draft-ietf-fecframe-raptor-06.txt   draft-ietf-fecframe-raptor-07.txt 
FEC Framework M. Watson FEC Framework M. Watson
Internet-Draft Netflix Internet-Draft Netflix
Intended status: Standards Track T. Stockhammer Intended status: Standards Track T. Stockhammer
Expires: May 27, 2012 Nomor Research Expires: May 27, 2012 Nomor Research
M. Luby M. Luby
Qualcomm Incorporated Qualcomm Incorporated
November 24, 2011 November 24, 2011
Raptor FEC Schemes for FECFRAME Raptor FEC Schemes for FECFRAME
draft-ietf-fecframe-raptor-06 draft-ietf-fecframe-raptor-07
Abstract Abstract
This document describes Fully-Specified Forward Error Correction This document describes Fully-Specified Forward Error Correction
(FEC) Schemes for the Raptor and RaptorQ codes and their application (FEC) Schemes for the Raptor and RaptorQ codes and their application
to reliable delivery of media streams in the context of FEC to reliable delivery of media streams in the context of FEC
Framework. The Raptor and RaptorQ codes are systematic codes, where Framework. The Raptor and RaptorQ codes are systematic codes, where
a number of repair symbols are generated from a set of source symbols 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 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 symbols that are sent to the receiver(s) within a source flow. The
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8.1. Formats and codes . . . . . . . . . . . . . . . . . . . . 15 8.1. Formats and codes . . . . . . . . . . . . . . . . . . . . 15
8.1.1. FEC Framework Configuration Information . . . . . . . 15 8.1.1. FEC Framework Configuration Information . . . . . . . 15
8.1.2. Source FEC Payload ID . . . . . . . . . . . . . . . . 15 8.1.2. Source FEC Payload ID . . . . . . . . . . . . . . . . 15
8.1.3. Repair FEC Payload ID . . . . . . . . . . . . . . . . 15 8.1.3. Repair FEC Payload ID . . . . . . . . . . . . . . . . 15
8.2. Procedures . . . . . . . . . . . . . . . . . . . . . . . . 17 8.2. Procedures . . . . . . . . . . . . . . . . . . . . . . . . 17
8.2.1. Source symbol construction . . . . . . . . . . . . . . 17 8.2.1. Source symbol construction . . . . . . . . . . . . . . 17
8.2.2. Derivation of Source FEC Packet Identification 8.2.2. Derivation of Source FEC Packet Identification
Information . . . . . . . . . . . . . . . . . . . . . 17 Information . . . . . . . . . . . . . . . . . . . . . 17
8.2.3. Repair packet construction . . . . . . . . . . . . . . 18 8.2.3. Repair packet construction . . . . . . . . . . . . . . 18
8.2.4. Procedures for RTP source flows . . . . . . . . . . . 18 8.2.4. Procedures for RTP source flows . . . . . . . . . . . 18
8.3. FEC Code Specification . . . . . . . . . . . . . . . . . . 18 8.3. FEC Code Specification . . . . . . . . . . . . . . . . . . 19
9. Security Considerations . . . . . . . . . . . . . . . . . . . 19 9. Security Considerations . . . . . . . . . . . . . . . . . . . 19
10. Session Description Protocol (SDP) Signaling . . . . . . . . . 19 10. Session Description Protocol (SDP) Signaling . . . . . . . . . 19
11. Congestion Control Considerations . . . . . . . . . . . . . . 19 11. Congestion Control Considerations . . . . . . . . . . . . . . 19
12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 20
12.1. Registration of FEC Scheme IDs . . . . . . . . . . . . . . 19 12.1. Registration of FEC Scheme IDs . . . . . . . . . . . . . . 20
13. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 20 13. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 20
14. References . . . . . . . . . . . . . . . . . . . . . . . . . . 20 14. References . . . . . . . . . . . . . . . . . . . . . . . . . . 20
14.1. Normative References . . . . . . . . . . . . . . . . . . . 20 14.1. Normative References . . . . . . . . . . . . . . . . . . . 20
14.2. Informative References . . . . . . . . . . . . . . . . . . 21 14.2. Informative References . . . . . . . . . . . . . . . . . . 21
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 21 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 21
1. Introduction 1. Introduction
The FEC Framework [RFC6363] describes a framework for the application The FEC Framework [RFC6363] describes a framework for the application
of Forward Error Correction to arbitrary packet flows. Modeled after of Forward Error Correction to arbitrary packet flows. Modeled after
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o The Initial Sequence Number of the source block, I o The Initial Sequence Number of the source block, I
Then the Encoding Symbol ID for packet with sequence number Ns is Then the Encoding Symbol ID for packet with sequence number Ns is
determined by the following formula: determined by the following formula:
ESI = ( Ns - I ) * LP ESI = ( Ns - I ) * LP
Note that all repair packet associated to a given Source Block MUST Note that all repair packet associated to a given Source Block MUST
contain the same Source Block Length and Initial Sequence Number. contain the same Source Block Length and Initial Sequence Number.
Note also that the source packet flow processed by the FEC encoder
MUST have consecutive sequence numbers. In case the incoming source
packet flow has a gap in the sequence numbers then implementors
SHOULD insert an ADU in the source block that complies to the format
of the source packet flow, but is ignored at the application with
high probability. For additional guidelines refer to [RFC6363],
Section 10.2, paragraph 5.
8.2.3. Repair packet construction 8.2.3. Repair packet construction
See Section 7.3.2 See Section 7.3.2
8.2.4. Procedures for RTP source flows 8.2.4. Procedures for RTP source flows
In the specific case of RTP source packet flows, then the RTP In the specific case of RTP source packet flows, then the RTP
Sequence Number field SHALL be used as the sequence number in the Sequence Number field SHALL be used as the sequence number in the
procedures described above. The length indication included in the procedures described above. The length indication included in the
Application Data Unit Information SHALL be the RTP payload length Application Data Unit Information SHALL be the RTP payload length
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