Internet DRAFT - draft-westerlund-mmusic-3gpp-sdp-rtsp
draft-westerlund-mmusic-3gpp-sdp-rtsp
Network Working Group M. Westerlund
Internet-Draft P. Frojdh
Intended status: Informational Ericsson
Expires: March 21, 2011 Sep 17, 2010
SDP and RTSP extensions defined for 3GPP Packet-switched Streaming
Service and Multimedia Broadcast/Multicast Service
draft-westerlund-mmusic-3gpp-sdp-rtsp-08
Abstract
The Packet-switched Streaming Service (PSS) and the Multimedia
Broadcast/Multicast Service (MBMS) defined by 3GPP use SDP and RTSP
with some extensions. This document provides information about these
extensions and registers the RTSP and SDP extensions with IANA.
Requirements Language
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 RFC 2119 [RFC2119].
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 March 21, 2011.
Copyright Notice
Copyright (c) 2010 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
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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
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Table of Contents
1. Definitions . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Glossary . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Applicability Statement . . . . . . . . . . . . . . . . . . . 5
4. PSS SDP Extensions . . . . . . . . . . . . . . . . . . . . . . 6
4.1. Video Buffering Attributes . . . . . . . . . . . . . . . . 6
4.2. Video Frame Size Attribute . . . . . . . . . . . . . . . . 7
4.3. Integrity Protection Configuration Attributes . . . . . . 7
4.4. The Alternative Attributes . . . . . . . . . . . . . . . . 7
4.5. Adaptation Attribute . . . . . . . . . . . . . . . . . . . 8
4.6. Quality of Experience Attribute . . . . . . . . . . . . . 8
4.7. Asset Information Attribute . . . . . . . . . . . . . . . 8
5. MBMS SDP Extensions . . . . . . . . . . . . . . . . . . . . . 9
5.1. MBMS Bearer Mode Declaration Attribute . . . . . . . . . . 9
5.2. FEC Flow ID Attribute . . . . . . . . . . . . . . . . . . 9
5.3. MBMS Repair Attribute . . . . . . . . . . . . . . . . . . 9
5.4. SDP Protocol Identifiers for FEC . . . . . . . . . . . . . 9
5.4.1. RTP Protocol Identifiers . . . . . . . . . . . . . . . 9
5.4.2. FEC Repair Data Identifier . . . . . . . . . . . . . . 10
5.5. Video Buffering Attribute . . . . . . . . . . . . . . . . 10
6. SDP Offer/Answer Consideration . . . . . . . . . . . . . . . . 10
7. PSS RTSP Extensions . . . . . . . . . . . . . . . . . . . . . 10
7.1. 3GPP-Link-Char Header . . . . . . . . . . . . . . . . . . 10
7.2. 3GPP-Adaptation Header . . . . . . . . . . . . . . . . . . 11
7.3. 3GPP-QoE-Metrics Header . . . . . . . . . . . . . . . . . 11
7.4. 3GPP-QoE-Feedback Header . . . . . . . . . . . . . . . . . 11
7.5. Video Buffer Headers . . . . . . . . . . . . . . . . . . . 11
7.6. Integrity Protection . . . . . . . . . . . . . . . . . . . 12
7.7. RTSP URI Extension . . . . . . . . . . . . . . . . . . . . 12
7.8. Fast Start-up and Content Switching . . . . . . . . . . . 12
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
8.1. SDP Registrations . . . . . . . . . . . . . . . . . . . . 13
8.2. RTSP Registrations . . . . . . . . . . . . . . . . . . . . 18
9. Security Considerations . . . . . . . . . . . . . . . . . . . 20
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 21
10.1. Normative References . . . . . . . . . . . . . . . . . . . 21
10.2. Informative References . . . . . . . . . . . . . . . . . . 21
10.3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
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Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 22
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1. Definitions
1.1. Glossary
3GP: 3GPP file format, a multi-media file format based on the ISO
base media file format, existing in different profiles intended
for multimedia messages, direct playback on clients, progressive
download, usage on servers to deliver on-demand multi-media
sessions in PSS, or servers sending MBMS sessions.
3GPP: Third Generation Partnership Project, see www.3gpp.org for
more information about this organization.
FEC: Forward Error Correction
MBMS: Multimedia Broadcast/Multicast Service, a service defined by
3GPP that utilizes broadcast or multicast technologhy in
combination with unicast for delivery of a wide range of content
to mobile terminals.
PSS: Packet-switched Streaming Service, a unicast-based streaming
service for delivery of on-demand or live streaming multi-media
content to mobile terminals.
RTSP: Real Time Streaming Protocol, see [RFC2326].
SDP: Session Description Protocol, see [RFC4566].
SRTP: Secure Real-time Transport Protocol, see [RFC3711].
QoE: Quality of Experience, the quality level of the the user
experience of a service. In PSS, this is estimated by a
combination of application-level metrics.
QoS: Quality of Service, the quality (properties) that the network
provides toward the upper layer service.
2. Introduction
3GPP has specified the Packet-switched Streaming Service (PSS) that
uses both RTSP [RFC2326] and SDP [RFC4566]. The service is specified
in technical specifications TS 26.233 [PSS-233] and TS 26.234
[PSS-234] in Release 4 and subsequent releases. The basic service
defined in Release 4 is enhanced in Release 5 with capability
exchange and in Release 6 with a number of features, such as
adaptation, digital rights management, progressive download as well
as a streaming server file-format defined in [PSS-3GP]. Fast
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start-up and content switching are addressed in Release 7.
3GPP has also specified the Multimedia Broadcast/Multicast Service
(MBMS) that uses SDP. The IP layer protocols used by this service
are specified in technical specification TS 26.346 Release 6 [MBMS].
Release 7 extends the MBMS User Service to also work with unicast
bearers for interactive and streaming traffic classes.
In the process of defining these services, there has occasionally
been a need to extend both SDP and RTSP functionalities. These
extensions have mostly been in the form of SDP attributes and RTSP
headers and option tags. 3GPP uses the name feature tags (like RTSP
2.0 for what RTSP 1.0 calls option tags), option tag is the name that
will be used in this document. The purpose of this informational
document is to register these SDP and RTSP extensions, in order to
avoid future conflicts, and also to raise the awareness of their
existence within IETF.
This document defines in Section 5.4 three SDP protocol identifiers
used in MBMS to enable the usage of block-based FEC. The SDP
protocol identifiers require an IETF RFC to be defined and
registered. Thus any semantic change will require a new IETF
approved RFC. The other SDP and RTSP extensions registered by this
document are not normatively defined in this document. Instead the
normative definitions are referenced by the registrations. 3GPP can
update the normative definition in future version of their
specifications. However to ensure that such a change is visible in
IETF at minimal IANA should be notified and the reference to the 3GPP
specification updated and preferably an updated version of this RFC
published.
The document begins with two chapters presenting the SDP extensions
for PSS and MBMS, respectively. Followed by a section noting that
offer/answer considerations are not applicable here. The subsequent
section presents the extensions of RTSP for PSS. The IANA
registration of SDP attributes and protocol identifiers is given in
Section 8.1, and the RTSP headers and option tags in Section 8.2.
For normative descriptions of all SDP and RTSP extensions we refer to
TS 26.234 [PSS-234] and TS 26.346 [MBMS].
3. Applicability Statement
This document describes 3GPP-defined extensions to SDP [RFC4566] and
RTSP [RFC2326] and registers attributes that are normatively defined
in 3GPP technical specifications 26.234, 26.244 and 26.346 up to the
referenced versions of the respective documents.
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The SDP and RTSP extensions have only been defined for usage with the
3GPP service in mind. The applicability for usage outside of these
services has not been considered nor addressed. Usage of these
attributes in other contexts may require further definitions or
clarifications. For example, all SDP attributes lack offer/answer
usage rules [RFC3264] which currently makes it impossible to use them
with offer/answer. Please note that change control of these SDP and
RTSP extensions belongs to 3GPP.
4. PSS SDP Extensions
The PSS specification [PSS-234] defines a number of different SDP
attributes for different purposes. They are listed below grouped by
their purpose. The text is intentionally not specific enough to
allow implementation from this document. The normative definition is
in the 3GPP technical specification cited.
4.1. Video Buffering Attributes
The following attributes are used to provide parameters for the video
buffer model provided in Annex G and Section 5.3.3.2 of [PSS-234].
The attributes were defined in Release 5 as "X-" attributes and were
at the time not considered for registration. In hindsight, however,
they should not have been "X-" attributes, and they should have been
registered, as the registration rules of SDP [RFC4566] point out.
Changing their names today is impossible due to the deployed base of
millions of mobile handsets supporting PSS, and therefore they are
registered in their current form.
All attributes are defined at media level.
o The "a=X-predecbufsize" attribute provides the size of the pre-
decoder buffer in bytes.
o The "a=X-initpredecbufperiod" attribute provides the time during
which a receiver should initially buffer, in 90kHz ticks, before
starting to consume the data in the buffer in order to ensure that
underflow does not occur, assuming correct data delivery.
o The "a=X-initpostdecbufperiod" attribute provides the initial
buffering period, in 90kHz ticks, for the post-decoder buffer
present in H.263 and MPEG-4 Visual.
o The "a=X-decbyterate" attribute indicates the maximum peak byte-
decoding rate used in the verification of the Annex G buffer model
expressed in bytes per second.
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o The "a=3gpp-videopostdecbufsize" attribute is used to indicate the
value used in determining the H.264 video post-decoder buffer
size.
Note that complete descriptions of these attributes can be found in
section 5.3.3.2 of [PSS-234].
4.2. Video Frame Size Attribute
This media-level attribute provides the receiver with the largest
picture size a specific H.263 payload type will carry within the
session. The attribute has the following form (see 5.3.3.2 of
[PSS-234]):
"a=framesize:<payload type number> <width>-<height>"
4.3. Integrity Protection Configuration Attributes
These attributes are all used to configure the integrity-protection
mechanism defined in Annex K (section K.2.2.1, K.2.2.2 and K.2.2.3)
of [PSS-234].
o The session-level attribute "a=3GPP-Integrity-Key" carries the
integrity key used to derive SRTP master keys for integrity
protection. The key is protected in different ways depending on a
method identifier. When using OMA DRM key management, the key is
encrypted using AES [AES] before it is base64 encoded [RFC4648].
o The media-level attribute "a=3GPP-SRTP-Config" is used to
configure SRTP for integrity protection and contains an integrity
nonce, a key salt used in deriving the SRTP master key from the
integrity key, and any SRTP configuration parameters, such as the
integrity tag length.
o The session-level attribute "a=3GPP-SDP-Auth" is used to carry an
authentication tag calculated over certain parts of the SDP to
prevent manipulation of the security attributes.
4.4. The Alternative Attributes
Two media and one session-level attributes are used in a mechanism
for providing alternative SDP lines. One or more SDP lines at media
level can be replaced, if desired, by alternatives. The mechanism is
backwards compatible in the way that a receiver that does not support
the attributes will get the default configuration. The different
alternatives can be grouped using different attributes that can be
specified hierarchically with a top and a lower level. 3GPP Release 6
supports grouping based on bit-rate, according to the SDP bandwidth
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modifiers AS and TIAS, and language.
The SDP attributes (see 5.3.3.3 and 5.3.3.4 of [PSS-234]) are:
o The media-level attribute "a=alt:<id>:<SDP-Line>" carries any SDP
line and an alternative identifier.
o The media-level attribute "a=alt-default-id:<id>" identifies the
default configuration to be used in groupings.
o The session-level attribute "a=alt-group" is used to group
different recommended media alternatives. Providing aggregated
properties for the whole group according to the grouping type.
Language and bit-rate are two defined grouping types.
4.5. Adaptation Attribute
The media-level SDP attribute "a=3GPP-Adaptation-Support" (see
5.3.3.5 in [PSS-234]) is defined as part of the negotiation procedure
of the PSS adaptation mechanism. The attribute carries a single
value indicating how often the RTCP "Next Application Data Unit"
(NADU) APP packet shall be included in sent RTCP compound packets.
The adaptation mechanism allows the client to provide the server with
information on the available transmission bit-rate and receiver
buffer status.
4.6. Quality of Experience Attribute
The session and media-level attribute "a=3GPP-QoE-Metrics" (see
5.3.3.6 of [PSS-234]]) is used to negotiate the usage of the quality
of experience metrics. The included parameters indicate which
metrics, over which duration there should be measurements, and how
often reports should be sent.
4.7. Asset Information Attribute
The session and media-level attribute "a=3GPP-Asset-Information" (see
5.3.3.7 of [PSS-234]) can exist in multiple instances in a
description and describes different types of asset information. The
different asset classes defined in Release 6 are: Title, Description,
Copyright, Performer, Author, Genre, Rating, Classification,
Keywords, Location, Album, and Recording Year. The different assets
are described with a BASE64-encoded asset box from the 3GP file
format [PSS-3GP].
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5. MBMS SDP Extensions
The MBMS specification [MBMS] defines a number of different SDP
attributes for different purposes. They are informatively listed
below.
5.1. MBMS Bearer Mode Declaration Attribute
The session and media-level attribute "a=mbms-mode" (see 7.3.2.7 of
[MBMS]) is used to describe MBMS broadcast mode media. The attribute
may be used at session level to set the default for all media and at
media level to specify differences between media. However, the
attribute is never used at session level when the session includes
MBMS multicast mode media, nor at media level to describe MBMS
multicast mode media.
5.2. FEC Flow ID Attribute
The media-level attribute "a=mbms-flowid" (see 8.3.1.9 of [MBMS])
maps one or more FEC source block flow IDs to their corresponding
destination IP addresses and UDP port numbers. It is present in each
SDP media block for repair packet streams.
5.3. MBMS Repair Attribute
The session and media-level attribute "a=mbms-repair" (see 8.3.1.8 of
[MBMS]) is used to provide FEC repair packets with non-FEC specific
parameters. FFor release 6, one such parameter is defined to specify
the required minimum receiver buffer time.
5.4. SDP Protocol Identifiers for FEC
MBMS defines a mechanism to provide block-based FEC for UDP-based
traffic. This solution uses the SDP protocol "proto" identifier to
identify the media streams that use the FEC shim layer. The media
streams may be either source streams or repair streams. As required
by SDP [RFC4566], these protocol identifiers are normatively defined
in this document in accordance with their usage specified by 3GPP.
5.4.1. RTP Protocol Identifiers
For FEC-protected RTP streams, the following two "proto" identifiers
are defined:
o UDP/MBMS-FEC/RTP/AVP
o UDP/MBMS-FEC/RTP/SAVP
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They indicate the usage of UDP [RFC0768] with MBMS FEC Source packet
formats, as defined in Section 8.2.2.4 of [MBMS], that transport RTP
packets in accordance with the AVP [RFC3551] or SAVP (Secure RTP)
[RFC3711] profiles, respectively. These protocol identifiers SHALL
use the FMT space rules that are used for RTP/AVP and RTP/SAVP,
respectively.
5.4.2. FEC Repair Data Identifier
A media stream carrying MBMS FEC repair information over UDP requires
its own "proto" identifier. Protocol identifier "UDP/MBMS-REPAIR"
identifies the FEC repair packet containing the protocol combination
of UDP [RFC0768] and FEC repair payload ID and repair symbols as
specified in Section 8.2.2.5 of [MBMS]. The FMT string is not used
and SHALL be set to "*".
5.5. Video Buffering Attribute
The PSS media-level buffer attribute "a=X-initpredecbufperiod"(See
Section 4.1) that specifies an initial buffering time is also used
for MBMS in Release 7. It is mainly intended for video streams, but
may be used for other media types as well (See Section 8.3.1.1 of
[MBMS]).
6. SDP Offer/Answer Consideration
The usage of the SDP attributes in an Offer/Answer [RFC3264] context
is not defined. These SDP attributes are defined for being used in a
declarative context, and for PSS specifically in RTSP [RFC2326]
context.
7. PSS RTSP Extensions
The RTSP extensions for PSS consist of a number of new RTSP headers
and option tags and a narrowing of URI usage in regards to 3GP files.
The headers and option tags are informatively described here; see
[PSS-234] for the normative declaration.
7.1. 3GPP-Link-Char Header
The "3GPP-Link-Char" header (see 5.3.2.1 of [PSS-234]) is used by
clients to provide the server with QoS information about the wireless
link it is currently using. The header can be used to provide the
server with three different QoS parameters:
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o Guaranteed Bandwidth
o Maximum Bandwidth
o Maximum Transfer Delay
The header may be included in RTSP requests using either of the
methods SETUP, PLAY, OPTIONS and SET_PARAMETER.
7.2. 3GPP-Adaptation Header
The "3GPP-Adaptation" header (see 5.3.2.2 of [PSS-234]) is used by
the client to provide the server with adaptation-related parameters
and to indicate support of the adaptation function. The header
carries the resource identification as a URI, the client's buffer
size, and the desired target time.
The header may be included in requests using the methods SETUP, PLAY,
OPTIONS and SET_PARAMETER. The response to a request using this
method shall include this header.
7.3. 3GPP-QoE-Metrics Header
The "3GPP-QoE-Metrics" header (see 5.3.2.3.1 of [PSS-234]) is used to
negotiate the usage of the quality of experience (QoE) metrics (see
Section 11 of [PSS-234]).
The header may be included in requests and responses using the SETUP,
SET_PARAMTER, OPTIONS or PLAY method.
7.4. 3GPP-QoE-Feedback Header
The "3GPP-QoE-Feedback" header (see 5.3.2.3.2 of [PSS-234]) is used
to carry QoE metrics from the client to the server when it reports,
which happens either during or at the end of the media delivery.
The header may be included in requests using the SET_PARAMETER,
PAUSE, or TEARDOWN method.
7.5. Video Buffer Headers
PSS uses several headers to provide the client with the different
buffer parameters. They provide the buffer status at the point of a
stream that a PLAY request plays from. These headers may only be
used in PLAY responses. See Section 5.3.2.4 and Annex G of [PSS-234]
for normative definitions.
The three "x-" headers were defined in 3GPP Release 5. When it was
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realized that they should not have been given "x-" names, it was to
late rename them due to deployment.
The RTSP headers are:
o x-predecbufsize
o x-initpredecbufperiod
o x-initpostdecbufperiod
o 3gpp-videopostdecbufsize
7.6. Integrity Protection
The integrity-protection mechanism defined in PSS Annex K uses the
"3GPP-Freshness-Token" (See Section K.2.2.4 of [PSS-234]) RTSP header
to carry a freshness token in DESCRIBE requests.
7.7. RTSP URI Extension
The PSS specification also defines syntax for referencing tracks
within the "3GP" file format [PSS-3GP]. The 3GP format is based on
the ISO base media file format and defined in several different
profiles, including a streaming-server profile, in Release 6.
This syntax is fully contained within the generic URI syntax defined
for RTSP URIs. It is only a syntax restriction that server
manufacturers follow to allow clients or proxies to understand what
encodes the track number in the URI. This is provided for
information only.
To identify a track within a 3GP file the last URI segment has to
contain a structure that is <alpha string>=<track nr> (See 5.3.3.1 of
[PSS-234]).
7.8. Fast Start-up and Content Switching
Release 7 of PSS defines a number of extensions in terms of headers
and option tags (See Section 5.5 of [PSS-234]) for support of fast
start-up and switching of content for on-demand and live applications
built on top of PSS. Clients are enabled to reuse the existing RTSP
control session and RTP resources while switching to new content.
The RTSP headers are:
o Switch-Stream
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o SDP-Requested
o Pipelined-Requests
The RTSP option tags are:
o 3gpp-pipelined
o 3gpp-switch
o 3gpp-switch-req-sdp
o 3gpp-switch-stream
8. IANA Considerations
8.1. SDP Registrations
IANA is requested to register the SDP attributes listed below in the
registry at http://www.iana.org/assignments/sdp-parameters. The
contact person for this registration is Magnus Westerlund
(magnus.westerlund@ericsson.com) Phone number +46 8 719 0000.
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SDP Protocol Identifiers ("proto"):
Name: UDP/MBMS-FEC/RTP/AVP
Long form: 3GPP MBMS FEC protected RTP/AVP over UDP
Type of name: proto
Purpose: 3GPP MBMS defines a mechanism to provide block-
based FEC for UDP-based traffic. This solution
uses the SDP protocol "proto" identifier to
identify the media streams that use the FEC
shim layer. This protocol identifier indicates
that the FEC protected data is RTP using the
AVP profile.
Reference: RFCXXXX, 3GPP TS 26.346
Name: UDP/MBMS-FEC/RTP/SAVP
Long form: 3GPP MBMS FEC protected RTP/SAVP over UDP
Type of name: proto
Purpose: 3GPP MBMS defines a mechanism to provide block-
based FEC for UDP-based traffic. This solution
uses the SDP protocol "proto" identifier to
identify the media streams that use the FEC
shim layer. This protocol identifier indicates
that the FEC protected data is RTP using the
Secure AVP profile (SAVP).
Reference: RFCXXXX, 3GPP TS 26.346
Name: UDP/MBMS-REPAIR
Long form: 3GPP MBMS FEC repair symbols over UDP
Type of name: proto
Purpose: 3GPP MBMS defines a mechanism to provide block-
based FEC for UDP-based traffic. This solution
uses the SDP protocol "proto" identifier to
identify the media streams that use the FEC
shim layer. This protocol identifier indicates
that the FEC repair data is sent over UDP.
Reference: RFCXXXX, 3GPP TS 26.346
SDP Attribute ("att-field"):
Attribute name: X-predecbufsize
Long form: Pre-decoder buffer size
Type of name: att-field
Type of attribute: Media level only
Subject to charset: No
Purpose: See Section 4.1
Reference: 3GPP TS 26.234, Section 5.3.3.2
Values: See Reference
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Attribute name: X-initpredecbufperiod
Long form: Pre-decoder initial buffering period
Type of name: att-field
Type of attribute: Media level only
Subject to charset: No
Purpose: See Section 4.1
Reference: 3GPP TS 26.234, Section 5.3.3.2
Values: See Reference
Attribute name: X-initpostdecbufperiod
Long form: Post-decoder initial buffering period
Type of name: att-field
Type of attribute: Media level only
Subject to charset: No
Purpose: See Section 4.1
Reference: 3GPP TS 26.234, Section 5.3.3.2
Values: See Reference
Attribute name: X-decbyterate
Long form: Peak decoding rate in bytes per second
Type of name: att-field
Type of attribute: Media level only
Subject to charset: No
Purpose: See Section 4.1
Reference: 3GPP TS 26.234, Section 5.3.3.2
Values: See Reference
Attribute name: 3gpp-videopostdecbufsize
Long form: Post decoder buffer size
Type of name: att-field
Type of attribute: Media level only
Subject to charset: No
Purpose: See Section 4.1
Reference: 3GPP TS 26.234, Section 5.3.3.2
Values: See Reference
Attribute name: framesize
Long form: Maximum Video Frame Size
Type of name: att-field
Type of attribute: Media level only
Subject to charset: No
Purpose: See Section 4.2
Reference: 3GPP TS 26.234, Section 5.3.3.2
Values: See Reference
Attribute name: 3GPP-Integrity-Key
Long form: 3GPP DRM Integrity Key
Type of name: att-field
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Type of attribute: Session level only
Subject to charset: No
Purpose: See Section 4.3
Reference: 3GPP TS 26.234, Sections 5.3.3.2 and K.2.2.1
Values: See Reference
Attribute name: 3GPP-SRTP-Config
Long form: 3GPP DRM SRTP Configuration
Type of name: att-field
Type of attribute: Media level only
Subject to charset: No
Purpose: See Section 4.3
Reference: 3GPP TS 26.234, Sections 5.3.3.2 and K.2.2.2
Values: See Reference
Attribute name: 3GPP-SDP-Auth
Long form: 3GPP DRM Integrity SDP Authentication
Type of name: att-field
Type of attribute: Session level only
Subject to charset: No
Purpose: See Section 4.3
Reference: 3GPP TS 26.234, Sections 5.3.3.2 and K.2.2.3
Values: See Reference
Attribute name: alt
Long form: Alternative SDP line
Type of name: att-field
Type of attribute: Media level only
Subject to charset: No
Purpose: See Section 4.4
Reference: 3GPP TS 26.234, Section 5.3.3.3
Values: See Reference
Attribute name: alt-default-id
Long form: Default alternative ID
Type of name: att-field
Type of attribute: Media level only
Subject to charset: No
Purpose: See Section 4.4
Reference: 3GPP TS 26.234, Section 5.3.3.3
Values: See Reference
Attribute name: alt-group
Long form: Grouping of SDP Line alternatives
Type of name: att-field
Type of attribute: Session level only
Subject to charset: No
Purpose: See Section 4.4
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Reference: 3GPP TS 26.234, Section 5.3.3.4
Values: See Reference
Attribute name: 3GPP-Adaptation-Support
Long form: 3GPP Adaptation Support
Type of name: att-field
Type of attribute: Media level only
Subject to charset: No
Purpose: See Section 4.5
Reference: 3GPP TS 26.234, Section 5.3.3.5
Values: See Reference
Attribute name: 3GPP-QoE-Metrics
Long form: 3GPP Quality of Experience Metrics
Type of name: att-field
Type of attribute: Session and Media level
Subject to charset: No
Purpose: See Section 4.6
Reference: 3GPP TS 26.234, Section 5.3.3.6
Values: See Reference
Attribute name: 3GPP-Asset-Information
Long form: 3GPP Asset Information
Type of name: att-field
Type of attribute: Session and Media level
Subject to charset: No
Purpose: See Section 4.7
Reference: 3GPP TS 26.234, Section 5.3.3.7
Values: See Reference
Attribute name: mbms-mode
Long form: MBMS Bearer Mode Declaration
Type of name: att-field
Type of attribute: Session and Media level
Subject to charset: No
Purpose: See Section 5.1
Reference: 3GPP TS 26.346, Section 7.3.2.7
Values: See Reference
Attribute name: mbms-flowid
Long form: FEC Flow ID
Type of name: att-field
Type of attribute: Media level
Subject to charset: No
Purpose: See Section 5.2
Reference: 3GPP TS 26.346, Section 8.3.1.9
Values: See Reference
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Attribute name: mbms-repair
Long form: MBMS Repair
Type of name: att-field
Type of attribute: Session and Media level
Subject to charset: No
Purpose: See Section 5.3
Reference: 3GPP TS 26.346, Section 8.3.1.8
Values: See Reference
8.2. RTSP Registrations
IANA is requested to register the RTSP headers listed below in the
RTSP 1.0 registry table "RTSP/1.0 Headers" at:
http://www.iana.org/assignments/rtsp-parameters.
Note: This registry requires Standards document, preferably an IETF
RFC. The document that defines the registered headers below is a
technical standards document from 3GPP, although the request for
registration is submitted using this document to achieve further
information spreading within IETF.
The contact person for this registration is Magnus Westerlund
(magnus.westerlund@ericsson.com) Phone number +46 8 719 0000.
Header Name: 3GPP-Freshness-Token
Purpose: See Section K.2 of 3GPP TS 26.234
Methods: DESCRIBE Requests
Reference: Section K.2.2.4 of 3GPP TS 26.234
Values: See Reference
Header Name: 3GPP-Link-Char
Purpose: See Section 5.3.2.1 of 3GPP TS 26.234
Methods: SETUP, PLAY, OPTIONS or SET_PARAMETER Requests
Reference: Section 5.3.2.1 of 3GPP TS 26.234
Values: See Reference
Header Name: 3GPP-Adaptation
Purpose: See Section 5.3.2.2 of 3GPP TS 26.234
Methods: SETUP, PLAY, OPTIONS, or SET_PARAMETER Requests
and Responses
Reference: Section 5.3.2.2 of 3GPP TS 26.234
Values: See Reference
Header Name: 3GPP-QoE-Metrics
Purpose: See Section 5.3.2.3.1 of 3GPP TS 26.234
Methods: SETUP, PLAY, OPTIONS, or SET_PARAMETER Requests
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and Responses
Reference: Section 5.3.2.3.1 of 3GPP TS 26.234
Values: See Reference
Header Name: 3GPP-QoE-Feedback
Purpose: See Section 5.3.2.3.2 of 3GPP TS 26.234
Methods: SET_PARAMETER, PAUSE, or TEARDOWN Requests
Reference: Section 5.3.2.3.2 of 3GPP TS 26.234
Values: See Reference
Header Name: Switch-Stream
Purpose: See Section 5.5.4.2 of 3GPP TS 26.234
Methods: PLAY Requests and Responses
Reference: Section 5.5.4.2 of 3GPP TS 26.234
Values: See Reference
Header Name: SDP-Requested
Purpose: See Section 5.5.4.4 of 3GPP TS 26.234
Methods: PLAY Requests
Reference: Section 5.5.4.4 of 3GPP TS 26.234
Values: See Reference
Header Name: Pipelined-Requests
Purpose: See Section 5.5.3 of 3GPP TS 26.234
Methods: SETUP and PLAY Requests
Reference: Section 5.5.3 of 3GPP TS 26.234
Values: See Reference
Header Name: x-predecbufsize
Purpose: See Section 5.3.2.4 of 3GPP TS 26.234
Methods: PLAY Response
Reference: Section 5.3.2.4 of 3GPP TS 26.234
Values: See Reference
Header Name: x-initpredecbufperiod
Purpose: See Section 5.3.2.4 of 3GPP TS 26.234
Methods: PLAY Response
Reference: Section 5.3.2.4 of 3GPP TS 26.234
Values: See Reference
Header Name: x-initpostdecbufperiod
Purpose: See Section 5.3.2.4 of 3GPP TS 26.234
Methods: PLAY Response
Reference: Section 5.3.2.4 of 3GPP TS 26.234
Values: See Reference
Header Name: 3gpp-videopostdecbufsize
Purpose: See Section 5.3.2.4 of 3GPP TS 26.234
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Methods: PLAY Response
Reference: Section 5.3.2.4 of 3GPP TS 26.234
Values: See Reference
Header Name: Supported
Purpose: See Section 5.5.2.2.2 of 3GPP TS 26.234
Methods: Any Request and Response
Reference: Section 5.5.2.2.2 of 3GPP TS 26.234
Values: See Reference
IANA is requested to register the RTSP Option tags (option tags)
listed below in the RTSP 1.0 registry table for RTSP/1.0 Option Tags
http://www.iana.org/assignments/rtsp-parameters.
Option tag: 3gpp-pipelined
Purpose: See Section 5.5.3 of 3GPP TS 26.234
Applies to: Client and Server
Reference: Section 5.5.3 of 3GPP TS 26.234
Values: See Reference
Option tag: 3gpp-switch
Purpose: See Section 5.5.4.2 of 3GPP TS 26.234
Applies to: Client and Server
Reference: Section 5.5.4.2 of 3GPP TS 26.234
Values: See Reference
Option tag: 3gpp-switch-req-sdp
Purpose: See Section 5.5.4.4 of 3GPP TS 26.234
Applies to: Client and Server
Reference: Section 5.5.4.4 of 3GPP TS 26.234
Values: See Reference
Option tag: 3gpp-switch-stream
Purpose: See Section 5.5.4.5 of 3GPP TS 26.234
Applies to: Client and Server
Reference: Section 5.5.4.5 of 3GPP TS 26.234
Values: See Reference
9. Security Considerations
SDP attributes are subject to modification by an attacker unless they
are integrity protected and authenticated. The security
consideration of the SDP specification [RFC4566] should be reviewed
in this regard. The registered SDP attributes are vulnerable to
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modification attacks or removal, which may result in problems of
serious nature, including failure to use service and reduced quality.
The registered RTSP headers are also vunerable to insertion, deletion
or modification attacks similar to SDP attributes. Also in this
case, it can result in failure of the service or reduced quality of
streaming content.
The three SDP protocol identifiers do not by themselves introduce any
additional security threats that don't exist for other protocol
identifiers in SDP. The media stream and the used protocols
identified and configured by the SDP protocol identifier may however
contain security issues by themselves.
10. References
10.1. Normative References
[MBMS] 3GPP TS 26.346 version 7.10.0 (2009-03), "Multimedia
Broadcast/Multicast Service (MBMS); Protocols and codecs".
[PSS-234] 3GPP TS 26.234 version 7.7.0 (2009-03), "Transparent end-
to-end Packet-switched Streaming Service (PSS); Protocols
and codecs,".
[PSS-3GP] 3GPP TS 26.244 version 7.3.0 (2007-12), "Transparent end-
to-end packet switched streaming service (PSS); 3GPP file
format (3GP)".
[RFC0768] Postel, J., "User Datagram Protocol", STD 6, RFC 768,
August 1980.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3551] Schulzrinne, H. and S. Casner, "RTP Profile for Audio and
Video Conferences with Minimal Control", STD 65, RFC 3551,
July 2003.
[RFC3711] Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K.
Norrman, "The Secure Real-time Transport Protocol (SRTP)",
RFC 3711, March 2004.
10.2. Informative References
[AES] ""Advanced Encryption Standard (AES)", FIPS PUB 197,
http://www.nist.gov/aes/.".
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[PSS-233] 3GPP TS 26.233 version 7.0.0 (2007-06), "Transparent end-
to-end packet switched streaming service (PSS) General
Description".
[RFC2326] Schulzrinne, H., Rao, A., and R. Lanphier, "Real Time
Streaming Protocol (RTSP)", RFC 2326, April 1998.
[RFC3264] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model
with Session Description Protocol (SDP)", RFC 3264,
June 2002.
[RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session
Description Protocol", RFC 4566, July 2006.
[RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data
Encodings", RFC 4648, October 2006.
10.3.
Authors' Addresses
Magnus Westerlund
Ericsson
Farogatan 6
Stockholm, SE-164 80
SWEDEN
Phone: +46 10 7190000
Fax: +46 10 757 55 50
Email: magnus.westerlund@ericsson.com
Per Frojdh
Ericsson
Farogatan 6
Stockholm, SE-164 80
SWEDEN
Phone: +46 10 7190000
Fax: +46 10 757 55 50
Email: per.frojdh@ericsson.com
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