下载地址:http://www.rosoo.net/Files/UpFiles/DevMedia/Protocol/draft-ietf-avt-rtp-howto-06.txt
Audio Video Transport Working M. Westerlund
Group Ericsson
Internet-Draft March 2, 2009
Intended status: Informational
Expires: September 3, 2009
How to Write an RTP Payload Format
draft-ietf-avt-rtp-howto-06
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Abstract
This document contains information on how to best write an RTP
payload format. Reading tips, design practices, and practical tips
on how to quickly and with good results produce an RTP payload format
specification. A template is also included with instructions that
can be used when writing an RTP payload format.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.1. Structure . . . . . . . . . . . . . . . . . . . . . . . . 5
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.1. Definitions . . . . . . . . . . . . . . . . . . . . . . . 6
2.2. Acronyms . . . . . . . . . . . . . . . . . . . . . . . . . 6
3. Preparations . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.1. Recommend Reading . . . . . . . . . . . . . . . . . . . . 8
3.1.1. IETF Process and Publication . . . . . . . . . . . . . 8
3.1.2. RTP . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.2. Important RTP details . . . . . . . . . . . . . . . . . . 13
3.2.1. The RTP Session . . . . . . . . . . . . . . . . . . . 13
3.2.2. RTP Header . . . . . . . . . . . . . . . . . . . . . . 14
3.2.3. RTP Multiplexing . . . . . . . . . . . . . . . . . . . 15
3.2.4. RTP Synchronization . . . . . . . . . . . . . . . . . 16
3.3. Signalling Aspects . . . . . . . . . . . . . . . . . . . . 17
3.3.1. Media Types . . . . . . . . . . . . . . . . . . . . . 17
3.3.2. Mapping to SDP . . . . . . . . . . . . . . . . . . . . 18
3.4. Transport Characteristics . . . . . . . . . . . . . . . . 21
3.4.1. Path MTU . . . . . . . . . . . . . . . . . . . . . . . 21
4. Specification Process . . . . . . . . . . . . . . . . . . . . 22
4.1. IETF . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
4.1.1. Steps from Idea to Publication . . . . . . . . . . . . 22
4.1.2. WG meetings . . . . . . . . . . . . . . . . . . . . . 24
4.1.3. Draft Naming . . . . . . . . . . . . . . . . . . . . . 24
4.1.4. How to speed up the process . . . . . . . . . . . . . 24
4.2. Other Standards bodies . . . . . . . . . . . . . . . . . . 25
4.3. Propreitary and Vendor Specific . . . . . . . . . . . . . 26
5. Designing Payload Formats . . . . . . . . . . . . . . . . . . 27
5.1. Features of RTP payload formats . . . . . . . . . . . . . 27
5.1.1. Aggregation . . . . . . . . . . . . . . . . . . . . . 27
5.1.2. Fragmentation . . . . . . . . . . . . . . . . . . . . 28
5.1.3. Interleaving and Transmission Re-Scheduling . . . . . 28
5.1.4. Media Back Channels . . . . . . . . . . . . . . . . . 29
5.1.5. Scalability . . . . . . . . . . . . . . . . . . . . . 29
5.1.6. High Packet Rates . . . . . . . . . . . . . . . . . . 30
6. Current Trends in Payload Format Design . . . . . . . . . . . 31
6.1. Audio Payloads . . . . . . . . . . . . . . . . . . . . . . 31
6.2. Video . . . . . . . . . . . . . . . . . . . . . . . . . . 31
6.3. Text . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
7. Important Specification Sections . . . . . . . . . . . . . . . 33
7.1. Security Consideration . . . . . . . . . . . . . . . . . . 33
7.2. Congestion Control . . . . . . . . . . . . . . . . . . . . 34
7.3. IANA Consideration . . . . . . . . . . . . . . . . . . . . 34
8. Authoring Tools . . . . . . . . . . . . . . . . . . . . . . . 36
8.1. Editing Tools . . . . . . . . . . . . . . . . . . . . . . 36
8.2. Verification Tools . . . . . . . . . . . .[FS:PAGE] . . . . . . . . 36
9. Open Issues . . . . . . . . . . . . . . . . . . . . . . . . . 37
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 38
11. Security Considerations . . . . . . . . . . . . . . . . . . . 39
12. RFC Editor Consideration . . . . . . . . . . . . . . . . . . . 40
13. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 41
14. Informative References . . . . . . . . . . . . . . . . . . . . 42
Appendix A. RTP Payload Format Template . . . . . . . . . . . . . 47
A.1. Title . . . . . . . . . . . . . . . . . . . . . . . . . . 47
A.2. Front page boilerplate . . . . . . . . . . . . . . . . . . 47
A.3. Abstract . . . . . . . . . . . . . . . . . . . . . . . . . 48
A.4. Table of Content . . . . . . . . . . . . . . . . . . . . . 48
A.5. Introduction . . . . . . . . . . . . . . . . . . . . . . . 48
A.6. Conventions, Definitions and Acronyms . . . . . . . . . . 48
A.7. Media Format Background . . . . . . . . . . . . . . . . . 48
A.8. Payload format . . . . . . . . . . . . . . . . . . . . . . 48
A.8.1. RTP Header Usage . . . . . . . . . . . . . . . . . . . 49
A.8.2. Payload Header . . . . . . . . . . . . . . . . . . . . 49
A.8.3. Payload Data . . . . . . . . . . . . . . . . . . . . . 49
A.9. Payload Examples . . . . . . . . . . . . . . . . . . . . . 49
A.10. Congestion Control Considerations . . . . . . . . . . . . 49
A.11. Payload Format Parameters . . . . . . . . . . . . . . . . 49
A.11.1. Media Type Definition . . . . . . . . . . . . . . . . 49
A.11.2. Mapping to SDP . . . . . . . . . . . . . . . . . . . . 51
A.12. IANA Considerations . . . . . . . . . . . . . . . . . . . 51
A.13. Securtiy Considerations . . . . . . . . . . . . . . . . . 51
A.14. References . . . . . . . . . . . . . . . . . . . . . . . . 52
A.14.1. Normative References . . . . . . . . . . . . . . . . . 52
A.14.2. Informative References . . . . . . . . . . . . . . . . 52
A.15. Author Addresses . . . . . . . . . . . . . . . . . . . . . 53
Author''''s Address . . . . . . . . . . . . . . . . . . . . . . . . . 54
(IETF) |