1、Information technology Dynamic adaptive streaming over HTTP (DASH) Part 1: Media presentation description and segment formats AMENDMENT 3: Authentication, MPD linking, Callback Event, Period Continuity and other Extensions Technologies de linformation Diffusion en flux adaptatif dynamique sur HTTP (
2、DASH) Partie 1: Description de la prsentation et formats de remise des mdias AMENDEMENT 3: Authentification, liaison MPD, vnement de rapel, continuit de la priode et autres extensions INTERNATIONAL STANDARD ISO/IEC 23009-1 Second edition 2014-05-15 Reference number ISO/IEC 23009-1:2014/Amd.3:2016(E)
3、 AMENDMENT 3 2016-10-15 ISO/IEC 2016 ii ISO/IEC 2016 All rights reserved COPYRIGHT PROTECTED DOCUMENT ISO/IEC 2016, Published in Switzerland All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or
4、 mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below or ISOs member body in the country of the requester. ISO copyright office Ch. de Blandonnet 8 CP 401 CH-1214 Vernier, Gen
5、eva, Switzerland Tel. +41 22 749 01 11 Fax +41 22 749 09 47 copyrightiso.org www.iso.org ISO/IEC 23009-1:2014/Amd.3:2016(E) ISO/IEC 23009-1:2014/Amd.3:2016(E) Foreword ISO (the International Organization for Standardization) and IEC (the International Electrotechnical Commission) form the specialize
6、d 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 committ
7、ees 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. The procedures
8、 used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the different types of document should be noted. This document was drafted in accordance with the editorial rules of
9、 the ISO/IEC Directives, Part 2 (see www.iso.org/directives). 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. Details of any patent rights id
10、entified during the development of the document will be in the Introduction and/or on the ISO list of patent declarations received (see www.iso.org/patents). Any trade name used in this document is information given for the convenience of users and does not constitute an endorsement. For an explanat
11、ion on the meaning of ISO specific terms and expressions related to conformit y assessment, as well as information about ISOs adherence to the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following URL: www.iso.org/iso/foreword.html. Amendment 3 to ISO/I
12、EC 23009-1:2014 was prepared by ISO/IEC JTC 1, Information technology, Subcommittee SC 29, Coding of audio, picture, multimedia and hypermedia information. ISO/IEC 2016 All rights reserved iii Information technology Dynamic adaptive streaming over HTTP (DASH) Part 1: Media presentation description a
13、nd segment formats AMENDMENT 3: Authentication, MPD linking, Callback Event, Period Continuity and other Extensions Page 2, Terms and definitions Add the following definition in 3.1: 3.1.X sub-asset media content component (or part thereof) identified as corresponding to a part of an asset Page 15,
14、Table 2 Add the following identifiers in Table 2: Scheme Identifier Clause in this document Informative description urn:mpeg:dash:period-continuity:2015 5.3.2.4 Period continuity signalling urn:mpeg:dash:period-connectivity:2015 5.3.2.4 Period connectivity signalling urn:mpeg:dash:mpd-as-linking:201
15、5 5.8.5.X MPD Adaptation Set Linking scheme. urn:mpeg:dash:sai:2015 5.8.5.Y Sub-Asset Scheme Identifier urn:mpeg:dash:client-authentication:2015 5.8.5.Z Client Authentication scheme. urn:mpeg:dash:content-authorization:2015 5.8.5.Z Content Access Authorization scheme. urn:mpeg:dash:event:callback:20
16、15 5.10.4.X DASH call back event.Page 9, Clause 4 Add in the second paragraph of 4.3, discussing Assets: Same asset over multiple periods may be identified by a DASH descriptor enabling DASH clients to maintain the continuity across periods boundaries. Furthermore, sub-assets composing the same asse
17、t may also identified using a similar method. For instance, if an asset is composed of multiple video components, sub-assets enable selecting the previously selected video component after an ad insertion. As such an asset can contain sub-assets that can be uniquely identified from one media content
18、period to another.ISO/IEC 23009-1:2014/Amd.3:2016(E) ISO 2016 All rights reserved 1 ISO/IEC 23009-1:2014/Amd.3:2016(E) Page 23, Table 4 Add at the end of Table 4:EmptyAdaptationSet 0.N specifies an Adaptation Set that does not contain any Representation element. The empty Adaptation Set is of the sa
19、me type as a regular Adaptation Set, but shall neither contain an xlink nor may it contain any Rep- resentation element. This element shall only be present, if an Essential Descriptor is present with schemeIDURI set to “urn:mpeg:dash:mpd-as-linking:2015”. For more details, see 5.8.5.8.Page 25, Claus
20、e 5 Add to schema:Page 25, Clause 5 Add new subclause: 5.3.2.4 Content Offering with multiple Periods Content with multiple Periods may be created for different reasons, for example: to enable splicing of content, for example for ad insertion; to provide synchronization in segment numbering, e.g. co
21、mpensate non-constant segment durations; to remove or add certain Representations in an Adaptation Set; to remove or add certain Adaptation Sets;2 ISO 2016 All rights reserved ISO/IEC 23009-1:2014/Amd.3:2016(E) to remove or add content offering on certain CDNs; to enable signalling of shorter segmen
22、ts, if produced by the encoder. Periods provide opportunities for resync, for ad insertion, for adding and removing Representations. However, in certain circumstances, the content across Period boundaries is continuous and in this case, continuous playout of the client is expected. In certain circum
23、stances, the Media Presentation is offered such that the next Period is a continuation of the content in the previous Period (certain media components are continued), possibly in the immediately following Period of that previous Period or in a later Period (e.g. after an advertisement Period had bee
24、n inserted). The content provider may express that the media components contained in two Adaptation Sets in two different Periods are associated by assigning equivalent Asset Identifiers to both Periods and by identifying both Adaptation Sets with identical value for the attribute id. Association ex
25、presses a logical continuation of the media component in the next Period and may, for example, be used by the client to continue playing an associated Adaptation Set in the new Period. In addition, two Adaptation Sets in one MPD are period-continuous if all of the following holds. The Adaptation Set
26、s are associated. The sum of the value of the presentationTimeOffset and the presentation duration of the Representations in one Adaptation Set are identical to the value of the presentationTimeOffset of the associated Adaptation Set in the next Period. If Representations in both Adaptation Sets hav
27、e the same value for id, then they shall have functionally equivalent Initialization Segments, i.e. the Initialization Segment may be used to continue the play-out of the Representation. The concatenation of the Initialization Segment of the first Period, if present, and all consecutive Media Segmen
28、ts in the Representation in the first Period and subsequently the concatenation with all consecutive Media Segments in the Representation of the second Period shall represent a conforming Segment sequence as defined in 4.5.4 conforming to the media type as specified in the mimeType attribute for the
29、 Representation in the first Period. Additionally, the mimeType attribute for the Representation in the next Period shall be the same as one of the first Period. Media Presentations should signal period-continuous Adaptation Sets by using a supplemental descriptor on Adaptation Set level with scheme
30、IdUri set to “urn:mpeg:dash:period- continuity:2015” with the value of the descriptor matching the value of an id of a Period that is contained in the MPD, and the value of the AdaptationSetid being the same in both Periods. MPD should signal period-continuous Adaptation Sets if the MPD contains Per
31、iods with identical Asset Identifiers. There exist special cases, for which the media in one Adaptation Set is a continuation of the previous one, but the timestamps are not continuous. Examples are timestamp wrap around, encoder reset, splicing, or other aspects. Two Adaptation Sets in one MPD are
32、period-connected if all conditions from period-continuity from above hold, except that the timestamps across Period boundaries may be non-continuous, but adjusted by the value of the presentationTimeOffset at the Period boundary. However, for example, the Initialization Segment is equivalent within
33、the two Adaptation Sets. Media Presentations should signal period-connected Adaptation Sets by using a supplemental descriptor on Adaptation Set level with schemeIdUri set to “urn:mpeg:dash:period- connectivity:2015”. Note that period continuity implies period connectivity. For appropriate client be
34、haviour, please refer to A.9. ISO 2016 All rights reserved 3 ISO/IEC 23009-1:2014/Amd.3:2016(E)Page 74, Clause 5 Add new subclause: 5.8.5.X DASH MPD Adaptation Set Linking scheme The URN “urn:mpeg:dash:mpd-as-linking:2015” is defined in order to provide information that the same Adaptation Set can b
35、e found in another MPD. The scheme may be used with Essential Property Descriptors together with an EmptyAdaptationSet element or with Supplemental Property Descriptors. The value provides a URL to the MPD, including appropriate anchors for Periods and Adaptation Set as defined in C.4.2, and optiona
36、lly, a timeline offset field to synchronize the data added as a white-space separated second item. If the value is not present, then the media time on the original MPD and the linked MPD are identical. If a timeOffset field is added, then this value expresses the difference between the media time of
37、 the Adaptation Set of the linked MPD and the media time in the originating MPD. Note that the number may be positive or negative. The timeoffset is in unit of timescale of the linked Adaptation Sets. The Descriptor shall only be used in combination with Adaptation Sets (regular or empty ones). If a
38、ll information is contained in the Adaptation Set, then a Supplemental Descriptor or an Essential Descriptor may be used. If the Adaptation Set does neither contain a Representation element, nor an xlink attribute, then an Empty Adaptation Set as well as an Essential Descriptor shall be used to indi
39、cate that the Adaptation Set is not fully described in this MPD. NOTE This scheme may be used for many use cases. However, one specific use case is the server-based mosaic channel as described in ISO/IEC 23009-3. The use case may be fulfilled by the combination of the Spatial Relationship Descriptio
40、n (SRD) as defined in Annex H and this scheme.Page 74, Clause 5 Add new subclause: 5.8.5.Y Sub-Asset Scheme Identifier In DASH MPD, sub-assets across Periods can be identified using the sub asset Scheme Identifier. This scheme is signalled using a specific SupplementalProperty descriptor at the Adap
41、tation Set or Sub- Representation level with schemeIdUri attribute set to “urn:mpeg:dash:sai:2015”. If two different Adaptation Sets or Sub-Representation from different Periods contain Sub-Asset Identifiers descriptors with the same value attribute, then the content in the Representation(s) contain
42、ed in these Adaptation Sets represent, at least, the same sub-asset. NOTE 1 The association between sub-assets and an Adaptation Set may change between Periods. For instance, an Adaptation Set may be associated with a sub-asset of an asset in one Period but with another sub-asset of the same asset i
43、n another Period. NOTE 2 Sub-Asset Identifier descriptor may be used by DASH clients to select Representation(s) to be processed after a Period change. A given Adaptation Set may contain more than one Sub-Asset Identifier descriptor indicating that the Representation(s) contained in this Adaptation
44、Set represent more than one identified part of the asset. NOTE 3 If the value for this descriptor is not recognized, the SubAsset Identifier descriptor may still be used to understand the equivalence of sub-asset identifiers across Periods. Processing of the descriptor scheme and value by the DASH c
45、lient is not essential for normal operation. 4 ISO 2016 All rights reserved ISO/IEC 23009-1:2014/Amd.3:2016(E)Page 74, Clause 5 Add new subclause: 5.8.5.Z Client Authentication and Content Access Authorization When client authentication and/or content access authorization functionality is needed, DA
46、SH may be used with different schemes, such as Open Authentication Technical Committee (OATC) Online Multimedia Authorization Protocol (OMAP), 13Open Standard for Authorization (OAuth) 2.0, 14OASIS Security Assertion Markup Language (SAML), 153GPP Generic Authentication Architecture (GAA), 16or 3GPP
47、 Generic Bootstrapping Architecture (GBA). 17This subclause describes generic signalling to support use of various authentication and authorization schemes. Typical access control methods include blocking HTTP requests that do not include a security token obtained by the authorization protocol where
48、in the security token is validated by a CDN before downloading the requested Media Segment, or encrypting Media Segments so that playback will be restricted unless the authorization protocol provides the client with a decryption key. For client authentication, a service may limit content delivery to
49、 authenticated clients and may use client identification information such as certificates, cookies, and embedded keys to determine subscription rights, etc. required to authorize playback of the Media Presentation. The details of such a scheme are outside the scope of this document. A client that does not support the signalled content access authorization would not be able to play the content. NOTE This subclause does not provide any requirements on cl
