1、 Reference numberISO/IEC 15938-1:2002/Amd.2:2006(E)ISO/IEC 2006INTERNATIONAL STANDARD ISO/IEC15938-1First edition2002-07-01AMENDMENT 22006-04-01Information technology Multimedia content description interface Part 1: Systems AMENDMENT 2: Fast access extension Technologies de linformation Interface de
2、 description du contenu multimdia Partie 1: Systmes AMENDEMENT 2: Extension daccs rapide International Organization for Standardization (ISO), 2006. All rights reserved. International Electrotechnical Commission (IEC), 2006. All rights reserved. NOT FOR RESALE.Amendment 2:2007 toNational Standard of
3、 CanadaCAN/CSA-ISO/IEC 15938-1:04Amendment 2:2006 to International Standard ISO/IEC 15938-1:2002 has been adopted withoutmodification (IDT) as Amendment 2:2007 to CAN/CSA-ISO/IEC 15938-1:04. This Amendment was reviewedby the CSA Technical Committee on Information Technology (TCIT) under the jurisdic
4、tion of the StrategicSteering Committee on Information Technology and deemed acceptable for use in Canada.August 2007ISO/IEC 15938-1:2002/Amd.2:2006(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobes licensing policy, this file may be printed or viewed but shal
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9、rg Web www.iso.org ii ISO/IEC 2006 All rights reservedAmendment 2:2007 toCAN/CSA-ISO/IEC 15938-1:04ISO/IEC 15938-1:2002/Amd.2:2006(E) ISO/IEC 2006 All rights reserved iiiForeword ISO (the International Organization for Standardization) and IEC (the International Electrotechnical Commission) form the
10、 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 techni
11、cal 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. Int
12、ernational 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 vo
13、ting. 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
14、 or all such patent rights. Amendment 2 to ISO/IEC 15938-1:2002 was prepared by Joint Technical Committee ISO/IEC JTC 1, Information technology, Subcommittee SC 29, Coding of audio, picture, multimedia and hypermedia information. Amendment 2:2007 toCAN/CSA-ISO/IEC 15938-1:04ISO/IEC 15938-1:2002/Amd.
15、2:2006(E) ISO/IEC 2006 All rights reserved 1Information technology Multimedia content description interface Part 1: Systems AMENDMENT 2: Fast access extension This document preserves the sectioning of ISO/IEC 15938-1. The text and figures given below are additions and/or modifications to those corre
16、sponding sections in ISO/IEC 15938-1. All figures and tables shall be renumbered due to the addition of several figures and tables. Add the following definitions to subclause 3.2 (keep alphabetical order), then renumber all definitions in subclause 3.2: path index key value representing the path to
17、the element to be indexed/located, and the relative path to the fields to be keyed/searched. value index key set of encoded field values to be keyed/searched. index stream set of Index Access Units which together form the whole of the indexing data, index decoder init initialisation data for an inde
18、x stream. index access unit index access unit header and associated structures forming a logical unit of access. index access unit header list of structures contained within this Index Access Unit path index structure allowing path index key to value index reference lookup. value index structure all
19、owing value index key to value sub index reference lookup. value sub-index structure allowing value index key to BiM stream reference lookup. node reference reference from one node to another within a list or B-Tree structure. data repository reference reference to data entry within the binary or st
20、ring data repository structures. BiM stream reference reference to a BiM encoded fragment within a BiM stream. Amendment 2:2007 toCAN/CSA-ISO/IEC 15938-1:04ISO/IEC 15938-1:2002/Amd.2:2006(E) 2 ISO/IEC 2006 All rights reservedlocal access unit default Access Unit associated with a Path Index. local B
21、iM stream reference reference to a BiM encoded fragment contained within the local access unit. remote BiM stream reference reference to a BiM encoded fragment contained within the BiM stream, where the access unit is specified by an access unit ID. value index reference reference to a value index s
22、tructure. value sub-index reference reference to a sub value index structure. position codes reference reference to a position codes entry within a position codes structure. position code location of an XML element within its parent element. position codes set of position code values for all element
23、s within a context path. BTree binary decision tree, where each node can have multiple keys. BTree order specifies the maximum number of child nodes of a node in a BTree. indexed element XML element to which an index refers. BiM stream reference format specifies the format of the BiM stream referenc
24、e. value encoding specifies how data has been encoded in value index key. Add the following subclause 5.9.1: 5.9.1 General Description Using the ISO/IEC 15938-1 index encoding, only fragments of the description that are of immediate interest to the terminal can be selectively acquired and combined w
25、ith the current description tree. The terminal can search the index information to determine which fragments contain a node at a given location which has a related node with a given value within the description. Additionally the terminal may search for fragments containing nodes which have related n
26、ode values falling within a given range. Amendment 2:2007 toCAN/CSA-ISO/IEC 15938-1:04ISO/IEC 15938-1:2002/Amd.2:2006(E) ISO/IEC 2006 All rights reserved 3The index information can also be compiled to allow the terminal to search for fragments containing nodes with multiple given related node locati
27、ons, and respective values, within the description. This can allow the terminal to perform searches with multiple conditions, without needing to consolidate multiple result sets. As the indexing stream is optional a stream may consist of either A DecoderInit and a description stream A DecoderInit, a
28、n IndexDecoderInit, an index stream, and a description stream. Before an index stream can be queried both the DecoderInit for the BiM stream to which the index stream belongs, and the IndexDecoderInit for the index stream must be acquired. However acquiring fragments from the description stream, wit
29、hout querying the index stream, only requires the DecoderInit to be acquired. Figure Amd2.1 Indexing Enabled Terminal Architecture Extension. All components of Systems Layer(Indexing) section are non-normative The Terminal Architecture for a BiM enabled terminal may be extended to support indexing,
30、as shown in Figure Amd2.1. Figure Amd2.1 shows only the extensions to the Terminal Architecture, and not the complete architecture. The components shown in the Systems Layer(BiM) section of Figure Amd2.1 are the existing components of the standard Terminal Architecture. Add the following subclause 5
31、.9.2: 5.9.2 Options for multi criteria query There are two main methods of querying for fragments when there are multiple criteria, multi-value indexing, and multi-stage indexing. These different methods are distinct and offer two complementary optimizations. Multi-value indexing allows the whole da
32、ta set to be indexed in a very compact manner. The size of the index stream and the number of comparisons of values is minimized, allowing the index to perform a multi criteria query using the smallest amount of index data and queries possible. Partitioning of indices with larger data Application Sy
33、stems Layer(Indexing) Delivery LayerSystems Layer(BiM) initialisation extractor SU decoder DecoderInit SU Decode Parameters context path decoder Schema index structure decoder IndexAccessUnit decoder IndexDecoderInit IndexAccessUnit Index structures Query IndexAccessUnitID AccessUnitID context path
34、Amendment 2:2007 toCAN/CSA-ISO/IEC 15938-1:04ISO/IEC 15938-1:2002/Amd.2:2006(E) 4 ISO/IEC 2006 All rights reservedsets allows maximum IndexAccessUnit sizes to be imposed. This is useful when the underlying transport layer has an imposed, or preferred size for a unit of access, as might be the case w
35、ith network packets, or transport layer data buffers. It is usual for several IndexAccessUnits to be required to complete a query, hence the IndexAccessUnit is not independent. Multi-stage indexing allows the data set to be sectioned into multiple smaller index stream segments. This increases both t
36、he overall size of the index stream and the number of value comparisons by a moderate amount. However, multi-stage indexing can facilitate more efficient use of resources in client terminal devices where caching of stream index data is necessary but the size of the stream index data prohibits cachin
37、g all of it. Caching is desirable where either the index stream is not always available or the acquisition time of Index Access Units from the index stream is significant. In a multi-stage index the data size of each independent segment of the index stream is reduced, allowing a whole segment of the
38、 index to be cached from the index stream into memory and searched independent of the Index Stream. This is often a better optimisation than attempting to cache a portion of an index arranged as a single segment. Multi-value indexing is intended to be used in situations where efficient index size is
39、 a priority and there are no significant restraints imposed by client terminal resources. There are two formats of multi-value indexing, composite value, and hierarchical single value indexing. In composite value indexing the values are stored as an N column table, where N is the number of related v
40、alues. In hierarchical single value indexing the values are stored as an N level tree, with the trees nodes containing 1 column tables (Lists). The composite value index is intended for use where there is unlikely to be multiple instances of the related node with the same value, whilst the hierarchi
41、cal single value indexing is intended for use where there are many instances of the related node with the same value in the BiM fragments to be indexed. It is important to take care to choose the order of the related nodes carefully, as the related node with most common values placed at the highest
42、level of the hierarchy will usually produce the smallest index stream and the minimum number of value compares when querying. Multi-stage indexing is intended for use in situations where client terminals with limited resources must access a very large amount of BiM fragments by index, and for which
43、there are a small number of search criteria common for most queries. The common criteria can be used to segment the index stream into a collection of index stream segments, each segment then being accessed and searched independently of other segments. This allows searches to start on an initial segm
44、ent stored in a cache and then progress to the relevant follow-on segment which, if not cached, must be acquired from the index stream. The search is therefore completed with a minimum number of acquisitions and without requiring the whole multi-stage index to be cached. Note that the method of cach
45、ing and cache maintenance is implementation dependent, and not defined in this specification. Note - Another situation where multi stage indexing can be used, is when consolidating multiple independent index streams. This may be the case if there are multiple providers of BiM fragments each with an
46、associated index stream. Consolidation of the index streams can be achieved easily by modifying each index stream to be a second stage segment. A first stage index would then be created to associate a provider to a second stage segment within the index stream. Change the following sentence at the en
47、d of subclause 7.1 as indicated: Several other coding modes are initialised in the DecoderInit related to the features used by the binary description stream: the insertion of elements, the transmission of schema information, references to fragments and a fixed length context path. And add the follow
48、ing sentence at the end of subclause 7.1: The fixed length context path mechanism provides a simplified addressing of nodes for usage scenarios where only a limited number of nodes need to be addressed. This is done by a table that uniquely maps fixed length codes to full context paths. Amendment 2:
49、2007 toCAN/CSA-ISO/IEC 15938-1:04ISO/IEC 15938-1:2002/Amd.2:2006(E) ISO/IEC 2006 All rights reserved 5In subclause 7.2.2, insert grey marked rows at the position indicated: If (! NoAdvancedFeatures) AdvancedFeatureFlags_Length 8+ vluimsbf8 /* FeatureFlags */ InsertFlag 1 bslbf AdvancedOptimisedDecodersFlag 1 bslbfAdditionalSchemaFlag 1 bslbf AdditionalSchemaUpdatesOnlyFlag 1 bslbfFragmentReferenceFlag 1 bslbf MPCOnlyFlag 1 bslbfHierarchyBasedSubstitutionCodingFlag 1 bslbf ContextPathTableFlag 1 bslbf ReservedBitsZero FeatureFlags
