ISO/IEC 23009-8:2022 情報技術— HTTPを介した動的適応ストリーミング（DASH）— Part 8: セッションベースのDASH操作 | ページ 2

3.1 用語と定義

このドキュメントでは、次の用語と定義が適用されます。

ISO および IEC は、次のアドレスで標準化に使用する用語データベースを維持しています。

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.

The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, 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 the ISO/IEC Directives, 2 (see www.iso.org/directives or www.iec.ch/members_experts/refdocs ).

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 identified 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 ) or the IEC list of patent declarations received (see https://patents.iec.ch ).

Any trade name used in this document is information given for the convenience of users and does not constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISO's adherence to the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www.iso.org/iso/foreword.html . In the IEC, see www.iec.ch/understanding-standards .

This document was prepared by Joint Technical Committee ISO/IEC JTC 1, Information technology, Subcommittee SC 29, Coding of audio, picture, multimedia and hypermedia information.

A list of all parts in the ISO/IEC 23009 series can be found on the ISO and IEC websites.

Introduction

Dynamic adaptive streaming over HTTP (DASH) enables 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, the ISO/IEC 23009 series focuses not on client or server procedures but on the data formats used to provide a DASH Media Presentation.

This document provides methods, interfaces and data for session-based operations to be used with the DASH standard. Session-based operations allows customization of requested segment URLs based on the information provided for a specific streaming session.

1 Scope

This document specifies the format of the Session-Based Description document and the MPD's extension to be used in session-based operations with MPEG DASH (ISO/IEC 23009-1).

2 Normative references

The following documents are referred to in the text in such a way that some or all of their content constitutes requirements 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.

3 Terms, definitions, abbreviated terms and notations

3.2 Abbreviated terms

3.3 Notation

This document follows the notation used in ISO/IEC 23009-1.

The following naming conventions apply in this document:

• Elements in an XML document are identified by an upper-case first letter and in boldface as Element . To express that an element Element1 is contained in another element Element2 , the following format is used: Element2.Element1 . If an element's name consists of two or more combined words, PascalCase is typically used, e.g. ImportantElement . Elements may be present either exactly once, or the minimum and maximum occurrence as defined by <minOccurs> ... <maxOccurs>.
• Attributes in an XML document are identified by a lower-case first letter and they are preceded by an '@'-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, camelCase 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 a 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 is provided in the schema fragment associated with the declaration. External specifications extending the namespace of DASH are expected to document the element name in the semantic table with an extension namespace prefix.
• JSON items are identified by a lower-case first letter. If an item consists of two or more combined words, camel-casing is typically used.
• Variables defined in the context of this document are specifically highlighted with italics, e.g., InternalVariable.
• 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.

Bibliography