Internet Engineering Task Force (IETF)                         M. Watson
Request for Comments: 6682                                       Netflix
Category: Standards Track                                 T. Stockhammer
ISSN: 2070-1721                                           Nomor Research
                                                                M. Luby
                                                  Qualcomm Incorporated
                                                            August 2012


     RTP Payload Format for Raptor Forward Error Correction (FEC)

Abstract

  This document specifies an RTP payload format for the Forward Error
  Correction (FEC) repair data produced by the Raptor FEC Schemes.
  Raptor FEC Schemes are specified for use with the IETF FEC Framework
  that supports the transport of repair data over both UDP and RTP.
  This document specifies the payload format that is required for the
  use of RTP to carry Raptor repair flows.

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/rfc6682.

















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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
  to this document.  Code Components extracted from this document must
  include Simplified BSD License text as described in Section 4.e of
  the Trust Legal Provisions and are provided without warranty as
  described in the Simplified BSD License.

Table of Contents

  1. Introduction ....................................................3
  2. Conventions, Definitions, and Acronyms ..........................3
  3. Media Format Background .........................................3
  4. Payload Format for FEC Repair Packets ...........................4
     4.1. RTP Header Usage ...........................................4
     4.2. Payload Header .............................................5
     4.3. Payload Data ...............................................5
  5. Congestion Control Considerations ...............................5
  6. Media Types .....................................................5
     6.1. Registration of the 'application/raptorfec' Media Type .....5
          6.1.1. Media Type Definition ...............................5
     6.2. Registration of the 'video/raptorfec' Media Type ...........7
          6.2.1. Media Type Definition ...............................7
     6.3. Registration of the 'audio/raptorfec' Media Type ...........8
          6.3.1. Media Type Definition ...............................8
     6.4. Registration of the 'text/raptorfec' Media Type ...........10
          6.4.1. Media Type Definition ..............................10
  7. Mapping to the Session Description Protocol (SDP) ..............12
  8. Offer/Answer Considerations ....................................12
  9. Declarative SDP Considerations .................................13
  10. Repair Flow Generation and Recovery Procedures ................13
     10.1. Overview .................................................13
     10.2. Repair Packet Construction ...............................14
     10.3. Usage of RTCP ............................................14
     10.4. Source Packet Reconstruction .............................14
  11. Session Description Protocol (SDP) Example ....................14
  12. IANA Considerations ...........................................15
  13. Security Considerations .......................................15
  14. References ....................................................16
     14.1. Normative References .....................................16
     14.2. Informative References ...................................17



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1.  Introduction

  The FEC Framework [RFC6363] defines a general framework for the use
  of Forward Error Correction in association with arbitrary packet
  flows, including flows over UDP and RTP [RFC3550].  Forward Error
  Correction operates by generating redundant data packets ("repair
  data") that can be sent independently from the original flow.  At a
  receiver, the original flow can be reconstructed provided a
  sufficient set of redundant data packets and possibly original data
  packets are received.

  The FEC Framework provides for independence between application
  protocols and FEC codes.  The use of a particular FEC code within the
  framework is defined by means of a FEC Scheme, which may then be used
  with any application protocol compliant to the framework.

  Repair data flows may be sent directly over a transport protocol,
  such as UDP, or they may be encapsulated within specialized
  transports for multimedia, such as RTP.

  This document defines the RTP payload format for the Raptor FEC
  Schemes defined in [RFC6681].

2.  Conventions, Definitions, and Acronyms

  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 [RFC2119].

3.  Media Format Background

  The Raptor and RaptorQ codes are efficient block-based fountain
  codes, meaning that from any group of source packets (or 'source
  block'), one can generate an arbitrary number of repair packets.  The
  Raptor and RaptorQ codes have the property that the original group of
  source symbols can be recovered with a very high probability from any
  set of symbols (source and repair) only slightly greater in number
  than the original number of source symbols.  The RaptorQ code
  additionally has the property that the probability that the original
  group of source symbols can be recovered from a set of symbols
  (source and repair) equal in number to the original number of source
  symbols is in many cases also very high.

  [RFC6681] defines six FEC Schemes for the use of the Raptor and
  RaptorQ codes with arbitrary packet flows.  The first two schemes are
  fully applicable to arbitrary packet flows (using Raptor and RaptorQ
  respectively).  The third and fourth schemes are slightly optimized
  versions of the first two schemes, which are applicable in



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  applications with relatively small block sizes.  The fifth and sixth
  schemes are variants of the third and fourth schemes, which are
  applicable to a single source flow that already has some kind of
  identifiable sequence number.  The presence of a sequence number in
  the source flow allows for backwards-compatible operation (the source
  flows do not need to be modified in order to apply FEC).  In this
  case, in the language of the FEC Framework, there is no need for an
  explicit FEC Source Payload ID; therefore, it is not included in the
  packets.

  This document specifies the payload format for RTP repair flows and
  can be used with any of the FEC Schemes defined in [RFC6681].

4.  Payload Format for FEC Repair Packets

4.1.  RTP Header Usage

  Header fields SHALL be set according to the rules of [RFC3550].  In
  addition, the following rules and definitions apply for the RTP
  headers used with FEC repair packets:

  o  Marker bit: The marker bit SHALL be set to 1 for the last
     protection RTP packet sent for each source block, and otherwise
     set to 0.

  o  Payload Type (PT): The payload type codes SHALL be assigned
     dynamically through non-RTP means.  If the Session Description
     Protocol (SDP) is used for signaling, the rules in Section 7
     apply.

  o  Timestamp: This field contains the time at which the packet is
     transmitted.  The time SHOULD be as close as possible to the
     packet's actual time of transmission.  The timestamp value has no
     use in the actual FEC protection process.  However,
     implementations SHOULD supply a value that can be used for packet-
     arrival timing or jitter calculations.  The timestamp rate is
     specified using the "rate" media type parameter defined in Section
     6.  The operator SHALL select a "rate" larger than 1000 Hz to
     provide sufficient resolution to the Real-Time Transport Control
     Protocol (RTCP) operations, and the operator SHOULD select the
     rate that matches the rate of the protected source RTP stream.

  o  Synchronization Source (SSRC): The SSRC values MUST be set
     according to [RFC3550].  The SSRC value of the RTP repair flow
     MUST be different from the SSRC value of the protected source
     flow.





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4.2.  Payload Header

  There is no payload header in this payload format.

4.3.  Payload Data

  Procedures and data formats for the use of Raptor Forward Error
  Correction in a FECFRAME context are fully defined in [RFC6363] and
  [RFC6681] and are not duplicated here.  The procedures of those
  documents apply in order to generate repair data streams to be
  carried by the payload formats defined in this document.

  The RTP Payload SHALL contain a Repair FEC Payload ID as defined in
  [RFC6363] and [RFC6681].

5.  Congestion Control Considerations

  See [RFC6363].

6.  Media Types

6.1.  Registration of the 'application/raptorfec' Media Type

  This RTP payload format is identified using the
  'application/raptorfec' media type that is registered in accordance
  with [RFC4855] and uses the template of [RFC4288].

6.1.1.  Media Type Definition

  Type name: application

  Subtype name: raptorfec

  Required parameters:

  o  rate: The RTP timestamp (clock) rate.  The RTP timestamp (clock)
     rate is specified in Hz and the format is unsigned integer.

  o  raptor-scheme-id: The value of this parameter is the FEC Scheme ID
     for the specific Raptor FEC Scheme that will be used as defined in
     [RFC6681].

  o  Kmax: The value of this parameter is the FEC Framework
     Configuration Information element, Maximum Source Block Length
     (MSBL), as defined in [RFC6681], encoded as a unsigned integer.
     For specific requirements for this value, refer to [RFC6681].





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  o  T: The value of this parameter is the FEC Framework Configuration
     Information element, encoding symbol size, as defined in
     [RFC6681], encoded as a unsigned integer.  For specific
     requirements for this value, refer to [RFC6681].

  o  repair-window: The maximum time that spans the source packets and
     the corresponding repair packets.  The size of the repair window
     is specified in microseconds and the format is unsigned integer.

  Optional parameters:

  o  P: The value of this parameter is the FEC Framework Configuration
     Information element, Payload ID Format, as defined in [RFC6681].
     The default value of this parameter (when it does not appear
     explicitly) is 'A'.

  Encoding considerations: This media type is framed and binary; see
  Section 4.8 in [RFC4288]

  Security considerations: Please see the security considerations in
  [RFC6363].

  Interoperability considerations:

  Published specification: [RFC6681]

  Applications that use this media type: Real-time multimedia
  applications like video streaming, audio streaming, and video
  conferencing.

  Additional information:

  Magic number(s): <none defined>

  File extension(s): <none defined>

  Macintosh file type code(s): <none defined>

  Person & email address to contact for further information:
  Thomas Stockhammer, [email protected]

  Intended usage: COMMON

  Restrictions on usage: This media type depends on RTP framing, and
  hence is only defined for transfer via RTP [RFC3550].  Transport
  within other framing protocols is not defined at this time.

  Author: Thomas Stockhammer, Nomor Research



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  Change controller: IETF PAYLOAD working group delegated from the
  IESG.

6.2.  Registration of the 'video/raptorfec' Media Type

  This RTP payload format is identified using the 'video/raptorfec'
  media type that is registered in accordance with [RFC4855] and uses
  the template of [RFC4288].

6.2.1.  Media Type Definition

  Type name: video

  Subtype name: raptorfec

  Required parameters:

  o  rate: The RTP timestamp (clock) rate.  The RTP timestamp (clock)
     rate is specified in Hz and the format is unsigned integer.

  o  raptor-scheme-id: The value of this parameter is the FEC Scheme ID
     for the specific Raptor FEC Scheme that will be used as defined in
     [RFC6681].

  o  Kmax: The value of this parameter is the FEC Framework
     Configuration Information element, MSBL, as defined in [RFC6681],
     encoded as a unsigned integer.  For specific requirements for this
     value, refer to [RFC6681].

  o  T: The value of this parameter is the FEC Framework Configuration
     Information element, encoding symbol size, as defined in
     [RFC6681], encoded as a unsigned integer.  For specific
     requirements for this value, refer to [RFC6681].

  o  repair-window: The maximum time that spans the source packets and
     the corresponding repair packets.  The size of the repair window
     is specified in microseconds, and the format is unsigned integer.

  Optional parameters:

  o  P: The value of this parameter is the FEC Framework Configuration
     Information element, Payload ID Format, as defined in [RFC6681].
     The default value of this parameter (when it does not appear
     explicitly) is 'A'.

  Encoding considerations: This media type is framed and binary; see
  Section 4.8 in [RFC4288].




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  Security considerations: Please see the security considerations in
  [RFC6363].

  Interoperability considerations:

  Published specification: [RFC6681]

  Applications that use this media type: Real-time multimedia
  applications like video streaming, audio streaming, and video
  conferencing.

  Additional information:

  Magic number(s): <none defined>

  File extension(s): <none defined>

  Macintosh file type code(s): <none defined>

  Person & email address to contact for further information:
  Thomas Stockhammer, [email protected]

  Intended usage: COMMON

  Restrictions on usage: This media type depends on RTP framing, and
  hence is only defined for transfer via RTP [RFC3550].  Transport
  within other framing protocols is not defined at this time.

  Author: Thomas Stockhammer, Nomor Research.

  Change controller: IETF PAYLOAD working group delegated from the
  IESG.

6.3.  Registration of the 'audio/raptorfec' Media Type

  This RTP payload format is identified using the 'audio/raptorfec'
  media type that is registered in accordance with [RFC4855] and uses
  the template of [RFC4288].

6.3.1.  Media Type Definition

  Type name: audio

  Subtype name: raptorfec







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  Required parameters:

  o  rate: The RTP timestamp (clock) rate.  The RTP timestamp (clock)
     rate is specified in Hz and the format is unsigned integer.

  o  raptor-scheme-id: The value of this parameter is the FEC Scheme ID
     for the specific Raptor FEC Scheme that will be used as defined in
     [RFC6681].

  o  Kmax: The value of this parameter is the FEC Framework
     Configuration Information element, MSBL, as defined in [RFC6681],
     encoded as a unsigned integer.  For specific requirements for this
     value, refer to [RFC6681].

  o  T: The value of this parameter is the FEC Framework Configuration
     Information element, encoding symbol size, as defined in
     [RFC6681], encoded as a unsigned integer.  For specific
     requirements for this value, refer to [RFC6681].

  o  repair-window: The maximum time that spans the source packets and
     the corresponding repair packets.  The size of the repair window
     is specified in microseconds and the format is unsigned integer.

  Optional parameters:

  o  P: The value of this parameter is the FEC Framework Configuration
     Information element, Payload ID Format, as defined in [RFC6681].
     The default value of this parameter (when it does not appear
     explicitly) is 'A'.

  Encoding considerations: This media type is framed and binary; see
  Section 4.8 in [RFC4288].

  Security considerations: Please see the security considerations in
  [RFC6363].

  Interoperability considerations:

  Published specification: [RFC6681]

  Applications that use this media type: Real-time multimedia
  applications like video streaming, audio streaming, and video
  conferencing.

  Additional information:

  Magic number(s): <none defined>




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  File extension(s): <none defined>

  Macintosh file type code(s): <none defined>

  Person & email address to contact for further information:
  Thomas Stockhammer, [email protected]

  Intended usage: COMMON

  Restrictions on usage: This media type depends on RTP framing, and
  hence is only defined for transfer via RTP [RFC3550].  Transport
  within other framing protocols is not defined at this time.

  Author: Thomas Stockhammer, Nomor Research.

  Change controller: IETF PAYLOAD working group delegated from the
  IESG.

6.4.  Registration of the 'text/raptorfec' Media Type

  This RTP payload format is identified using the 'text/raptorfec'
  media type that is registered in accordance with [RFC4855] and uses
  the template of [RFC4288].

6.4.1.  Media Type Definition

  Type name: text

  Subtype name: raptorfec

  Required parameters:

  o  rate: The RTP timestamp (clock) rate.  The RTP timestamp (clock)
     rate is specified in Hz and the format is unsigned integer.

  o  raptor-scheme-id: The value of this parameter is the FEC Scheme ID
     for the specific Raptor FEC Scheme that will be used as defined in
     [RFC6681].

  o  Kmax: The value of this parameter is the FEC Framework
     Configuration Information element, MSBL, as defined in [RFC6681],
     encoded as a unsigned integer.  For specific requirements for this
     value, refer to [RFC6681].

  o  T: The value of this parameter is the FEC Framework Configuration
     Information element, encoding symbol size, as defined in
     [RFC6681], encoded as a unsigned integer.  For specific
     requirements for this value, refer to [RFC6681].



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  o  repair-window: The maximum time that spans the source packets and
     the corresponding repair packets.  The size of the repair window
     is specified in microseconds and the format is unsigned integer.

  Optional parameters:

  o  P: The value of this parameter is the FEC Framework Configuration
     Information element, Payload ID Format, as defined in [RFC6681].
     The default value of this parameter (when it does not appear
     explicitly) is 'A'.

  Encoding considerations: This media type is framed and binary; see
  Section 4.8 in [RFC4288].

  Security considerations: Please see the security considerations in
  [RFC6363].

  Interoperability considerations:

  Published specification: [RFC6681]

  Applications that use this media type: Real-time multimedia
  applications like video streaming, audio streaming, and video
  conferencing.

  Additional information:

  Magic number(s): <none defined>

  File extension(s): <none defined>

  Macintosh file type code(s): <none defined>

  Person & email address to contact for further information:
  Thomas Stockhammer, [email protected]

  Intended usage: COMMON

  Restrictions on usage: This media type depends on RTP framing, and
  hence is only defined for transfer via RTP [RFC3550].  Transport
  within other framing protocols is not defined at this time.

  Author: Thomas Stockhammer, Nomor Research.

  Change controller: IETF PAYLOAD working group delegated from the
  IESG.





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7.  Mapping to the Session Description Protocol (SDP)

  Applications that are using RTP transport commonly use the Session
  Description Protocol (SDP) [RFC4566] to describe their RTP sessions.
  The information that is used to specify the media types in an RTP
  session has specific mappings to the fields in an SDP description.
  Note that if an application does not use SDP to describe the RTP
  sessions, an appropriate mapping must be defined and used to specify
  the media types and their parameters for the control/description
  protocol employed by the application.

  The mapping of the above defined payload format media type and its
  parameters SHALL be done according to Section 3 of [RFC4855],
  following the suggestion therein regarding the mapping of payload-
  format-specific parameters into the "a=fmtp" field.

  When the RTP payload formats defined in this document are used, the
  media type parameters defined above MUST use the media types in this
  document and MUST NOT use those specified in [RFC6364].

8.  Offer/Answer Considerations

  When offering Raptor FEC over RTP using SDP in an Offer/Answer model
  [RFC3264], the following considerations apply:

  o  Each combination of the Kmax and T parameters produces different
     FEC data and is not compatible with any other combination.  A
     sender application MAY desire to provide multiple offers with
     different sets of Kmax and T values, which is possible as long as
     the parameter values are valid.  The receiver SHOULD normally
     choose the offer with the largest value of the product of Kmax and
     T that it supports.

  o  The size of the repair window is related to the maximum delay
     between the transmission of a source packet and the associated
     repair packet.  This directly impacts the buffering requirement on
     the receiver side and the receiver must consider this when
     choosing an offer.

  o  When the P parameter is not present, the receiver MUST use FEC
     Payload ID Format A.  In an answer that selects an offer in which
     the P parameter was omitted, the P parameter MUST either be
     omitted, or included with value "A".








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9.  Declarative SDP Considerations

  In declarative usage, like SDP in the Real-Time Streaming Protocol
  (RTSP) [RFC2326] or the Session Announcement Protocol (SAP)
  [RFC2974], the following considerations apply:

  o  The payload format configuration parameters are all declarative
     and a participant MUST use the configuration that is provided for
     the session.

  o  More than one configuration MAY be provided (if desired) by
     declaring multiple RTP payload types.  In this case, the receivers
     should choose the repair session that is best for them.

10.  Repair Flow Generation and Recovery Procedures

10.1.  Overview

  This document only specifies repair flow construction when the repair
  packets are delivered with RTP.  Source packet construction is
  covered in [RFC6681].  This section provides an overview on how to
  generate a repair flow, including the repair packets and how to
  reconstruct missing source packets from a set of available source and
  repair packets.  Detailed algorithms for the generation of Raptor and
  RaptorQ symbols are provided in [RFC5053] and [RFC6330],
  respectively.

  As per the FEC Framework document [RFC6363], the FEC Framework
  Configuration Information includes, among others, the identification
  of the repair flow(s) and the source flow(s).  Methods to convey FEC
  Framework Configuration Information are provided in [FEC-SIG].
  Specifically, the reader is referred to the SDP elements document
  [RFC6364], which describes the usage of the 'SDP' encoding format as
  an example encoding format for FEC Framework Configuration
  Information.

  For the generation of a repair flow:

  o  repair packets SHALL be constructed according to Section 10.2, and

  o  RTCP SHALL be used according to Section 10.3.

  For the reconstruction of a source packet of a source RTP session at
  the receiver, based on the availability of a source RTP session and a
  repair RTP session, the procedures in Section 10.4 may be used.






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10.2.  Repair Packet Construction

  The construction of the repair packet is fully specified in Section
  4.  A repair packet is constructed by the concatenation of

  o  an RTP header as specified in Section 4.1, and

  o  payload data as defined in Section 4.3.

  Repair Packet Construction may make use of the Sender Operation for
  RTP repair flows as specified in see [RFC6363], Section 4.2.

10.3.  Usage of RTCP

  RTCP SHALL be used according to [RFC3550].  If the repair RTP session
  is sent in a separate RTP session, the two sessions MUST be
  associated using RTCP CNAME (Canonical Name).

10.4.  Source Packet Reconstruction

  Source Packet Reconstruction may make use of the receiver operation
  for the case of RTP repair flows as specified in [RFC6363], Section
  4.3.  Depending on the FEC Scheme using the ones defined in
  [RFC6681], the appropriate source blocks are formed.  If enough data
  for decoding any or all of the missing source payloads in the source
  block has been received, the respective FEC decoding procedures are
  applied.

  In case the FEC Scheme uses Raptor codes as defined in [RFC5053],
  then the Example FEC Decoder, as specified in [RFC5053], Section 5.5,
  may be used.

  In case the FEC Scheme uses RaptorQ codes as defined in [RFC6330],
  then the Example FEC Decoder, as specified in [RFC6330], Section 5.4,
  may be used.

11.  Session Description Protocol (SDP) Example

  This section provides an SDP [RFC4566] example.  Assume we have one
  source video stream (mid:S1) and one FEC repair stream (mid:R1).  The
  'group' attribute and the FEC grouping semantics defined in [RFC5888]
  and [RFC5956], respectively, are used to associate source and repair
  flows.  We form one FEC group with the "a=group:FEC S1 R1" line.  The
  source and repair streams are sent to the same port on different
  multicast groups.  The repair window is set to 200 ms.






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  v=0
  o=ali 1122334455 1122334466 IN IP4 fec.example.com
  s=Raptor RTP FEC Example
  t=0 0
  a=group:FEC-FR S1 R1
  m=video 30000 RTP/AVP 100
  c=IN IP4 233.252.0.1/127
  a=rtpmap:100 MP2T/90000
  a=fec-source-flow: id=0
  a=mid:S1
  m=application 30000 RTP/AVP 110
  c=IN IP4 233.252.0.2/127
  a=rtpmap:110 raptorfec/90000
  a=fmtp:110 raptor-scheme-id=1; Kmax=8192; T=128;
          P=A; repair-window=200000
  a=mid:R1

12.  IANA Considerations

  IANA has registered 'application/raptorfec' as specified in Section
  6.1.1, 'video/raptorfec' as specified in Section 6.2.1,
  'audio/raptorfec' as specified in Section 6.3.1, and 'text/raptorfec'
  as specified in Section 6.4.1.  The media type has also been added to
  the IANA registry for "RTP Payload Format media types"
  (http://www.iana.org/assignments/rtp-parameters).

13.  Security Considerations

  Security Considerations related to the use of the FEC Framework are
  addressed in [RFC6363].  These considerations apply in full to users
  of the RTP payload formats defined in this document, since these are
  defined in terms of the FEC Framework.

  No further security considerations related specifically to the Raptor
  FEC Schemes defined in [RFC6681] have been identified.

  RTP packets using the payload format defined in this specification
  are subject to the security considerations discussed in the RTP
  specification [RFC3550] and in any applicable RTP profile.  The main
  security considerations for the RTP packet carrying the RTP payload
  format defined within this memo are confidentiality, integrity, and
  source authenticity.  Confidentiality is achieved by encrypting the
  RTP payload.  Integrity of the RTP packets is achieved through a
  suitable cryptographic integrity protection mechanism.  Such a
  cryptographic system can also allow the authentication of the source
  of the payload.  A suitable security mechanism for this RTP payload
  format should provide confidentiality, integrity protection, and at
  least source authentication capable of determining if an RTP packet



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  is from a member of the RTP session.  Note that the appropriate
  mechanism to provide security to RTP and payloads following this memo
  MAY vary.  It is dependent on the application, transport, and
  signaling protocol employed.  Therefore, a single mechanism is not
  sufficient; although, if suitable, using the Secure Real-Time
  Transport Protocol (SRTP) [RFC3711] is RECOMMENDED.  Other mechanisms
  that may be used are IPsec [RFC4301] and Transport Layer Security
  (TLS) [RFC5246] (RTP over TCP); other alternatives exist.

14.  References

14.1.  Normative References

  [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
             Requirement Levels", BCP 14, RFC 2119, March 1997.

  [RFC3550]  Schulzrinne, H., Casner, S., Frederick, R., and V.
             Jacobson, "RTP: A Transport Protocol for Real-Time
             Applications", STD 64, RFC 3550, July 2003.

  [RFC4288]  Freed, N. and J. Klensin, "Media Type Specifications and
             Registration Procedures", BCP 13, RFC 4288, December 2005.

  [RFC4855]  Casner, S., "Media Type Registration of RTP Payload
             Formats", RFC 4855, February 2007.

  [RFC6363]  Watson, M., Begen, A., and V. Roca, "Forward Error
             Correction (FEC) Framework", RFC 6363, October 2011.

  [RFC6364]  Begen, A., "Session Description Protocol Elements for the
             Forward Error Correction (FEC) Framework", RFC 6364,
             October 2011.

  [RFC6681]  Watson, M., Stockhammer, T., and M. Luby, "Raptor Forward
             Error Correction (FEC) Schemes for FECFRAME", RFC 6681,
             August 2012.

  [RFC4566]  Handley, M., Jacobson, V., and C. Perkins, "SDP: Session
             Description Protocol", RFC 4566, July 2006.

  [RFC3264]  Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model
             with Session Description Protocol (SDP)", RFC 3264, June
             2002.

  [RFC3711]  Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K.
             Norrman, "The Secure Real-time Transport Protocol (SRTP)",
             RFC 3711, March 2004.




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RFC 6682              RTP Payload Format for Raptor          August 2012


  [RFC4301]  Kent, S. and K. Seo, "Security Architecture for the
             Internet Protocol", RFC 4301, December 2005.

  [RFC5246]  Dierks, T. and E. Rescorla, "The Transport Layer Security
             (TLS) Protocol Version 1.2", RFC 5246, August 2008.

  [RFC5053]  Luby, M., Shokrollahi, A., Watson, M., and T. Stockhammer,
             "Raptor Forward Error Correction Scheme for Object
             Delivery", RFC 5053, October 2007.

  [RFC6330]  Luby, M., Shokrollahi, A., Watson, M., Stockhammer, T.,
             and L. Minder, "RaptorQ Forward Error Correction Scheme
             for Object Delivery", RFC 6330, August 2011.

14.2.  Informative References

  [RFC2326]  Schulzrinne, H., Rao, A., and R. Lanphier, "Real Time
             Streaming Protocol (RTSP)", RFC 2326, April 1998.

  [RFC2974]  Handley, M., Perkins, C., and E. Whelan, "Session
             Announcement Protocol", RFC 2974, October 2000.

  [RFC5888]  Camarillo, G. and H. Schulzrinne, "The Session Description
             Protocol (SDP) Grouping Framework", RFC 5888, June 2010.

  [RFC5956]  Begen, A., "Forward Error Correction Grouping Semantics in
             the Session Description Protocol", RFC 5956, September
             2010.

  [FEC-SIG]  Asati, R., "Methods to convey FEC Framework Configuration
             Information", Work in Progress, February 2012.




















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Authors' Addresses

  Mark Watson
  Netflix
  100 Winchester Circle
  Los Gatos, CA 95032
  United States

  EMail: [email protected]


  Thomas Stockhammer
  Nomor Research
  Brecherspitzstrasse 8
  Munich 81541
  Germany

  EMail: [email protected]


  Michael Luby
  Qualcomm Research Berkeley
  2030 Addison Street
  Berkeley, CA 94704
  United States

  EMail: [email protected]
























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