Internet DRAFT - draft-ietf-fecframe-rtp-raptor
draft-ietf-fecframe-rtp-raptor
FEC Framework Working Group M. Watson
Internet-Draft Netflix
Intended status: Standards Track T. Stockhammer
Expires: August 27, 2012 Nomor Research
M. Luby
Qualcomm Incorporated
February 24, 2012
RTP Payload Format for Raptor FEC
draft-ietf-fecframe-rtp-raptor-07
Abstract
This document specifies an RTP Payload Format for Forward Error
Correction repair data produced by the Raptor FEC Schemes. Raptor
FEC Schemes are specified for use with the IETF FEC Framework which
supports transport of repair data over both UDP and RTP. This
document specifies the Payload Format which is required for the use
of RTP to carry Raptor repair flows.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on August 27, 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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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 . . . . . . . . . . . . 4
3. Media Format Background . . . . . . . . . . . . . . . . . . . 5
4. Payload Format . . . . . . . . . . . . . . . . . . . . . . . . 6
4.1. RTP Header Usage . . . . . . . . . . . . . . . . . . . . . 6
4.2. Payload Header . . . . . . . . . . . . . . . . . . . . . . 6
4.3. Payload Data . . . . . . . . . . . . . . . . . . . . . . . 6
5. Congestion Control Considerations . . . . . . . . . . . . . . 7
6. Media Types . . . . . . . . . . . . . . . . . . . . . . . . . 8
6.1. Registration of the application/raptorfec media type . . . 8
6.1.1. Media Type Definition . . . . . . . . . . . . . . . . 8
6.2. Registration of the video/raptorfec media type . . . . . . 9
6.2.1. Media Type Definition . . . . . . . . . . . . . . . . 9
6.3. Registration of the audio/raptorfec media type . . . . . . 11
6.3.1. Media Type Definition . . . . . . . . . . . . . . . . 11
6.4. Registration of the text/raptorfec media type . . . . . . 13
6.4.1. Media Type Definition . . . . . . . . . . . . . . . . 13
7. Mapping to SDP . . . . . . . . . . . . . . . . . . . . . . . . 15
8. Offer/Answer considerations . . . . . . . . . . . . . . . . . 16
9. Declarative SDP Considerations . . . . . . . . . . . . . . . . 17
10. Repair Flow Generation and Recovery Procedures . . . . . . . . 18
10.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . 18
10.2. Repair Packet Construction . . . . . . . . . . . . . . . . 18
10.3. Usage of RTCP . . . . . . . . . . . . . . . . . . . . . . 18
10.4. Source Packet Reconstruction . . . . . . . . . . . . . . . 19
11. Session Description Protocol (SDP) Example . . . . . . . . . . 20
12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 21
13. Security Considerations . . . . . . . . . . . . . . . . . . . 22
14. References . . . . . . . . . . . . . . . . . . . . . . . . . . 23
14.1. Normative References . . . . . . . . . . . . . . . . . . . 23
14.2. Informative References . . . . . . . . . . . . . . . . . . 24
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 25
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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") which 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 [I-D.ietf-fecframe-raptor].
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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].
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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 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.
[I-D.ietf-fecframe-raptor] 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
optimised versions of the first two schemes which are applicable in
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 which 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 and it is therefore 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
[I-D.ietf-fecframe-raptor].
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4. Payload Format
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
header 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 SDP is used for signaling,
the 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 RTCP operations and the
operator SHOULD select the rate that matches the rate of the
protected source RTP stream.
o 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.
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
[I-D.ietf-fecframe-raptor] 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 FEC Repair Payload as defined in
[RFC6363] and [I-D.ietf-fecframe-raptor].
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5. Congestion Control Considerations
See [RFC6363].
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6. Media Types
6.1. Registration of the application/raptorfec media type
This RTP payload format is identified using the application/raptorfec
media type which is registered in accordance with [RFC4855] and using
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
[I-D.ietf-fecframe-raptor].
o Kmax: The value of this parameter is the FEC Framework
Configuration Information element "Maximum Source Block Length" as
defined in [I-D.ietf-fecframe-raptor] encoded as a decimal
integer. For specific requirements for this value refer to
[I-D.ietf-fecframe-raptor].
o T: The value of this parameter is the FEC Framework Configuration
Information element "Encoding Symbol Size" as defined in
[I-D.ietf-fecframe-raptor] encoded as a decimal integer. For
specific requirements for this value refer to
[I-D.ietf-fecframe-raptor].
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
[I-D.ietf-fecframe-raptor]. 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 security consideration in
[RFC6363]
Interoperability considerations:
Published specification: [I-D.ietf-fecframe-raptor]
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, stockhammer@nomor.de
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 Audio/Video Transport 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 which is registered in accordance with [RFC4855] and using the
template of [RFC4288].
6.2.1. Media Type Definition
Type name: video
Subtype name: raptorfec
Required parameters:
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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
[I-D.ietf-fecframe-raptor].
o Kmax: The value of this parameter is the FEC Framework
Configuration Information element "Maximum Source Block Length" as
defined in [I-D.ietf-fecframe-raptor] encoded as a decimal
integer. For specific requirements for this value refer to
[I-D.ietf-fecframe-raptor].
o T: The value of this parameter is the FEC Framework Configuration
Information element "Encoding Symbol Size" as defined in
[I-D.ietf-fecframe-raptor] encoded as a decimal integer. For
specific requirements for this value refer to
[I-D.ietf-fecframe-raptor].
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
[I-D.ietf-fecframe-raptor]. 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 security consideration in
[RFC6363]
Interoperability considerations:
Published specification: [I-D.ietf-fecframe-raptor]
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, stockhammer@nomor.de
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 Audio/Video Transport 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 which is registered in accordance with [RFC4855] and using the
template of [RFC4288].
6.3.1. Media Type Definition
Type name: audio
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
[I-D.ietf-fecframe-raptor].
o Kmax: The value of this parameter is the FEC Framework
Configuration Information element "Maximum Source Block Length" as
defined in [I-D.ietf-fecframe-raptor] encoded as a decimal
integer. For specific requirements for this value refer to
[I-D.ietf-fecframe-raptor].
o T: The value of this parameter is the FEC Framework Configuration
Information element "Encoding Symbol Size" as defined in
[I-D.ietf-fecframe-raptor] encoded as a decimal integer. For
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specific requirements for this value refer to
[I-D.ietf-fecframe-raptor].
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
[I-D.ietf-fecframe-raptor]. 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 security consideration in
[RFC6363]
Interoperability considerations:
Published specification: [I-D.ietf-fecframe-raptor]
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, stockhammer@nomor.de
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 Audio/Video Transport working group delegated
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from the IESG.
6.4. Registration of the text/raptorfec media type
This RTP payload format is identified using the text/raptorfec media
type which is registered in accordance with [RFC4855] and using 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
[I-D.ietf-fecframe-raptor].
o Kmax: The value of this parameter is the FEC Framework
Configuration Information element "Maximum Source Block Length" as
defined in [I-D.ietf-fecframe-raptor] encoded as a decimal
integer. For specific requirements for this value refer to
[I-D.ietf-fecframe-raptor].
o T: The value of this parameter is the FEC Framework Configuration
Information element "Encoding Symbol Size" as defined in
[I-D.ietf-fecframe-raptor] encoded as a decimal integer. For
specific requirements for this value refer to
[I-D.ietf-fecframe-raptor].
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
[I-D.ietf-fecframe-raptor]. 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 security consideration in
[RFC6363]
Interoperability considerations:
Published specification: [I-D.ietf-fecframe-raptor]
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, stockhammer@nomor.de
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 Audio/Video Transport working group delegated
from the IESG.
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7. Mapping to SDP
Applications that are using RTP transport commonly use 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].
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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 offer multiple offers with
different sets of Kmax and T values 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 which 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 that case, the receivers
should choose the repair session that is best for them.
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10. Repair Flow Generation and Recovery Procedures
10.1. Overview
This document only specifies the repair flow construction when the
repair packets are delivered with RTP. Source packet construction is
covered in [I-D.ietf-fecframe-raptor]. This section provides an
overview on how to generate a repair flow including the repair
packets and on 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
[I-D.ietf-fecframe-config-signaling]. Specifically, the reader is
referred to the SDP elements document [RFC6364], which describes the
usage of '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 packets of a source RTP session at
the receiver based on the availability of a source RTP session and an
repair RTP session the procedures in Section 10.4 may be used.
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
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using RTCP CNAME.
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 in use of the ones defined in
[I-D.ietf-fecframe-raptor], the appropriate source blocks are formed.
If enough data for decoding of 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 specifed 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.
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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.
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
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12. IANA Considerations
This memo requests that IANA registers 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 is also
requested to be added to the IANA registry for "RTP Payload Format
MIME types" (http://www.iana.org/assignments/rtp-parameters).
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13. Security Considerations
Security Considerations related to the use of the FEC Framework are
addressed in [RFC6363]. These consideration 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 [I-D.ietf-fecframe-raptor] 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
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.
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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.
[I-D.ietf-fecframe-raptor]
Watson, M., Stockhammer, T., and M. Luby, "Raptor FEC
Schemes for FECFRAME", draft-ietf-fecframe-raptor-06 (work
in progress), November 2011.
[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.
[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
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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.
[I-D.ietf-fecframe-config-signaling]
Asati, R., "Methods to convey FEC Framework Configuration
Information", draft-ietf-fecframe-config-signaling-06
(work in progress), September 2011.
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Authors' Addresses
Mark Watson
Netflix
100 Winchester Circle
Los Gatos, CA 95032
U.S.A.
Email: watsonm@netflix.com
Thomas Stockhammer
Nomor Research
Brecherspitzstrasse 8
Munich 81541
Germany.
Email: stockhammer@nomor.de
Michael Luby
Qualcomm Incorporated
3165 Kifer Road
Santa Clara, CA 95051
U.S.A.
Email: luby@qualcomm.com
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