Raptor Forward Error Correction (FEC) Schemes for FECFRAME
RFC 6681

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Internet Engineering Task Force (IETF)                         M. Watson
Request for Comments: 6681                                       Netflix
Category: Standards Track                                 T. Stockhammer
ISSN: 2070-1721                                           Nomor Research
                                                                 M. Luby
                                                   Qualcomm Incorporated
                                                             August 2012

       Raptor Forward Error Correction (FEC) Schemes for FECFRAME

Abstract

   This document describes Fully-Specified Forward Error Correction
   (FEC) Schemes for the Raptor and RaptorQ codes and their application
   to reliable delivery of media streams in the context of the FEC
   Framework.  The Raptor and RaptorQ codes are systematic codes, where
   a number of repair symbols are generated from a set of source symbols
   and sent in one or more repair flows in addition to the source
   symbols that are sent to the receiver(s) within a source flow.  The
   Raptor and RaptorQ codes offer close to optimal protection against
   arbitrary packet losses at a low computational complexity.  Six FEC
   Schemes are defined: two for the protection of arbitrary packet
   flows, two that are optimized for small source blocks, and two for
   the protection of a single flow that already contains a sequence
   number.  Repair data may be sent over arbitrary datagram transport
   (e.g., UDP) or using RTP.

Status of This Memo

   This is an Internet Standards Track document.

   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.

   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/rfc6681.

Watson, et al.               Standards Track                    [Page 1]
RFC 6681                    Raptor FEC Scheme                August 2012

Copyright Notice

   Copyright (c) 2012 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   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
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   include Simplified BSD License text as described in Section 4.e of
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   described in the Simplified BSD License.

   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.

Watson, et al.               Standards Track                    [Page 2]
RFC 6681                    Raptor FEC Scheme                August 2012

Table of Contents

   1. Introduction ....................................................4
   2. Document Outline ................................................5
   3. Requirements Notation ...........................................5
   4. Definitions and Abbreviations ...................................5
      4.1. Definitions ................................................6
      4.2. Abbreviations ..............................................6
   5. General Procedures for Raptor FEC Schemes .......................6
   6. Raptor FEC Schemes for Arbitrary Packet Flows ...................8
      6.1. Introduction ...............................................8
      6.2. Formats and Codes ..........................................8
           6.2.1. FEC Framework Configuration Information .............8
           6.2.2. Source FEC Payload ID ...............................9
           6.2.3. Repair FEC Payload ID ..............................10
      6.3. Procedures ................................................11
           6.3.1. Source Symbol Construction .........................11
           6.3.2. Repair Packet Construction .........................12