RTP Payload Format for Video Codec 1 (VC-1)
RFC 4425

• Status
• IESG evaluation record
• IESG writeups
• Email expansions
• History

• Versions
• 06

Network Working Group                                         A. Klemets
Request for Comments: 4425                                     Microsoft
Category: Standards Track                                  February 2006

              RTP Payload Format for Video Codec 1 (VC-1)

Status of This Memo

   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.

Copyright Notice

   Copyright (C) The Internet Society (2006).

Abstract

   This memo specifies an RTP payload format for encapsulating Video
   Codec 1 (VC-1) compressed bit streams, as defined by the Society of
   Motion Picture and Television Engineers (SMPTE) standard, SMPTE 421M.
   SMPTE is the main standardizing body in the motion imaging industry,
   and the SMPTE 421M standard defines a compressed video bit stream
   format and decoding process for television.

Klemets                     Standards Track                     [Page 1]
RFC 4425              RTP Payload Format for VC-1          February 2006

Table of Contents

   1. Introduction ....................................................2
      1.1. Conventions Used in This Document ..........................3
   2. Definitions and Abbreviations ...................................3
   3. Overview of VC-1 ................................................5
      3.1. VC-1 Bit Stream Layering Model .............................6
      3.2. Bit-stream Data Units in Advanced Profile ..................7
      3.3. Decoder Initialization Parameters ..........................7
      3.4. Ordering of Frames .........................................8
   4. Encapsulation of VC-1 Format Bit Streams in RTP .................9
      4.1. Access Units ...............................................9
      4.2. Fragmentation of VC-1 frames ..............................10
      4.3. Time Stamp Considerations .................................11
      4.4. Random Access Points ......................................13
      4.5. Removal of HRD Parameters .................................14
      4.6. Repeating the Sequence Layer Header .......................14
      4.7. Signaling of Media Type Parameters ........................15
      4.8. The "mode=1" Media Type Parameter .........................16
      4.9. The "mode=3" Media Type Parameter .........................16
   5. RTP Payload Format Syntax ......................................17
      5.1. RTP Header Usage ..........................................17
      5.2. AU Header Syntax ..........................................18
      5.3. AU Control Field Syntax ...................................19
   6. RTP Payload Format Parameters ..................................20
      6.1. Media type Registration ...................................20
      6.2. Mapping of media type parameters to SDP ...................28
      6.3. Usage with the SDP Offer/Answer Model .....................29
      6.4. Usage in Declarative Session Descriptions .................31
   7. Security Considerations ........................................32
   8. Congestion Control .............................................33
   9. IANA Considerations ............................................34
   10. References ....................................................34
      10.1. Normative References .....................................34
      10.2. Informative References ...................................35

1.  Introduction

   This memo specifies an RTP payload format for the video coding
   standard Video Codec 1, also known as VC-1.  The specification for
   the VC-1 bit stream format and decoding process is published by the
   Society of Motion Picture and Television Engineers (SMPTE) as SMPTE
   421M [1].

   VC-1 has a broad applicability, as it is suitable for low bit rate
   Internet streaming applications to High Definition Television (HDTV)
   broadcast and Digital Cinema applications with nearly lossless
   coding.  The overall performance of VC-1 is such that bit rate

Klemets                     Standards Track                     [Page 2]
RFC 4425              RTP Payload Format for VC-1          February 2006

   savings of more than 50% are reported [9] when compared with MPEG-2.
   See [9] for further details about how VC-1 compares with other
   codecs, such as MPEG-4 and H.264/AVC.  (In [9], VC-1 is referred to
   by its earlier name, VC-9.)

   VC-1 is widely used for downloading and streaming movies on the
   Internet, in the form of Windows Media Video 9 (WMV-9) [9], because
   the WMV-9 codec is compliant with the VC-1 standard.  VC-1 has also
   recently been adopted as a mandatory compression format for the
   high-definition DVD formats HD DVD and Blu-ray.