ISO/IEC 23009-1:2012

INTERNATIONAL ISO/IEC
STANDARD 23009-1
First edition
2012-04-01


Information technology — Dynamic
adaptive streaming over HTTP (DASH) —
Part 1:
Media presentation description and
segment formats
Technologies de l'information — Diffusion en flux adaptatif dynamique
sur HTTP (DASH) —
Partie 1: Description de la présentation et formats de remise des
médias




Reference number
ISO/IEC 23009-1:2012(E)
©
ISO/IEC 2012

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ISO/IEC 23009-1:2012(E)
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ISO/IEC 23009-1:2012(E)
Contents Page
Foreword .v
Introduction.vi
1 Scope.1
2 Normative references.1
3 Terms, definitions, symbols and abbreviated terms .2
3.1 Terms and definitions .2
3.2 Symbols and abbreviated terms .5
3.3 Conventions.6
4 Introduction.6
4.1 System description .6
4.2 DASH client model .7
4.3 DASH data model overview.8
4.4 Protocols .11
4.5 Media Stream and Representation properties.11
4.6 Brands .13
4.7 Schemes.13
5 Media Presentation.14
5.1 General .14
5.2 Media Presentation Description.14
5.3 Hierarchical data model.16
5.4 Media Presentation Description updates.54
5.5 MPD assembly .55
5.6 Base URL Processing .57
5.7 Program information .58
5.8 Descriptors.59
5.9 DASH metrics descriptor.65
6 Segment formats . 67
6.1 Introduction.67
6.2 Segment types .67
6.3 Segment formats for ISO base media file format.69
6.4 Segment formats for MPEG-2 transport streams.72
7 Combined semantics of MPD and Segment formats.78
7.1 Introduction.78
7.2 General .79
7.3 Media Presentation based on the ISO base media file format.80
7.4 Media Presentation based on MPEG-2 TS .82
8 Profiles.84
8.1 Definition .84
8.2 Full profile .85
8.3 ISO Base media file format On Demand profile .85
8.4 ISO Base media file format live profile.87
8.5 ISO Base media file format main profile .88
8.6 MPEG-2 TS main profile.89
8.7 MPEG-2 TS simple profile.90
Annex A (informative) Example DASH client behaviour .92
A.1 Introduction.92
A.2 Overview.92
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ISO/IEC 23009-1:2012(E)
A.3 Segment list generation . 93
A.4 Seeking . 96
A.5 Support for trick modes . 97
A.6 Switching Representations. 97
A.7 Reaction to error codes . 98
A.8 Encoder clock drift control . 98
Annex B (normative) MPD schema. 99
Annex C (normative) MIME type registration for MPD . 105
C.1 Introduction . 105
C.2 MIME type and subtype. 105
C.3 Parameters . 106
Annex D (normative) DASH Metrics . 107
D.1 Introduction . 107
D.2 DASH-Metrics client reference model . 107
D.3 Definition of observation points. 107
D.4 Semantics of the DASH metrics . 108
Annex E (normative) Byte range requests with regular HTTP GET methods. 114
E.1 Background. 114
E.2 Construction rule. 114
E.3 Examples . 115
Annex F (informative) Guidelines for extending DASH with other delivery formats. 116
F.1 Adding delivery formats to DASH. 116
F.2 Media Presentation authoring rules. 116
Annex G (informative) MPD Examples and MPD Usage. 117
G.1 Example MPD for ISO Base media file format On Demand profile . 117
G.2 Example for ISO Base media file format Live profile . 118
G.3 Example for MPEG-2 TS Live profile. 119
G.4 Example for multiple stereo views. 120
G.5 Example for SVC alternative streams. 121
G.6 Example for trick play support. 122
G.7 Example for content protected by multiple schemes . 123
G.8 Example for usage of Role descriptor. 124
Bibliography . 126
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ISO/IEC 23009-1:2012(E)
Foreword
ISO (the International Organization for Standardization) and IEC (the International Electrotechnical
Commission) form the specialized system for worldwide standardization. National bodies that are members of
ISO or IEC participate in the development of International Standards through technical committees
established by the respective organization to deal with particular fields of technical activity. ISO and IEC
technical committees collaborate in fields of mutual interest. Other international organizations, governmental
and non-governmental, in liaison with ISO and IEC, also take part in the work. In the field of information
technology, ISO and IEC have established a joint technical committee, ISO/IEC JTC 1.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of the joint technical committee is to prepare International Standards. Draft International
Standards adopted by the joint technical committee are circulated to national bodies for voting. Publication as
an International Standard requires approval by at least 75 % of the national bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO and IEC shall not be held responsible for identifying any or all such patent rights.
ISO/IEC23009-1 was prepared by Joint Technical Committee ISO/IECJTC 1, Information technology,
Subcommittee SC 29, Coding of audio, picture, multimedia and hypermedia information.
ISO/IEC 23009 consists of the following parts, under the general title Information technology — Dynamic
adaptive streaming over HTTP (DASH):
 Part 1: Media presentation description and segment formats
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ISO/IEC 23009-1:2012(E)
Introduction
Dynamic Adaptive Streaming over HTTP (DASH) is intended to support a media-streaming model for delivery
of media content in which control lies exclusively with the client. Clients may request data using the HTTP
protocol from standard web servers that have no DASH-specific capabilities. Consequently, this part of
ISO/IEC 23009 focuses not on client or server procedures but on the data formats used to provide a DASH
Media Presentation.
This part of ISO/IEC 23009 primarily specifies formats for the Media Presentation Description and Segments.
It is applicable to streaming services over the Internet.
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INTERNATIONAL STANDARD ISO/IEC 23009-1:2012(E)
Information technology — Dynamic adaptive streaming over
HTTP (DASH) —
Part 1:
Media presentation description and segment formats
1 Scope
This part of ISO/IEC 23009 primarily specifies formats for the Media Presentation Description and Segments
for dynamic adaptive streaming delivery of MPEG media over HTTP. It is applicable to streaming services
over the Internet.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ITU-T Rec. H.222.0 | ISO/IEC 13818-1, Information technology – Generic coding of moving pictures and
associated audio information: Systems
ISO/IEC 14496-10, Information technology – Coding of audio-visual objects – Part 10: Advanced Video
Coding
ISO/IEC 14496-12, Information technology – Coding of audio-visual objects – Part 12: ISO base media file
format (technically identical to ISO/IEC 15444-12)
ISO/IEC 23003-3, Information technology – MPEG audio technologies – Part 3: Unified speech and audio
coding
IETF RFC 1521, MIME (Multipurpose Internet Mail Extensions) Part One: Mechanisms for Specifying and
Describing the Format of Internet Message Bodies, September 1993
IETF RFC 1738, Uniform Resource Locators (URL), December 1994
IETF RFC 2141, URN Syntax, May 1997
IETF RFC 2616, Hypertext Transfer Protocol – HTTP/1.1, June 1999
IETF RFC 3023, XML Media Types, January 2001
IETF RFC 3406, Uniform Resource Names (URN) Namespace Definition Mechanisms, October 2002
IETF RFC 3986, Uniform Resource Identifier (URI): Generic Syntax, January 2005
IETF RFC 4122, A Universally Unique IDentifier (UUID) URN Namespace, July 2005
IETF RFC 4337, MIME Type Registration for MPEG-4, March 2006
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ISO/IEC 23009-1:2012(E)
IETF RFC 5646, Tags for Identifying Languages, September 2009
IETF RFC 6381, The 'Codecs' and 'Profiles' Parameters for "Bucket" Media Types, August 2011
W3C XLINK XML Linking Language (XLink) Version 1.1, W3C Recommendation 06, May 2010
3 Terms, definitions, symbols and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1.1
access unit
unit of a media stream with an assigned Media Presentation time
3.1.2
accessibility
degree to which a media content or certain media content components are available to as many people as
possible
3.1.3
Adaptation Set
set of interchangeable encoded versions of one or several media content components
3.1.4
available Segment
Segment that is accessible at its assigned HTTP-URL and a possibly assigned byte range, that is the request
with an HTTP GET results in a reply of the Segment and 2xx status code
3.1.5
Bitstream Switching Segment
Segment that if present contains essential data to switch to the Representation it is assigned to
3.1.6
complementary Representation
Representation which complements at least one dependent Representation
3.1.7
continuous media
media with an inherent notion of time, for example, speech, audio, video, timed text or timed metadata
3.1.8
DASH metric
metric identified by a key and defined in this part of ISO/IEC 23009
3.1.9
dependent Representation
Representation for which Segments from its complementary Representations are necessary for presentation
and/or decoding of the contained media content components
3.1.10
earliest presentation time
smallest presentation time of any access unit of a Media Segment or Subsegment for a media stream
3.1.11
group
collection of Adaptation Sets that are not expected to be presented simultaneously
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ISO/IEC 23009-1:2012(E)
3.1.12
HTTP-URL
URL with a fixed scheme of “http” or “https”
3.1.13
Index Segment
Segment that primarily contains indexing information for Media Segments
3.1.14
Initialization Segment
Segment containing metadata that is necessary to present the media streams encapsulated in Media
Segments
3.1.15
media content
one media content period or a contiguous sequence of media content periods
3.1.16
media content component
one continuous component of the media content with an assigned media component type that can be
encoded individually into a media stream
3.1.17
media content component type
a single type of media content such as audio, video, or text
3.1.18
media content period
set of media content components that have a common timeline as well as relationships on how they can be
presented
3.1.19
Media Presentation
collection of data that establishes a bounded or unbounded presentation of media content
3.1.20
Media Presentation Description
MPD
formalized description for a Media Presentation for the purpose of providing a streaming service
3.1.21
Media Presentation timeline
concatenation of the timeline of all Periods which itself is common to all Representations in the Period
3.1.22
Media Segment
Segment that complies with media format in use and enables playback when combined with zero or more
preceding segments, and an Initialization Segment (if any)
3.1.23
media stream
encoded version of a media content component
3.1.24
Media Subsegment
Subsegment that only contains media data but no Segment Index
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ISO/IEC 23009-1:2012(E)
3.1.25
MPD start time
approximate presentation start time of a Media Segment signalled in MPD
3.1.26
MPD duration
approximate presentation duration of a Media Segment signalled in MPD
3.1.27
Period
interval of the Media Presentation, where a contiguous sequence of all Periods constitutes the Media
Presentation
3.1.28
presentation time
time associated to an access unit that maps it to the Media Presentation timeline
3.1.29
remote element
element that is not fullly contained in the MPD document but is referenced in the MPD with an HTTP-URL
3.1.30
Representation
collection and encapsulation of one or more media streams in a delivery format and associated with
descriptive metadata
3.1.31
Segment
unit of data associated with an HTTP-URL and optionally a byte range that are specified by an MPD
3.1.32
Segment availability start time
time instant in wall-clock time at which a Segment becomes an available Segment
3.1.33
Segment availability end time
time instant in wall-clock time at which a Segment ceases to be an available Segment
3.1.34
Segment Index
compact index of the time range to byte range mapping within a Media Segment separately from the MPD
3.1.35
stream access point
SAP
position in a Representation enabling playback of a media stream to be started using only the information
contained in Representation data starting from that position onwards (preceded by initializing data in the
Initialization Segment, if any)
3.1.36
Sub-Representation
part of a Representation described in the MPD that is present in the entire Period
3.1.37
Subsegment
unit within Media Segments that is indexed by a Segment Index
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ISO/IEC 23009-1:2012(E)
3.1.38
valid Segment URL
HTTP-URL that is promised to reference a Segment during its Segment availability period
3.1.39
wall-clock time
time as stated by UTC
3.2 Symbols and abbreviated terms
For the purposes of this document, the following symbols and abbreviated terms apply.
AVC advanced video coding
CAT conditional access table
DASH dynamic adaptive streaming over HTTP
DM  DASH Metrics
DRM digital rights management
ECM entitlement control message
HTTP hypertext transfer protocol
IDR  instantaneous decoding refresh
ISOBMFF ISO base media file format
MPD Media Presentation Description
MVC multi-view video coding
PAT  program association table
PCR program clock reference
PES packetized elementary stream
PID  packet identifier
PMT program map table
PSI  program specific information
PTS  presentation time stamp
SAP stream access point
SEI  supplementary enhancement information
SVC scalable video coding
TCP transmission control protocol
TLS  transport layer security
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ISO/IEC 23009-1:2012(E)
TS  transport stream
URI  uniform resource identifier
URL uniform resource locator
URN uniform resource name
UTC coordinated universal time
UUID universally unique identifier
XML extensible mark-up language
3.3 Conventions
The following naming conventions apply in this document.
 Elements in an XML document are identified by an upper-case first letter and in bold face as
Element. To express that an element Element1 is contained in another element Element2, we
may write Element2.Element1. If an element's name consists of two or more combined words,
camel-casing is typically used, e.g. ImportantElement. Elements may be present either exactly
once, or the minimum and maximum occurence is defined by . .
 Attributes in an XML document are identified by a lower-case first letter as well as they are preceded
by a ‘@’-sign, e.g. @attribute. To point to a specific attribute @attribute contained in an element
Element, one may write Element@attribute. If an attribute's name consists of two or more
combined words, camel-casing is typically used after the first word, e.g.
@veryImportantAttribute. Attributes may have assigned a status in the XML as mandatory (M),
optional (O), optional with default value (OD) and conditionally mandatory (CM).
 Namespace qualification of elements and attributes is used as per XML standards, in the form of
namespace:Element or @namespace:attribute The fully qualified namespace will be provided
in the schema fragment associated with the declaration.
 Variables defined in the context of this document are specifically highlighted with italics, e.g.
InternalVariable.
 Structures that are defined as part of the hierarchical data model are identified by an upper-case first
letter, e.g. Period, Adaptation Set, Representation, Segment, etc.
 The term "this clause" refers to the entire clause included within the same first heading number. The
term "this subclause" refers to all text contained in the subclause with the lowest hierarchy heading.
4 Introduction
4.1 System description
Dynamic Adaptive Streaming over HTTP (DASH) specifies XML and binary formats that enable delivery of
media content from standard HTTP servers to HTTP clients and enable caching of content by standard HTTP
caches.
This part of ISO/IEC 23009 primarily defines two formats:
 The Media Presentation Description (MPD) describes a Media Presentation, i.e. a bounded or
unbounded presentation of media content. In particular, it defines formats to announce resource
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ISO/IEC 23009-1:2012(E)
identifiers for Segments and to provide the context for these identified resources within a Media
Presentation. These resource identifiers are HTTP-URLs possibly combined with a byte range.
 The Segment formats specify the formats of the entity body of the HTTP response to an HTTP GET
request or a partial HTTP GET with the indicated byte range using HTTP/1.1 as defined in RFC 2616
to a resource identified in the MPD. Segments typically contain efficiently coded media data and
metadata according to or aligned with common media formats.
The MPD provides sufficient information for a client to provide a streaming service to the user by accessing
the Segments through the protocol specified in the scheme of the defined resources. In the context of this part
of ISO/IEC 23009 the assumed protocol is HTTP/1.1. Such a client is referred to as a DASH Client in the
remainder of 23009-1. However, this part of ISO/IEC 23009 does not provide a normative specification for
such a client.
Figure 1 shows a possible deployment architecture in which the formats defined in this part of ISO/IEC 23009
may be used. Boxes with solid lines indicate devices that are mentioned in this specification as they host or
process the formats defined in this specification whereas dashed boxes are conceptual or transparent. This
part of ISO/IEC 23009 deals with the definition of formats that are accessible on the interface to the DASH
Client, indicated by the solid lines. Any other formats or interfaces are not in scope of this Part of
ISO/IEC 23009. In the considered deployment scenario, it is assumed that the DASH Client has access to an
MPD. The MPD provides sufficient information for the DASH Client to provide a streaming service to the user
by requesting Segments from an HTTP server and demultiplexing, decoding and rendering the included media
streams.

Figure 1 — Example system for DASH formats
4.2 DASH client model
The design of the formats defined in this part of ISO/IEC 23009 is based on the informative client model as
shown in Figure 2. The figure illustrates the logical components of a conceptual DASH client model. In this
figure the DASH Access Engine receives the Media Presentation Description (MPD), constructs and issues
requests and receives Segments or parts of Segments. In the context of this part of ISO/IEC 23009, the output
of the DASH Access Engine consists of media in MPEG container formats (ISO/IEC 14496-12 ISO Base
Media File Format or ISO/IEC 13818-1 MPEG-2 Transport Stream), or parts thereof, together with timing
information that maps the internal timing of the media to the timeline of the Media Presentation. In Annex F of
this part of ISO/IEC 23009, guidance on enabling the use of this part of ISO/IEC 23009 with other container
formats is provided.
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ISO/IEC 23009-1:2012(E)
Figure 2 — DASH Client Model
4.3 DASH data model overview
DASH is intended to support a media-streaming model for delivery of media content in which control lies
exclusively wit
...