与[1]一起使用。新模式为“RGB+”、“RG+B”、“R+GB”、“BGR+”、“BG+R”和“B+GR”。这些采样模式分别使用与RGB和BGR颜色采样模式相同的样品包装顺序（见[1]第4.3节），但每个样品的颜色深度必须使用一个额外的位用于标有+符号的组件。强制参数“depth=N”表示未标记的组件使用每个样本的N位，但标记的组件使用N+1位。有效载荷格式的所有其他特征如[1]中所定义。
The primary use of these colour sampling modes is to enable efficient packing of data into small pixel groups ("pgroups"). The most common use case is expected to be video with "depth=5", where the additional bit of colour depth for the marked component enables a single pixel to fit into two octets without padding. The new colour sampling modes MAY be used for other depths, however, should that prove useful.
这些颜色采样模式的主要用途是将数据有效打包到小像素组（“PG组”）。最常见的用例预计是“深度=5”的视频，其中标记组件的额外颜色深度位使单个像素能够装入两个八位字节，而无需填充。新的颜色取样模式可用于其他深度，但是，如果证明有用的话。
A common uncompressed video format is RGB with 5 bits for the Red and Blue components and 6 bits for the Green component, for a total of 16 bits per pixel. Using the sampling modes defined in this memo, this can be signalled in Session Description Protocol (SDP) according to the following example:
常见的未压缩视频格式是RGB，红色和蓝色分量为5位，绿色分量为6位，每像素16位。使用本备忘录中定义的采样模式，可根据以下示例在会话描述协议（SDP）中发出信号：
v=0
o=jdoe 2890844526 2890842807 IN IP4 192.0.2.5
s=-
c=IN IP4 192.0.2.6
t=2873397496 2873404696
m=video 51372 RTP/AVP 99
a=rtpmap:99 raw/90000
a=fmtp:99 sampling=RG+B; width=1024; height=768; depth=5;
colorimetry=SMPTE240M
v=0
o=jdoe 2890844526 2890842807 IN IP4 192.0.2.5
s=-
c=IN IP4 192.0.2.6
t=2873397496 2873404696
m=video 51372 RTP/AVP 99
a=rtpmap:99 raw/90000
a=fmtp:99 sampling=RG+B; width=1024; height=768; depth=5;
colorimetry=SMPTE240M
The last line has been wrapped due to formatting constraints of this memo, and forms one complete line in the SDP file.
由于此备忘录的格式限制，最后一行已被包装，并在SDP文件中形成一个完整的行。
The security considerations of [1] apply. No additional security considerations are introduced by support for new colour sampling modes.
[1]中的安全注意事项适用。支持新的颜色采样模式不会引入额外的安全注意事项。
The video/raw media type is extended with six new values for the "sampling" parameter according to the rules defined in Section 6.2 of [1]. The new values are "RGB+", "RG+B", "R+GB", "BGR+", "BG+R", and "B+GR" as described in this memo.
根据[1]第6.2节中定义的规则，视频/原始媒体类型扩展为“采样”参数的六个新值。如本备忘录所述，新值为“RGB+”、“RG+B”、“R+GB”、“BGR+”、“BG+R”和“B+GR”。
Thanks to Jeremy Searle and Andrew Lee at Westland Helicopters.
感谢Westland直升机公司的Jeremy Searle和Andrew Lee。
[1] Gharai, L. and C. Perkins, "RTP Payload Format for Uncompressed Video", RFC 4175, September 2005.
[1] Gharai，L.和C.Perkins，“未压缩视频的RTP有效载荷格式”，RFC4175，2005年9月。
[2] Schulzrinne, H., Casner, S., Frederick, R., and V. Jacobson, "RTP: A Transport Protocol for Real-Time Applications", STD 64, RFC 3550, July 2003.
[2] 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。
[3] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997.
[3] Bradner，S.，“RFC中用于表示需求水平的关键词”，BCP 14，RFC 2119，1997年3月。
Author's Address
作者地址
Colin Perkins University of Glasgow Department of Computing Science 17 Lilybank Gardens Glasgow G12 8QQ UK
柯林帕金斯格拉斯哥大学计算科学系17 LIYBANK花园格拉斯哥G128QQ英国
EMail: csp@csperkins.org
EMail: csp@csperkins.org
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