ITU-R BR 1351-1998 Requirements for the Application of Digital Technology to Audio Archiving Systems for Radio Broadcasting《将数字技术应用于无线电广播的音频归档系统的要求》.pdf

《ITU-R BR 1351-1998 Requirements for the Application of Digital Technology to Audio Archiving Systems for Radio Broadcasting《将数字技术应用于无线电广播的音频归档系统的要求》.pdf》由会员分享，可在线阅读，更多相关《ITU-R BR 1351-1998 Requirements for the Application of Digital Technology to Audio Archiving Systems for Radio Broadcasting《将数字技术应用于无线电广播的音频归档系统的要求》.pdf（7页珍藏版）》请在麦多课文档分享上搜索。

1、Rec. ITU-R BR.1351 1RECOMMENDATION ITU-R BR.1351REQUIREMENTS FOR THE APPLICATION OF DIGITAL TECHNOLOGYTO AUDIO ARCHIVING SYSTEMS FOR RADIO BROADCASTING(Questions ITU-R 215/10 and ITU-R 216/10)(1998)Rec. ITU-R BR.1351The ITU Radiocommunication Assembly,consideringthat many broadcasting companies poss

2、ess vast audio archives, whose exploitation is expected to play a key role inaudio production in the near future;that most of the materials, being stored in analogue formats, are in danger due to the ageing of the media;that digital storage formats, allowing for lossless copy operations, are expecte

3、d to bring substantial benefits to the assetmanagement;that the technology allows for the design of automated digital archives;that the new multimedia technology permits the handling of the audio materials and the relative documentativeinformation (metadata) as composite objects;that low cost inform

4、ation technology equipment is able to manage real time CD quality audio,recommendsthat the design of digital audio archives for radio broadcasting should be based on the user requirements given inAnnex 1.ANNEX 1Requirements for the application of digital technologyto audio archiving systems for radi

5、o broadcastingArchive functional architectureTypes of informationThe types of information that an audio broadcasting archive must contain can be categorized as:1) audio programmes;2) metadata.The audio programmes can be considered as made of the following types of objects:1) sound material;2) ancill

6、ary data:a) synchronous;b) asynchronous.The sound materials can comprise assembled programmes, single contributions or purchased records (CD or vinyl).Ancillary data, comprising objects of various types like still pictures, text or animations, can optionally complement thesound materials. The ancill

7、ary data can require synchronization with the main programme, as in case of subtitles, or beasynchronous, as in the case of teletext.2 Rec. ITU-R BR.1351The metadata is composed of multimedia information which is useful to better qualify and retrieve the audio content. Itcan be divided into: textual

8、 documents; images; graphics; EDL; cue points; hyperlinks; attributes.The type and organization of metadata varies according to the programme genre and state of development of the item,e.g., contributions not yet included in a programme will probably have a lower level of documentation than a progra

9、mmewhich has already been transmitted.Archive architectureIn a broadcast archive two main modules can be distinguished: the content library and the index library.Content libraryThe content library is the part of the archive that contains and manages the media on which copies of the audioprogrammes a

10、re stored and is thus responsible for the storage and preservation of the materials.It is responsible for performing the following functions:Archiving: All of the operations required to introduce new materials into the content library, including verification ofthe signal quality, generation of backu

11、p copies, etc.Preservation: All of the maintenance operations that must be performed to ensure proper preservation of the materials,like periodic checking of the state of deterioration of the media and regeneration of the content on new media whenneeded.Delivery: The procedures and means employed to

12、 provide a user with the required material for reuse in production.Several ways of delivery can be implemented depending on the technology available: file transfer; synchronous transfer (streaming) on various types of links (analogue, digital, IT), generally in real time; medium delivery.Index libra

13、ryThe index library contains all the metadata needed to retrieve and browse the content of the archive.Information contained: audio programmes (browsing quality); textual documents; images; EDL; cue points; attributes.At least the following functions must be provided:Documentation: All of the proced

14、ures required to gather, link and compile the information that will permit the retrievalof the programme content. Part of the information can be imported from the production, part can be generated by thesystem automatically and part must be input manually.Rec. ITU-R BR.1351 3Retrieval: Various metho

15、ds provided to query the index library. The most common consists of specifying the value ofpre-formatted fields, like Title, Author, Production date, etc. More sophisticated methods can be implemented based oncontent search, provided that suitable algorithms are included for comparing objects of var

16、ious nature such as audio, stillpictures, video and free text.Browsing: Through the browsing operation, the users can listen to a preview of the material selected during retrieval, byaccessing a low-quality copy of the audio contained in the index library. Even if the quality of this signal is gener

17、ally toolow to be used in production, it serves various important functions, like precisely locating the audio excerpt that must bedownloaded from the content library or remote editing.UsersDifferent kinds of user can be identified that have different needs and priorities for access to the archive:a

18、) Production techniciansThey must have high priority access to the content library, while less sophisticated indexing functions are generallyrequired. This is especially so in news and sports environments, where production is often working on an extremelytight schedule, system reliability and fast t

19、ransfer rates are mandatory requirements.b) Programme makers and journalistsThey use the system for documentation purposes only. Thus, access to the content library is not needed, providedthat pre-viewing is available from the index library. On the other hand, sophisticated search functions are requ

20、ired.c) DocumentatorsTheir task is to assemble the documentation of the new items introduced into the archive. This job can generally beaccomplished by browsing low quality versions of the materials, so that access to the content library can beavoided. The user interface for this category must be de

21、signed very carefully, as they need to be able to screenautomatically generated information, like audio indexes, to link in external multimedia objects and to input textualinformation and audio indexes.d) External usersExternal users can have access to selected parts of the archive. Both the documen

22、tation and the content can berequired, but, in most cases, the materials are delivered in an intermediate quality format to preserve copyright.Special attention must be paid to security and accounting issues when this category of users is enabled.User requirementsContent libraryArchivingAudio qualit

23、yAs the materials stored in the archive can be reused in production, no quality loss must be implied by the archivingprocess. The content library must be able to support all the audio formats used in production so that any item can bestored in its original format without any possible loss of informa

24、tion. Materials received in compressed formats, ing from contribution links or news gathering systems, should be stored in compressed form rather than decodedinto PCM, so that during future retransmission appropriate transcoding algorithms, if available, can be applied, thereforeavoiding the need fo

25、r cascaded codecs.Automatic certification of new materialsIf an audio item, while entering the archive, needs to be copied to a medium different to that of the original one, thefidelity of the copy against that of the original must be verified. It is desirable that automatic systems be developed top

26、erform this task without need of human assistance. If this goal cannot be achieved, a human assisted operation based onautomatic pre-analysis would already represent a step forward with respect to the present situation.4 Rec. ITU-R BR.1351PreservationDurability of the mediaIt is well known that any

27、storage medium is subject to deterioration due to usage, ageing and atmospheric conditions.Thus, periodic regeneration of the material on new media must be performed. Due to the dimensions of the archives, thisoperation is very time and resource consuming and should be performed as seldom as possibl

28、e. Even if automaticdetection of endangered material with subsequent automatic regeneration is available, the average lifetime of the mediashould be in the order of several years to reduce the time critical nature of the monitoring process.Automatic verification of the state of conservation of the m

29、ediaIt is desirable that, when using automated digital libraries, the state of preservation of the media is automatically andconstantly monitored. This feature can be implemented by adopting recording formats having robust error detection andcorrection mechanisms that are widely used in the informat

30、ion technology world. In addition, it is desirable to be able tocommunicate, to the system, parameters to determine how often the correction mechanism is employed. By monitoringthese parameters, it can be statistically determined when the regeneration of the content of a given medium is required.Los

31、sless copy operationsAs periodic regeneration of the materials cannot be avoided, the low loss of copy operations must be guaranteed. Thus,recording systems with verification after copy capability should be employed in preference to recording systems onlyable to work in stream mode with error concea

32、lment.Management of different media formatsMass storage technology is rapidly evolving, delivering media with higher and higher recording densities and transferspeeds. The automation system of the content library should therefore be able to handle heterogeneous media formats, sothat various formats

33、can coexist within the library, allowing for a seamless migration to newer formats in the course oftime.DeliveryAutomation capabilityAutomated media handling is an essential step in reducing the management costs of the archives and to substantiallyincrease the performance of the whole system as well

34、 as to implement new features like automatic monitoring of themedia ageing. Thus, the choice of the media formats supported by the content library must take account of theavailability on the market of suitable robotized libraries. For cost and efficiency reasons, higher packing density formatsshould

35、 be preferred.Near on-line availabilityAny items selected from the index library should be ready for delivery to the user within a few minutes from the initialrequest. The actual delivery time will also depend upon the connection available from the library to the user location.Delivery methodsSevera

36、l delivery methods can be implemented according to the storage technology and the distance between the libraryand the users. If information technology (IT) storage systems are used, the delivery is best implemented throughcomputer network protocols, as the maximum flexibility in network topology can

37、 be obtained. In this case the transfercan occur as a normal file transfer, asynchronously from real time playback, at a speed independent of the load and typeof the network. If digital audio technology is used for storage, the transfer must be done at real time. It can still beimplemented via compu

38、ter networks, provided that enough bandwidth can be guaranteed by the system at any time,otherwise a dedicated audio connection or contribution link must be available. A further method, useful when notransmission link is available between the archive and the receiving site or the material is not urg

39、ent, consists of thedelivery of a medium containing a copy of the wanted items via traditional mail.Rec. ITU-R BR.1351 5Partial downloadingTo minimize the bandwidth requirements, it must be possible to specify the transfer of selected parts of an item,identified via the browsing function in the inde

40、x library. Pre-editing capabilities are also desirable.Integration with production standardsTo avoid inefficiencies and the possible loss of quality due to transcoding, the archiving storage formats should becompatible with those used in production. This implies that both the signal format and the f

41、ile format (if applicable)must be compatible. The use of IT could increase the possibility of exchanging programme related multimediainformation between production facility and archive.Fast access from productionFor some kinds of material, like news and sport, it is very important to have materials

42、from the archive available atproduction facilities almost in real time. Thus, it must be possible to implement privileged connections between thearchive and production.Fault toleranceAs production staff will rely more and more on the archive facility, access to the content library to production must

43、 beguaranteed without service interruption. The system must be protected from staff hardware and software faults and fromimproper access.Copyright managementMethods must be provided to verify copyright violations on the delivered materials.Index libraryDocumentationMultimedia dataAs the description

44、of an audio item can be formed by formatted alphanumeric records (e.g., Title, Author, Date), othermultimedia objects (text documents, still pictures or graphics) or pointer meta-data, (EDL and cue lists), the indexlibrary should be able to manage multimedia information. A simple storage and downloa

45、ding of bulk data without anycapability of interpretation is not satisfactory, as it shifts the burden of managing multimedia objects onto the userapplication and onto the network. The archive manager must be able to make new types of data known to the systemwhen needed. The system must be flexible

46、enough to allow for different types of aggregation of information, dependingon the specific programme content.Multi-layer indexingA programme can be documented at various levels. For example, a news report can have an entry in the data base as awhole, but, in certain situations, an entry for any new

47、s contained can provide a more convenient access. Thus the samepiece of audio material can have more than one entry in the data base, and all of them must be properly linked together,for example in a hierarchical tree. Further studies are required to define which levels of indexing are useful and ho

48、w theyshould be organized.Automatic audio indexingThe indexing of audio programmes, if done manually, is a very time consuming operation, so it is desirable that tools beprovided to segment the material automatically into units with a logical meaning. If this goal cannot be achieved bytodays technol

49、ogy, human assisted tools could provide a useful aid.6 Rec. ITU-R BR.1351Automatic gathering of currently available informationPart of the documentation of a programme is often available at the production facility. As an example, the list and timingof the news contained in a news report is certainly available during production, as well as the script of the news (with thepossible exception of field interviews). If common standards are adopted both at the production and facilities archiving,and proper links are set, the documentation efforts could be minimized by importin